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Sample records for lnsub 2sisub 2osub

  1. Li{sub 35}Ln{sub 9}Si{sub 30}N{sub 59}O{sub 2}F with Ln = Ce, Pr - highly condensed nitridosilicates

    Energy Technology Data Exchange (ETDEWEB)

    Lupart, Saskia; Durach, Dajana; Schnick, Wolfgang [Department Chemie, Lehrstuhl fuer Anorganische Festkoerperchemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

    2011-10-15

    The isotypic nitridosilicates Li{sub 35}Ln{sub 9}Si{sub 30}N{sub 59}O{sub 2}F (Ln = Ce, Pr) were synthesized by reaction of LnF{sub 3} and LiN{sub 3} with Si(NH){sub 2} in liquid lithium flux in weld shut tantalum ampoules. The crystal structures of the isotypic compounds were solved and refined on the basis of single-crystal X-ray diffraction (P anti 3c1 (no. 165), Z = 2; Li{sub 35}Ce{sub 9}Si{sub 30}N{sub 59}O{sub 2}F:, a = 1479.9(2), c = 1538.3(3) pm, R{sub 1} = 0.0526, 1671 data, 175 parameters; Li{sub 35}Pr{sub 9}Si{sub 30}N{sub 59}O{sub 2}F: a = 1477.3(2), c = 1533.9(3) pm, R{sub 1} = 0.0441, 1331 data, 175 parameters). The silicate substructure represents a 3D network of all side corner sharing SiN{sub 4} tetrahedra. At one discrete and not condensed mixed anion position an atomic ratio O:F = 2:1 is assumed in order to achieve charge neutrality. With an atomic ratio Si:N = 30:59, the degree of condensation of the silicate substructure is slightly above κ = 1/2. Accordingly, there are triply crosslinking N{sup [3]} atoms in the silicate substructure. The obtained structures prove that by employing the lithium flux technique not only nitridosilicates with a low degree of condensation can be obtained by using rather mild reaction conditions at low temperatures. Lattice energy calculations (MAPLE) and EDX measurements confirmed the electrostatic bonding interactions and the chemical composition. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Electronic structures and Eu{sup 3+} photoluminescence behaviors in Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhiya, E-mail: zhangzhiya@lzu.edu.cn [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000 (China); Wang Yuhua [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000 (China); Zhang Feng [Department of Materials Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China); Cao Haining [Computational Science Center, Korea Institute of Science and Technology, Seoul, 136-791 (Korea, Republic of)

    2011-04-14

    Research highlights: > Host excitation near the band gap of Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7} is analyzed. > The calculated result well explains Eu{sup 3+} PL behaviors in Y{sub 2}Si{sub 2}O{sub 7} and La{sub 2}Si{sub 2}O{sub 7}. > The electronic structure and Eu{sup 3+} VUV PL in La{sub 2}Si{sub 2}O{sub 7} are first estimated. - Abstract: The electronic structures and linear optical properties of Y{sub 2}Si{sub 2}O{sub 7} (YSO) and La{sub 2}Si{sub 2}O{sub 7} (LSO) are calculated by LDA method based on the theory of DFT. Both YSO and LSO are direct-gap materials with the direct band gap of 5.89 and 6.06 eV, respectively. The calculated total and partial density of states indicate that in both YSO and LSO the valence band (VB) is mainly constructed from O 2p and the conduction band (CB) is mostly formed from Y 4d or La 5d. Both the calculated VB and CB of YSO exhibit relatively wider dispersion than that of LSO. In addition, the CB of YSO presents more electronic states. Meanwhile, the VB of LSO shows narrower energy distribution with higher electronic states density. The theoretical absorption of YSO shows larger bandwidth and higher intensity than that of LSO. The results are compared with the experimental host excitations and impurity photoluminescence in Eu{sup 3+}-doped YSO and LSO.

  3. Electric and magnetic properties of oxidic titanium bronzes of rare earths Lnsub(2/3+x)TiOsub(3+-y) with perovskite structure

    International Nuclear Information System (INIS)

    Bazuev, G.V.; Makarova, O.V.; Shvejkin, G.P.

    1983-01-01

    A study was made on electric and magnetic properties of oxidic titanium bronzes of rare earths and their dependence on rare earth nature and the degree of rare earth sublattice filling was followed. Data on Lnsub(2/3)TiOsub(3-y) (Ln-Ce, Nd) anion-deficient perovskites are given as well. Investigated Cesub(2/3)TiOsub(2.985) and Ndsub(2/3)TiOsub(2.875) phases as well as defectless with respect to oxygen Lnsub(2/3)TiOsub(3) phases have rhombic structure of perovskite type with ordered position of Ln 3 + cations and vacancies. Specific electric resistance and thermoelectromotive force factor were determined in vacuum at 290-1173 K for samples in the form of parallelepiped of 3x5x25 mm 3 size. Magnetic susceptibility chi was determined at 77-300 K by Faraday method using a device based on magnetic balancewith electromagnetic compensation. Relative error during chi measuring didn't exceed +-2%. Collectivized behaviour of d-electrons of Ti 3 + cations in oxidic titanium bronzes of rare earths: Lnsub(2/3+x)TiOsub(3+-y) (Ln-La, Ce, Nd; 0 < x < 1/3), conditioned by formation of narrow, partly filled π*-zone, was established on the basis of measuring specific electric resistance and magnetic susceptibility

  4. Electric and magnetic properties of oxidic titanium bronzes of rare earths Lnsub(2/3+x)TiOsub(3+-y) with perovskite structure

    Energy Technology Data Exchange (ETDEWEB)

    Bazuev, G V; Makarova, O V; Shvejkin, G P [AN SSSR, Sverdlovsk. Inst. Khimii

    1983-01-01

    A study was made on electric and magnetic properties of oxidic titanium bronzes of rare earths and their dependence on rare earth nature and the degree of rare earth sublattice filling was followed. Data on Lnsub(2/3)TiOsub(3-y) (Ln-Ce, Nd) anion-deficient perovskites are given as well. Investigated Cesub(2/3)TiOsub(2.985) and Ndsub(2/3)TiOsub(2.875) phases as well as defectless with respect to oxygen Lnsub(2/3)TiOsub(3) phases have rhombic structure of perovskite type with ordered position of Ln/sup 3 +/ cations and vacancies. Specific electric resistance and thermoelectromotive force factor were determined in vacuum at 290-1173 K for samples in the form of parallelepiped of 3x5x25 mm/sup 3/ size. Magnetic susceptibility chi was determined at 77-300 K by Faraday method using a device based on magnetic balance with electromagnetic compensation. Relative error during chi measuring didn't exceed +-2%. Collectivized behaviour of d-electrons of Ti/sup 3 +/ cations in oxidic titanium bronzes of rare earths: Lnsub(2/3+x)TiOsub(3+-y) (Ln-La, Ce, Nd; 0 < x < 1/3), conditioned by formation of narrow, partly filled ..pi..*-zone, was established on the basis of measuring specific electric resistance and magnetic susceptibility.

  5. Spectroscopic and structural properties of polycrystalline Y{sub 2}Si{sub 2}O{sub 7} doped with Er{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Marciniak, L., E-mail: L.Marciniak@int.pan.wroc.pl [Institute for Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland); Hreniak, D.; Strek, W. [Institute for Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland); Piccinelli, F., E-mail: fabio.piccinelli@univr.it [Laboratorio di Chimica dello Stato Solido, DB, Università di Verona and INSTM, UdR Verona, Strada Le Grazie 15, 37134 Verona (Italy); Speghini, A.; Bettinelli, M. [Laboratorio di Chimica dello Stato Solido, DB, Università di Verona and INSTM, UdR Verona, Strada Le Grazie 15, 37134 Verona (Italy); Miritello, M., E-mail: maria.miritello@ct.infn.it [CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy); Lo Savio, R.; Cardile, P.; Priolo, F. [CNR-IMM MATIS and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, 95123 Catania (Italy)

    2016-02-15

    Powders of yttrium disilicate (Y{sub 2}Si{sub 2}O{sub 7}) doped with Er{sup 3+} have been prepared by the sol–gel method. The structure of the obtained powders has been determined. Room temperature emission spectra have been recorded and excited state decay profiles have been analyzed. Differences between the spectroscopic properties of Er{sup 3+} in monoclinic α-Y{sub 2}Si{sub 2}O{sub 7} (space group P-1) and β-Y{sub 2}Si{sub 2}O{sub 7} (space group C2/m) polymorphs have been investigated and shown. The significant broadening of the emission spectra recorded for the α phase compared to the one for the β phase was discussed in terms of higher number of Y{sup 3+} sites (4) present in the α phase with respect to only one Y{sup 3+} site in the case of β phase. The higher value of the luminescence decay time of β phase (11.2 ms) compared to the α phase (8.5 ms) is associated with the higher site symmetry of β-Y{sub 2}Si{sub 2}O{sub 7}. Moreover it was found that Er{sup 3+} concentration affects the shape of the {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} emission band. It results in changes of the relative emission intensities of peaks localized at 1527 nm and 1532 nm; this indicates changes of the Y{sup 3+} sites occupation on increasing the Er{sup 3+} concentration. The luminescence lifetime was observed to decrease with the increase of Er{sup 3+} concentration. The spectroscopic results have been compared with the ones relative to thin films of Y{sub 2}Si{sub 2}O{sub 7}:Er{sup 3+} with a similar composition. The lower value of the luminescence decay time observed for thin films compared to the powder of α phase was explained with the changes of the particles packing resulting in the change of the effective refractive index.

  6. Improved scintillation luminescence and thermal stability of In{sub 2}Si{sub 2}O{sub 7} ceramic phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jian; Cao, Lei; Feng, Yongyi [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Huang, Yanlin, E-mail: hang@suda.edu.cn [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Wang, Yaorong [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Qin, Lin [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2017-03-15

    In{sub 2}Si{sub 2}O{sub 7} is a known indium-based scintillator with fast ultraviolet photoluminescence. Unfortunately the emission only can be detected below 200 K. the poor thermal stability limits its application at room temperature. In this work, the luminescence improvement of In{sub 2}Si{sub 2}O{sub 7} was realized by F{sup −}-ions doping in the lattices. The ceramic phosphors were via typical solid-state reaction method. The pure crystalline phase with thortveirite-type structure was confirmed by X-ray diffraction (XRD) Rietveld refinements. The photoluminescence (PL) emission and excitation spectra together with the luminescence thermal stability were tested. The fluorescence decay curves CIE emission Stokes shifts were measured. The ceramic samples could present blue luminescence with maximum wavelength at about 340 nm under the excitation of UV light or high energy X-ray irradiation. The pure sample only presents luminescence below 200 K, however, the F-doping can be greatly enhance the luminescence thermal stability. The F-doped In{sub 2}Si{sub 2}O{sub 7} could present emission signals with fast decay lifetime of 850 ns at room temperature. The luminescence transitions from the In{sup 3+}-O{sup 2−} charge transfer (CT) were discussed on the structure properties.

  7. Synthesis of Li{sub 2}Si{sub 2}O{sub 5}-coated LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2} cathode materials with enhanced high-voltage electrochemical properties for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shengjie; Wu, Hao; Huang, Ling; Xiang, Mingwu; Liu, Heng; Zhang, Yun, E-mail: y_zhang@scu.edu.cn

    2016-07-25

    Ni-rich ternary layered oxides, (LiNi{sub x} [M]{sub 1−x}O{sub 2}, x ≥ 0.5, M = Co and Mn), have become one of the mainstream cathode materials for next-generation lithium-ion batteries due to their high capacity and cost efficiency compared with LiCoO{sub 2}. However, the high-voltage operation of the Ni-rich oxides (>4.3 V) required for high capacity is inevitably accompanied with a rapid capacity decay over numerous cycles. In this work, we reported a surface coating of LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2} with Li{sub 2}Si{sub 2}O{sub 5}via a facile and efficient synthetic approach, which involves the employment of silicic acid (H{sub 2}SiO{sub 3}) as remover to react with the surface residual lithium compounds (e.g. Li{sub 2}CO{sub 3} and LiOH) of LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2} and consequent formation of a robust and complete Li{sup +}-conductive Li{sub 2}Si{sub 2}O{sub 5} protective coating layer. The structure and morphology of the coated cathode materials are fully characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Compared with the pristine LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2}, coating with the Li{sup +}-conductive Li{sub 2}Si{sub 2}O{sub 5} is found to be very effective for improving the rate capability of the LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2} when evaluated at a high cut-off voltage up to 4.5 V. Specifically, 1 wt. % H{sub 2}SiO{sub 3}-treated LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2} electrode exhibits high discharge specific capacities of 213.9 and 121.6 mAh g{sup −1} at 0.1 and 10 C, respectively, whereas the pristine electrode only shows 196.8 and 92.1 mAh g{sup −1}. Besides, the surface-modified LiNi{sub 0.6}Co{sub 0.2}Mn{sub 0.2}O{sub 2} electrode also manifests an enhanced long-term cycling stability (67% capacity retention after 200 cycles at 5 C), much better than the pristine

  8. Electrical and dielectric spectroscopic characterization of polycrystalline Dy/sub 2/Si/sub 2/O/sub 7/

    International Nuclear Information System (INIS)

    Ameer, S.; Maqsood, A.

    2011-01-01

    The compound Dy/sub 2/Si/sub 2/O/sub 7/ exists in two polymorphs, the low temperature triclinic phase (type B) and a high temperature orthorhombic phase (type E). The dc and ac electrical conductivities of E-Dy/sub 2/Si/sub 2/O/sub 7/ are measured in the temperature range 290-510 K and frequency range 1 kHz to 1 MHz. The dc electrical transport data are analyzed according to Mott's variable-range hopping model. The disorder parameter (T/sub o/) and density of states at fermi level are obtained. The ac conductivity sigma/sub ac/ (omega) is obtained through the dielectric parameters. The ac conductivity can be expressed as sigma/sub ac/ (omega) = B sigma/sup s/ , where s is slope and it decreases with increase in temperature. The conduction mechanism in the compound is discussed in low and high temperature regions in the light of theoretical models. (author)

  9. Performance improvement of charge-trap memory by using a stacked Zr{sub 0.46}Si{sub 0.54}O{sub 2}/Al{sub 2}O{sub 3} charge-trapping layer

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Zhenjie; Hu, Dan; Zhang, Xiwei; Zhao, Yage [College of Physics and Electronic Engineering, Anyang Normal University, Anyang 455000 (China); Li, Rong [School of Mathematics and Statistics, Anyang Normal University, Anyang 455000 (China)

    2016-11-15

    The postdeposition annealing (PDA)-treated charge-trap flash memory capacitor with stacked Zr{sub 0.46}Si{sub 0.54}O{sub 2}/Al{sub 2}O{sub 3} charge-trapping layer flanked by a SiO{sub 2} tunneling oxide and an Al{sub 2}O{sub 3} blocking oxide was fabricated and investigated. It is observed that the memory capacitor exhibits prominent memory characteristics with large memory windows 12.8 V in a ±10 V gate sweeping voltage range, faster program/erase speed, and good data-retention characteristics even at 125 C compared to a single charge-trapping layer (Zr{sub 0.46}Si{sub 0.54}O{sub 2}, Zr{sub 0.79}Si{sub 0.21}O{sub 2}, and Zr{sub 0.46}Al{sub 1.08}O{sub 2.54}). The quantum wells and introduced interfacial traps of the stacked trapping layer regulate the storage and loss behavior of charges, and jointly contribute to the improved memory characteristics. Hence, the memory capacitor with a stacked trapping layer is a promising candidate in future nonvolatile charge-trap memory device design and application. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Red emitting phosphors of Eu{sup 3+} doped Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y) for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Niumiao [National Key Laboratory of Photoelectric Technology and Functional Materials Culture Base in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069 (China); Guo, Chongfeng, E-mail: guocf@nwu.edu.cn [National Key Laboratory of Photoelectric Technology and Functional Materials Culture Base in Shaanxi Province, National Photoelectric Technology and Functional Materials & Application of Science and Technology International Cooperation Base, Institute of Photonics & Photon-Technology, Northwest University, Xi’an 710069 (China); Yin, Luqiao; Zhang, Jianhua [Key Laboratory of Advanced Display and System Applications (Shanghai University), Ministry of Education, Shanghai 200072 (China); Wu, Mingmei, E-mail: ceswmm@mail.sysu.edu.cn [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, No. 135, Xingang Xi Road, Guangzhou 510275 (China)

    2015-06-25

    Highlights: • Layered red phosphors Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y):Eu{sup 3+} were prepared. • The synthesis parameters of phosphors were optimized. • PL and thermal stability of the samples were investigated. • LED devices were also fabricated including the present red phosphor. - Abstract: A series of Eu{sup 3+} doped Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10} (Ln = Gd, Y) red-emitting phosphors for application in ultraviolet based light emitting diodes (LEDs) were successfully synthesized by a modified sol–gel method. Their structure and luminescent properties were characterized by powder X-ray diffraction (XRD), photoluminescence excitation (PLE) and emission (PL) spectra and absorption spectra, according to these results the optimal compositions and synthesis parameters were determined. In addition, the thermal stabilities of the phosphors were investigated according to the temperature-dependent PL spectra. The red and white-LEDs (W-LEDs) comprising the Na{sub 2}Ln{sub 2}Ti{sub 3}O{sub 10}:Eu{sup 3+} (Ln = Gd, Y) red emitting phosphors were fabricated with a near-ultraviolet (n-UV) chip. In comparison with Na{sub 2}Y{sub 1.4}Eu{sub 0.6}Ti{sub 3}O{sub 10}, the Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} phosphor offers higher brightness, quantum efficiency, and excellent thermal stability. W-LEDs comprising Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} showed bright white emission with a color rendering index (Ra) of 82, a color temperature of 2151 K, and Commission Internationale de I’Eclairage (CIE) color coordinates of (0.34, 0.37). The phosphor Na{sub 2}Gd{sub 0.6}Eu{sub 1.4}Ti{sub 3}O{sub 10} is more suitable candidate for application in LEDs.

  11. Tritium release in Li{sub 4}SiO{sub 4} and Li{sub 4.2}Si{sub 0.8}Al{sub 0.2}O{sub 4} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Linjie, E-mail: zhaolinjie1989@163.com; Long, Xinggui, E-mail: xingguil@caep.cn; Peng, Shuming, E-mail: pengshuming@caep.cn; Chen, Xiaojun; Xiao, Chengjian; Ran, Guangming; Li, Jiamao

    2016-12-15

    Li{sub 4+x}Si{sub 1−x}Al{sub x}O{sub 4} solid solution materials, which were designed as the advanced tritium breeders, were obtained by indirect solid state reactions. The behaviors of tritium release from Li{sub 4}SiO{sub 4} and Li{sub 4.2}Si{sub 0.8}Al{sub 0.2}O{sub 4} powders were investigated by temperature programmed desorption. The tritium release curves show different characteristics for the Li{sub 4}SiO{sub 4} and Li{sub 4.2}Si{sub 0.8}Al{sub 0.2}O{sub 4} ceramics. The main tritium release peak in the Li{sub 4}SiO{sub 4} and Li{sub 4.2}Si{sub 0.8}Al{sub 0.2}O{sub 4} powders is at approximately 600 °C after a high dose irradiation. Moreover, the temperature of the tritium release from Li{sub 4.2}Si{sub 0.8}Al{sub 0.2}O{sub 4} was lower than that of the release from Li{sub 4}SiO{sub 4}. This suggests a possible advantage to using the solid solutions as the advanced tritium breeding materials.

  12. Synthesis and photoluminescence properties of Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17}:Eu{sup 3+} red phosphors for white LED applications

    Energy Technology Data Exchange (ETDEWEB)

    Annadurai, G.; Kennedy, S. Masilla Moses, E-mail: kennedysmm@ssn.edu.in

    2016-01-15

    Novel pellyite type Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17}:Eu{sup 3+} red emitting phosphors with different Eu{sup 3+} contents were synthesized by the solid state reaction method. The crystal structure, photoluminescence properties and concentration quenching of Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17}:Eu{sup 3+} phosphors were investigated. Powder X-ray diffraction measurements confirmed the structure of the samples. The photoluminescence emission (PL) and excitation (PLE) spectra were measured. The results showed that the dominant hypersensitive red emission peak of the phosphors Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17}:Eu{sup 3+} was located at 613 nm attributed to the Eu{sup 3+} transition ({sup 5}D{sub 0}→{sup 7}F{sub 2}) which could be effectively excited by 395 nm (near-UV). The latter band matched well with the emission from the near-UV LED chips. The intensity ratio of {sup 5}D{sub 0}→{sup 7}F{sub 2} to {sup 5}D{sub 0}→{sup 7}F{sub 1} transition showed slight variation with Eu{sup 3+} concentrations. The Eu{sup 3+} emission intensity was maximum for 9 mol%. The luminescence quantum efficiency was determined and also the decay profiles were obtained and analyzed. In addition, the Commission International del'Eclairage (CIE) chromaticity coordinates of Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17}:0.09Eu{sup 3+} phosphor were calculated to be 0.637 and 0.362. The experimental results demonstrated that the Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17}:Eu{sup 3+} red emitting phosphor is a potential candidate for white light emitting diodes (WLEDs) pumped by near-UV chip. - Highlights: • A novel Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17}:Eu{sup 3+} red phosphor was synthesized. • The samples yielded a dominant PL emission of Eu{sup 3+} at 613 nm. • Eu{sup 3+} concentration was optimized to be 9 mol% in Ba{sub 2}CaZn{sub 2}Si{sub 6}O{sub 17.} • CIE chromaticity coordinates were estimated from the emission spectrum.

  13. Self-reduction process and enhanced blue emission in SrAl{sub 2}Si{sub 2}O{sub 8}: Eu, Tb via electron transfer from Tb{sup 3+} to Eu{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwei; Wang, Lili; Li, Minhong; Ran, Weiguang; Deng, Zhihan; Houzong, Ruizhi; Shi, Jinsheng [Department of Chemistry and Pharmaceutical Science, Qingdao Agricultural University, Qingdao 266109, Shandong, (China)

    2017-06-15

    Eu, Tb co-doped SrAl{sub 2}Si{sub 2}O{sub 8} luminescent materials were synthesized via a high-temperature solid-state reaction. Excitation spectra of SrAl{sub 2}Si{sub 2}O{sub 8}: Eu{sup 2+} gives two broad excitation bands maximizing at 270 and 330 nm, resulting from splitting Eu{sup 2+} energy levels in octahedral crystal field. Eu single doped SrAl{sub 2}Si{sub 2}O{sub 8} luminescent material exhibits two emission bands at about 406 and 616 nm. Intensity of the blue emission from Eu{sup 2+} is always strong, compared with that of the red emission band of Eu{sup 3+}. Reduction from Eu{sup 3+} to Eu{sup 2+} can be explained with the model of charge compensation. Blue emission in SrAl{sub 2}Si{sub 2}O{sub 8}: xEu was strengthened after incorporation of Tb, which can be explained by electron transfer from Tb{sup 3+} to Eu{sup 3+} (Tb{sup 3+} + Eu{sup 3+} → Tb{sup 4+} + Eu{sup 2+}). Under 230 nm excitation, intensity of Tb{sup 3+} emission was nearly unchanged and that of Eu{sup 2+} was increased, obviously due to the delivery of more electrons to Eu{sup 3+}. The strongest emission of Eu{sup 2+} in 0.09Eu/0.06Tb co-doped SrAl{sub 2}Si{sub 2}O{sub 8} and excited at 270 and 330 nm was remarkably enhanced by about four times compared to that of 0.15Eu Single doped SrAl{sub 2}Si{sub 2}O{sub 8}. All of the results indicate that SrAl{sub 2}Si{sub 2}O{sub 8}:xEu, yTb are potential blue emitting luminescent materials for UV-LEDs. More importantly, this research may provide a new perspective in designing broad band blue luminescent materials. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Luminescence and luminescence quenching of Sr{sub 3}Lu{sub 2}(Si{sub 3}O{sub 9}){sub 2}:Ce{sup 3+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Mikalauskaite, I.; Raudonyte-Svirbutaviciene, E. [Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Linkeviciute, A. [State Research Institute, Centre for Physical Sciences and Technology, Sauletekio Avenue 3, LT-10257 Vilnius (Lithuania); Urbonas, M. [Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania); Katelnikovas, A., E-mail: arturas.katelnikovas@chf.vu.lt [Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko 24, LT-03225 Vilnius (Lithuania)

    2017-04-15

    A series of near-UV to blue emitting Sr{sub 3}Lu{sub 2}(Si{sub 3}O{sub 9}){sub 2}:Ce{sup 3+} phosphors were prepared by a solid state reaction. The optical properties of synthesized phosphors were investigated as a function of Ce{sup 3+} concentration and temperature. These luminescent materials strongly absorb UV radiation shorter than 360 nm. The optimal Ce{sup 3+} concentration was 0.1% (external quantum efficiency ca. 45%). Temperature dependent measurements showed that Sr{sub 3}Lu{sub 2}(Si{sub 3}O{sub 9}){sub 2}:Ce{sup 3+} phosphors possess good thermal stability and loses only about 40% to 50% of initial intensity in the temperature range of 77–500 K depending on activator concentration.

  15. A fresnoite-structure-related mixed valent titanium(III/IV) chlorosilicate, Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl: A flux crystal growth route to Ti(III) containing oxides

    Energy Technology Data Exchange (ETDEWEB)

    Abeysinghe, Dileka; Smith, Mark D.; Loye, Hans-Conrad zur, E-mail: zurloye@mailbox.sc.edu

    2017-06-15

    Single crystals of mixed valent barium titanium(III/IV) chlorosilicate, Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl{sub 0.91}O{sub 0.09}, were grown in a high temperature molten chloride flux involving an in situ reduction step. The fresnoite structure related Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl{sub 0.91}O{sub 0.09} crystallizes in the tetragonal space group P4/mbm with lattice parameters of a=8.6717(2) Å, c=18.6492(5) Å. The title compound exhibits a 3D structure consisting of 2D layers of fused Ti{sub 2}O{sub 9} and Si{sub 4}O{sub 12} groups and 2D layers of fused Ti{sub 2}O{sub 9}Cl{sub 2} and Si{sub 2}O{sub 7} groups that are linked via barium atoms. The in situ reduction of Ti(IV) to Ti(III) is achieved via the addition of metallic Mg to the flux to function as the reducing agent. The temperature dependence of the magnetic susceptibility shows simple paramagnetism above 100 K. There is a discontinuity in the susceptibility data below 100 K, which might be due to a structural change that takes place resulting in charge ordering. - Graphical abstract: The fresnoite structure related novel reduced barium titanium chlorosilicate, Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl{sub 0.91}O{sub 0.09}, were synthesized via flux method. An in situ reduction of Ti(IV) to Ti(III) achieved using Mg metal. The 3D structure consists 2D layers of fused Ti{sub 2}O{sub 9} and Si{sub 4}O{sub 12} and 2D layers of fused Ti{sub 2}O{sub 9}Cl{sub 2} and Si{sub 2}O{sub 7} connected via barium atoms. Compound shows simple paramagnetism above 100 K. - Highlights: • The fresnoite related Ba{sub 3}Ti{sub 2}Si{sub 4}O{sub 14}Cl{sub 0.91}O{sub 0.09} were grown via molten flux method. • The in situ reduction of Ti(IV) to Ti(III) is achieved using metallic Mg. • 2D layers of Ti{sub 2}O{sub 9} and Si{sub 4}O{sub 12} and Ti{sub 2}O{sub 9}Cl{sub 2} and Si{sub 2}O{sub 7} connect via Ba atoms. • The magnetic susceptibility shows simple paramagnetism above 100 K.

  16. Variation with temperature in thermophysical properties of D-Er/sub 2/Si/sub 2/O/sub 7/

    International Nuclear Information System (INIS)

    Maqsood, A.; Kamran, K.; Rehman, A.U.

    2007-01-01

    The first measurements of the thermal conductivity, thermal diffusivity and volumetric heat capacity of polycrystalline D-Er/sub 2/Si/sub 2/O/sub 7/ have been made simultaneously in the temperature range 77-300K. Both the thermal conductivity and thermal diffusivity follow a modified Eucken's law in the temperature region mentioned here. The heat capacity at constant pressure (C/sub p/), determined from the volumetric heat capacity, agrees with the calculated one at room temperature. (author)

  17. Synthesis and characterisation of the n = 2 Ruddlesden–Popper phases Ln{sub 2}Sr(Ba)Fe{sub 2}O{sub 7} (Ln = La, Nd, Eu)

    Energy Technology Data Exchange (ETDEWEB)

    Gurusinghe, Nicola N.M. [School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Figuera, Juand de la; Marco, José F. [Instituto de Quimica-Fisica “Rocasolano”, CSIC, Serrano 119, 28006 Madrid (Spain); Thomas, Michael F. [Department of Physics, University of Liverpool, Liverpool. L69 3BX (United Kingdom); Berry, Frank J., E-mail: f.j.berry.1@bham.ac.uk [School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Greaves, Colin [School of Chemistry, The University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2013-09-01

    Graphical abstract: - Highlights: • Some Ruddlesden–Popper phases have been characterised. • Substitution on the A site influences cationic order. • The magnetic moment redirects with temperature - Abstract: A series of n = 2 Ruddlesden–Popper phases A{sub 2}B{sub 2}O{sub 7} of composition Ln{sub 2}Sr(Ba)Fe{sub 2}O{sub 7} (Ln = La, Nd, Eu) have been prepared. La{sub 2}SrFe{sub 2}O{sub 7} and La{sub 2}BaFe{sub 2}O{sub 7} crystallise in the tetragonal space group I4/mmm. The structures of Eu{sub 2}SrFe{sub 2}O{sub 7} and Nd{sub 2}SrFe{sub 2}O{sub 7} are best described in space group P4{sub 2}/mnm. Substitution on the A site with smaller lanthanide- and larger alkaline metal- ions leads to enhanced cationic order in these phases and reflects increasing differences in cationic radii. All the compounds are antiferromagnetically ordered between 298 and 2 K. In La{sub 2}SrFe{sub 2}O{sub 7} the magnetic moment lies along [1 1 0] at all temperatures between 298 and 2 K whereas in La{sub 2}BaFe{sub 2}O{sub 7} the magnetic moment at 298 K lies along the crystallographic x-axis but redirects from the [1 0 0] to the [1 1 0] direction between 210 and 190 K and is retained in this direction until 2 K. In Nd{sub 2}SrFe{sub 2}O{sub 7} the magnetic moment at 298 K lies along [1 1 0] but rotates from [1 1 0] to [0 0 1] between 17 and 9 K. A series of {sup 57}Fe Mössbauer spectra recorded from La{sub 2}SrFe{sub 2}O{sub 7} between 290 and 600 K indicate a magnetic ordering temperature of T{sub N} ≥ 535 K.

  18. Sintering behaviour and phase relationships of Si[sub 3]N[sub 4] ceramics in the Si[sub 3]N[sub 4]-SiO[sub 2]-MgO-Y[sub 2]O[sub 3] system. Sinterverhalten und Phasenbeziehungen von Si[sub 3]N[sub 4]-Keramiken im System Si[sub 3]N[sub 4]-SiO[sub 2]-MgO-Y[sub 2]O[sub 3

    Energy Technology Data Exchange (ETDEWEB)

    Mahoney, F.M.

    1992-10-12

    The aim of this work is the investigation of the sintering or crystallisation behaviour of Si[sub 3]N[sub 4] ceramics depending on the additive composition in the Si[sub 3]N[sub 4]-SiO[sub 2]-MgO-Y[sub 2]O[sub 3] system. With regard to the complicated manufacturing process of sintered and heat-treated Si[sub 3]N[sub 4] ceramics, one should first determine which additive compositions make complete compression possible. The effect of the composition on the volume and the viscosity of the melting phase should be cleared up, where determining the Si[sub 3]N[sub 4] solubility relative to the additive composition is of special importance. The phase relationships between Si[sub 3]N[sub 4] and the possible crystalline secondary phases should be determined for the crystallisation behaviour. Due to the very fine distribution of only a 5-15% proportion of additive in conventional Si[sub 3]N[sub 4] samples, a characterisation of the secondary phases is difficult to carry out with X-ray or REM/EDX analysis. Therefore, experiments with oxy-nitridic model samples were carried out in this work, which have the same phase relationships as conventional Si[sub 3]N[sub 4] compositions, but with an appreciably higher proportion of additive. The possibility of transferring the results of the model samples were tested on examples of three Si[sub 3]N[sub 4] ceramics. (orig.)

  19. Studies on the Ln/sub 2/O/sub 3/ (Ln: rare-earth elements)-SrO-V/sub 2/O/sub 3/ system, 1. Phase diagrams at 1400/sup 0/C

    Energy Technology Data Exchange (ETDEWEB)

    Shin-ike, T [Osaka Dental Coll., Hirakata (Japan); Adachi, G; Shiokawa, J

    1980-11-01

    Rare-earth oxides Ln/sub 2/O/sub 3/ (Ln : Nd, Eu or Er), strontium oxide SrO and vanadium oxide V/sub 2/O/sub 3/ were mixed in a given molecular ratio, heated at 1400/sup 0/C in vacuum. The products were examined by an x-ray diffraction method to study the phase relations of the ternary systems. On heating, part of the trivalent vanadium was oxidized to the tetravalent state by atmospheric oxygen. In this experimental condition, the following ternary-phase solid solutions were identified: perovskite type Nd sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.3. cubic, x < 0.3: orthorhombic) and Eu sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.4: cubic, x < 0.4: orthorhombic), K/sub 2/NiF/sub 4/ type SrO.Nd sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.3) and SrO.Eu sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.4) and Eu/sub 3/Ti/sub 2/O/sub 7/ type SrO.2Nd sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.3) and SrO.2Eu sub(1-x)Sr sub(x)VO sub(3-0.1x) (x > 0.4). For the Er/sub 2/O/sub 3/-SrO-V/sub 2/O/sub 3/ system, only a mixture of Er/sub 2/O/sub 3/, SrVO sub(2.9), ErVO/sub 3/, SrO and V/sub 2/O/sub 3/ was obtained.

  20. Site selective, time and temperature dependent spectroscopy of Eu{sup 3+} doped apatites (Mg,Ca,Sr){sub 2}Y{sub 8}Si{sub 6}O{sub 26}

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, T., E-mail: t.jansen@fh-muenster.de [Münster University of Applied Sciences, Stegerwaldstrasse 39, 48565 Steinfurt (Germany); Jüstel, T. [Münster University of Applied Sciences, Stegerwaldstrasse 39, 48565 Steinfurt (Germany); Kirm, M.; Mägi, H.; Nagirnyi, V.; Tõldsepp, E.; Vielhauer, S. [Institute of Physics, University of Tartu, W. Ostwald Str. 1, 50411 Tartu (Estonia); Khaidukov, N.M. [N. S. Kurnakov Institute of General and Inorganic Chemistry, 31 Leninskiy Prospekt, 119991 Moscow (Russian Federation); Makhov, V.N. [P.N. Lebedev Physical Institute, 53 Leninskiy Prospekt, 119991 Moscow (Russian Federation)

    2017-06-15

    This work concerns the optical properties of alkaline earth yttrium apatites according to the composition AE{sub 2}Y{sub 8}Si{sub 6}O{sub 26} (AE=Mg, Ca, Sr) doped with Eu{sup 3+}, which are materials of interest for LED applications. Using a multistep preparation route, which includes hydrothermal synthesis of precursors for solid state reaction, ceramic samples were prepared and their structural and optical properties characterised. More particularly, this work relates to site-selective spectroscopy, since the compounds comprise two distinguishable crystallographic sites within the host structure, where Eu{sup 3+} can be substituted. It also describes the temperature dependent photoluminescence, which thermal quenching temperature (T{sub 1/2}) for Sr{sub 2}Y{sub 8}Si{sub 6}O{sub 26}:Eu{sup 3+} and Ca{sub 2}Y{sub 8}Si{sub 6}O{sub 26}:Eu{sup 3+} is in the range of 561 K and 591 K respectively, whereas Mg{sub 2}Y{sub 8}Si{sub 6}O{sub 26}:Eu{sup 3+} shows bi-sigmoidal quenching behaviour in the range between 210 and 452 K.

  1. Synthesis, microstructure and magnetic properties of Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite core

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian, E-mail: snove418562@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Fan, Xi’an, E-mail: groupfxa@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Wu, Zhaoyang, E-mail: wustwuzhaoyang@163.com [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Li, Guangqiang [The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China); Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan, Hubei 430081 (China)

    2015-11-15

    Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} soft magnetic composite core have been synthesized via a modified stöber method combined with following high temperature sintering process. Most of conductive Fe{sub 3}Si{sub 0.7}Al{sub 0.3} particles could be uniformly coated by insulating SiO{sub 2} using the modified stöber method. The Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles exhibited good soft magnetic properties with low coercivity and high saturation magnetization. The reaction 4Al+3SiO{sub 2}=2α-Al{sub 2}O{sub 3}+3Si took place during the sintering process. As a result the new Fe{sub 3}Si/Al{sub 2}O{sub 3} composite was formed. The Fe{sub 3}Si/Al{sub 2}O{sub 3} composite core displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher electrical resistivity and lower core loss than the pure Fe{sub 3}Si{sub 0.7}Al{sub 0.3} core. The method of introducing insulating layers surrounding magnetic particles provides a promising route to develop new and high compact soft magnetic materials with good magnetic and electric properties. - Graphical abstract: In Fe{sub 3}Si/Al{sub 2}O{sub 3} composite, Fe{sub 3}Si phases are separated by Al{sub 2}O{sub 3} layers and the eddy currents are confined in Fe{sub 3}Si phases, thus increasing resistivity and reducing core loss. - Highlights: • Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} core–shell particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} cores were prepared. • Fe{sub 3}Si{sub 0.7}Al{sub 0.3} particles could be uniformly coated by nano-sized SiO{sub 2} clusters. • Fe{sub 3}Si{sub 0.7}Al{sub 0.3}@SiO{sub 2} particles and Fe{sub 3}Si/Al{sub 2}O{sub 3} cores showed good soft magnetic properties. • Fe{sub 3}Si/Al{sub 2}O{sub 3} had lower core loss and better frequency stability than Fe{sub 3}Si{sub 0.7}Al{sub 0.3} cores.

  2. Structural and luminescence properties of Gd{sub 2}Si{sub 2}O{sub 7}:Ce prepared by solution combustion followed by heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Shinde, Seema; Pitale, Shreyas; Singh, S.G.; Ghosh, M.; Tiwari, B.; Sen, S.; Gadkari, S.C., E-mail: gadkari@barc.gov.in; Gupta, S.K.

    2015-05-05

    Highlights: • Synthesis of triclinic and orthorhombic phases of Gd{sub 2}Si{sub 2}O{sub 7}:Ce by a two step process. • Method involves solution combustion followed by a post heat treatment. • Ce concentration is found to affect the orthorhombic phase formation temperature. • First time reporting a double exponential decay in nano sized Gd{sub 2}Si{sub 2}O{sub 7}:Ce. - Abstract: A method comprising solution combustion followed by a heat treatment has been employed to synthesize cerium doped gadolinium pyrosilicate (Gd{sub 2}Si{sub 2}O{sub 7}:Ce, or GPS:Ce) compounds. The powder obtained after the combustion was annealed at 1200 °C for 4 h and 1600 °C for 3 h to synthesize triclinic and orthorhombic phases of the GPS, respectively. Structural and morphological characterizations of the synthesized compounds were carried out using X-ray diffraction and electron microscopy (SEM, TEM) techniques. A change in the enthalpy was observed in the differential thermal analysis data as a consequence of triclinic to orthorhombic phase transition in the GPS. Luminescence spectra and fluorescence decay time were measured at room temperature to characterize emission centers created in GPS compounds doped with trivalent rare earth ion (Ce{sup 3+}). The triclinic GPS:Ce phase exhibited photoluminescence peaks at 379 nm and 410 nm while for the orthorhombic phase emissions at 353 nm and 380 nm were observed. A multi-component exponential decay pattern of the luminescence is observed for both the GPS:Ce phases. In addition, samples of the orthorhombic GPS:Ce were found to exhibit X-ray excited luminescence (XEL)

  3. Scintillation properties of Ce:(La,Gd){sub 2}Si{sub 2}O{sub 7} at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kurosawa, Shunsuke, E-mail: kurosawa@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Miyagi (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Shishido, Toetsu; Sugawara, Takamasa; Nomura, Akiko; Yubuta, Kunio; Suzuki, Akira; Murakami, Rikito [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Miyagi (Japan); Pejchal, Jan [New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Institute of Physics, AS CR, Cukrovarnická 10, 162 53 Prague (Czech Republic); Yokota, Yuui; Kamada, Kei [New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Miyagi (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Miyagi (Japan); C and A Corporation, 6-6-40 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

    2015-02-01

    Temperature dependence of scintillation properties was investigated for (Ce{sub 0.01}, Gd{sub 0.90}, La{sub 0.09}){sub 2}Si{sub 2}O{sub 7} grown by floating zone method. The light output over 35,000 photons/MeV was found constant in the temperature range from 0 °C to 150 °C. In addition, FWHM energy resolution of Ce:La-GPS (roughly 7–8%) at 662 keV remained constant up to 100 °C. Thus, this crystal can be applied to oil well logging or other radiation detection application at high temperature conditions.

  4. Synthesis and characterization of K{sub 2}Ln{sub 2/3}Ta{sub 2}O{sub 7}·nH{sub 2}O (Ln= La, Pr, Nd), layered tantalates photo catalysts for water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Valencia S, H.; Tavizon, G. [UNAM, Instituto de Quimica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Pfeiffer, H. [UNAM, Instituto de Investigaciones en Materiales, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Acosta, D. [UNAM, Instituto de Fisica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Negron M, A., E-mail: hvalencia@utp.edu.co [UNAM, Instituto de Ciencias Nucleares, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico)

    2015-07-01

    Three compounds of the K{sub 2}Ln{sub 2/3}Ta{sub 2}O{sub 7} (Ln = La, Nd, Pr) cation-deficient Ruddlesden-Popper series were prepared by the Pechini (polymeric complex) method. The crystal structures of the hydrated form of these compounds were determined by Rietveld analysis of the X-ray power diffraction data and High Resolution Transmission Electron Microscopy (HRTEM). The samples were also analyzed to determine specific area (Bet), degree of hydration (Thermogravimetric analysis), and photo catalytic activity for hydrogen evolution from water and aqueous methanol solution. (Author)

  5. Syntheses, crystal structures and solid-state properties of the lanthanoid-containing nanoclusters [(Ln{sub 2}PW{sub 10}O{sub 38}){sub 4}(W{sub 3}O{sub 8})(OH){sub 4}(H{sub 2}O){sub 2}]{sup 26-}

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Rakesh; Saini, Mukesh Kumar; Hussain, Firasat [Department of Chemistry, University of Delhi (India)

    2014-12-15

    A series of lanthanoid-substituted polyoxometalates have been synthesized by a self-assembly process in potassium chloride solution by the reaction of dilacunary [P{sub 2}W{sub 19}O{sub 69}(H{sub 2}O)]{sup 14-} with mid- and late-lanthanoid Ln(NO{sub 3}){sub 3}.nH{sub 2}O salts leading to the formation of the tetrameric tungstophosphates [(Ln{sub 2}PW{sub 10}O{sub 38}){sub 4}(W{sub 3}O{sub 8})(OH){sub 4}(H{sub 2}O){sub 2}]{sup 26-} [Ln = Y{sup 3+} (1), Sm{sup 3+} (2), Eu{sup 3+} (3), Gd{sup 3+} (4), Tb{sup 3+} (5), Dy{sup 3+} (6), Ho{sup 3+} (7), Er{sup 3+} (8), Tm{sup 3+} (9), Yb{sup 3+} (10)]. The polyanions were isolated as potassium or mixed-alkali salts. Most of the compounds were characterized by single-crystal X-ray diffraction and various analytical techniques, such as FTIR, UV/Vis, {sup 31}P NMR and photoluminescence spectroscopy, magnetism, as well as thermogravimetric analysis. The FTIR spectra suggest that all the compounds are isomorphous. The crystal structures of these complexes consist of four A-[α-PW{sub 10}O{sub 36}]{sup 7-} units, each incorporating two Ln{sup III} ions to create four Keggin-like anions that further assemble with three additional tungstate units to form a tetramer species with C{sub 2} symmetry. The photoluminescent properties of 3a and 6a were investigated following photoexcitation at room temperature. The magnetic properties of 3a, 4a, 5a and 6a were investigated at room temperature, the complexes exhibiting paramagnetic behaviour. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Effect of surface reactions on steel, Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} counterparts on their tribological performance with polytetrafluoroethylene filled composites

    Energy Technology Data Exchange (ETDEWEB)

    Shen, J.T.; Top, M. [Materials Innovation Institute M2i, Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Ivashenko, O.; Rudolf, P. [Department of Surfaces and Thin Films, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Pei, Y.T., E-mail: y.pei@rug.nl [Materials Innovation Institute M2i, Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Department of Advanced Production Engineering, Engineering and Technology Institute Groningen, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); De Hosson, J.Th.M., E-mail: j.t.m.de.hosson@rug.nl [Materials Innovation Institute M2i, Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

    2015-03-15

    Highlights: • The influence of surface reactions with PTFE on the tribo-performance of different counterparts is revealed. • Experiments confirm that friction can be greatly reduced by two F-terminated surfaces sliding over each other. • Al−F and Fe−F chemical bonding form on the surface of alumina and steel counterpart balls during sliding against PTFE-containing composite. • No Si−F bonding formed on Si{sub 3}N{sub 4} ball under the same condition, leading to higher friction and wear. - Abstract: The influence of surface reactions on the tribo-performance of steel, Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4} balls sliding against polytetrafluoroethylene/SiO{sub 2}/epoxy composites was investigated. Al{sub 2}O{sub 3} ball were found to exhibit the best tribo-performance, namely a low coefficient of friction and the lowest wear rates of both the composites and the counterpart ball, when sliding against the PTFE filled composites. The difference in the tribo-performance of the Al{sub 2}O{sub 3} ball and the Si{sub 3}N{sub 4} ball can neither be attributed to the different morphology of the worn composite surfaces nor to the amount of PTFE transferred onto the wear surfaces. Instead we found that the friction is greatly reduced in the case of the Al{sub 2}O{sub 3} ball because two fluoro-terminated surfaces are sliding over each other; in fact, the formation of Al−F bonding was confirmed by X-ray photoelectron spectroscopy.

  7. Synthesis of ceramic powders of La{sub 9,56} (SiO{sub 4}){sub 6}O{sub 2,34} and La{sub 9,8}Si{sub 5,7}Mg{sub O,3}O{sub 26,}4 by modified sol-gel process; Sintese de pos ceramicos de La{sub 9,56} (SiO{sub 4}){sub 6}O{sub 2,34} e La{sub 9,8}Si{sub 5,7}Mg{sub O,3}O{sub 26,}4 por processo sol-gel modificado

    Energy Technology Data Exchange (ETDEWEB)

    Lira, Sabrina Lopes; Paiva, Mayara Rafaela Soares; Misso, Agatha Matos; Elias, Daniel Ricco; Yamagata, Chieko, E-mail: yamagata@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais

    2012-07-01

    Lanthanum silicate oxyapatite materials are promising for application as electrolyte in solid oxide fuel cells because of high ionic conductivity at temperatures between 600 deg C and 800 deg C. In this work, oxyapatites with the composition La{sub 9,56}(SiO{sub 4}){sub 6}O{sub 2,34}, and La{sub 9,8}Si{sub 5,7}Mg{sub 0,3}O{sub 26,4} were synthesized by using the sol-gel method, followed by precipitation. Initially, the gel of silica was synthesized from sodium silicate solution, by acid catalysis using lanthanum and magnesium chloride solution. Then, the La and Mg hydroxides were precipitated with NaOH in the gel. The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and measurements of specific surface area. The crystalline oxyapatite phase of La{sub 9,56}(SiO{sub 4}){sub 6}O{sub 2,34}, and was La{sub 9,8}Si{sub 5,7}Mg{sub 0,3}O{sub 26,4} obtained by calcination at 900 deg C for 2 and 1h respectively (author)

  8. Crystallization of pyroxene phases and physico-chemical properties of glass-ceramics based on Li{sub 2}O–Cr{sub 2}O{sub 3}–SiO{sub 2} eutectic glass system

    Energy Technology Data Exchange (ETDEWEB)

    Salman, S.M.; Salama, S.N.; Abo-Mosallam, H.A., E-mail: abomosallam@yahoo.com.au

    2015-01-15

    The crystallization characteristics, crystalline phase assemblages and solid solution phases developed due to thermally crystallized glasses based on the Li{sub 2}SiO{sub 3}–Li{sub 2}Si{sub 2}O{sub 5}–LiCrSi{sub 2}O{sub 6} (1028 ± 3 °C) eutectic glass system by replacing some trivalent oxides instead of Cr{sub 2}O{sub 3} were investigated. The microhardness and chemical durability of the glass-ceramics were also determined. Lithium meta and disilicate (Li{sub 2}SiO{sub 3} and Li{sub 2}Si{sub 2}O{sub 5}), lithium gallium silicate (LiGaSiO{sub 4}), and varieties of pyroxene phases, including Cr-pyroxene phase, i.e. lithium-kosmochlor (LiCrSi{sub 2}O{sub 6}), lithium aluminum silicate (LiAlSi{sub 2}O{sub 6}), lithium indium silicate (LiInSi{sub 2}O{sub 6}) and pyroxene solid solution of Li-aegerine type [Li (Fe{sub 0.5}, Cr{sub 0.5}) Si{sub 2}O{sub 6}] were the main crystalline phases formed in the crystallized glasses. There is no evidence for the formation of solid solution or liquid immiscibility gaps between LiAlSi{sub 2}O{sub 6} or LiInSi{sub 2}O{sub 6} phases and LiCrSi{sub 2}O{sub 6} phase. However, LiCrSi{sub 2}O{sub 6} and LiFeSi{sub 2}O{sub 6} components were accommodated in the pyroxene structure under favorable conditions of crystallization to form monomineralic pyroxene solid solution phase of the probably formula [Li (Fe{sub 0.5}, Cr{sub 0.5}) Si{sub 2}O{sub 6}]. The type and compatibility of the crystallized phases are discussed in relation to the compositional variation of the glasses and heat-treatment applied. The microhardness values of the crystalline materials ranged between 5282 and 6419 MPa while, the results showed that the chemical stability of the glass-ceramics was better in alkaline than in acidic media. - Highlights: • Glass ceramics based on Li{sub 2}O–Cr{sub 2}O{sub 3}–SiO{sub 2} eutectic (1028 ± 3 °C) glass were prepared. • LiCrSi{sub 2}O{sub 6} and LiFeSi{sub 2}O{sub 6} phases form monomineralic pyroxene solid

  9. Upgradation in SCADA and PLC of existing LN{sub 2} control system for SST-1

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, Pradip, E-mail: pradip@ipr.res.in; Mahesuria, Gaurang; Panchal, Rohit; Patel, Rakesh; Sonara, Dashrath; Pitroda, Dipen; Nimavat, Hiren; Tanna, Vipul; Pradhan, Subrata

    2016-11-15

    Highlights: • The control system of LN{sub 2} Management System of SST-1 is designed on PLC and SCADA. • The implementation and results of up-gradation in PLC and SCADA are reported. • The up-gradation in PLC and SCADA has improved the reliability & availability of SST-1 LN{sub 2} system. - Abstract: Helium Refrigerator/Liquefier system of Steady State Superconducting Tokamak (SST-1) incorporates Liquid Nitrogen (LN{sub 2}) pre-cooling system. LN{sub 2} is used for 80 K thermal shields of SST-1, current feeder system and integrated flow distribution and control system. The LN{sub 2} management system is distributed system and requires automatic control. Initially LN{sub 2} control system had Citect based Supervisory Control and Data Acquisition (SCADA) and Koyo make Programmable Logic Controller (PLC). With the passage of time and due to unavailability of their hardware, it is being obsoleted. So, the requirements of new PLC and SCADA systems have been envisaged to make uninterruptable operation of SST-1 cryogenic system. Therefore, Wonderware SCADA and Schneider Electric make PLC is programmed to replace Citect SCADA and Koyo PLC. New control features have been added in upgraded control system for better management of LN{sub 2} system. This upgradation of SCADA and PLC is completed, tested successfully and in operation. Operational performance highlights of the new upgraded system are presented in this paper.

  10. Structural characteristics and physical properties of diortho(pyro)silicate crystals of lanthanides yttrium and scandium grown by the Czochralski technique

    Energy Technology Data Exchange (ETDEWEB)

    Anan' eva, G.V.; Karapetyan, V.E.; Korovkin, A.M.; Merkulyaeva, T.I.; Peschanskaya, I.A.; Savinova, I.P.; Feofilov, P.P. (Gosudarstvennyj Opticheskij Inst., Leningrad (USSR))

    1982-03-01

    Optically uniform monocrystals of diortho (pyro) silicates of lanthanides, yttrium, and scandium were grown by the Czochralski technique. Four structural types of Ln/sub 2/(Si/sub 2/O/sub 7/) crystals were determined by the roentgenographic method. The presence of structural subgroups was also supported by the method of spectroscopic probes. Structural parameters were determined and data on certain physical properties (fusion temperature, density, refractive indices, transparency) of investigated crystals were presented. The generation of induced emission at lambda=1.057 ..mu..m was obtained in La/sub 2/(Si/sub 2/O/sub 7/)-Nd/sup 3 +/ crystal.

  11. Development of electrolyte-supported intermediate-temperature single-chamber solid oxide fuel cells using Ln{sub 0.7}Sr{sub 0.3}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} (Ln = Pr, La, Gd) cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz de Larramendi, I.; Ruiz de Larramendi, J.I.; Rojo, T. [Departamento de Quimica Inorganica, Universidad del Pais Vasco, Apdo.644, 48080 Bilbao (Spain); Lamas, D.G.; Cabezas, M.D.; Walsoee de Reca, N.E. [CINSO, CONICET-CITEFA, J.B. de La Salle 4397 (B1603ALO) Villa Martelli, Pcia. de Buenos Aires (Argentina)

    2009-09-05

    Iron-cobalt-based perovskite oxides with general formula Ln{sub 0.7}Sr{sub 0.3}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} (where Ln = La, Pr and Gd) have been investigated for their application as intermediate-temperature cathodes in solid oxide fuel cells (SOFCs). Powdered samples of these materials were synthesized by a novel gel combustion process and then characterized by X-ray powder diffraction (XPD) and scanning electron microscopy (SEM). XPD patterns were satisfactorily indexed with an orthorhombic GdFeO{sub 3}-type structure and, for all samples, a mean particle size of less than 1 {mu}m was estimated from the SEM data. Experimental single-chamber SOFCs using with these materials as cathodes and NiO-SDC (samaria-doped ceria) and SDC as anode and electrolyte, respectively, were evaluated at 600 C in a methane/oxygen mixtures. Peak power densities of 65.4, 48.7 and 46.2 mW cm{sup -2} were obtained for Ag vertical stroke Ln{sub 0.7}Sr{sub 0.3}Fe{sub 0.8}Co{sub 0.2}O{sub 3-{delta}} vertical stroke SDC vertical stroke NiO-SDC vertical stroke Pt cells with Ln = Pr, La and Gd, respectively. The relatively high power density obtained for the Pr compound shows that it could be an interesting material for cathode of single-chamber SOFCs. (author)

  12. The ‘sub’ metallide oxide hydrides Sr{sub 21}Si{sub 2}O{sub 5}H{sub 12+x} and Ba{sub 21}M{sub 2}O{sub 5}H{sub 12+x} (M = Zn, Cd, Hg, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Jehle, Michael; Hoffmann, Anke [Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, D-79104 Freiburg (Germany); Kohlmann, Holger [Institut für Anorganische Chemie, Universität Leipzig, Johannisallee 29, D-04103 Leipzig (Germany); Scherer, Harald [Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, D-79104 Freiburg (Germany); Röhr, Caroline, E-mail: caroline@ruby.chemie.uni-freiburg.de [Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, D-79104 Freiburg (Germany)

    2015-02-25

    Highlights: • The sub metallide oxide hydrides (Sr/Ba){sub 21}M{sub 2}O{sub 5}H{sub 12+x} were prepared for 14 M elements. • M covers a wide range of elements, from the Zn group to the pentels. • The ionic partial structure contains isolated M anions and suboxide clusters [O{sub 5}A{sub 18}]. • The H-content was determined by neutron diffraction and {sup 1}H/{sup 2}D MAS-NMR spectroscopy. • Band structure calculations support the H/D content and distribution. - Abstract: The title compounds sporting a great variety of anions M of different formal charges have been synthesized from melts of the composition A:M:O:H/D = 21:2:5:24, using BaH{sub 2}/SrH{sub 2} as hydrogen sources. All phases were characterized by means of single crystal X-ray data [cubic, space group Fd3{sup ¯}m; Sr{sub 21}Si{sub 2}O{sub 5}H{sub 12+x}: a = 1911.90(1) pm, R1 = 0.0201; for the barium phases with Zn (a = 2041.7(3) pm, R1 = 0.077), Cd (a = 2063.3(1) pm, R1 = 0.051), Hg (a = 2050.7(1) pm, R1 = 0.059), In (a = 2060.7(1) pm, R1 = 0.101), Tl (a = 2068.1(10) pm, R1 = 0.0485), Si (a = 2033.6(1) pm, R1 = 0.045), Ge (a = 2035.6(1) pm, R1 = 0.037), Sn (a = 2053.2(2) pm, R1 = 0.054), Pb (a = 2059.7(1) pm, R1 = 0.056), As (a = 2023.0(3) pm, R1 = 0.087), Sb (a = 2041.9(1) pm, R1 = 0.067) and Bi (a = 2045.9(1) pm, R1 = 0.075)]. Neutron powder diffraction data collected for the Ba silicide (both H and D compound) were refined by the Rietveld method (a = 2037.0(1), R{sub p} = 0.0173; wR{sub p} = 0.0304, R(F{sup 2}) = 0.086). The statistically occupied (H/D)(1) site 96g, which corresponds to the carbon position inSr{sub 21}Si{sub 2}O{sub 5}C{sub 6}, together with two further sparsely occupied sites (H/D)(2,3), yields the overall composition Ba{sub 21}Si{sub 2}O{sub 5}D{sub 14}. The hydrogen content, its chemical character and the distribution among the three H/D positions was evaluated by {sup 1}H/{sup 2}H MAS NMR spectroscopy for the Si, Ge and Sb compound. The crystal structure exhibits two

  13. Decay pathway and high-temperature luminescence of Eu{sup 3+} in Ca{sub 2}Gd{sub 8}Si{sub 6}O{sub 26}

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, M.D. [Engineering Materials Department, College of Engineering, University of California, Santa Barbara, CA 93106-5050 (United States)], E-mail: chambers@engineering.ucsb.edu; Rousseve, P.A.; Clarke, D.R. [Engineering Materials Department, College of Engineering, University of California, Santa Barbara, CA 93106-5050 (United States)

    2009-03-15

    The temperature-dependent luminescence of Eu:Ca{sub 2}Gd{sub 8}Si{sub 6}O{sub 26} and its decay pathways are investigated in order to assess the utility of the material as a thermometric phosphor. Non-radiative decays are found to compete with radiative processes even at room temperature. A decay pathway involving decay through charge-transfer states is proposed based on the decay profiles of emissions from {sup 5}D{sub 1} and {sup 5}D{sub 0} levels and on the temperature sensitivity of the spectra as observed after excitation by several wavelengths. The implications of this on solid-state lighting are also discussed.

  14. ACRT technique for the single crystal growth of the heavy fermion compound YbRh{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Witt, Sebastian; Kliemt, Kristin; Butzke, Constantin; Krellner, Cornelius [Goethe University Frankfurt, 60438 Frankfurt am Main (Germany)

    2016-07-01

    In the heavy fermion compound YbRh{sub 2}Si{sub 2} the antiferromagnetic ordering below 70 mK close to a quantum critical point is well-studied. Beneath the magnetic ordering a new phase transition was found recently at 2 mK. It is necessary to prepare large and high-quality single crystals for studying the nature of this new phase transition. Besides the optimization of the single crystal growth it is important to investigate single crystals with different isotopes at this phase transition. Here, we report the crystal growth of YbRh{sub 2}Si{sub 2} with the accelerated crucible rotation technique (ACRT). ACRT shows for other compounds, e.g. YAG (yttrium aluminum garnet, Y{sub 3}Al{sub 5}O{sub 12}), that this technique can reduce flux impurities and enhance the yield of larger crystals. We also report the attempt to receive metallic isotopes of ytterbium with metallothermic reduction. Crystals with different isotopes of silicon and ytterbium can be used for NMR measurements to investigate the underlying phenomena of quantum criticality in more detail.

  15. X-ray photoelectron spectroscopic study of direct reforming catalysts Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln = La, Nd, and Sm) for high temperature-operating solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Keunsoo [Department of Engine Research, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Daejeon 305-343 (Korea, Republic of); Jeong, Jihoon [Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX 78712 (United States); Azad, Abul K. [Faculty of Integrated Technologies, University Brunei Darussalam, Jalan Tunku Link, Gadong BE1410 (Brunei Darussalam); Jin, Sang Beom [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yusung-Gu, Daejeon 305-719 (Korea, Republic of); Kim, Jung Hyun, E-mail: jhkim2011@hanbat.ac.kr [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-Daero, Yusung-Gu, Daejeon 305-719 (Korea, Republic of)

    2016-03-01

    Graphical abstract: Measured Ti 2p peaks and deconvolution peaks of Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} under oxidizing condition (left) and NSTM under reducing condition (right). - Highlights: • Chemical states of Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln: La, Nd and Sm) were analyzed. • Charge compensation occurred with the reduction of Mn and Ti. • The Nd substitution effect allowed some Ti to convert into a metallic behavioral component. • NSTM and SSTM had a large amount of lattice oxygen; however, LSTM retained a large quantity of adsorbed oxygen. - Abstract: Chemical states of lanthanide doped perovskite for direct reforming anode catalysts, Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (Ln = La, Nd, and Sm) have been studied by X-ray Photoelectron Spectroscopy (XPS) in order to determine the effects of various lanthanide substitution in complex perovskites for high temperature-operating solid oxide fuel cells (HT-SOFC). The charge state of lanthanide ions remained at 3+ and the binding energies of the lanthanide ions in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} were located in a relatively lower range compared to those of conventional lanthanide oxides. Mn and Ti were regarded as charge compensation components in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}; Mn was more influential than Ti. In the cases of substituting Nd and Sm into Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d}, some portion of Ti showed metallic behavior; the specific Mn satellite peak indicating an electro-catalytic effect had occurred. Three types of oxygen species comprised of lattice oxygen, carbonate species, and adsorbed oxygen species were observed in Ln{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} from the O 1s spectra; a high portion of lattice oxygen was observed in both Nd{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub 3±d} (NSTM) and Sm{sub 0.5}Sr{sub 0.5}Ti{sub 0.5}Mn{sub 0.5}O{sub

  16. Piezoelectric Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} crystal: crystal growth, piezoelectric and acoustic properties

    Energy Technology Data Exchange (ETDEWEB)

    Roshchupkin, Dmitry; Emelin, Evgenii [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); National University of Science and Technology MISiS, Moscow (Russian Federation); Ortega, Luc [Univ. Paris-Sud, CNRS, UMR 8502, Laboratoire de Physique des Solides, Orsay Cedex (France); Plotitcyna, Olga; Irzhak, Dmitry [Russian Academy of Sciences, Institute of Microelectronics Technology and High-Purity Materials, Chernogolovka, Moscow District (Russian Federation); Erko, Alexei; Zizak, Ivo; Vadilonga, Simone [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institute for Nanometre Optics and Technology, Berlin (Germany); Buzanov, Oleg [FOMOS Materials Co., Moscow (Russian Federation); Leitenberger, Wolfram [Universitaet Potsdam Institut fuer Physik, Potsdam (Germany)

    2016-08-15

    Ca{sub 3}NbGa{sub 3}Si{sub 2}O{sub 14} (CNGS), a five-component crystal of lanthanum-gallium silicate group, was grown by the Czochralski method. The parameters of the elementary unit cell of the crystal were measured by powder diffraction. The independent piezoelectric strain coefficients d{sub 11} and d{sub 14} were determined by the triple-axis X-ray diffraction in the Bragg and Laue geometries. Excitation and propagation of surface acoustic waves (SAW) were studied by high-resolution X-ray diffraction at BESSY II synchrotron radiation source. The velocity of SAW propagation and power flow angles in the Y-, X- and yxl/+36 {sup circle} -cuts of the CNGS crystal were determined from the analysis of the diffraction spectra. The CNGS crystal was found practically isotropic by its acoustic properties. (orig.)

  17. Unusual antiferromagnetic structure of YbCo{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mufti, N. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Department of Physics, State University of Malang, Malang (Indonesia); Kaneko, K. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai (Japan); Hoser, A. [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Berlin (Germany); Gutmann, M. [ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot (United Kingdom); Geibel, C.; Stockert, O. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Krellner, C. [Max-Planck-Institut fuer Chemische Physik fester Stoffe, Dresden (Germany); Physikalisches Institut, Goethe-Universitaet Frankfurt, Frankfurt (Germany)

    2016-07-01

    We report on extensive powder and single crystal neutron diffraction experiments to study the magnetic structure in YbCo{sub 2}Si{sub 2} below the Neel temperature T{sub N} = 1.7 K in detail. Representation analysis has been used to find the possible magnetic structure models compatible with the experiments. Two different magnetically ordered phases can clearly be distinguished. At lowest temperatures a commensurate magnetic structure with a propagation vector k{sub 1} = (0.25 0.25 1) and equal moments or about 1.4 μ{sub B}/Yb is found, while the intermediate phase (T > 0.9 K) is characterized by an incommensurate amplitude-modulated magnetic structure with k{sub 2} = (0.25 0.086 1). The magnetic structure in YbCo{sub 2}Si{sub 2} is in stark contrast to all other compounds of the RCo{sub 2}Si{sub 2} family (R = rare earth element) likely due to some itineracy of the Yb 4f states being responsible for the magnetism.

  18. An anti CuO{sub 2}-type metal hydride square net structure in Ln{sub 2}M{sub 2}As{sub 2}H{sub x} (Ln = La or Sm, M = Ti, V, Cr, or Mn)

    Energy Technology Data Exchange (ETDEWEB)

    Mizoguchi, Hiroshi; Park, SangWon; Hosono, Hideo [Tokyo Institute of Technology, Yokohama (Japan). Materials Research Center for Element Strategy; Hiraka, Haruhiro; Ikeda, Kazutaka; Otomo, Toshiya [High-Energy Accelerator Research Organization (KEK), Tsukuba (Japan). Inst. of Materials Structure Science

    2015-03-02

    Using a high pressure technique and the strong donating nature of H{sup -}, a new series of tetragonal La{sub 2}Fe{sub 2}Se{sub 2}O{sub 3}-type layered mixed-anion arsenides, Ln{sub 2}M{sub 2}As{sub 2}H{sub x}, was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x∼3). In these compounds, an unusual M{sub 2}H square net, which has anti CuO{sub 2} square net structures accompanying two As{sup 3-} ions, is sandwiched by (LaH){sub 2} fluorite layers. Notably, strong metal-metal bonding with a distance of 2.80 Aa was confirmed in La{sub 2}Ti{sub 2}As{sub 2}H{sub 2.3}, which has metallic properties. In fact, these compounds are situated near the boundary between salt-like ionic hydrides and transition-metal hydrides with metallic characters.

  19. Synthesis and luminescent properties of Sr{sub 2}Gd{sub 6.8}Eu{sub 1.2}Si{sub 6(1−x)}P{sub 6x}O{sub 26} oxyapatites

    Energy Technology Data Exchange (ETDEWEB)

    Ishchenko, A.V., E-mail: a-v-i@mail.ru [Ural Federal University, 620002 Ekaterinburg (Russian Federation); Zuev, M.G. [Ural Federal University, 620002 Ekaterinburg (Russian Federation); Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Vasin, A.A. [Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Yagodin, V.V.; Viktorov, L.V.; Shulgin, B.V. [Ural Federal University, 620002 Ekaterinburg (Russian Federation)

    2016-01-15

    The solid solutions Sr{sub 2}Gd{sub 6.8}Eu{sub 1.2}Si{sub 6(1−x)}P{sub 6x}O{sub 26−δ} (where x=0–0.15 and δ is oxygen nonstoichiometry) were synthesized. The structural properties of the crystal lattice of the solid solutions and the peculiarities of Eu{sup 3+} and P{sup 5+} dopants substitution for matrix ions have been considered. The photo-, X-ray and pulsed cathode luminescence properties have been studied. It has been found that substitution of (SiO{sub 4}){sup 4−} by (PO{sub 4}){sup 3−} tetrahedron in Eu{sup 3+}-doped oxyapatites does not bring significant changes to bands structure Eu{sup 3+} in luminescence spectra under different excitation (UV, X-ray, pulse cathode beam). However, the increase of P{sup 5+} concentration in Sr{sub 2}Gd{sub 6.8}Eu{sub 1.2}Si{sub 6(1−x)}P{sub 6x}O{sub 26–δ} compounds leads to a decrease of integral intensity of Eu{sup 3+} luminescence bands due to local environment symmetry modifications and covalency degree changes. Two nonequivalent optical Eu{sup 3+} centers have been found. These compounds are of interest for efficient X-ray phosphors, display devices and LED engineering material creation. - Highlights: • The luminescence properties were studied upon UV, X-ray and pulse cathode beam. • P{sup 5+} doping of Sr{sub 2}Gd{sub 6.8}Eu{sub 1.2}Si{sub 6}O{sub 26} leads to luminescence intensity reduction. • At least two types of optical centers formed by Eu{sup 3+} ions were found. • The structural features of Sr{sub 2}Gd{sub 6.8}Eu{sub 1.2}Si{sub 6(1−x)}P{sub 6x}O{sub 26} were reported. • Partial replacement of Si by P does not change the Sr{sub 2}Gd{sub 6.8}Eu{sub 1.2}Si{sub 6}O{sub 26} structure.

  20. Synthesis, crystal structure and photoluminescence of a new Eu-doped Sr containing sialon (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Yamane, Hisanori, E-mail: yamane@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Shimooka, Satoshi; Uheda, Kyota [Mitsubishi Chemical Group, Science and Technology Research Center, Inc. 1000 Kamoshida-cho, Aoba-ku, Yokohama 227-8502 (Japan)

    2012-06-15

    Colorless transparent platelet single crystals of a novel Eu{sup 2+}-doped strontium silicon aluminum oxynitride, (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}, were prepared at 1800 Degree-Sign C and 0.92 MPa of N{sub 2}. Fundamental reflections of electron and X-ray diffraction of the crystals were indexed with a face-centered orthorhombic unit cell (a=5.8061(5) A, b=37.762(3) A, c=9.5936(9) A). Diffuse streaks elongated in the b-axis direction were observed around the fundamental reflections hkl with h=2n+1 of the electron and X-ray diffraction, indicating stacking faults of (0 1 0)[1 0 0]/2. A crystal structure model without the stacking faults was obtained using the X-ray diffraction data of the fundamental reflections with the space group Fdd2. A SiN{sub 4}-tetrahedron double layer of [SiN{sub 2}]{sub 2} and a Sr/Eu double layer of [(Sr{sub 0.94}Eu{sub 0.06})Al{sub 1.2}Si{sub 0.8}N{sub 0.8} O{sub 1.2}]{sub 2} are stacked alternately along the b-axis direction. The title compound showed an emission with a peak wavelength of 490 nm under 334 nm excitation at room temperature. - Graphical abstract: Single crystals of a novel Eu{sup 2+}-doped strontium silicon aluminum oxynitride, (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}, having stacking faults on the (0 1 0) plane of an orthorhombic cell, were prepared at 1800 Degree-Sign C and 0.92 MPa of N{sub 2}. The compound showed emission with a peak wavelength of 490 nm under 334 nm excitation at room temperature. Highlights: Black-Right-Pointing-Pointer A new compound Eu{sup 2+}-doped (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6} was prepared. Black-Right-Pointing-Pointer Stacking faults in the compound were clarified by electron and X-ray diffraction. Black-Right-Pointing-Pointer A basic crystal structure model was obtained based on the X-ray diffraction data. Black-Right-Pointing-Pointer An

  1. Electrochemical detection of volatile organic compounds using a Na{sub 3}Zr{sub 2}Si{sub 2}PO{sub 12}/Bi{sub 2}Cu{sub 0.1}V{sub 0.9}O{sub 5.35} heterojunction device

    Energy Technology Data Exchange (ETDEWEB)

    Kida, Tetsuya, E-mail: kida@mm.kyushu-u.ac.jp [Department of Energy and Material Sciences, Faculty of Engineering Sciences, Kyushu University, Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Morinaga, Naoki; Kishi, Shotaro [Department of Molecular and Material Sciences, Interdisciplinary Graduate School of Engineering Science, Kyushu University, Kasuga-Koen 6-1, Kasuga, Fukuoka 816-8580 (Japan); An, Ki-Mun; Sim, Kyoung-Won; Chae, Bu-Young [Department of Materials Science and Engineering, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Kim, Jung-kwan [Education Center for Green Industry-friendly Fusion Technology (GIFT), Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Ryu, Bong-Ki [Department of Materials Science and Engineering, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Shimanoe, Kengo [Department of Energy and Material Sciences, Faculty of Engineering Sciences, Kyushu University, Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan)

    2011-09-01

    Highlights: > A device combining a sodium ion conductor of NASICON (Na{sub 3}Zr{sub 2}Si{sub 2}PO{sub 12}) with an oxygen ion conductor of BiCuVOx (Bi{sub 2}Cu{sub 0.1}V{sub 0.9}O{sub 5.35}) was fabricated. > The device can electrochemically detect volatile organic compounds (VOCs). > The electrochemical oxidation of VOCs with oxide ions occurred as the sensing reaction. > The formation of an oxygen ion-conductive layer at the interface between NASICON and BiCuVOx was suggested. - Abstract: A fast sodium ion conductor, NASICON (Na{sub 3}Zr{sub 2}Si{sub 2}PO{sub 12}), has been widely used for gas sensor applications. In this study, we demonstrate that a device combining NASICON with an oxygen-ion conductor of BiCuVOx (Bi{sub 2}Cu{sub 0.1}V{sub 0.9}O{sub 5.35}) can electrochemically detect volatile organic compounds (VOCs), such as ethanol, formaldehyde, and toluene. The sensing electrode made of BiCuVOx was attached onto a sintered NASICON disk at high temperature to produce an interfacial layer that had a different morphology and composition from those of NASICON and BiCuVOx, as observed by scanning electron microscopy-energy dispersive X-ray spectroscopy analysis. The device in which NASICON was fitted with the BiCuVOx-based electrode was found to efficiently detect VOCs in ppm concentrations. The sensor signal (electromotive force) exceeded 100 mV in response to 10 ppm HCOH at 400 deg. C, demonstrating the high sensitivity of the device. It also exhibited a relatively quick response, reproducible and stable sensor signals, and high selectivity to VOCs. The sensor responses followed behavior typical for mixed-potential-type gas sensors based on oxygen-ion conductors. It was thus suggested that the electrochemical oxidation of VOCs with oxide ions took place at the interfacial oxygen ion-conductive layer that was formed by the reaction of NASICON with BiCuVOx.

  2. Metal–organic frameworks assembled from lanthanide and 2,5-pyridinedicaboxylate with cubane-like [Ln{sub 4}(OH){sub 4}] building units

    Energy Technology Data Exchange (ETDEWEB)

    Abdelbaky, Mohammed S.M. [Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, University of Oviedo—CINN, Oviedo 33006 (Spain); Amghouz, Zakariae, E-mail: amghouz.uo@uniovi.es [Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, University of Oviedo—CINN, Oviedo 33006 (Spain); Servicios Científico-Técnicos, University of Oviedo—CINN, Oviedo 33006 (Spain); Fernández-Zapico, Eva; García-Granda, Santiago; García, José R. [Departamentos de Química Física y Analítica y Química Orgánica e Inorgánica, University of Oviedo—CINN, Oviedo 33006 (Spain)

    2015-09-15

    tremendous attention due to the unique characteristic of lanthanide cations, such as variable coordination numbers and geometries which often lead to novel complex structures, and also to their magnetic and photoluminescence properties. Herein, three LOFs formulated as [Ln{sub 4}(OH){sub 4}(25p){sub 4}(H{sub 2}O){sub 3}]·H{sub 2}O (Ln=Y, Yb) and [Y{sub 6}(OH){sub 8}(25p){sub 5}(H{sub 2}O){sub 2}] have been obtained by hydrothermal method and characterized, and the photoluminescence properties of the Eu and Tb doped compounds are discussed. - Highlights: • Three novel LnOFs has been synthesized and characterized. • Crystal structures are based on tetranuclear cuban-like [Ln{sub 4}(OH){sub 4}]{sup 8+} clusters. • 25pYb and 25pY-1 are based on isolated [Ln{sub 4}(OH){sub 4}]{sup 8+} clusters. • 25pY-2 is based on infinite inorganic chains built up from [Y{sub 4}(OH){sub 4}]{sup 8+} clusters. • Photoluminescence studies show strong red and green light emissions.

  3. Synthetic shibkovite K(K{sub 1.67}H{sub 2}O{sub 0.33})(Ca{sub 1.3}Na{sub 0.7})[Zn{sub 3}Si{sub 12}O{sub 30}]: the crystal structure and comparative crystal chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kiriukhina, G. V., E-mail: g-biralo@yandex.ru; Yakubovich, O. V.; Dimitrova, O. V. [Moscow State University, Faculty of Geology (Russian Federation)

    2015-01-15

    The structure of a single crystal of a synthetic analog of mineral shibkovite K(K{sub 1.67}H{sub 2}O{sub 0.33})(Ca{sub 1.3}Na{sub 0.7})[Zn{sub 3}Si{sub 12}O{sub 30}] (milarite structure type) obtained by hydrothermal synthesis in the AlPO{sub 4}-K{sub 3}PO{sub 4}-CaCO{sub 3}-Na{sub 2}CO{sub 3}-ZnCO{sub 3}-SiO{sub 2}-H{sub 2}O system has been solved (R = 0.0406) by X-ray diffraction analysis: a = 10.5327(2) Å, c = 14.2019(3) Å, sp. gr. P6/mcc, Z = 2, and ρ{sub calcd} = 2.90 g/cm{sup 3}. The crystal-chemical features of the new phase are studied in comparison with the other terms of the milarite group. It is shown that the crystallization conditions for minerals and synthetic analogs of this group determine the presence or absence of crystallization water in the structures of compounds.

  4. Sol–gel assisted synthesis and photoluminescence property of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} red phosphor for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wentao, E-mail: zhangwentao2005@163.com [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, Chengdu 610059 (China); Wang, Yulong; Gao, Yang [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Long, Jianping [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China); Mineral Resources Chemistry Key Laboratory of Sichuan Higher Education Institutions, Chengdu 610059 (China); Li, Junfeng [College of Materials and Chemistry & Chemical Engineering, Chengdu University of Technology, Chengdu 610059 (China)

    2016-05-15

    Eu{sup 2+}, Dy{sup 3+} co-doped Sr{sub 2}Si{sub 5}N{sub 8} red phosphors were prepared using a sol–gel-nitridation method at a lower temperature comparing with traditional solid state reaction. Effects of synthesis process, Eu{sup 2+} and Dy{sup 3+} doping concentration on the crystal structure and luminescence property of as-prepared phosphors were investigated. X-ray diffraction patterns indicated that all Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} phosphors have the standard phase of Sr{sub 2}Si{sub 5}N{sub 8} structure. With a broad excitation from UV to blue light, a strong emission of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} with 4f{sup 6}5d{sup 1}→4f{sup 7} transition of Eu{sup 2+} ions was obtained at red region in photoluminescence spectra. Emission peaks in spectra were red-shifted from 611 to 632 nm for all Sr{sub 2}Si{sub 5}N{sub 8}:xEu{sup 2+} as Eu{sup 2+} ion concentrations increased, which due to Eu{sup 2+} ions occupying from the tenfold coordinated site (Sr1) to the eightfold coordinated site (Sr2). These Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} phosphors with Dy{sup 3+} co-doping showed excellent luminescence properties, included emission intensity and luminescence quenching. It is potential that Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} phosphors can be applied in white LEDs combining with blue InGaN LEDs. - Highlights: • Eu{sup 2+}/Dy{sup 3+} co-doped Sr{sub 2}Si{sub 5}N{sub 8} red phosphor were prepared by sol–gel-nitridation. • Sol–gel-nitridation method decreased the crystallization temperature of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} effectively. • Luminescence properties of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} were improved obviously by Dy{sup 3+} co-doping. • Luminescence properties of Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}, Dy{sup 3+} phosphors are superior to commercial Y{sub 2}O{sub 2}S:Eu{sup 3+}.

  5. An anti CuO{sub 2}-type metal hydride square net structure in Ln{sub 2}M{sub 2}As{sub 2}H{sub x} (Ln = La or Sm, M = Ti, V, Cr, or Mn)

    Energy Technology Data Exchange (ETDEWEB)

    Mizoguchi, Hiroshi; Park, SangWon; Hosono, Hideo [Materials Research Center for Element Strategy, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Hiraka, Haruhiro; Ikeda, Kazutaka; Otomo, Toshiya [Institute of Materials Structure Science, High-Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan)

    2015-03-02

    Using a high pressure technique and the strong donating nature of H{sup -}, a new series of tetragonal La{sub 2}Fe{sub 2}Se{sub 2}O{sub 3}-type layered mixed-anion arsenides, Ln{sub 2}M{sub 2}As{sub 2}H{sub x}, was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x∼3). In these compounds, an unusual M{sub 2}H square net, which has anti CuO{sub 2} square net structures accompanying two As{sup 3-} ions, is sandwiched by (LaH){sub 2} fluorite layers. Notably, strong metal-metal bonding with a distance of 2.80 Aa was confirmed in La{sub 2}Ti{sub 2}As{sub 2}H{sub 2.3}, which has metallic properties. In fact, these compounds are situated near the boundary between salt-like ionic hydrides and transition-metal hydrides with metallic characters. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Crystal field excitations of YbMn{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mole, R.A. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234 (Australia); School of Physical, Environmental and Mathematical Sciences, The University of New South Wales at the Australian Defence Force Academy, Canberra, ACT 2600 (Australia); Hofmann, M. [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales at the Australian Defence Force Academy, Canberra, ACT 2600 (Australia); Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, 85747 Garching (Germany); Adroja, D.T. [ISIS Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 OQX (United Kingdom); Moze, O. [Dipartimento di Fisica, Università degli Studi di Modena e Reggio Emilia, Modena (Italy); Campbell, S.J., E-mail: stewart.campbell@adfa.edu.au [School of Physical, Environmental and Mathematical Sciences, The University of New South Wales at the Australian Defence Force Academy, Canberra, ACT 2600 (Australia)

    2013-12-15

    The crystal field excitations of the rare earth intermetallic compound YbMn{sub 2}Si{sub 2} have been measured by inelastic neutron scattering over the temperature range 2.5–50 K. The YbMn{sub 2}Si{sub 2} spectra exhibit three low energy excitations (∼3–7 meV) in the antiferromagnetic AFil region above the magnetic phase transition at T{sub N2} = 30(5) K. The crystal field parameters have been determined for YbMn{sub 2}Si{sub 2} in the antiferromagnetic AFil region. A further two inelastic excitations (∼9 meV, 17 meV) are observed below T{sub N2}=30(5) K, the temperature at which the high temperature antiferromagnetic structure is reported to exhibit doubling of the magnetic cell. Energy level diagrams have been determined for Yb{sup 3+} ions in the different sites above (single site) and below the magnetic transition temperature (two sites). The excitation energies for both sites are shown to be temperature independent with the temperature dependences of the transition intensities for the two sites described well by a simple Boltzmann model. The spectra below T{sub N2} cannot be described fully in terms of molecular field models based on either a single Yb{sup 3+} site or two Yb{sup 3+} sites. This indicates that the magnetic behaviour of YbMn{sub 2}Si{sub 2} is more complicated than previously considered. The inability to account fully for excitations below the magnetic phase transition may be due to an, as yet, unresolved structural transition associated with the magnetic transition. - Highlights: • The inelastic neutron scattering from YbMn{sub 2}Si{sub 2} has been investigated over the temperature range 2.5–50 K. • The crystal field splitting has been monitored through the magnetic transition at 30(5) K. • We have determined the crystal field parameters for the antiferromagnetic AFil region. • The transition intensities are described well by Boltzmann occupancy models. • The spectra below the magnetic transition have been analysed by

  7. Enstatite, Mg/sub 2/Si/sub 2/O/sub 6/: A neutron diffraction refinement of the crystal structure and a rigid-body analysis of the thermal vibration

    Energy Technology Data Exchange (ETDEWEB)

    Ghose, S.; Schomaker, V.; McMullan, R.K.

    1986-01-01

    Synthetic enstatite, Mg/sub 2/Si/sub 2/O/sub 6/, is orthorhombic, space group Pbca, with eight formula units per cell and lattice parameters a = 18.235(3), b = 8.818(1), c = 5.179(1) A at 23/sup 0/C. A least-squares structure refinement based on 1790 neutron intensity data converged with an agreement factor R(F/sup 2/) = 0.032, yielding Mg-O and Si-O bond lengths with standard deviations of 0.0007 and 0.0008 A, respectively. The variations observed in the Si-O bond lengths within the silicate tetrahedra A and B are caused by the differences in primary coordination of the oxygen atoms and the proximity of the magnesium ions to the silicon atoms. The latter effect is most pronounced for the bridging bonds of tetrahedron. A. The smallest O-Si-O angle is the result of edge-sharing by the Mg(2) octahedron and the A tetrahedron. An analysis of rigid-body thermal vibrations of the two crystallographically independent (SiO/sub 4/) tetrahedra indicates considerable librational motion, leading to a thermal correction of apparent Si-O bond lengths as large as +0.002 A at room temperature.

  8. Superconductivity in CeCu/sub 2/Si/sub 2/: dependence of Tsub(c) on alloying and stoichiometry

    Energy Technology Data Exchange (ETDEWEB)

    Spille, H; Rauchschwalbe, U; Steglich, F [Technische Hochschule Darmstadt (Germany, F.R.). Inst. fuer Festkoerperphysik

    1938-01-01

    The authors have determined the transition temperatures of the alloy systems (Ce,M)Cu/sub 2/Si/sub 2/ with M = La, Y, Sc, Ce(Cu,T)/sub 2/Si/sub 2/ with T = Ag, Au, Mn, Ru, Rh, Pd and CeCu/sub 2/(Si,Ge)/sub 2/ as well as of CeCu/sub 2/Si/sub 2/ samples with varying stoichiometry. In each case, alloying is found to depress Tsub(c), the critical concentrations necessary to destroy superconductivity ranging between < 1 at.% and 10 at.%. Off-stoichiometry samples with a Cu- or Ce-deficiency of a few at.% are not superconducting, while samples prepared with a comparable excess of Cu or Ce show sharp transitions at Tsub(c) >approx. 600 mK. It is inferred that stoichiometric CeCu/sub 2/Si/sub 2/ contains substantial concentrations of Cu- and Ce-vacancies, which hinder superconductivity. First results on CeCu/sub 2/Si/sub 2/ single crystals, which exhibit bulk superconductivity, are also reported.

  9. Synthesis, structure and chemical bonding of CaFe{sub 2−x}Rh{sub x}Si{sub 2} (x=0, 1.32, and 2) and SrCo{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hlukhyy, Viktor, E-mail: viktor.hlukhyy@lrz.tu-muenchen.de; Hoffmann, Andrea V.; Fässler, Thomas F.

    2013-07-15

    The finding of superconductivity in Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2} put the attention on the investigation of compounds that crystallize with ThCr{sub 2}Si{sub 2} structure type such as AT{sub 2}X{sub 2} (A=alkali/alkaline earth/rare earth element; T=transition metal and X=element of the 13–15th group). In this context the silicides CaFe{sub 2}Si{sub 2}, CaFe{sub 0.68(6)}Rh{sub 1.32(6)}Si{sub 2}, CaRh{sub 2}Si{sub 2} and SrCo{sub 2}Si{sub 2} have been synthesized by reaction of the elements under an argon atmosphere. Single crystals were obtained by special heat treatment in welded niobium/tantalum ampoules. The compounds were investigated by means of powder and single crystal X-ray diffraction. All compounds crystallize in the ThCr{sub 2}Si{sub 2}-type structure with space group I4/mmm (No. 139): a=3.939(1) Å, c=10.185(1) Å, R{sub 1}=0.045, 85 F{sup 2} values, 8 variable parameters for CaFe{sub 2}Si{sub 2}; a=4.0590(2) Å, c=9.9390(8) Å, R{sub 1}=0.030, 90 F{sup 2} values, 10 variable parameters for CaFe{sub 0.68(6)}Rh{sub 1.32(6)}Si{sub 2}; a=4.0695(1) Å, c=9.9841(3) Å, R{sub 1}=0.031, 114 F{sup 2} values, 9 variable parameters for CaRh{sub 2}Si{sub 2}; and a=3.974(1) Å, c=10.395(1) Å, R{sub 1}=0.036, 95 F{sup 2} values, 8 variable parameters for SrCo{sub 2}Si{sub 2}. The structure of SrCo{sub 2}Si{sub 2} contains isolated [Co{sub 2}Si{sub 2}]{sup 2−} 2D-layers in the ab-plane whereas in CaFe{sub 2−x}Rh{sub x}Si{sub 2} the [T{sub 2}Si{sub 2}] layers (T=Fe and Rh) are interconnected along the c-axis via Si3Si bonds resulting in a three-dimentional (3D) [T{sub 2}Si{sub 2}]{sup 2−} polyanions and therefore belong to the so-called collapsed form of the ThCr{sub 2}Si{sub 2}-type structure. The SrCo{sub 2}Si{sub 2} and CaRh{sub 2}Si{sub 2} are isoelectronic to the parent 122 iron–pnictide superconductors AeFe{sub 2}As{sub 2} (Ae=alkaline earth elements), whereas CaFe{sub 2}Si{sub 2} is a full substituted variant (As/Si) of CaFe{sub 2}As{sub 2

  10. Nernst effect of Ni-doped NdBa{sub 2}Cu{sub 3}O{sub 7-{delta}} and transport properties in UPt{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Johannsen, Niko

    2008-05-15

    In this thesis, the Nernst effect in high-temperature superconductors is investigated. Large Nernst voltages were found to survive up to temperatures that reach far out of the superconducting phase. This was extensively studied thereafter in wide doping range of the high-T{sub c}'s. We were able to significantly expand these studies by tuning T{sup *} and T{sup {nu}} independently. This was done by inducing Ni ions into the CuO planes of NdBa{sub 2}{l_brace}Cu{sub 1-y}Ni{sub y}{r_brace}{sub 3}O{sub 7-{delta}} which allowed to study the Nernst effect in a wide parameter range. This is done on one hand in dependence of the oxygen content which varies the charge carrier concentration. On the other hand, the Ni concentration is varied from 0% to 12%, thereby enhancing T{sup *} and simultaneously suppressing T{sub c} with increasing concentrations. The temperatures to which the anomalous Nernst signal is detectable is the onset temperature T{sup {nu}}. The goal of this work was to find out whether T{sup {nu}} follows T{sub c} or T{sup *}. The onset temperatures of the anomalous Nernst signals are determined as the slightest detectable deviation from the quasiparticle background above T{sub c}. In the second part of this work, the Nernst effect and other transport properties of UPt{sub 2}Si{sub 2}, including electrical ones such as the resistivity and the Hall effect and thermal ones, as the thermal conductivity, the thermopower and the Righi-Leduc effect were investigated. (orig.)

  11. Evidence for unconventional d-wave superconducting state in CeCu{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Vieyra, Hugo A.; Geibel, Christoph; Steglich, Frank; Oeschler, Niels [Max-Planck-Institute for Chemical Physics of Solids, Dresden 01187 (Germany); Parker, David [US Naval Research Laboratory, Washington, DC 20375 (United States); Jeevan, Hirale S. [I. Physik. Institut, Georg-August-Universitaet Goettingen, Goettingen 37077 (Germany)

    2010-07-01

    The heavy-fermion CeCu{sub 2}Si{sub 2} represents a prime system to study unconventional superconductivity in the vicinity of a magnetic instability. Within the homogeneity range of pure CeCu{sub 2}Si{sub 2} different ground states can be obtained. S-type crystals exhibit a superconducting transition at T{sub c}=0.6 K, whereas A/S-type show in addition antiferromagnetic order at T{sub N}=0.8 K. In recent years, the synthesis techniques have been optimized in order to obtain large high-quality single crystals with well defined ground state properties. This allows the systematic study of the superconducting order parameter and its variation at the border with magnetic order. In this work, we present angular dependent resistivity measurements on high-quality S- and A/S-type single-crystalline CeCu{sub 2}Si{sub 2} samples. The experimental results for the angular dependence of the upper critical field B{sub c2} as well as theoretical calculations taking into account effects like the strong Pauli paramagnetism, hint towards an unconventional d-wave symmetry of the order parameter in CeCu{sub 2}Si{sub 2}.

  12. Order parameter in CeCu{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Vieyra, Hugo A.; Brando, Manuel; Oeschler, Niels; Seiro, Silvia; Geibel, Christoph; Steglich, Frank [Max-Planck-Institute for Chemical Physics of Solids, Dresden (Germany); Jeevan, Hirale S. [I. Physikalisches Institut, Georg-August-Universitaet Goettingen (Germany); Parker, David [US Naval Research Laboratory, Washington, DC (United States)

    2011-07-01

    Understanding the interplay between magnetism and unconventional superconductivity remains a key challenge in solid-state physics. A clear example is the archetypical heavy-fermion compound CeCu{sub 2}Si{sub 2} which exhibits superconductivity (T{sub c}=600 mK) in the vicinity of a magnetic quantum critical point. It is believed that magnetic fluctuations mediate superconductivity and its order parameter possesses d-wave symmetry, both ideas still under debate. In this work, a high-quality single crystal with a purely superconducting ground state (S type) has been chosen to investigate the low-temperature thermal- and electric-transport characteristics of the superconducting state. Non-vanishing contributions of low-energy quasiparticle excitations to the thermal transport ({kappa}{sub 0}/T>0) suggest the presence of nodal structure in CeCu{sub 2}Si{sub 2}. In turn, angle-dependent resistivity measurements of the upper critical field H{sub c2} point towards unconventional superconductivity with d-wave symmetry of the order parameter. Theoretical calculations reveal the strong influence of Pauli paramagnetic effects and a d{sub xy} symmetry of the gap function.

  13. Magnetic and transport properties of the (Tb{sub 1-} {sub x} Y {sub x} )Mn{sub 2}Si{sub 2} and TbMn{sub 2}(Si{sub 1-} {sub y} Ge {sub y} ){sub 2} systems

    Energy Technology Data Exchange (ETDEWEB)

    Granovsky, S.A. [Department of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory GSP-2 119992 Moscow (Russian Federation) and TU Dresden, Institut fuer Festkoerperphysik, D-01062, Dresden (Germany)]. E-mail: ser@plms.phys.msu.ru; Gaidukova, I.Yu. [Department of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory GSP-2 119992 Moscow (Russian Federation); Doerr, M. [TU Dresden, Institut fuer Festkoerperphysik, D-01062, Dresden (Germany); Loewenhaupt, M. [TU Dresden, Institut fuer Festkoerperphysik, D-01062, Dresden (Germany); Markosyan, A.S. [Department of Physics, M.V. Lomonosov Moscow State University, Leninskie Gory GSP-2 119992 Moscow (Russian Federation)

    2005-04-15

    Magnetic and transport characteristics of pseudo-ternary compounds (Tb{sub 1-} {sub x} Y {sub x} )Mn{sub 2}Si{sub 2} and TbMn{sub 2}(Si{sub 1-} {sub y} Ge {sub y} ){sub 2} have been studied. The role of the 4f-3d exchange and Mn-Mn distances in the formation of the magnetic structure of these compounds is discussed.

  14. LiCa{sub 3}Si{sub 2}N{sub 5} - A Lithium nitridosilicate with a [Si{sub 2}N{sub 5}]{sup 7-} double-chain

    Energy Technology Data Exchange (ETDEWEB)

    Lupart, Saskia; Schnick, Wolfgang [Department Chemie, Lehrstuhl fuer Anorganische Festkoerperchemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

    2012-10-15

    The lithium nitridosilicate LiCa{sub 3}Si{sub 2}N{sub 5} was synthesized by the reaction of calcium with Si(NH){sub 2} and Li{sub 3}N in weld shut tantalum ampoules at 900 C. The structure of LiCa{sub 3}Si{sub 2}N{sub 5} [space group C2/c, no. 15, a = 5.1454(10), b = 20.380(4), c = 10.357(2) Aa, β = 91.24(3) , wR{sub 2} = 0.1084, 863 data, 102 parameters] consists of [Si{sub 2}N{sub 5}]{sup 7-} double-chains including edge-sharing tetrahedra. The lithium atoms in the crystal structure are situated in strands along the crystallographic b axis. Lattice energy calculations (MAPLE) and EDX measurements confirmed the electrostatic bonding interactions and the chemical composition. The {sup 29}Si and {sup 7}Li solid-state MAS NMR spectroscopic investigations are reported. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Improvement of photoluminescence properties and thermal stability of Y{sub 2.9}Ce{sub 0.1}Al{sub 5−x}Si{sub x}O{sub 12} phosphors with Si{sub 3}N{sub 4} addition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Fangfang [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Song, Kaixin, E-mail: kxsong@hdu.edu.cn [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Jiang, Jun [Ningbo Institute of Materials Technologies and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wu, Song; Zheng, Peng [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Huang, Qingming [Instrument Analysis and Testing Center, Fuzhou University, Fuzhou 350002 (China); Xu, Junming; Qin, Huibin [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2014-12-05

    Highlights: • Y{sub 2.9}Ce{sub 0.1}Al{sub 5−x}Si{sub x}O{sub 12} phosphors were prepared by solid-state reaction in reduced air ambience. • Si{sup 4+} could be incorporated into the host lattice of Y{sub 3}Al{sub 5}O{sub 12} through partial occupation of the Al{sup 3+} sites. • Si{sub 3}N{sub 4} addition can improve photoluminescence efficiency and thermal stability of Y{sub 3}Al{sub 5}O{sub 12}:Ce. - Abstract: A series of Si{sub 3}N{sub 4} doping Y{sub 2.9}Ce{sub 0.1}Al{sub 5−x}Si{sub x}O{sub 12−3x/2}N{sub 4x/3} phosphors were prepared by solid-state reaction in 95%N{sub 2}–5%H{sub 2} reduced air ambience. The XRD characteristics plus Rietveld refinement results shows that the as-sintered powders are unique crystal phase with the same crystal structure of Y{sub 3}Al{sub 5}O{sub 12} (PDF No. 79-1891). The N element was not detected by the analysis of X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectrum (EDS). The photoluminescence spectra (PL and PLE) tests show that the exciting and emitting intensity of PLE and PL gradually increase due to the increase of Si{sub 3}N{sub 4} concentration. Meanwhile, the phosphorescence decay times are prolonged from 45 ns (x = 0) to 78 ns (x = 0.3), under the monitor of 530 nm wavelength. The thermoluminescence tests (TL) confirm the thermal stability of as-phosphors with Si{sub 3}N{sub 4} addition is much better than that of the pristine Y{sub 2.9}Ce{sub 0.1}Al{sub 5}O{sub 12} phosphors.

  16. Tuning ZrFe{sub 4}Si{sub 2} by Ge and Y substitution

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Katharina [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Institute of Solid State Physics, TU Dresden (Germany); Mufti, Nandang; Bergmann, Christoph; Rosner, Helge; Geibel, Christoph [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Goltz, Til; Klauss, Hans-Henning [Institute of Solid State Physics, TU Dresden (Germany); Woike, Theo [Institute for Structural Physics, TU Dresden (Germany)

    2016-07-01

    The intermetallic compound series AFe{sub 4}X{sub 2} (A = Y, Lu, Zr; X = Si, Ge) presents a rare case of magnetic frustrated metallic systems. In particular ZrFe{sub 4}Si{sub 2} is of strong interest because our results indicate this system to be very close to a quantum critical point (QCP) where Fe magnetic order disappears. To get a deeper insight into its ground state, we performed a detailed study of Ge and Y substituted ZrFe{sub 4}Si{sub 2}. The isovalent substitution of Ge for Si induces a negative chemical pressure as Ge is larger than Si. As expected from this, the substitution results in the formation of a well-defined antiferromagnetic order with Neel temperatures increasing up to 25 K at 40 % Ge. This confirms ZrFe{sub 4}Si{sub 2} to be extremely close to the QCP, just on the magnetic side of it. With the second substitution series Y{sub x}Zr{sub 1-x}Fe{sub 4}Si{sub 2} we investigate the development from the highly reduced antiferromagnetic order in ZrFe{sub 4}Si{sub 2} towards the two magnetic transitions at 56 K and 76 K, which we see in YFe{sub 4}Si{sub 2}.

  17. Oxide meets silicide. Synthesis and single-crystal structure of Ca{sub 21}SrSi{sub 24}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Reckeweg, Olaf; DiSalvo, Francis J. [Cornell Univ., Ithaca, NY (United States). Dept. of Chemistry and Chemical Biology

    2017-06-01

    A few black, rectangular thin plates of Ca{sub 21}SrSi{sub 24}O{sub 2} were obtained by serendipity in a solid-state reaction of calcium metal, strontium chloride and silicon powder at 1200 K for 2 days designed to produce 'Ca{sub 2}SrCl{sub 2}[Si{sub 3}]'. The title compound forms next to some CaSi and some remaining educts. Ca{sub 21}SrSi{sub 24}O{sub 2} crystallizes in the monoclinic space group C2/m (no. 12) with unit cell parameters of a=1895.2(2), b=450.63(5) and c=1397.33(18) pm and β=112.008(7) (Z=1). The title compound shows planar, eight-membered, kinked Si{sub 8} chains with Si-Si distances between 241.4 and 245.0 pm indicating bonding interactions and kinked 'rope ladders' connecting the chains with interatomic Si-Si distances in the range 268.1-274.7 pm. Embedded in between these silicon substructures are columns of oxygen centered, apex sharing [(Ca{sub 1-x} Sr{sub x}){sub 6/2}O] octahedra and calcium ions.

  18. Coloring problem and magnetocaloric effect of Gd{sub 3}Co{sub 2.2}Si{sub 1.8}

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jinlei, E-mail: materyao@gmail.com [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China); Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada); Morozkin, A.V. [Department of Chemistry, Moscow State University, Leninskie Gory, House 1, Building 3, GSP-2, Moscow 119992 (Russian Federation); Mozharivskyj, Yurij [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1 (Canada)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer Gd{sub 3}Co{sub 2.2}Si{sub 1.8} adopts the Er{sub 3}Ge{sub 4} structure (space group Cmcm). Black-Right-Pointing-Pointer Si and Co show site preference. Black-Right-Pointing-Pointer The electronic factors determine the site occupation of Si and Co. Black-Right-Pointing-Pointer Gd{sub 3}Co{sub 2.2}Si{sub 1.8} order ferromagnetically below 172 K. - Abstract: The Gd{sub 3}Co{sub 2.2}Si{sub 1.8} compound was synthesized by arc melting the constituent elements and subsequent annealing at 1070 K for 120 h. It adopts the Dy{sub 3}Co{sub 2.2}Si{sub 1.8}-type structure with the space group Cmcm and the unit cell parameters of a = 4.1176(7) A, b = 10.305(2) A, c = 12.778(2) A and V = 542.2(2) A{sup 3}. The Co and Si atoms preferentially occupy the 8f and 4a/4c sites, respectively. The atomic electronegativity and electron density at a given site determine its site occupation, according to the analysis of the electronic structure. Gd{sub 3}Co{sub 2.2}Si{sub 1.8} orders ferromagnetically with the Curie temperature of 172 K. The isothermal magnetic entropy change, -{Delta}S{sub m}, reaches the maximum value of 7.09 J/kg K at 170 K for a field change of 0-50 kOe.

  19. Phase transformations during HLnTiO{sub 4} (Ln=La, Nd) thermolysis and photocatalytic activity of obtained compounds

    Energy Technology Data Exchange (ETDEWEB)

    Silyukov, Oleg I., E-mail: olegsilyukov@yandex.ru; Abdulaeva, Liliia D.; Burovikhina, Alena A.; Rodionov, Ivan A.; Zvereva, Irina A.

    2015-03-15

    Layered HLnTiO{sub 4} (Ln=La, Nd) compounds belonging to Ruddlesden–Popper phases were found to form partially hydrated compounds Ln{sub 2}Ti{sub 2}O{sub 7}·xH{sub 2}O during thermal dehydration as well as defect oxides Ln{sub 2}□Ti{sub 2}O{sub 7} as final products. Further heating of metastable defect Ln{sub 2}□Ti{sub 2}O{sub 7} substances leads to the formation of pyrochlore-type oxides Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}, with subsequent transformation under higher temperatures to stable layered 110-type perovskites Ln{sub 2}Ti{sub 2}O{sub 7}. The occurring structure transformations lead to an increase of photocatalytic activity in the order of HLnTiO{sub 4}<Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O2}□Ti{sub 2}O{sub 7}<Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}2}Ti{sub 2}O{sub 7} in the reaction of hydrogen evolution from aqueous isopropanol solution. - Graphical abstract: Layered HLnTiO{sub 4} (Ln=La, Nd) compounds form partially hydrated Ln{sub 2}Ti{sub 2}O{sub 7}·xH{sub 2}O compounds during thermal dehydration, further heating results to the formation to defect oxides Ln{sub 2}□Ti{sub 2}O{sub 7}, pyrochlor-type oxides Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}, with subsequent transformation to layered 110-type perovskites Ln{sub 2}Ti{sub 2}O{sub 7}. Structure transformations lead to an increase of photocatalytic activity in the order of HLnTiO{sub 4}<Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O2}□Ti{sub 2}O{sub 7}<Ln{sub 2}Ti{sub 2}O{sub 7} {sub (p)}2}Ti{sub 2}O{sub 7}. - Highlights: • We studied dehydration and further thermolysis of HLnTiO{sub 4} (Ln=La, Nd) compounds. • XRD, STA and solid state IR studies were carried out. • A new series of metastable Ln{sub 2}Ti{sub 2}O{sub 7}·yH{sub 2}O compounds was obtained. • We examined the photocatalytic activity of all obtained compounds. The hydrogen evolution rate increased in the course of the structure changes during thermolysis.

  20. Deposition and characterization of pulsed direct current magnetron sputtered Al{sub 95.5}Cr{sub 2.5}Si{sub 2} (N{sub 1-x}O{sub x}) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Najafi, H., E-mail: hossein.najafi@epfl.c [Institut de Physique de la Matiere Condensee (IPMC), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Lausanne (Switzerland); Shetty, A.; Karimi, A. [Institut de Physique de la Matiere Condensee (IPMC), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015, Lausanne (Switzerland); Morstein, M. [Platit AG, Advanced Coating Systems, CH-2545 Selzach (Switzerland)

    2010-10-29

    Aluminum rich oxynitride thin films were prepared using pulsed direct current (DC) magnetron sputtering from an Al{sub 95.5}Cr{sub 2.5}Si{sub 2} (at.%) target. Two series of films were deposited at 400 {sup o}C and 650 {sup o}C by changing the O{sub 2}/(O{sub 2} + N{sub 2}) ratio in the reactive gas from 0% (pure nitrides) to 100% (pure oxides). The films were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and nanoindentation. The results showed the existence of three different regions of microstructure and properties with respect to the oxygen concentration. For the samples deposited at 650 {sup o}C in the nitrogen rich region (O{sub 2}/(O{sub 2} + N{sub 2}) {<=} 0.08), the formation of the h-AlN (002) and Al-N bond were confirmed by XRD and XPS measurements. The hardness of the films was around 30 GPa. In the intermediate region (0.08 {<=} O{sub 2}/(O{sub 2} + N{sub 2}) {<=} 0.24), the presence of an amorphous structure and the shifting of the binding energies to lower values corresponding to non-stoichiometric compounds were observed and the hardness decreased to 12 GPa. The lowering of mechanical properties was attributed to the transition of the clean target to the reacted target under non-steady state deposition conditions. In the oxygen rich region (0.24 {<=} (O{sub 2}/(O{sub 2} + N{sub 2}) {<=} 1), the existence of {alpha}-Al{sub 2}O{sub 3}-(113), {alpha}-Al{sub 2}O{sub 3}-(116) and Al-O bonds confirmed the domination of this phase in this region of deposition and the hardness increased again to 30-35 GPa. Films deposited at 400 {sup o}C showed the same behavior except in the oxygen rich region, where hardness remains low at about 12-14 GPa.

  1. Color-tunable and luminescence properties of phosphors of Ce{sup 3+} and Tb{sup 3+} co-doped La{sub 5}Si{sub 3}O{sub 12}N for UV w-LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Junru; Chen, Jian; Liu, Yangai, E-mail: liuyang@cugb.edu.cn

    2016-02-15

    A series of Ce{sup 3+}, Tb{sup 3+} and Ce{sup 3+}/Tb{sup 3+} co-doped in La{sub 5}Si{sub 3}O{sub 12}N phosphors were synthesized by conventional high temperature solid state reaction method. With the increase of Tb{sup 3+}, the green emission was realized in (La{sub 0.94−y}Ce{sub 0.06}Tb{sub y}){sub 5}Si{sub 3}O{sub 12}N phosphors on the basis of the efficient energy transfer from Ce{sup 3+} to Tb{sup 3+} with an efficiency (η{sub T}) over 58.72%. The room temperature PL decay curves of the Ce{sup 3+} ions in (La{sub 0.94−y}Ce{sub 0.06}Tb{sub y}){sub 5}Si{sub 3}O{sub 12}N phosphors monitored at 460 nm with an excitation at 365 nm indicated that the energy transfer process between Ce{sup 3+} and Tb{sup 3+} indeed took place. The CIE chromaticity diagrams for (La{sub 0.94−y}Ce{sub 0.06}Tb{sub y}){sub 5}Si{sub 3}O{sub 12}N phosphors were also observed, which shows the color tuned from blue to blue-greenish to green with the increase of Tb{sup 3+} concentration from 0.01 to 0.08. These results demonstrated that Tb{sup 3+} ion with low 4f–4f absorption efficiency in near UV region can play the role of an activator in narrow green-emitting phosphor through efficient energy feeding by allowing 4f–5d absorption of Ce{sup 3+} with high oscillator strength. All the results indicated that the Ce{sup 3+} and Tb{sup 3+} activated La{sub 5}Si{sub 3}O{sub 12}N phosphor may be good candidates for blue-green components in n-UV white LEDs. - Highlights: • A series of Ce{sup 3+}, Tb{sup 3+} and Ce{sup 3+}/Tb{sup 3+} co-doped in La{sub 5}Si{sub 3}O{sub 12}N phosphors were synthesized by high temperature solid state reaction method. • The green emission was realized in (La{sub 0.94−y}Ce{sub 0.06}Tb{sub y})Si{sub 3}O{sub 12}N phosphors on the basis of the highly efficient energy transfer. • The Ce{sup 3+} and Tb{sup 3+} activated La{sub 5}Si{sub 3}O{sub 12}N phosphor may be good candidates for blue-green components in n-UV white LEDs.

  2. Hydrogen absorption in U{sub 3}Si{sub 2} and its impact on electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Mašková, Silvie, E-mail: maskova@mag.mff.cuni.cz [Department of Condensed Matter Physics, Charles University, Prague 2, The Czech Republic (Czech Republic); Miliyanchuk, Khrystyna [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Lviv (Ukraine); Havela, Ladislav [Department of Condensed Matter Physics, Charles University, Prague 2, The Czech Republic (Czech Republic)

    2017-04-15

    U{sub 3}Si{sub 2} reversibly absorbs hydrogen at very low H{sub 2} pressures (kPa range), yielding U{sub 3}Si{sub 2}H{sub 1.8}. One characteristic desorption temperature implies that there is only one type of H sites. U{sub 3}Si{sub 2} is a weak Pauli paramagnet (χ < 2·10{sup −8} m{sup 3}/mol U) with the shortest inter-uranium distances between the U atoms in different sheets (d{sub U-U} = 332 pm). The volume-expanded (10%) hydride is a spin fluctuator with temperature dependent magnetic susceptibility and a weak ferromagnetic component gradually arising below T = 100 K. The location of U{sub 3}Si{sub 2}H{sub 1.8} at the verge of magnetic ordering is evidenced by the low temperature specific heat with an upturn in C/T and a dramatic enhancement of the Sommerfeld coefficient of electronic specific heat γ, which reaches 500 mJ/mol f.u. K{sup 2}. - Highlights: •U{sub 3}Si{sub 2} can be hydrogenated at very low H{sub 2} pressure, yielding U{sub 3}Si{sub 2}H{sub 1.8}. •The H absorption to a single H-site is reversible. •Hydrogenation leads to the expansion of the unit cell by 10%. •U{sub 3}Si{sub 2} is a weak Pauli paramagnet. •The hydride is a spin fluctuator with temperature dependent magnetic susceptibility.

  3. Electronic structure of Ti/sub 2/O/sub 3/, V/sub 2/O/sub 3/, and Cr/sub 2/O/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Bondarenko, T N; Zhurakovskii, E A; Dzeganovskii, V P [AN Ukrainskoj SSR, Kiev. Inst. Problem Materialovedeniya

    1975-11-01

    Electronic structure of oxides Ti/sub 2/O/sub 3/, V/sub 2/O/sub 3/, Cr/sub 2/O/sub 3/ was elucidated by means of X-ray and ESCA methods and the results were compared with the data obtained by other methods and with the available models of electronic structures. Energy diagram of V/sub 2/O/sub 3/ and common energy scale of X-ray spectra of Ti and Cr in Ti/sub 2/O/sub 3/ and Cr/sub 2/O/sub 3/ are presented. X-ray spectra show that these oxides possess the states which are related genetically to the M4p-states i.e. the X-ray data complement essentially to the result of optical and electrophysical measurements. MO and M/sub 2/O/sub 3/ compounds in the region of Fermi level have overlapping emission and absorption spectra which is specific to the matters with the metallic type of bonding. Actually TiO, VO, Ti/sub 2/O/sub 3/ and V/sub 2/O/sub 3/ have metallic type of bonding. However such overlap was observed in Cr/sub 2/O/sub 3/ as well whose forbidden zone according to photoconductivity measurments is about 3 eV. Absence of energy gap between emission and absorption spectra in Cr/sub 2/O/sub 3/ may be explained by traces of impurities which convert dielectrics conductors - impurities act as agents caus:ng filling or generation of vacancies rather than independent allowing additives. On the other hand this may be due to the defects in Cr/sub 2/O/sub 3/ lattice which may cause appearance of excited states in forbidden zone. These investigations enable to draw energy diagram of V/sub 2/O/sub 3/ and to combine the spectra of M in Ti/sub 2/O/sub 3/ into common energy scheme. Analysis of the diagram and combined spectra revealed great similarity in the electronic structures of M/sub 2/O/sub 3/ oxides (M - Ti, V, Cr) .

  4. Theoretical reconsideration of antiferromagnetic Fermi surfaces in URu{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Yamagami, Hiroshi, E-mail: yamagami@cc.kyoto-su.ac.jp [Department of Physics, Faculty of Science, Kyoto Sangyo University, Kyoto 603-8555 (Japan)

    2011-01-01

    In an itinerant 5f-band model, the antiferromagnetic (AFM) Fermi surfaces of URu{sub 2}Si{sub 2} are reconsidered using a relativistic LAPW method within a local spin-density approximation, especially taking into account the lattice parameters dependent on pressures. The reduction of the z-coordinate of the Si sites results in the effect of flattening the Ru-Si layers of URu{sub 2}Si{sub 2} crystal structure, thus weakening a hybridization/mixing between the U-5f and Ru-4d states in the band structure. Consequently the 5f bands around the Fermi level are more flat in the dispersion with decreasing the z-coordinate, thus producing three closed Fermi surfaces like 'curing-stone', 'rugby-ball' and 'ball'. The origins of de Haas-van Alphen branches can be qualitatively interpreted from the obtained AFM Fermi surfaces.

  5. Properties of the divalent-Yb compound YbAu{sub 2}Si{sub 2} under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kaštil, J.; Míšek, M.; Kamarád, J.; Arnold, Z. [Institute of Physics AS CR, v.v.i., Na Slovance 1999/2, 182 21 Prague 8 (Czech Republic); Vlášková, K. [Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 12116 Prague 2 (Czech Republic); Prchal, J., E-mail: prchal@karlov.mff.cuni.cz [Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 12116 Prague 2 (Czech Republic); Diviš, M.; Doležal, P.; Prokleška, J.; Valenta, J.; Fikáček, J.; Rudajevová, A.; Kriegner, D. [Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Ke Karlovu 5, 12116 Prague 2 (Czech Republic)

    2017-01-15

    Polycrystalline YbAu{sub 2}Si{sub 2} has been prepared by arc melting and a non-standard anisotropic thermal expansion is observed at low temperatures. A non-magnetic Yb{sup 2+} valence state is derived from magnetization, magnetic-susceptibility, heat-capacity and electrical-conductivity measurements in the temperature range from 0.3 to 300 K and at external pressures up to 3.2 GPa. By both experimental and theoretical investigations, YbAu{sub 2}Si{sub 2} is confirmed to be a system with a weak electron-electron correlations and a small electron-phonon interaction. Application of hydrostatic pressure does not reveal any change of state in the range of applied pressures.

  6. Thermal decomposition of (UO{sub 2})O{sub 2}(H{sub 2}O){sub 22H{sub 2}O: Influence on structure, microstructure and hydrofluorination

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R. [Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille (France); Hall de Recherche de Pierrelatte, AREVA NC, BP 16, 26701 Pierrelatte (France); Rivenet, M., E-mail: murielle.rivenet@ensc-lille.fr [Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille (France); Berrier, E. [Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille (France); Waele, I. de [Université de Lille, CNRS, UMR 8516 – LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille (France); Arab, M.; Amaraggi, D.; Morel, B. [Hall de Recherche de Pierrelatte, AREVA NC, BP 16, 26701 Pierrelatte (France); Abraham, F. [Univ. Lille, CNRS, Centrale Lille, ENSCL, Univ. Artois, UMR 8181 - UCCS - Unité de Catalyse et Chimie du Solide, F-59000 Lille (France)

    2017-01-15

    The thermal decomposition of uranyl peroxide tetrahydrate, (UO{sub 2})O{sub 2}(H{sub 2}O){sub 2}.2H{sub 2}O, was studied by combining high temperature powder X-ray diffraction, scanning electron microscopy, thermal analyses and spectroscopic techniques (Raman, IR and {sup 1}H NMR). In situ analyses reveal that intermediates and final uranium oxides obtained upon heating are different from that obtained after cooling at room temperature and that the uranyl precursor used to synthesize (UO{sub 2})O{sub 2}(H{sub 2}O){sub 22H{sub 2}O, sulfate or nitrate, has a strong influence on the peroxide thermal behavior and morphology. The decomposition of (UO{sub 2})O{sub 2}(H{sub 2}O){sub 22H{sub 2}O ex sulfate is pseudomorphic and leads to needle-like shaped particles of metastudtite, (UO{sub 2})O{sub 2}(H{sub 2}O){sub 2}, and UO{sub 3-x}(OH){sub 2x}·zH{sub 2}O, an amorphous phase found in air in the following of (UO{sub 2})O{sub 2}(H{sub 2}O){sub 2} dehydration. (UO{sub 2})O{sub 2}(H{sub 2}O){sub 22H{sub 2}O and the compounds resulting from its thermal decomposition are very reactive towards hydrofluorination as long as their needle-like morphology is kept.

  7. First-principles investigations on the electronic structures of U{sub 3}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tong [College of Information & Communication, Harbin Engineering University, Harbin, 150001 (China); Qiu, Nianxiang [Engineering Laboratory of Specialty Fibers and Nuclear Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, 315201 (China); Wen, Xiaodong [State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, P.O. Box 165, Taiyuan, Shanxi, 030001 (China); Synfuels China, 100195 (China); Tian, Yonghui [College of Life Science, Sichuan University, Chengdu, Sichuan, 610064 (China); He, Jian [Center for Translational Medicine, Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, 116023 (China); Luo, Kan; Zha, Xianhu; Zhou, Yuhong; Huang, Qing; Lang, Jiajian [Engineering Laboratory of Specialty Fibers and Nuclear Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, 315201 (China); Du, Shiyu, E-mail: dushiyu@nimte.ac.cn [Engineering Laboratory of Specialty Fibers and Nuclear Energy Materials, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, 315201 (China)

    2016-02-15

    U{sub 3}Si{sub 2} has been widely utilized as a high-power uranium fuel for research reactors due to its high density of uranium. However, theoretical investigations on this material are still scarce up to now. For this reason, the computational study via density functional theory (DFT) is performed on the U{sub 3}Si{sub 2} compound in this work. The properties of U{sub 3}Si{sub 2}, such as stable crystalline structures, density of states, charge distributions, formation energy of defects, as well as the mechanical properties are explored. The calculation results show that the U{sub 3}Si{sub 2} material is metallic and brittle, which is in good agreement with the previous experimental observations. The formation energy of uranium vacancy defect is predicted to be the lowest, similar with that of UN. The theoretical investigation of this work is expected to provide new insight of uranium silicide fuels.

  8. Si{sub 2}Sb{sub 2}Te{sub 5} phase change material studied by an atomic force microscope nano-tip

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yanbo; Min Guoquan; Zhang Jing; Zhou Weimin; Wan Yongzhong; Zhang Jianping; Li Xiaoli [Laboratory of Nano-Technology, Shanghai Nanotechnology Promotion Center, Shanghai 200237 (China); Zhang Ting; Niu Xiaoming; Song Zhitang; Feng Songlin, E-mail: liuyanbo@snpc.org.c, E-mail: tzhang@mail.sim.ac.c [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2009-06-01

    The Si{sub 2}Sb{sub 2}Te{sub 5} phase change material has been studied by applying a nano-tip (30 nm in diameter) on an atomic force microscopy system. Memory switching from a high resistance state to a low resistance state has been achieved, with a resistance change of about 1000 times. In a typical I-V curve, the current increases significantly after the voltage exceeds approx4.3 V. The phase transformation of a Si{sub 2}Sb{sub 2}Te{sub 5} film was studied in situ by means of in situ X-ray diffraction and temperature dependent resistance measurements. The thermal stability of Si{sub 2}Sb{sub 2}Te{sub 5} and Ge{sub 2}Sb{sub 2}Te{sub 5} was characterized and compared as well.

  9. Elastic response of URu{sub 2}Si{sub 2} under high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Yanagisawa, Tatsuya; Mombetsu, Shota; Hidaka, Hiroyuki; Amitsuka, Hiroshi [Dept. of Physics, Hokkaido Univ., Sapporo (Japan); Akatsu, Mitsuhiro [Grad. School of Science and Technology, Niigata Univ., Niigata (Japan); Yasin, S.; Zherlitsyn, S.; Wosnitza, J. [Hochfeld-Magnetlabor Dresden, Helmholtz-Zentrum Dresden-Rossendorf and TU Dresden, Dresden (Germany); Huang, K.; Janoschek, M.; Maple, M.B. [Dept. of Physics, Univ. of California, San Diego, La Jolla (United States)

    2015-07-01

    We have measured the elastic constants, C{sub 44}, C{sub 66}, (C{sub 11}-C{sub 12})/2 in URu{sub 2}Si{sub 2} by means of high-frequency ultrasonic measurements in pulsed magnetic fields up to 68.7 T in a wide temperature range from 1.5 to ∝120 K. We found a reduction of (C{sub 11}-C{sub 12})/2 for magnetic field H parallel [001] that appears only in the temperature and magnetic field region in which URu{sub 2}Si{sub 2} exhibits a heavy-electron state and hidden order. This change in (C{sub 11}-C{sub 12})/2 appears to be a response of the 5f electrons to an orthorhombic and volume conservative strain field ε{sub xx}-ε{sub yy} with Γ{sub 3} symmetry. The lattice instability is likely related to a symmetry-breaking band instability that arises due to the hybridization of the localized 5f electrons with the conduction electrons and is probably linked to the hidden-order parameter of this compound. Recent progress obtained by our measurements of the transverse ultrasonic modes C{sub 44} and C{sub 66} will also be discussed.

  10. Lithium Superionic Conductor Li{sub 9.42}Si{sub 1.02}P{sub 2.1}S{sub 9.96}O{sub 2.04} with Li{sub 10}GeP{sub 2}S{sub 12}-Type Structure in the Li{sub 2}S–P{sub 2}S{sub 5}–SiO{sub 2} Pseudoternary System: Synthesis, Electrochemical Properties, and Structure–Composition Relationships

    Energy Technology Data Exchange (ETDEWEB)

    Hori, Satoshi [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama (Japan); Suzuki, Kota; Hirayama, Masaaki [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama (Japan); Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama (Japan); Kato, Yuki [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama (Japan); Battery Research Division, Higashifuji Technical Center, Toyota Motor Corporation, Susono, Shizuoka (Japan); Battery AT, Advanced Technology 1, Toyota Motor Europe NV/SA, Zaventem (Belgium); Kanno, Ryoji, E-mail: kanno@echem.titech.ac.jp [Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama (Japan); Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama (Japan)

    2016-12-07

    Lithium superionic conductors with the Li{sub 10}GeP{sub 2}S{sub 12} (LGPS)-type structure are promising materials for use as solid electrolytes in the next-generation lithium batteries. A novel member of the LGPS family, Li{sub 9.42}Si{sub 1.02}P{sub 2.1}S{sub 9.96}O{sub 2.04} (LSiPSO), and its solid solutions were synthesized by quenching from 1273 K in the Li{sub 2}S–P{sub 2}S{sub 5}–SiO{sub 2} pseudoternary system. The material exhibited an ionic conductivity as high as 3.2 × 10{sup −4} S cm{sup −1} at 298 K, as well as the high electrochemical stability to lithium metal, which was improved by the introduction of oxygen into the LGPS-type structure. An all-solid-state cell with a lithium metal anode and LSiPSO as the separator showed excellent performance with a high reversibility of 100%. Thus, oxygen doping is an effective way of improving the electrochemical stability of LGPS-type structure.

  11. Study of the magnetic properties of CeCu{sub 2}(Si{sub 1-x}Ge{sub x}){sub 2} by means of neutron scattering; Untersuchung der magnetischen Eigenschaften von CeCu{sub 2}(Si{sub 1-x}Ge{sub x}){sub 2} mittels Neutronenstreuung

    Energy Technology Data Exchange (ETDEWEB)

    Faulhaber, Enrico

    2008-07-01

    In 1979 the first heavy-fermion superconductor CeCu{sub 2}Si{sub 2} was discovered by Steglich et al. The system is near a quantum critical point (QCP), where the magnetic order is just suppressed. The distance to the QCP can be varied with hydrostatic pressure as well as by germanium substitution on the silicon site. Next to the superconductivity in CeCu{sub 2}Si{sub 2} one finds distinct magnetic phases while increasing the germanium content. CeCu{sub 2}Si{sub 2} shows a magnetic order of a spin-density-type below T{sub N}-0.8 K, whereas the heavy fermion system CeCu{sub 2}Ge{sub 2} orders below T{sub N}=4.1 K as an antiferromagnet. The focus of this thesis is on neutron-diffraction in the system CeCu{sub 2}(Si{sub 1-x}Ge{sub x}){sub 2}. Starting with a sample with a high germanium content of x=0.45, the magnetic structures are investigated in detail. Following a step-by-step approach, samples with reduced x are investigated subsequently to figure out the properties of pure CeCu{sub 2}Si{sub 2}, which were not accessible before. Furthermore, the complex interaction between magnetism and superconductivity is investigated in detail. Using a specially designed setup, the ac-susceptibility could be recorded simultaneously during the neutron diffraction experiments. Due to the direct correlation between antiferromagnetic signals and diamagnetic features, the microscopic coexistence of superconductivity and magnetic order can be ruled out. Instead, a phase separation on the microscopic scale is found. (orig.)

  12. Properties of lithium disilicate reinforced with ZrO{sub 2} (3mol%Y{sub 2}O{sub 3}; Propriedades de dissilicato de litio reforcado com ZrO{sub 2} (3mol%Y{sub 2}O{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Alves, M.F.R.P.; Cossu, C.M.F.A.; Santos, C., E-mail: manuelfellipealves@gmail.com [Universidade do Estado do Rio de Janeiro (UERJ), Resende, RJ (Brazil). Faculdade de Tecnologia; Silva, C.L.M. [Centro Universitario de Volta Redonda (UniFOA), Volta Redonda, RJ (Brazil); Simba, B.G. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Guaratingueta, SP (Brazil). Faculdade de Engenharia; Fernandes, M.H.F. [Universidade de Aveiro (Portugal)

    2016-07-01

    The new generation of dental ceramics based on lithium disilicate, Li{sub 2}Si{sub 2}O{sub 5}, allows the production of restorative prosthetic with reduced times compared to alumina and / or zirconia (Y-TZP). A great limitation of their use is related low fracture strength of such glass-ceramics, which reduces their use in unit fixed prosthesis. In this work, lithium disilicate reinforced with 10% ZrO{sub 2} (3-mol% Y{sub 2}O{sub 3}) is characterized by relative density, crystalline phase, hardness, fracture toughness and microstructural aspects. Lithium metasilicate and tetragonal zirconia, prior to heat treatment. After thermal treatment under vacuum at 840 deg C-8min the lithium metasilicate is converted to lithium disilicate as the ZrO{sub 2} phase remains in the tetragonal structure. This maintenance of the tetragonal phase ensures the material a good fracture toughness, reaching average values near 2MPam{sup 1/2}, while the average hardness of 600HV. Morphological analysis of the samples indicates that ZrO{sub 2} particles are uniformly dispersed in the matrix composed of high aspect ratio lithium disilicate grains, which contributes to the results presented.. A critical analysis of the performance of toughening mechanisms such as cracks deflection, phase transformation of ZrO{sub 2} (T-M), residual stress between the matrix and the reinforcement are presented, discussed and compared with other ceramic materials used in dentistry restorer. (author)

  13. Effects of thermal oxidation duration on the structural and electrical properties of Nd{sub 2}O{sub 3}/Si system

    Energy Technology Data Exchange (ETDEWEB)

    Hetherin, Karuppiah; Ramesh, S.; Wong, Yew Hoong [University of Malaya, Department of Mechanical Engineering, Faculty of Engineering, Kuala Lumpur (Malaysia)

    2017-08-15

    A study on the growth, structure and electrical properties of Nd{sub 2}O{sub 3} was carried out experimentally on RF sputtered thin film on Si followed by thermal oxidation at 700 C at different oxidation durations (5, 10, 15 and 20 min). The structural and chemical properties were studied by X-ray diffraction analysis, Fourier transform infrared analysis, Raman analysis and high resolution transmission electron microscopy analysis. The formation of cubic-Nd{sub 2}O{sub 3}, orthorhombic-Nd{sub 2}Si{sub 2}O{sub 7}, monoclinic-SiO{sub 2}, tetragonal-SiO{sub 2} and hexagonal-SiO{sub 2} was detected. A single interfacial layer was detected for the sample oxidized at 15 min and double interfacial layers were detected for the samples oxidized at 5, 10 and 20 min. The sample oxidized at 15 min possessed the best electrical properties which were attributed by the highest Nd{sub 2}O{sub 3} intensity, largest SiO{sub 2} crystallite structure, thinnest interfacial and oxide layer, highest barrier height, lowest effective oxide charges, slow trap density and average interface trap density. (orig.)

  14. New Ce{sup 3+} doped Ca{sub 2}YMgScSi{sub 3}O{sub 12} garnet ceramic phosphor for white LED converters

    Energy Technology Data Exchange (ETDEWEB)

    Khaidukov, N. [Kurnakov Institute of General and Inorganic Chemistry, Russian Academy of Sciences, Moscow (Russian Federation); Zorenko, Yu.; Zorenko, T.; Iskaliyeva, A.; Paprocki, K. [Institute of Physics, Kazimierz Wielki University Bydgoszcz (Poland); Zhydachevskii, Y.; Suchocki, A. [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland); Deun, R. van [L3 - Luminescent Lanthanide Lab, Department of Inorganic and Physical Chemistry, Ghent University (Belgium); Batentschuk, M. [Department of Materials Science and Engineering VI, Institute of Materials for Energy and Electronic Technology (i-IMEET), University of Erlangen-Nuremberg, Erlangen (Germany)

    2017-05-15

    The results on crystallization and investigation of the luminescent properties of a new prospective ceramic phosphor based on the Ce{sup 3+} doped Ca{sub 2}YMgScSi{sub 3}O{sub 12} silicate garnet are presented for the first time in this work. The luminescent properties of Ca{sub 2}YMgScSi{sub 3}O{sub 12}:Ce were compared with the properties of the reference Ca{sub 3}Sc{sub 2}Si{sub 3}O{sub 12}:Ce ceramic sample. Without any doubt, the results of this research can be suitable for the development of a new generation of white converters based on the Ca{sup 2+}-Si{sup 4+} garnet compounds. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Ternary silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and quaternary derivatives RERh{sub 4}Si{sub 2-x}Sn{sub x} (RE = Y, Nd, Sm, Gd-Lu) - structure, chemical bonding, and solid state NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vosswinkel, Daniel; Benndorf, Christopher; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Eckert, Hellmut [Muenster Univ. (Germany). Inst. fuer Physikalische Chemie; Sao Paulo Univ., Sao Carlos (Brazil). Inst. of Physics; Matar, Samir F. [Bordeaux Univ., CNRS, ICMCB, UPR 9048, Pessac (France)

    2016-11-01

    The silicides ScIr{sub 4}Si{sub 2} and RERh{sub 4}Si{sub 2} (RE = Sc, Y, Tb-Lu) and silicide stannides RERh{sub 4}Si{sub 2-x}Sn{sub x}(RE = Y, Nd, Sm, Gd-Lu) were synthesized from the elements by arc-melting and subsequent annealing. The new compounds crystallize with the orthorhombic YRh{sub 4}Ge{sub 2} type structure, space group Pnma. They were characterized by X-ray powder patterns and several structures were refined from single crystal X-ray diffractometer data. The main structural motifs of this series of silicides are tricapped trigonal prisms formed by the transition metal and rare earth atoms. One of the two crystallographically independent silicon sites allows for formation of solid solutions with tin, exemplarily studied for ErRh{sub 4}Si{sub 2-x}Sn{sub x}. Electronic structure calculations reveal strong covalent Rh-Si bonding as the main stability factor. Multinuclear ({sup 29}Si, {sup 45}Sc, and {sup 89}Y) magic-angle spinning (MAS) NMR spectra of the structure representatives with diamagnetic rare-earth elements (Sc, Y, Lu) are found to be consistent with the crystallographic data and specifically confirm the selective substitution of Sn in the Si2 sites in the quaternary compounds YRh{sub 4}SiSn and LuRh{sub 4}SiSn.

  16. In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructured nanoparticles with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Xing, Yonglei [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Que, Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Yin, Xingtian; He, Zuoli; Liu, Xiaobin; Yang, Yawei; Shao, Jinyou [Electronic Materials Research Laboratory, International Center for Dielectric Research, Key Laboratory of the Ministry of Education, School of Electronic and Information Engineering, State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Kong, Ling Bing, E-mail: ELBKong@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

    2016-11-30

    Highlights: • Visible-light photocatalytic activities of the nanostructured In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructures were studied. • Effect of In{sub 2}O{sub 3} content on the photocatalytic activity of the In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructure was evaluated. • 0.1In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} heterostructure photocatalyst shows a superior photocatalytic activity. • Based on Mott-Schottky analysis and active species detection, a mechanism for the separation of photogenerated carriers is proposed. • The effective separation process of the photogenerated electron-hole pairs was testified by photocurrent test. - Abstract: In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7} composite photocatalysts with various contents of cubic In{sub 2}O{sub 3} nanoparticles were fabricated by using impregnation method. A thriving modification of Bi{sub 2}Sn{sub 2}O{sub 7} by an introduction of In{sub 2}O{sub 3} was confirmed by using X-ray diffraction, UV–vis diffuse reflectance spectrometry, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The samples composed of hybrids of In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} exhibited a much higher photocatalytic activity for the degradation of Rhodamine B under visible light, as compared with pure In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} nanoparticles. Optimized composition of the composite photocatalysts was 0.1In{sub 2}O{sub 3}/Bi{sub 2}Sn{sub 2}O{sub 7}, which shows a rate constant higher than those of pure In{sub 2}O{sub 3} and Bi{sub 2}Sn{sub 2}O{sub 7} by 4.06 and 3.21 times, respectively. Based on Mott-Schottky analysis and active species detection, the photoexcited electrons in the conduction band of In{sub 2}O{sub 3} and the holes in the valence band of Bi{sub 2}Sn{sub 2}O{sub 7} participated in reduction and oxidation reactions, respectively. Hence, ·OH, ·O{sub 2}{sup −} and h

  17. Structure and crystallization of B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Yin, E-mail: zjbcy@126.co [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Xiao Hanning [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Shuguang Chen; Tang Bingzhong [College of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China)

    2009-05-01

    B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} glasses with different B{sub 2}O{sub 3}/Al{sub 2}O{sub 3} ratios of 0.4-1.3 were prepared by the melting-quenching method at 1500-1600 deg. C for 2 h. Fragility index F was used to estimate the glass-forming ability. The infrared (IR) absorption curves and differential scanning calorimetry (DSC) curves of the glasses have been investigated for estimating the influence of the B{sub 2}O{sub 3}/Al{sub 2}O{sub 3} ratio on glass structure and crystallization of the B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} glass system. The crystallization kinetics of the glasses were described by activation energy (E) for crystallization and calculated by the Kissinger method. X-ray diffraction (XRD) and SEM analyses were also used to describe the types and morphologies of the crystals precipitated from the B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} glasses. The results show that with the increase of B{sub 2}O{sub 3}/Al{sub 2}O{sub 3} ratio, glass stability improves and the trend of crystallization decreases relatively. However, when the B{sub 2}O{sub 3}/Al{sub 2}O{sub 3} ratio reaches 1.3, boron-abnormal phenomenon appears and results in the raising trend of crystallization. Rod-like crystals of Al{sub 4}B{sub 2}O{sub 9} and Al{sub 20}B{sub 4}O{sub 36} were observed in the crystallized samples.

  18. Routes for synthesis and characterization of the Lu{sub 1-x}Ca{sub x}Cu{sub 2}Si{sub 2} series

    Energy Technology Data Exchange (ETDEWEB)

    Radaelli, Matheus; Piva, Mario Moda; Christovam, Denise S.; Ribeiro, Ana L.A.; Pagliuso, Pascoal G., E-mail: goiba@ifi.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2016-07-01

    Full text: New materials design always plays an important role in condensed matter physics. When CeCu{sub 2} Si{sub 2} was discovered,a new front in the field of superconductivity on strongly correlated materials started and led to the discovery of many classes of related materials. In such materials, the interplay between magnetism (affected by the hybridization strength between local f electrons and conduction electrons) and heavy-fermion superconductivity is still a matter of controversy and intense studies. Based on these materials, one can explore the structural and stoichiometric similarities among the several classes of related compounds to develop routes for new materials design of novel heavy fermion superconductors.The non-magnetic reference compound LuCu{sub 2}Si{sub 2} crystallizes in a ThCr{sub 2}Si{sub 2}-type structure (I4/mmm) and presents a metallic-like temperature dependent resistivity [2]. As such, it can be used as a based compound to search for 3d-based magnetic analogs of CeCu{sub 2}Si{sub 2}. In this work, we have performed Lu-site substitutions (Ba,Sr,Ca) in order to tune the orbital differentiation of the Cu 3d bands and potentially induce magnetism. We will discuss experiments of x-ray powder diffraction, elemental analysis (EDS, WDS), resistivity and DC magnetic susceptibility on single crystals Lu{sub 1-x}Ca{sub x}Cu{sub 2}Si{sub 2} (X{sub nominal} = 0, 0.3 and 0.5) grown from Tin-flux and evaluate the efficiency of different kinds of dopant to induce magnetism. (author)

  19. Fluorocarbon based atomic layer etching of Si{sub 3}N{sub 4} and etching selectivity of SiO{sub 2} over Si{sub 3}N{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chen [Department of Physics, and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu [Department of Materials Science and Engineering, and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Lai, Chiukin Steven; Hudson, Eric A. [Lam Research Corporation, 4400 Cushing Parkway, Fremont, California 94538 (United States)

    2016-07-15

    Angstrom-level plasma etching precision is required for semiconductor manufacturing of sub-10 nm critical dimension features. Atomic layer etching (ALE), achieved by a series of self-limited cycles, can precisely control etching depths by limiting the amount of chemical reactant available at the surface. Recently, SiO{sub 2} ALE has been achieved by deposition of a thin (several Angstroms) reactive fluorocarbon (FC) layer on the material surface using controlled FC precursor flow and subsequent low energy Ar{sup +} ion bombardment in a cyclic fashion. Low energy ion bombardment is used to remove the FC layer along with a limited amount of SiO{sub 2} from the surface. In the present article, the authors describe controlled etching of Si{sub 3}N{sub 4} and SiO{sub 2} layers of one to several Angstroms using this cyclic ALE approach. Si{sub 3}N{sub 4} etching and etching selectivity of SiO{sub 2} over Si{sub 3}N{sub 4} were studied and evaluated with regard to the dependence on maximum ion energy, etching step length (ESL), FC surface coverage, and precursor selection. Surface chemistries of Si{sub 3}N{sub 4} were investigated by x-ray photoelectron spectroscopy (XPS) after vacuum transfer at each stage of the ALE process. Since Si{sub 3}N{sub 4} has a lower physical sputtering energy threshold than SiO{sub 2}, Si{sub 3}N{sub 4} physical sputtering can take place after removal of chemical etchant at the end of each cycle for relatively high ion energies. Si{sub 3}N{sub 4} to SiO{sub 2} ALE etching selectivity was observed for these FC depleted conditions. By optimization of the ALE process parameters, e.g., low ion energies, short ESLs, and/or high FC film deposition per cycle, highly selective SiO{sub 2} to Si{sub 3}N{sub 4} etching can be achieved for FC accumulation conditions, where FC can be selectively accumulated on Si{sub 3}N{sub 4} surfaces. This highly selective etching is explained by a lower carbon consumption of Si{sub 3}N{sub 4} as compared to Si

  20. Improvement of photoluminescence intensity of Ce-doped Y{sub 3}Al{sub 5}O{sub 12} phosphor by Si{sub 3}N{sub 4} addition

    Energy Technology Data Exchange (ETDEWEB)

    Shyu, Jiin-Jyh, E-mail: jjshyu@ttu.edu.tw; Yang, Chia-Wei

    2017-06-01

    Yttrium aluminum garnet (Y{sub 3}Al{sub 5}O{sub 12}, YAG) has been widely used as a host for luminescent ions. The present paper describes the effects of Si{sub 3}N{sub 4} addition on the formation and photoluminescence properties of the Ce-doped YAG yellow phosphors. Phosphor powders with the nominal compositions of Y{sub 2.95}Ce{sub 0.05}Al{sub 5-m}Si{sub m}O{sub 12-m}N{sub m} (m = 0–0.6) were prepared by calcining the mixed raw materials at 1500 °C in nitrogen atmosphere. X-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscopy equipped with an energy dispersive x-ray spectrometer were used to characterize the structure of the calcined powders. The photoluminescence properties were measured with fluorescence spectrophotometry. It was found that in the range of m = 0–0.27, single phase YAG solid solution (s.s.) in which the Y, Al, and O sites are partially occupied by Ce, Si, and N ions, respectively. The nitrogen ions do not distribute homogeneously over the YAG lattice. The tendency to bond with nitrogen ion for the cations is (Y, Ce) > Si > Al. With the increase in the Si{sub 3}N{sub 4} content, the increase in both the Ce{sup 3+}/(Ce{sup 3+} + Ce{sup 4+}) ratio and the Ce-N bonds improve the intensity of the photoluminescent emission. At m = 0.27, the emission intensity reaches a maximum which is about 2.5 and 1.6 times of that for the Si{sub 3}N{sub 4}-free composition (m = 0) calcined in air and nitrogen, respectively. When the Si{sub 3}N{sub 4} content (m) is higher than 0.27, the emission intensity decreases due to the existence of residual Si{sub 3}N{sub 4} phase. - Highlights: • Addition of Si{sub 3}N{sub 4} can increase the emission intensity of YAG:Ce up to 2.5 times. • Increase in the Ce{sup 3+}/Ce{sup 4+} ratio and the number of Ce-N bonds improve the emission. • The tendency to bond with nitrogen ion for cations in YAG:Ce is (Y, Ce) > Si > Al. • The incomplete dissolution

  1. Removal of diethyl phthalate from water solution by adsorption, photo-oxidation, ozonation and advanced oxidation process (UV/H{sub 2}O{sub 2}, O{sub 3}/H{sub 2}O{sub 2} and O{sub 3}/activated carbon)

    Energy Technology Data Exchange (ETDEWEB)

    Medellin-Castillo, Nahum A. [Centro de Investigacion y Estudios de Posgrado, Facultad de Ingenieria, Universidad Autonoma de San Luis Potosi, Av. Dr. M. Nava No.6, San Luis de Potosi, 78290 (Mexico); Ocampo-Perez, Raul [Centro de Investigacion y Estudios de Posgrado, Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, San Luis Potosi, 78290 (Mexico); Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Granada, 18071, Granada (Spain); Leyva-Ramos, Roberto [Centro de Investigacion y Estudios de Posgrado, Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, San Luis Potosi, 78290 (Mexico); Sanchez-Polo, Manuel [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Granada, 18071, Granada (Spain); Rivera-Utrilla, Jose, E-mail: jrivera@ugr.es [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Granada, 18071, Granada (Spain); Mendez-Diaz, Jose D. [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Granada, 18071, Granada (Spain)

    2013-01-01

    The objective of this work was to compare the effectiveness of conventional technologies (adsorption on activated carbon, AC, and ozonation) and technologies based on advanced oxidation processes, AOPs, (UV/H{sub 2}O{sub 2}, O{sub 3}/AC, O{sub 3}/H{sub 2}O{sub 2}) to remove phthalates from aqueous solution (ultrapure water, surface water and wastewater). Diethyl phthalate (DEP) was chosen as a model pollutant because of its high water solubility (1080 mg/L at 293 K) and toxicity. The activated carbons showed a high adsorption capacity to adsorb DEP in aqueous solution (up to 858 mg/g), besides the adsorption mechanism of DEP on activated carbon is governed by dispersive interactions between {pi} electrons of its aromatic ring with {pi} electrons of the carbon graphene planes. The photodegration process showed that the pH solution does not significantly affect the degradation kinetics of DEP and the first-order kinetic model satisfactorily fitted the experimental data. It was observed that the rate of decomposition of DEP with the O{sub 3}/H{sub 2}O{sub 2} and O{sub 3}/AC systems is faster than that with only O{sub 3}. The technologies based on AOPs (UV/H{sub 2}O{sub 2}, O{sub 3}/H{sub 2}O{sub 2}, O{sub 3}/AC) significantly improve the degradation of DEP compared to conventional technologies (O{sub 3}, UV). AC adsorption, UV/H{sub 2}O{sub 2}, O{sub 3}/H{sub 2}O{sub 2}, and O{sub 3}/AC showed a high yield to remove DEP; however, the disadvantage of AC adsorption is its much longer time to reach maximum removal. The best system to treat water (ultrapure and natural) polluted with DEP is the O{sub 3}/AC one since it achieved the highest DEP degradation and TOC removal, as well as the lower water toxicity. -- Highlights: Black-Right-Pointing-Pointer Activated carbons showed a high adsorption capacity (up to 858 mg/g) to remove DEP. Black-Right-Pointing-Pointer The pH solution did not significantly affect the photodegradation kinetics of DEP. Black

  2. Glass formation and properties of glasses in V/sub 2/O/sub 5/-B/sub 2/O/sub 3/-P/sub 2/O/sub 5/ system

    Energy Technology Data Exchange (ETDEWEB)

    Sedmale, G P; Vajvad, Ya A; Arkhipova, S E; Laukmanis, L A

    1987-01-01

    The glass formation in the system V/sub 2/O/sub 5/-B/sub 2/O/sub 3/-P/sub 2/O/sub 5/ and the properties of the obtained glasses have been studied by methods including that of the mathematical design and the treatment of the obtained data on ECM. The glass formation region is limited by the molar content of V/sub 2/O/sub 5/ 30-80%, B/sub 2/O/sub 3/ 0-45%, P/sub 2/O/sub 5/ 20-65%. The chemical stability data show that at the molar content of V/sub 2/O/sub 5/ 45-50% the transfer of vanadium from the state of the modificator to the glass-forming agent takes place. For the studied glasses the electron mechanism of conductivity is the dominating one.

  3. High-field study of the heavy-fermion material URu{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Scheerer, Gernot Werner; Knafo, William; Ballon, Geraldine; Jaudet, Cyril; Proust, Cyril; Vignolles, David [Laboratoire National des Champs Magnetiques Intenses, UPR 3228, CNRS- UJF-UPS-INSA, Toulouse (France); Aoki, Dai; Flouquet, Jacques [Institut Nanosciences et Cryogenie, SPSMS, CEA-Grenoble (France); Mari, Alain [Laboratoire de Chimie de Coordination, Toulouse (France)

    2012-07-01

    URu{sub 2}Si{sub 2} is known for its ''hidden-order'' state below T{sub 0} = 17.5 K, where the order parameter is still not identified. A magnetic field along the c-axis induces a cascade of low-temperature phase transitions between 35 and 39 T from the ''hidden order'' to a polarized paramagnetic state. We have performed electrical transport and magnetization measurements in pulsed magnetic fields on ultra clean URu{sub 2}Si{sub 2} samples. We established the H-T-phase diagram for H parallel c in extended scales up to 60 T and 60 K. The vanishing of a high-temperature crossover at around 40-50 K, presumably related to intersite electronic correlations, precedes the polarization of the magnetic moments, as well as the destabilization of the ''hidden-order'' phase. Strongly sample-quality dependent magnetoresistivity confirms the Fermi surface reconstructions in a high magnetic field along c and at T{sub 0}. Shubnikov-de Haas quantum oscillations are also presented.

  4. Polyaniline as a cathode for O/sub 2/ reduction - kinetics of the reaction with H/sub 2/O/sub 2/ and use of the polymer in a model H/sub 2/O/sub 2/ fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Doubova, L.; Mengoli, G.; Musiani, M.M.; Valcher, S.

    1989-03-01

    Oxygen reduction at a polyaniline cathode occurs in aqueous sulfuric acid through a chemical-electrochemical route which involves the intermediate oxidation of leucoemeraldine to emeraldine with the formation of H/sub 2/O/sub 2/. This paper specifically deals with the conversion of leucoemeraldine to emeraldine by H/sub 2/O/sub 2/ whose kinetics, apparently second order on the charge exchange, are similar to those found for the reaction with O/sub 2/, although they occur at lower rate. The catalytic four electron O/sub 2/ reduction mediated by the Fe(III)/Fe(II) couple which decomposes H/sub 2/O/sub 2/ is not fully achieved. However, polyaniline proved to be a reliable cathode for O/sub 2/, sustaining the working of a model H/sub 2//O/sub 2/ fuel cell.

  5. Activity of RE/sub 2/O/sub 3/ in liquid La/sub 2/O/sub 3/-Al/sub 2/O/sub 3/-CaF/sub 2/ and Ce/sub 2/O/sub 3/-CaO-CaF/sub 2/ slags

    International Nuclear Information System (INIS)

    Changzhen, W.; Shuqing, Y.; Qieng, D.

    1985-01-01

    In the course of electro-slag refining, if the slag contains rare earth oxides, the amount of rare earth introduced to the steel depends on the composition of the slag and other conditions. The main aim of this investigation is to study the activity of RE/sub 2/O/sub 3/ in the electro-slags of various compositions. One is the La/sub 2/O/sub 3/-CaO-CaF/sub 2/ ternary slag system and the other is the Ce/sub 2/O/sub 3/-CaO-CaF/sub 2/ slag system. The iso-activity diagram for RE/sub 2/O/sub 3/ and the liquid boundary for slags system were estimated

  6. Al{sub 2}O{sub 3} reinforced nanoparticle ZrO{sub 2} (3at%?Y{sub 2}O{sub 3}); Al{sub 2}O{sub 3} reforcado com nanoparticulas de ZrO{sub 2}(3%mol Y{sub 2}O{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Cossu, C.M.F.A.; Alves, M.F.R.P.; Campos, L.Q.B.; Magnago, R.O.; Santos, C., E-mail: caio.cossu@usp.br [Universidade do Estado do Rio de Janeiro (UERJ), Resende, RJ (Brazil). Faculdade de Tecnologia; Simba, B.G. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Guaratingueta, SP (Brazil). Faculdade de Engenharia

    2016-07-01

    This work developed a composite Al{sub 2}O{sub 3}-based reinforced with nanoparticles of ZrO{sub 2} (Y{sub 2}O{sub 3}), to evaluate the effect of the content of ZrO{sub 2} nanoparticles (Y{sub 2}O{sub 3}) on the mechanical properties. Mixtures containing a matrix of Al{sub 2}O{sub 3} with fractions in weight of 3%, 5%, 10% and 15%, ZrO{sub 2} (Y{sub 2}O{sub 3}), and were mixed in mortar mill. Mixtures received 5% polymeric binder (PVA); and after adding the binder, the material was pressed uniaxially to 50MPa, and then sintered at a temperature of 1600 ° C - 2h. The sintered products were characterized by X-ray diffraction, scanning electron microscopy (SEM), relative density, hardness and fracture toughness. The results of X-ray diffraction showed that Al{sub 2}O{sub 3} and tetragonal ZrO{sub 2} as crystal phases found after sintering. Furthermore, the relative green density of 55% was predominant in the compact; and after sintering, varied depending on the ZrO{sub 2} content, reaching 97% in sintered compositions with 3% ZrO{sub 2} nanoparticles (Y{sub 2O}3). The hardness of the samples showed values of 1670HV and the maximum toughness of 3.2 MPa × m{sup 1/2}, directly influenced by the presence of nanoparticles ZrO{sub 2} uniformly dispersed in the matrix Al{sub 2}O{sub 3}, which results in at least two main mechanisms tenacifiers: transformation of tetragonal-monoclinic phase of zirconia, and compressive residual strain between the two phases present, Al{sub 2}O{sub 3} and tetragonal ZrO{sub 2}. (author)

  7. First-principle study of silicon cluster doped with rhodium: Rh{sub 2}Si{sub n} (n = 1–11) clusters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuai; Luo, Chang Geng; Li, Hua Yang [Department of Physics, Nanyang Normal University, Nanyang 473061 (China); Lu, Cheng, E-mail: lucheng@calypso.cn [Department of Physics, Nanyang Normal University, Nanyang 473061 (China); State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Li, Gen Quan; Lu, Zhi Wen [Department of Physics, Nanyang Normal University, Nanyang 473061 (China)

    2015-06-15

    The geometries, stabilities and electronic properties of rhodium-doped silicon clusters Rh{sub 2}Si{sub n} (n = 1–11) have been systematically studied by using density functional calculations at the B3LYP/GENECP level. The optimized results show that the lowest-energy isomers of Rh{sub 2}Si{sub n} clusters favor three-dimensional structures for n = 2–11. Based on the averaged binding energy, fragmentation energy, second-order energy difference and HOMO-LUMO energy gap, the stabilities of Rh{sub 2}Si{sub n} (n = 1–11) clusters have been analyzed. The calculated results suggest that the Rh{sub 2}Si{sub 6} cluster has the strongest relative stability and the doping with rhodium atoms can reduce the chemical stabilities of Si{sub n} clusters. The natural population and natural electron configuration analysis indicate that there is charge transfer from the Si atoms and 5s orbital of the Rh atoms to the 4d and 5p orbitals of Rh atoms. The analysis of electron localization function reveal that the Si–Si bonds are mainly covalent bonds and the Si–Rh bonds are almost ionic bonds. Moreover, the vertical ionization potential, vertical electron affinity, chemical hardness, chemical potential, vibrational spectrum and polarizability are also discussed. - Highlights: • The geometric structures of Rh{sub 2}Si{sub n} (n = 1–11) clusters are determined. • The stabilities and electronic properties of Rh{sub 2}Si{sub n} clusters are discussed. • The Rh{sub 2}Si{sub 6} cluster has the higher stability than other clusters. • The doped rhodium atoms can reduce the chemical stabilities of Si{sub n} clusters.

  8. Mechanochemical synthesis of magnetically hard anisotropic RFe{sub 10}Si{sub 2} powders with R representing combinations of Sm, Ce and Zr

    Energy Technology Data Exchange (ETDEWEB)

    Gabay, A.M., E-mail: gabay@udel.edu; Hadjipanayis, G.C.

    2017-01-15

    Alloy synthesis consisting of mechanical activation followed by annealing was explored as a method of manufacturing medium-grade permanent magnet materials with a reduced content of the critical rare earth elements. Four R{sub x}Fe{sub 10}Si{sub 2} alloys with R=Sm, Sm{sub 0.7}Zr{sub 0.3}, Sm{sub 0.3}Ce{sub 0.3}Zr{sub 0.4} and Ce{sub 0.6}Zr{sub 0.4} (nominal compositions) were prepared from mixtures of Sm{sub 2}O{sub 3}, CeO{sub 2}, ZrO{sub 2}, Fe{sub 2}O{sub 3} and Si powders in the presence of a reducing agent Ca and a CaO dispersant. The collected alloy particles typically consisted of few joined submicron crystals. For R=Sm, X-ray diffraction analysis reveals a significant amount of the unwanted Th{sub 2}Zn{sub 17}-type compound forming alongside the desired ThMn{sub 12}-type 1:12 compound. A more pure 1:12 phase could be obtained for R=Ce{sub 0.6}Zr{sub 0.4}, but it exhibited a room-temperature coercivity of less than 1 kOe. The most pure 1:12 phase and the highest values of the coercivity (10.8 kOe) and calculated maximum energy product (13.8 MGOe) were obtained for R=Sm{sub 0.7}Zr{sub 0.3} processed at 1150 °C. The calculated maximum energy products of the Sm{sub 0.3}Ce{sub 0.3}Zr{sub 0.4}Fe{sub 10}Si{sub 2} particles, with half of their rare earths constituents represented by the relatively abundant Ce, was 10.1 MGOe. - Highlights: • 30% Zr substitution for Sm improves prospects of the alloys as permanent magnets. • Pure ThMn{sub 12}-type structure could only be obtained in the Zr-substituted alloys. • Obtained powders exhibit better properties than nanocrystalline Sm(Fe,M){sub 12} alloys. • If fully dense, alloy containing only 2.3 at% Sm would energy product of 10 MGOe.

  9. Structure and crystallization kinetics of Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Yin [College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Xiao Hanning [College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China)]. E-mail: zjbcy@126.com; Guo Wenming [College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China); Guo Weiming [College of Materials Science and Engineering, Hunan University, Changsha, Hunan 410082 (China)

    2006-05-15

    The experimental IR (infrared spectra) and differential scanning calorimetry (DSC) curves of Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses, containing 30-60 mol% Bi{sub 2}O{sub 3}, have been investigated in the article. The composition dependence of IR absorption suggests that addition of Bi{sub 2}O{sub 3} results in a change in the short-range order structure of the borate matrix. The increase of Bi{sub 2}O{sub 3} content causes a progressive conversion of [BO{sub 3}] to [BO{sub 4}] units. Bi{sub 2}O{sub 3}, in the form of [BiO{sub 6}] octahedral units, plays the role of glass former. The crystallization kinetics of Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses were described by thermal stability indexes (k {sub gl}, {delta}T), activation energy (E) for crystallization and numerical factors(n, m) depending on the nucleation process and growth morphology, which were calculated by Satava method and the modified Ozawa-Chen method. When Bi{sub 2}O{sub 3} {<=} 45 mol%, the increase of Bi{sub 2}O{sub 3} tends to improve the thermal stabilities of the glasses. In this case, k {sub gl} may be more suitable for estimating the glass thermal stability in above composition range than {delta}T. A further increase of Bi{sub 2}O{sub 3} content will increase the crystallization trends of investigated glasses. Two possible kinds of growth mechanisms were involved in Bi{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses: one-dimensional growth and two-dimensional growth. Moreover, structures of crystallized glasses were observed by X-ray diffraction (XRD). BiBO{sub 3} crystal with special non-linear optical properties can be obtained when Bi{sub 2}O{sub 3} {>=} 50 mol%.

  10. Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon [Hanyang University, 408-2, 4th Engineering Bldg, Sa 3-dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of); Cho, Jeon-Wook; Ryoo, Hee-Suk [Korea Electrotechnology Research Institute, Changwon, Gyungnam 641-120 (Korea, Republic of); Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr [Hanyang University, 408-2, 4th Engineering Bldg, Sa 3-dong, Sangrok-gu, Ansan 426-791 (Korea, Republic of)

    2013-11-15

    Highlights: •The electrical conductivity of PPLP in LN{sub 2} was successfully measured. •Based on the measured value of PPLP, DC field analysis was performed. •The electric field distribution was altered according to the DC applying stages. •The maximum electric field was observed during polarity reversal situation. •DC field analysis is important to determine the optimum design of DC HTS devices. -- Abstract: High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN{sub 2}). Electrical conductivity of PPLP in LN{sub 2} has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN{sub 2} were presented in this paper. Based on the experimental works, DC electric

  11. Dependence of optical properties on the composition of (Ba{sub 1−x−y}Sr{sub x}Eu{sub y})Si{sub 2}O{sub 2}N{sub 2} phosphors for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Mei, E-mail: zmjenny@163.com; He, Xin; Luo, Jianyi; Zeng, Qingguang

    2014-10-15

    BaSi{sub 2}O{sub 2}N{sub 2}: Eu{sup 2+} is an efficient phosphor because of its high quantum yield and quenching temperature. Partial substitution of Ba{sup 2+} by Sr{sup 2+} is the most promising approach to tune the color of phosphors. In this study, a series of (Ba{sub 1−x−y}Sr{sub x}Eu{sub y})Si{sub 2}O{sub 2}N{sub 2} (x = 0.0–0.97, y = 0.00–0.10) phosphors are synthesized via high-temperature solid-state reactions. Intense green to yellow phosphors can be obtained by the partial substitution of the host lattice cation Ba{sup 2+} by either Sr{sup 2+} or Eu{sup 2+}. The luminescent properties and the relationships among the lowest 5d absorption bands, Stokes shifts, centroid shifts, and the splitting of Eu{sup 2+} are studied systematically. Then, based on (Ba{sub 1−x−y}Sr{sub x}Eu{sub y})Si{sub 2}O{sub 2}N{sub 2} phosphors and near-ultraviolet (∼395 nm)/blue (460 nm) InGaN chips, intense green–yellow light emitting diodes (LEDs) and white LEDs are fabricated. (Ba{sub 0.37}Sr{sub 0.60})Si{sub 2}O{sub 2}N{sub 2}: 0.03Eu{sup 2+} phosphors present the highest efficiency, and the luminous efficiency of white LEDs can reach 17 lm/w. These results indicate that (Ba{sub 1−x−y}Sr{sub x}Eu{sub y})Si{sub 2}O{sub 2}N{sub 2} phosphors are promising candidates for solid-state lighting. - Highlights: • The optical properties of Eu{sup 2+} in the (Ba, Sr)Si{sub 2}O{sub 2}N{sub 2} solid-solutions are studied systematically. • The relationship among the lowest 5d absorption bands, Stocks shifts etc.of Eu{sup 2+} are also studied. • The electroluminescent properties of pc-LEDs are studied in details.

  12. Development and characterization of nickel catalysts supported in CeO{sub 2}-ZrO{sub 2}-Al{sub 2}O{sub 3}, CeO{sub 2}-La{sub 2}O{sub 3}-Al{sub 2}O{sub 3} e ZrO{sub 2}-La{sub 2}O{sub 3}-Al{sub 2}O{sub 3} matrixes evaluated for methane reforming reactions; Desenvolvimento e caracterização de catalisadores de níquel suportados em matrizes CeO{sub 2}-ZrO{sub 2}-Al{sub 2}O{sub 3}, CeO{sub 2}-La{sub 2}O{sub 3}-Al{sub 2}O{sub 3} e ZrO{sub 2}-La{sub 2}O{sub 3}-Al{sub 2}O{sub 3} avaliados para as reações de reforma do metano

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, Amanda Jordão de

    2012-07-01

    Nowadays, the methane reforming is large interest industrial for the take advantage of these gas in production the hydrogen and synthesis gas (syngas). Among in the reactions of methane stand of the reactions steam reforming and carbon dioxide reforming of methane. The main catalysts uses in the methane reforming is Ni/Al{sub 2}O{sub 3}. However, the supported-nickel catalyst is susceptible to the deactivation or the destruction by coke deposition. The carbon dissolves in the nickel crystallite and its diffuses through the nickel, leading for formation of the carbon whiskers, which results in fragmentation of the catalyst. Modification of such catalysts, like incorporation of suitable promoters, is desirable to achieve reduction of the methane hydrogenolysis and/or promotion of the carbon gasification. Catalysts 5%Ni/Al{sub 2}O{sub 3} supported on solid solutions formed by ZrO{sub 2}-CeO{sub 2}, La{sub 2}O{sub 3} and CeO{sub 2}-ZrO{sub 2}-La{sub 2}O{sub 3} were prepared, characterized and evaluated in reactions steam and carbon dioxide reforming and partial oxidation of methane with objective the value effect loading solution solid in support. The supports were prepared by co-precipitation method and catalysts were prepared by impregnation method and calcined at 500 deg C. The supports and catalysts were characterized by Nitrogen Adsorption, method -rays diffraction (XRD), X-rays dispersive spectroscopy (XDS), spectroscopy in the region of the ultraviolet and the visible (UV-vis NIR) to and temperature programmed reduction (TPR), Raman Spectroscopy, X-ray absorption spectroscopy and Thermogravimetric Analysis. After all the catalytic reactions check which the addition of solid solution is beneficial for Ni/Al{sub 2}O{sub 3} catalysts and the best catalysts are Ni/CeO{sub 2}-La{sub 2}O{sub 3}-Al{sub 2}O{sub 3}. (author)

  13. 3-D MnNb{sub 2}O{sub 6} nanogears from 1-D Nb{sub 2}O{sub 5} nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Hu Weibing, E-mail: w.hu@tom.com [School of Chemical and Environmental Engineering, Hubei Institute for Nationalities, Enshi 445000 (China); Cui Zhicai [School of Chemical and Environmental Engineering, Hubei Institute for Nationalities, Enshi 445000 (China); Mi Yuanzhu [School of Chemistry and Environmental Engineering, Yangtze University, Nanhuan Road 1, Jingzhou 434023 (China)

    2012-04-16

    Graphical abstract: The geometry morphology of Nb-based nanomaterial evolved from long Nb{sub 2}O{sub 5} nanorods to a mixture of short Nb{sub 2}O{sub 5} nanorods and MnNb{sub 2}O{sub 6} 6-teeth nanogears, and eventually to fully developed pure 3-D nanogears. Highlights: Black-Right-Pointing-Pointer MnNb{sub 2}O{sub 6} nanogears have been generated by a simple solvothermal process when the Mn: Nb ratio was 1:1. Black-Right-Pointing-Pointer MnNb{sub 2}O{sub 6} 6-teeth nanogears accompanied with MnNb{sub 2}O{sub 6} 5-teeth nanogears are got when the Mn:Nb ratio reached 1:2. Black-Right-Pointing-Pointer The nanomaterial consists of nanorods and 6-teeth nanogears at low Mn:Nb molar ratio(1:4). Black-Right-Pointing-Pointer Pure long Nb{sub 2}O{sub 5} nanorods are achieved by only using NbCl{sub 5} - Abstract: MnNb{sub 2}O{sub 6} nanogears have been generated by using mixed NbCl{sub 5} and MnCl{sub 2} at an optimized ratio of 1:1 in a cyclohexanol solvent in a simple solvothermal process. It has shown that the Mn:Nb ratio determines the shape of the products. Detailed characterization by electron microscopy has shown that increasing the Mn{sup +2} concentration during the solvo-thermal synthesis promotes a morphological evolution from relatively long Nb{sub 2}O{sub 5} nanorods to a mixture of short Nb{sub 2}O{sub 5} nanorods and MnNb{sub 2}O{sub 6} 6-teeth nanogears, then to a mixture of short Nb{sub 2}O{sub 5} nanorods and more MnNb{sub 2}O{sub 6} 6-teeth nanogears, then to more and more MnNb{sub 2}O{sub 6} 6-teeth nanogears that are occasionally accompanied with under-developed MnNb{sub 2}O{sub 6} 5-teeth nanogears, and eventually to fully developed pure 3-D nanogears. The driving force for such interesting geometry transformations is attributed to the inclusion of Mn{sup 2+} into the Nb{sub 2}O{sub 5} template at low Mn{sup 2+} concentrations, which introduces internal stresses to the Nb{sub 2}O{sub 5} nanorods. At high Mn{sup 2+} concentrations, close to the

  14. Raman active high energy excitations in URu{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Buhot, Jonathan [Laboratoire Matériaux et Phénomènes Quantiques, UMR 7162 CNRS, Université Paris Diderot - Paris 7, Bât. Condorcet, 75205 Paris Cedex 13 (France); High Field Magnet Laboratory (HFML - EMFL), Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525 ED Nijmegen (Netherlands); Gallais, Yann; Cazayous, Maximilien; Sacuto, Alain [Laboratoire Matériaux et Phénomènes Quantiques, UMR 7162 CNRS, Université Paris Diderot - Paris 7, Bât. Condorcet, 75205 Paris Cedex 13 (France); Piekarz, Przemysław [Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakòw (Poland); Lapertot, Gérard [Université Grenoble Alpes, INAC-SPSMS, F-38000 Grenoble (France); CEA, INAC-SPSMS, F-38000 Grenoble (France); Aoki, Dai [Université Grenoble Alpes, INAC-SPSMS, F-38000 Grenoble (France); CEA, INAC-SPSMS, F-38000 Grenoble (France); Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Méasson, Marie-Aude, E-mail: marie-aude.measson@univ-paris-diderot.fr [Laboratoire Matériaux et Phénomènes Quantiques, UMR 7162 CNRS, Université Paris Diderot - Paris 7, Bât. Condorcet, 75205 Paris Cedex 13 (France)

    2017-02-01

    We have performed Raman scattering measurements on URu{sub 2}Si{sub 2} single crystals on a large energy range up to ∼1300 cm{sup −1} and in all the Raman active symmetries as a function of temperature down to 15 K. A large excitation, active only in the E{sub g} symmetry, is reported. It has been assigned to a crystal electric field excitation on the Uranium site. We discuss how this constrains the crystal electric field scheme of the Uranium ions. Furthermore, three excitations in the A{sub 1g} symmetry are observed. They have been associated to double Raman phonon processes consistently with ab initio calculations of the phonons dispersion.

  15. On the mechanisms of titanium particle reactions in O{sub 2}/N{sub 2} and O{sub 2}/Ar atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Andrzejak, Timothy A.; Shafirovich, Evgeny; Varma, Arvind [School of Chemical Engineering, Purdue University, West Lafayette, IN (United States)

    2009-02-15

    Combustion of titanium particles in air may potentially be used for the in situ synthesis of nanoscale TiO{sub 2} particles, which can photocatalytically degrade chemical and biological air pollutants. The knowledge of Ti particle reactions in O{sub 2}-containing atmospheres is required to develop this method. In the present work, large ({proportional_to}3 mm) single Ti particles were heated by a laser in O{sub 2}/N{sub 2} and O{sub 2}/Ar environments. High-speed digital video recording, thermocouple measurements and quenching at different stages of the process were used for diagnostics. Analysis of the obtained temperature-time curves and quenched particles does not show a significant influence of nitrogen on the oxidation of solid Ti. In all experiments, noticeable surface oxidation started at temperatures between {proportional_to}850 and {proportional_to}950 C, leading to a sharp temperature rise at {proportional_to}1400 C. During prolonged heating at the Ti melting point (1670 C), a liquid TiO{sub 2} bead formed and, after an induction period, ejected fragments. It was shown that this phenomenon may result from an excess of oxygen in the liquid bead. Fragment ejection in O{sub 2}/N{sub 2} atmospheres was more intense than in O{sub 2}/Ar, indicating that N{sub 2} accelerates the oxidation of liquid Ti. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  16. Performance test of PSA-type O{sub 2} separator for efficient O{sub 2} supply to room ventilation system combined with CO{sub 2} adsorption module

    Energy Technology Data Exchange (ETDEWEB)

    Han, Gi Bo; Jang, Jung Hee; Choi, Changsik [Institute for Advanced Engineering, Yongin (Korea, Republic of); Lee, Tae Jin [School of Chemical Engineering Yeungnam University, Gyeongsan (Korea, Republic of)

    2016-04-15

    High purity O{sub 2} concentrated by the PSA-type O{sub 2} separator was applied to a room ventilation system combined with CO{sub 2} adsorption module to remove the indoor CO{sub 2} for the indoor air quality. And then the room was occupied by several persons to breathe for the O{sub 2} consumption and CO{sub 2} generation. As a result, the indoor air quality was improved by the ventilation system combined with the O{sub 2} supply and the CO{sub 2} adsorption module. It was due to the fact that the CO{sub 2} concentration was not steeply increased, but also even decreased and then the increasing rate of the O{sub 2} concentration with the O{sub 2} supply was simultaneously increased by the CO{sub 2} removal despite the CO{sub 2} generation and O{sub 2} consumption with the four persons' breathing. As a representative result, in the case of supplying the high purity O{sub 2} of 30 L/min under using the CO{sub 2} adsorption module, the best performance with the highest increasing rate of O{sub 2} concentration and the lowest increasing rate of CO{sub 2} concentration was obtained among the various cases, and then the increasing rates of CO{sub 2} radiation and O{sub 2} concentration were -2.3 ppm/min and 33.3%/min, respectively.

  17. Nb/sub 2/Te/sub 2/O/sub 9/ and Ta/sub 2/Te/sub 2/O/sub 9/: Two new mixed oxides of Te(IV)

    International Nuclear Information System (INIS)

    Gaitan, M.; Jerez, A.; Pico, C.; Veiga, M.L.

    1987-01-01

    Nb/sub 2/Te/sub 2/O/sub 9/ and Ta/sub 2/Te/sub 2/O/sub 9/ were prepared by solid state reactions between amorphous TeO/sub 3/(s) and metallic pentoxides of Nb and Ta. A crystallographic analysis carried out by X-ray diffraction showed that these compounds are isostructural (space group: P2/sub 1//C. a = 6.883 A, b = 7.853 A, c = 14.591 A, β = 103.66 for Nb/sub 2/Te/sub 2/O/sub 9/ and a = 7.10 A, b = 7.48 A, c = 14.62 A, β = 102.9 for Ta/sub 2/Te/sub 2/O/sub 9/). The IR spectra and thermal decomposition processes of both mixed oxides were studied

  18. Fabrication of heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalyst and efficient photodegradation of organic contaminants under visible-light

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Meng; Li, Shuangli; Yan, Tao; Ji, Pengge; Zhao, Xia; Yuan, Kun; Wei, Dong [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Du, Bin, E-mail: dubin61@gmail.com [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

    2017-07-05

    Highlights: • The product shows efficient activity in photodegradation of RhB, BPA, and phenol. • The BBOC-10 heterojunction exhibits the best activity under visible light. • Suppressed recombination of photo-generated carriers lead to the activity enhancement. - Abstract: Heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalysts were fabricated by a facile one-pot hydrothermal method, in which melem served as the sacrificial reagent to supply carbonate anions. The as-synthesized Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction catalysts were characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscope. The XRD patterns of Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} catalysts showed the distinctive peaks of Bi{sub 2}O{sub 2}CO{sub 3} and Bi{sub 2}O{sub 4}. The SEM and TEM results showed that the pure Bi{sub 2}O{sub 2}CO{sub 3} possessed large plate morphology, while Bi{sub 2}O{sub 4} were composed of various nanorods and particles. As for Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction, it was obviously observed that Bi{sub 2}O{sub 4} nanorods and particles were grown on the surfaces of Bi{sub 2}O{sub 2}CO{sub 3} plates. The visible light driven photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction photocatalyst was evaluated by decomposing dyes, phenol, and bisphenol A in water. Compared with Bi{sub 2}O{sub 2}CO{sub 3} and Bi{sub 2}O{sub 4}, the Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalysts have exhibited remarkable enhanced activity under visible light. The excellent activity can be mainly attributed to the enhanced separation efficiency of photo-generated carriers. Controlled experiments using different radical scavengers proved that ·O{sub 2}{sup −} and h{sup +} played the main role in decomposing organic pollutants. The results of this work would

  19. Anti-bombing insensitivity life of molybdenum cathode doped with La{sub 2}O{sub 3} and Y{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jinshu [School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China)]. E-mail: wangjsh@bjut.edu.cn; Wang Yiman [School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China); Zhou Meiling [School of Materials Science and Engineering, Beijing University of Technology, Beijing 100022 (China)

    2006-03-15

    Anti-bombing insensitivity of La{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Mo secondary emitter has been studied in this paper. The variation of maximum secondary emission coefficient {delta} {sub max} with time was measured. The cathode after life experiment was analyzed by means of HRM, SEM, EDS and XRD. The results showed that {delta} {sub max} of La{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Mo cathode operating at 1100 deg. C under continuous electron bombardment of 300 W/cm{sup 2} was still about 2.5 after 1000 h operation, indicating that this kind of cathode had good anti-bombing insensitivity. In the internal part of the cathode, RE{sub 2}O{sub 3} (rare earth oxide) and molybdenum grains distributed alternately and there existed a certain relationship between crystallographic orientation of RE{sub 2}O{sub 3} and that of molybdenum. It was found that a RE{sub 2}O{sub 3} layer was formed on the surface after operation. The high {delta} {sub max} of La{sub 2}O{sub 3}-Y{sub 2}O{sub 3}-Mo cathode was related to the RE{sub 2}O{sub 3} layer on the surface and the amount of nanosized La{sub 2}O{sub 3} particles on the Y{sub 2}O{sub 3} layer.

  20. Generation of H{sub 2} and CO by solar thermochemical splitting of H{sub 2}O and CO{sub 2} by employing metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Rao, C.N.R., E-mail: cnrrao@jncasr.ac.in; Dey, Sunita

    2016-10-15

    Generation of H{sub 2} and CO by splitting H{sub 2}O and CO{sub 2} respectively constitutes an important aspect of the present-day concerns with energy and environment. The solar thermochemical route making use of metal oxides is a viable means of accomplishing these reduction reactions. The method essentially involves reducing a metal oxide by heating and passing H{sub 2}O or CO{sub 2} over the nonstoichiometric oxide to cause reverse oxidation by abstracting oxygen from H{sub 2}O or CO{sub 2}. While ceria, perovskites and other oxides have been investigated for this purpose, recent studies have demonstrated the superior performance of perovskites of the type Ln{sub 1−x}A{sub x}Mn{sub 1−y}M{sub y}O{sub 3} (Ln=rare earth, A=alkaline earth, M=various +2 and +3 metal ions), in the thermochemical generation of H{sub 2} and CO. We present the important results obtained hitherto to point out how the alkaine earth and the Ln ions, specially the radius of the latter, determine the performance of the perovskites. The encouraging results obtained are exemplefied by Y{sub 0.5}Sr{sub 0.5}MnO{sub 3} which releases 483 µmol/g of O{sub 2} at 1673 K and produces 757 µmol/g of CO from CO{sub 2} at 1173 K. The production of H{sub 2} from H{sub 2}O is also quite appreciable. Modification of the B site ion of the perovskite also affects the performance. In addition to perovskites, we present the generation of H{sub 2} based on the Mn{sub 3}O{sub 4}/NaMnO{sub 2} cycle briefly. - Graphical abstract: Ln{sub 0.5}A{sub 0.5}Mn{sub 1−x}M{sub x}O{sub 3} (Ln=lanthanide; A=Ca, Sr; M=Al, Ga, Sc, Mg, Cr, Fe, Co) perovskites are employed for the two step thermochemical splitting of CO{sub 2} and H{sub 2}O for the generation of CO and H{sub 2}. - Highlights: • Perovskite oxides based on Mn are ideal for the two-step thermochemical splitting of CO{sub 2} and H{sub 2}O. • In Ln{sub 1−x}A{sub x}MnO{sub 3} perovskite (Ln=rare earth, A=alkaline earth) both Ln and A ions play major roles

  1. Density functional study on the heterogeneous oxidation of NO over α-Fe{sub 2}O{sub 3} catalyst by H{sub 2}O{sub 2}: Effect of oxygen vacancy

    Energy Technology Data Exchange (ETDEWEB)

    Song, Zijian, E-mail: szj22zc15@163.com [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China); Wang, Ben, E-mail: benwang@hust.edu.cn [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China); Yu, Jie, E-mail: yujie@hust.edu.cn [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China); Ma, Chuan, E-mail: machuan628@163.com [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China); Zhou, Changsong, E-mail: zhouchangsong@hust.edu.cn [School of Energy and Mechanical Engineering, Nanjing Normal University, 210042, Nanjing (China); Chen, Tao, E-mail: chentao_hust@foxmail.com [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China); Yan, Qianqian [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China); Wang, Ke, E-mail: m201570959@hust.edu.cn [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China); Sun, Lushi, E-mail: sunlushi@hust.edu.cn [State Key Laboratory of Coal Combustion, School of Energy and Power Engineering, Huazhong University of Science and Technology, 430074, Wuhan (China)

    2017-08-15

    Highlights: • NO and H{sub 2}O{sub 2} adsorption on perfect and oxygen defect α-Fe{sub 2}O{sub 3} (0 0 1) surface were studied by DFT calculations. • H{sub 2}O{sub 2} shows high chemical reactivity for its adsorption on oxygen defect α-Fe{sub 2}O{sub 3} (0 0 1) surface. • Oxygen vacancy plays an important role of the catalytic oxidation of NO by H{sub 2}O{sub 2} over the α-Fe{sub 2}O{sub 3} catalyst surfaces. • Mechanism of NO oxidation over α-Fe{sub 2}O{sub 3} (0 0 1) surface by H{sub 2}O{sub 2} was explained. - Abstract: Catalytic oxidation with H{sub 2}O{sub 2} is a promising method for NOx emission control in coal-fired power plants. Hematite-based catalysts are attracting increased attention because of their surface redox reactivity. To elucidate the NO oxidation mechanism on α-Fe{sub 2}O{sub 3} surfaces, density functional theory (DFT) calculations were conducted by investigating the adsorption characteristics of nitric oxide (NO) and hydrogen peroxide (H{sub 2}O{sub 2}) on perfect and oxygen defect α-Fe{sub 2}O{sub 3} (0 0 1) surfaces. Results show that NO was molecularly adsorbed on two kinds of surfaces. H{sub 2}O{sub 2} adsorption on perfect surface was also in a molecular form; however, H{sub 2}O{sub 2} dissociation occurred on oxygen defect α-Fe{sub 2}O{sub 3} (0 0 1) surface. The adsorption intensities of the two gas molecules in perfect α-Fe{sub 2}O{sub 3} (0 0 1) surface followed the order NO > H{sub 2}O{sub 2}, and the opposite was true for the oxygen defect α-Fe{sub 2}O{sub 3} (0 0 1). Oxygen vacancy remarkably enhanced the adsorption intensities of NO and H{sub 2}O{sub 2} and promoted H{sub 2}O{sub 2} decomposition on catalyst surface. As an oxidative product of NO, HNO{sub 2} was synthesized when NO and H{sub 2}O{sub 2} co-adsorbed on the oxygen defect α-Fe{sub 2}O{sub 3} (0 0 1) surface. Analyses of Mulliken population, electron density difference, and partial density of states showed that H{sub 2}O{sub 2} decomposition

  2. Short Communication on “In-situ TEM ion irradiation investigations on U{sub 3}Si{sub 2} at LWR temperatures”

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Yinbin, E-mail: ymiao@anl.gov [Argonne National Laboratory, Lemont, IL 60439 (United States); Harp, Jason [Idaho National Laboratory, Idaho Fall, ID 83415 (United States); Mo, Kun [Argonne National Laboratory, Lemont, IL 60439 (United States); Bhattacharya, Sumit [Northwestern University, Evanston, IL 60208 (United States); Baldo, Peter; Yacout, Abdellatif M. [Argonne National Laboratory, Lemont, IL 60439 (United States)

    2017-02-15

    The radiation-induced amorphization of U{sub 3}Si{sub 2} was investigated by in-situ transmission electron microscopy using 1 MeV Kr ion irradiation. Both arc-melted and sintered U{sub 3}Si{sub 2} specimens were irradiated at room temperature to confirm the similarity in their responses to radiation. The sintered specimens were then irradiated at 350 °C and 550 °C up to 7.2 × 10{sup 15} ions/cm{sup 2} to examine their amorphization behavior under light water reactor (LWR) conditions. U{sub 3}Si{sub 2} remains crystalline under irradiation at LWR temperatures. Oxidation of the material was observed at high irradiation doses.

  3. Direct Synthesis of H{sub 2}O{sub 2} over Ti-Containing Molecular Sieves Supported Gold Catalysts: A Comparative Study for In-situ-H{sub 2}O{sub 2}-ODS of Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Han; Song, Haiyan; Chen, Chunxia; Han, Fuqin; Hu, Shaozheng [Northeast Forestry Univ., Harbin (China); Liu, Guangliang [Univ. of Connecticut, Storrs (United States); Chen, Ping; Zhao, Zhixi [Xinjiang Normal Univ., Urumqi (China)

    2013-10-15

    Direct synthesis of H{sub 2}O{sub 2} and in situ oxidative desulfurization of model fuel over Au/Ti-HMS and Au/TS-1 catalysts has been comparatively investigated in water or methanol. Maximum amount (82%) of active Au{sup 0} species for H{sub 2}O{sub 2} synthesis was obtained. Au/Ti-HMS and Au/TS-1 exhibited the contrary performances in H{sub 2}O{sub 2} synthesis as CH{sub 3}OH/H{sub 2}O ratio of solvent changed. H{sub 2}O{sub 2} decomposition and hydrogenation in water was inhibited by the introduction of methanol. Effect of O{sub 2}/H{sub 2} ratio on H{sub 2}O{sub 2} concentration, H{sub 2} conversion and H{sub 2}O{sub 2} selectivity revealed a relationship between H{sub 2}O{sub 2} generation and H2 consumption. The highest dibenzothiophene removal rate (83.2%) was obtained over Au/Ti-HMS in methanol at 1.5 of O{sub 2}/H{sub 2} ratio and 60 .deg. C. But removal of thiophene over Au/TS-1 should be performed in water without heating to obtain a high removal rate (61.3%). Meanwhile, H{sub 2} conversion and oxidative desulfurization selectivity of H{sub 2} were presented.

  4. One-pot synthesis of porphyrin functionalized γ-Fe{sub 2}O{sub 3} nanocomposites as peroxidase mimics for H{sub 2}O{sub 2} and glucose detection

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qingyun, E-mail: qyliu@sdust.edu.cn; Zhang, Leyou; Li, Hui; Jia, Qingyan; Jiang, Yanling; Yang, Yanting; Zhu, Renren

    2015-10-01

    Meso-tetrakis(4-carboxyphenyl)-porphyrin-functionalized γ-Fe{sub 2}O{sub 3} nanoparticles (H{sub 2}TCPP-γ-Fe{sub 2}O{sub 3}) were successfully prepared by one-pot method under hydrothermal conditions and were found to possess intrinsic peroxidase-like activity. The H{sub 2}TCPP-γ-Fe{sub 2}O{sub 3} nanocomposites can catalytically oxidize peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H{sub 2}O{sub 2} to produce a blue color reaction, which can be easily observed by the naked eye. Furthermore, kinetic studies indicate that the H{sub 2}TCPP-γ-Fe{sub 2}O{sub 3} nanocomposites have an even higher affinity to TMB than that of the natural enzyme, horseradish peroxidase (HRP). On the basis of the high activity, the reaction provides a simple, sensitive and selective method for colorimetric detection of H{sub 2}O{sub 2} over a range of 10–100 μM with a minimum detection limit of 1.73 μM. Moreover, H{sub 2}TCPP-γ-Fe{sub 2}O{sub 3}/glucose oxidase (GOx)/TMB system provides a novel colorimetric sensor for glucose and shows good response toward glucose detection over a range of 5–25 μM with a minimum detection limit of 2.54 μM. The results indicated that it is a simple, cheap, convenient, highly selective, sensitive and easy handling colorimetric assay. Results of a fluorescent probe suggest that the catalase-mimic activity of the H{sub 2}TCPP-γ-Fe{sub 2}O{sub 3} nanocomposites effectively catalyze the decomposition of H{sub 2}O{sub 2} into H{sub 2}O and O{sub 2}. - Graphical abstract: 5,10,15,20-Tetrakis(4-carboxyl phenyl)-porphyrin (H{sub 2}TCPP)-γ-Fe{sub 2}O{sub 3} nanocomposites were demonstrated to possess intrinsic peroxidase-like activity and showed a higher catalytic activity, compared to that of γ-Fe{sub 2}O{sub 3} nanoparticles alone. - Highlights: • Porphyrin-functionalized γ-Fe{sub 2}O{sub 3} nanoparticles were prepared by one-pot method. • The porphyrin-γ-Fe{sub 2}O{sub 3} nanocomposites were found to possess

  5. Sinterability and conductivity of barium doped aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} electrolyte of solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Cao Xiaoguo [Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China); Jiang Sanping, E-mail: s.jiang@curtin.edu.au [Fuels and Energy Technology Institute and Department of Chemical Engineering, Curtin University, Perth, WA 6102 (Australia)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer Ba doping enhances the sintering and densification properties of aluminium lanthanum apatite. Black-Right-Pointing-Pointer Ba doping improves the oxide conductivity of aluminium lanthanum apatite. Black-Right-Pointing-Pointer The enhancement of Ba doping is mainly due to the significantly reduced grain boundary resistance of the aluminium lanthanum apatite. - Abstract: Apatite ceramics are interesting alternative solid oxide fuel cells (SOFCs) electrolytes because of their open structure for the transportation of oxide ions and their good chemical stability. This study reports the influence of barium doping on the microstructure, sinterability and oxide conductivity properties of the aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5}. SEM results show that lanthanum substitution with barium improves the sinterability of apatite ceramics. The barium doping also enhances the conductivity of the aluminium lanthanum silicates. The oxygen ion conductivity of La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} sintered at 1600 Degree-Sign C is 2.21 Multiplication-Sign 10{sup -2} S cm{sup -1} at 800 Degree-Sign C, higher than 9.81 Multiplication-Sign 10{sup -3} S cm{sup -1} of La{sub 10}Si{sub 5}AlO{sub 26.5} sample prepared under the same conditions. The results in the present study demonstrate that doping Ba on the La site for aluminium lanthanum oxyapatite reduces the sintering temperature and improves the ion conductivity. The enhancement of Ba dopant is mainly on the improvement of the densification and thus substantially reduced grain boundary resistance of aluminium lanthanum oxyapatite particularly at low temperatures.

  6. Simulation of accident-tolerant U{sub 3}Si{sub 2} fuel using FRAPCON code

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Daniel S.; Silva, Antonio T.; Abe, Alfredo Y.; Muniz, Rafael O.R., E-mail: dsgomes@ipen.br, E-mail: teixeira@ipen.br, E-mail: alfredo@ctmsp.mar.mil.br, E-mail: rafael.orm@gmail.com [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Giovedi, Claudia, E-mail: claudia.giovedi@ctmsp.mar.mil.br [Universidade de São Paulo (USP), São Paulo, SP (Brazil). Departamento de Engenharia Naval e Oceânica

    2017-07-01

    The research on accident-tolerant fuels (ATFs) increased after the Fukushima event. This benefited risk management in nuclear operations. In this investigation, the physical properties of the materials being developed for the ATF program were compared with those of the standard UO{sub 2} - Zr fuel system. The research efforts in innovative fuel design include rigorous characterization of thermal, mechanical, and chemical assessment, with the objectives of making the burnup cycle longer, increasing power density, and improving safety performance. Fuels must reach a high uranium density - above that supported by UO{sub 2} - and possess coating that exhibits better oxidation resistance than Zircaloy. The uranium density and thermal conductivity of ATFs, such as U{sub 3}Si{sub 2}, UN, and UC, is higher than that of UO{sub 2}; their combination with advanced cladding provides possible fuel - cladding options. An ideal combination of fuel and cladding must increase fuel performance in loss-of-coolant scenarios. The disadvantages of U{sub 3}Si{sub 2}, UN, and UC are their swelling rates, which are higher than that of UO{sub 2}. The thermal conductivities of ATFs are approximately four times higher than that of UO2. To prevent the generation of hydrogen due to oxidation of zirconium-based alloys in contact with steam, cladding options, such as ferritic alloys, were studied. It was verified that FeCrAl alloys and SiC provide better response under severe conditions because of their thermophysical properties. The findings of this study indicate that U{sub 3}Si{sub 2} and the FeCrAl fuel cladding concept should replace UO{sub 2} - Zr as the fuel system of choice. (author)

  7. Correlation Between Electrical Conductivity and Catalytic Property in 78V{sub 2}O{sub 5}–15P{sub 2}O{sub 5}–7B{sub 2}O{sub 3} Glass Containing Fe{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hwa-Jin; Kim, Jong-hwan; Ryu, Bong-Ki [Pusan National University, Busan (Korea, Republic of)

    2016-12-15

    In this study, we established a correlation between the electrical conductivity and catalytic properties of vanadium borophosphate glass containing Fe{sub 2}O{sub 3}. Glasses were synthesized in the 78V{sub 2}O{sub 5}–15P{sub 2}O{sub 5}–7B{sub 2}O{sub 3} ternary-system containing x mol% Fe{sub 2}O{sub 3} (x = 1, 5, 7.5, and 10). Electrical conductivity was measured at 45 ℃ for samples heat-treated at 340 ℃ for 12 h. To examine catalytic effects, we used TGA measurements of a mixture of fatty acid and sample powders. Fourier transform infrared spectroscopy (FTIR) was used to analyze the structural changes after crystallization, while X-ray photoelectron spectroscopy (XPS) analysis indicated changes with different valence state ions. X-ray diffraction (XRD) analysis of the structure array verified these inferred changes. Conductivity and catalytic effects are discussed in relation to the migration of vanadate ions and iron ions with different valence states due to the increase crystallinity.

  8. Structures, stabilities, and electronic properties of small-sized Zr{sub 2}Si{sub n} (n=1-11) clusters. A density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jing-He; Liu, Chang-Xin [Henan Institute of Education, Zhengzhou (China). Dept. of Physics; Wang, Ping; Zhang, Shuai; Lu, Cheng [Nanyang Normal Univ (China). Dept. of Physics; Yang, Gui [Anyang Normal Univ. (China). Dept. of Physics and Electrical Engineering

    2015-07-01

    Ab initio methods based on density functional theory at B3LYP level have been applied in investigating the equilibrium geometries, growth patterns, relative stabilities, and electronic properties of Zr{sub 2}-doped Si{sub n} clusters. The optimisation results shown that the lowest-energy configurations for Zr{sub 2}Si{sub n} clusters do not keep the corresponding silicon framework unchanged, which reflects that the doped Zr atoms dramatically affect the most stable structures of the Si{sub n} clusters. By analysing the relative stabilities, it is found that the doping of zirconium atoms reduces the chemical stabilities of silicon host. The Zr{sub 2}Si{sub 4} and Zr{sub 2}Si{sub 7} clusters are the magic numbers. The natural population and natural electronic configuration analyses indicated that the Zr atoms possess positive charge for n=1-6 and negative charge for n=7-11. In addition, the chemical hardness, chemical potential, infrared, and Raman spectra are also discussed.

  9. Electrical resistivity of the Kondo system Ce{sub 1-x}La{sub x}Pt{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Bouziane, K.; Du Plessis, P. de V [f-Electron Magnetism and Heavy-Fermion Physics Programme, Department of Physics, University of the Witwatersrand, Private Bag 3, PO Wits 2050, Johannesburg (South Africa)

    1999-04-19

    The electrical resistivities of the Kondo system Ce{sub 1-x}La{sub x}Pt{sub 2}Si{sub 2} (0 {<=} x {<=} 1) are reported. It is observed that the resistivities of the alloy samples are reduced considerably as a result of annealing the samples. The results furthermore indicate the evolution from dense Kondo behaviour to single-ion incoherent Kondo scattering as x is increased. The resistivity in the dense Kondo regime shows a maximum which drops from T{sub max}=62 K for CePt{sub 2}Si{sub 2} to T{sub max}=36 K for x=0.2. Using the relationship T{sub max} {proportional_to} T{sub K} {proportional_to} exp(-1/JN(E{sub F})) where T{sub K} is the Kondo temperature, J is the exchange integral and N(E{sub F}) is the density of states at the Fermi level E{sub F}, and the experimentally observed values of T{sub max}(X) leads to vertical bar JN(E{sub F})vertical bar {sub 0} = 0.0645 {+-} 0.0004. (author)

  10. A [Mo{sub 2}O{sub 2}S{sub 2}]-based ring system incorporating tartrate as the bridging ligand. Synthesis, structure and catalytic activity of Cs{sub 4}[Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sub 2}(μ{sub 4}-tart){sub 2} (tart=[C{sub 4}H{sub 2}O{sub 6}]{sup 4-})

    Energy Technology Data Exchange (ETDEWEB)

    Qian, Ting-Ting; Cui, Yu-Jie; Xin, Zhifeng; Jia, Ai-Quan; Zhang, Qian-Feng [Anhui Univ. of Technology, Anhui (China). Inst. of Molecular Engineering and Applied Chemistry and Anhui Province Key Lab. of Metallurgy Engineering and Resources Recycling

    2017-08-01

    Treatment of [Mo{sub 2}S{sub 2}O{sub 2}(H{sub 2}O){sub 6}]{sup 2+} with racemic tartaric acid (tartH{sub 4}) in the presence of sodium hydroxide and cesium chloride in aqueous solution led to the isolation of a new tetra-molybdenum ring cluster Cs{sub 4}[Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sub 2}(μ{sub 4}-tart){sub 2}. The cyclic cluster polyanion consists of two dinuclear [Mo{sub 2}O{sub 2}(μ-S){sub 2}]{sup 2+} moieties and two bridging tart{sup 4-} ligands. The cyclic polyoxothiomolybdate cluster, supported on the mesoporous silica SBA-15, was tested for heterogenerous catalysis in thiophene hydrodesulfurization.

  11. Systems Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O at 25 deg C. Sistemy Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O pri 25 grad S

    Energy Technology Data Exchange (ETDEWEB)

    Skvortsov, V G; Sadetdinov, Sh V; Akimov, V M; Mitrasov, Yu N; Petrova, O V; Klopov, Yu N [Chuvashskij Gosudarstvennyj Pedagogicheskij Inst., Cheboksary (Russian Federation) Universitet Druzhby Narodov, Moscow (Russian Federation)

    1994-02-01

    Phase equilibriums in the Li[sub 2]B[sub 4]O[sub 7] (Na[sub 2]B[sub 4]O[sub 7], K[sub 2]B[sub 4]O[sub 7])-N[sub 2]H[sub 3]H[sub 4]OH-H[sub 2]O systems were investigated by methods of isothermal solubility, refractometry and PH-metry at 25 deg C for the first time. Lithium and sodium tetraborates was established to form phases of changed composition mM[sub 2]B[sub 4]O[sub 7][center dot]nN[sub 2]H[sub 3]C[sub 2]H[sub 4]OH[center dot]XH[sub 2]O, where M=Li, Na with hydrazine ethanol. K[sub 2]B[sub 4]O[sub 7][center dot]4H[sub 2]O precipitates in solid phase in the case of potassium salt. Formation of isomorphous mixtures was supported by X-ray diffraction and IR spectroscopy methods.

  12. Thermal behavior of GeO{sub 2} doped PbO-B{sub 2}O{sub 3}-ZnO-Bi{sub 2}O{sub 3} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Yin [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Xiao Hanning [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)]. E-mail: hnxiao@hnu.cn; Guo Weiming [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China); Guo Wenming [College of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

    2006-05-15

    PbO-B{sub 2}O{sub 3}-ZnO-Bi{sub 2}O{sub 3} glass is a representative system for vacuum and electronic sealing. Effects of GeO{sub 2} on thermal properties of the glass have been investigated in this paper. Activation energy for crystallization, glass structure, the type of crystals were characterized by differential scanning calorimetry, infrared spectroscopy, X-ray diffraction and optical microscopy. Results indicate that the addition of GeO{sub 2} (0.4-2 wt.%) to PbO-B{sub 2}O{sub 3}-ZnO-Bi{sub 2}O{sub 3} glass can suppress crystallization of the glass and decrease the sealing temperature. With the increase of GeO{sub 2} content, germanate crystals were revealed, resulting in a slight increase of sealing temperature. When the content of GeO{sub 2} is 0.7 wt.%, the glass possesses the highest stability and lowest sealing temperature (400 deg. C), which is desirable for low-temperature sealing. The coefficient of thermal expansion of PbO-B{sub 2}O{sub 3}-ZnO-Bi{sub 2}O{sub 3} glass was measured by dilatometry. The result shows that the coefficient of thermal expansion of the glass increases with the content of GeO{sub 2}. The adjustability of the coefficient of thermal expansion would expand the applications of PbO-B{sub 2}O{sub 3}-ZnO-Bi{sub 2}O{sub 3} glass. A flexural strength of 28.3 MPa was obtained at the GeO{sub 2} content of 0.7 wt.%, showing good mechanical property for sealing process.

  13. Evidence of superoxide radical contribution to demineralization of sulfamethoxazole by visible-light-driven Bi{sub 2}O{sub 3}/Bi{sub 2}O{sub 2}CO{sub 3}/Sr{sub 6}Bi{sub 2}O{sub 9} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shiyuan; Niu, Junfeng, E-mail: junfengn@bnu.edu.cn; Bao, Yueping; Hu, Lijuan

    2013-11-15

    Highlights: • Bi{sub 2}O{sub 3}/Bi{sub 2}O{sub 2}CO{sub 3}/Sr{sub 6}Bi{sub 2}O{sub 9} can degrade SMX efficiently using visible light. • 36% of TOC reduction was achieved after 120 min treatment. • The main mineralization products were confirmed. • Formation of O{sub 2}·{sup −} was evidenced by using ESR and a chemiluminescent probe. -- Abstract: Photocatalytic degradation of sulfamethoxazole (SMX) was investigated using Bi{sub 2}O{sub 3}/Bi{sub 2}O{sub 2}CO{sub 3}/Sr{sub 6}Bi{sub 2}O{sub 9} (BSO) photocatalyst under visible light (>420 nm) irradiation. The photochemical degradation of SMX followed pseudo-first-order kinetics. The reaction kinetics was determined as a function of initial SMX concentrations (5–20 mg L{sup −1}), initial pH (3–11) and BSO concentrations (6–600 mg L{sup −1}). Approximately, 90% of SMX (10 mg L{sup −1}) degradation and 36% of TOC reduction were achieved at pH 7.0 after 120 min irradiation. The main mineralization products, including NH{sub 4}{sup +}, NO{sub 3}{sup −}, SO{sub 4}{sup 2−} and CO{sub 2}, as well as intermediates 3-amino-5-methylisoxazole (AMI), p-benzoquinone (BZQ), and sulfanilic acid (SNA) were detected in aqueous solution. The formation of O{sub 2}·{sup −} radical was evidenced by using electron spin resonance and a chemiluminescent probe, luminal. A possible degradation mechanism involving excitation of BSO, followed by charge injection into the BSO conduction band and formation of reactive superoxide radical (O{sub 2}·{sup −}) was proposed for the mineralization of SMX. During the reaction, the O{sub 2}·{sup −} radical attacks the sulfone moiety and causes the cleavage of the S-N bond, which leads to the formation of two sub-structure analogs, AMI and SNA.

  14. Application of bias correction methods to improve U{sub 3}Si{sub 2} sample preparation for quantitative analysis by WDXRF

    Energy Technology Data Exchange (ETDEWEB)

    Scapin, Marcos A.; Guilhen, Sabine N.; Azevedo, Luciana C. de; Cotrim, Marycel E.B.; Pires, Maria Ap. F., E-mail: mascapin@ipen.br, E-mail: snguilhen@ipen.br, E-mail: lvsantana@ipen.br, E-mail: mecotrim@ipen.br, E-mail: mapires@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil)

    2017-07-01

    The determination of silicon (Si), total uranium (U) and impurities in uranium-silicide (U{sub 3}Si{sub 2}) samples by wavelength dispersion X-ray fluorescence technique (WDXRF) has been already validated and is currently implemented at IPEN's X-Ray Fluorescence Laboratory (IPEN-CNEN/SP) in São Paulo, Brazil. Sample preparation requires the use of approximately 3 g of H{sub 3}BO{sub 3} as sample holder and 1.8 g of U{sub 3}Si{sub 2}. However, because boron is a neutron absorber, this procedure precludes U{sub 3}Si{sub 2} sample's recovery, which, in time, considering routinely analysis, may account for significant unusable uranium waste. An estimated average of 15 samples per month are expected to be analyzed by WDXRF, resulting in approx. 320 g of U{sub 3}Si{sub 2} that would not return to the nuclear fuel cycle. This not only impacts in production losses, but generates another problem: radioactive waste management. The purpose of this paper is to present the mathematical models that may be applied for the correction of systematic errors when H{sub 3}BO{sub 3} sample holder is substituted by cellulose-acetate {[C_6H_7O_2(OH)_3_-_m(OOCCH_3)m], m = 0∼3}, thus enabling U{sub 3}Si{sub 2} sample’s recovery. The results demonstrate that the adopted mathematical model is statistically satisfactory, allowing the optimization of the procedure. (author)

  15. {sup 29}Si nuclear magnetic resonance study of URu{sub 2}Si{sub 2} under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Shirer, K.R., E-mail: krshirer@ucdavis.edu [Department of Physics, University of California, Davis, CA 95616 (United States); Dioguardi, A.P.; Bush, B.T.; Crocker, J.; Lin, C.H.; Klavins, P. [Department of Physics, University of California, Davis, CA 95616 (United States); Cooley, J.C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Maple, M.B. [Department of Physics and Institute for Pure and Applied Physical Sciences, University of California, San Diego, La Jolla, CA 92093-0319 (United States); Chang, K.B.; Poeppelmeier, K.R. [Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Curro, N.J. [Department of Physics, University of California, Davis, CA 95616 (United States)

    2016-01-15

    We report {sup 29}Si nuclear magnetic resonance measurements of single crystals and aligned powders of URu{sub 2}Si{sub 2} under pressure in the hidden order and paramagnetic phases. We find that the Knight shift decreases with applied pressure, consistent with previous measurements of the static magnetic susceptibility. Previous measurements of the spin lattice relaxation time revealed a partial suppression of the density of states below 30 K. This suppression persists under pressure, and the onset temperature is mildly enhanced.

  16. Analysis of the properties of silicon nitride based ceramic (Si{sub 3}N{sub 4}) cutting tool using different addictive; Analise das propriedades de ferramenta de corte ceramicas de nitreto de silicio (Si{sub 3}N{sub 4}) usando diferentes aditivos

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Joaquim Lopes; Souza, Jose Vitor Candido de; Raymundo, Emerson Augusto [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Silva, Oliverio Macedo Moreira [Centro Tecnico Aeroespacial (CTA), Sao Jose dos Campos, SP (Brazil)

    2013-06-15

    The constant search for new materials is part of the scientific and technological development of the industries. Ceramic been presenting important developments in terms of scientific and technological development, highlighting the predominance of covalent ceramics, which has important applications where abrasion resistance and hardness are required. Between covalent materials, several research papers in search of property improvements and cost reduction. However the production of ceramics of silicon nitride (Si{sub 3}N{sub 4}) with a reduced cost is possible only if used methods and different additives. The aim of this work is the development of compositions based on silicon nitride (Si{sub 3}N{sub 4}) using different additives such as Y{sub 2}O{sub 3}, CeO{sub 2}, Al{sub 2}O{sub 3} , and CTR{sub 2}O{sub 3} in varying amounts. For the development of ceramics, the mixtures were homogenized, dried, compacted and sintered using the sintering process of 1850°C for 1 hour, with a heating rate of 25°C/min. The characterizations were performed as a function of relative density by Archimedes method, the mass loss measured before and after sintering, phase analysis by X-ray diffraction, microstructure by scanning electron microscopy (SEM), and hardness and fracture toughness indentation method. The results showed relative density 97-98, Vickers hardness 17-19 GPa, fracture toughness from 5.6 to 6.8 MPa.m{sup 1/2}. The different phases were obtained depending on the types of additives used. The obtained results are promising for tribological applications. (author)

  17. Lattice dynamics of ZnAl{sub 2}O{sub 4} and ZnGa{sub 2}O{sub 4} under high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Moreno, S.; Rodriguez-Hernandez, P.; Munoz, A. [Departamento de Fisica Fundamental II, MALTA Consolider Team, Instituto de Materiales y Nanotecnologia Universidad de La Laguna, La Laguna 38205, Tenerife (Spain); Romero, A.H. [CINVESTAV-Queretaro Libramiento Norponiente No 2000 Real de Juriquilla 76230 Queretaro, Qro (Mexico); Manjon, F.J. [Instituto de Diseno para la Fabricacion y Produccion Automatizada, MALTA Consolider Team, Universitat Politecnica de Valencia, 46022 Valencia (Spain); Errandonea, D. [Fundacion General de la Universidad de Valencia ICMUV, MALTA Consolider Team, Edificio de Investigacion, C/Dr. Moliner 50, Burjassot, 46100 Valencia (Spain); Rusu, E.; Ursaki, V.V. [Institute of Applied Physics, Academy of Sciences of Moldova, 2028 Chisinau (Moldova)

    2011-01-15

    In this work we present a first-principles density functional study of the vibrational properties of ZnAl{sub 2}O{sub 4} and ZnGa{sub 2}O{sub 4} as function of hydrostatic pressure. Based on our previous structural characterization of these two compounds under pressure, herewith, we report the pressure dependence on both systems of the vibrational modes for the cubic spinel structure, for the CaFe{sub 2}O{sub 4}-type structure (Pnma) in ZnAl{sub 2}O{sub 4} and for marokite (Pbcm) ZnGa{sub 2}O{sub 4}. Additionally we report a second order phase transition in ZnGa{sub 2}O{sub 4} from the marokite towards the CaTi{sub 2}O{sub 4}-type structure (Cmcm), for which we also calculate the pressure dependence of the vibrational modes at the {gamma} point. Our calculations are complemented with Raman scattering measurements up to 12 GPa that show a good overall agreement between our calculated and measured mode frequencies. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Microbial O{sub 2} consumption in the Aespoe tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Kotelnikova, S.; Pedersen, Karsten [Goeteborg Univ. (Sweden). Dept. of Cell and Molecular Biology, Microbiology

    1998-04-01

    The report presents data on microbial O{sub 2} reduction activities by microorganisms obtained with different techniques: Winkler method, gas chromatography, most probable numbering, enrichment technique, inhibitor analysis and radiotracer measurements. The samples were collected from boreholes and open funnel ponds at Aespoe in 1996-1998. The evaluation of the microbial activities in open ponds predicts the future microbial activities after the O{sub 2} intrusion around the future repository. The metabolic potential of the microbial population inhabiting groundwater was evaluated on the basis of electron donors available and microbial 16S rRNA gene diversity. The contribution of different microbial groups to the O{sub 2} reduction was elucidated using specific inhibitors selectively affecting different microbial groups. Our experiments show that microbial O{sub 2} reduction occurs in deep groundwater. Carbon dioxide was produced concurrently with O{sub 2} reduction confirming the biogenic nature of the reduction. The populations developed O{sub 2} reduction rates and capacity depending on the initial concentration of dissolved O{sub 2} reduction. Rates of O{sub 2} reduction ranged from 0.32 to 4.5 {mu}M/day. Depending on temperature and the type of groundwater the approximate time needed for consumption of 500 {mu}M of dissolved O{sub 2} ranged from 0.31 to 3.99 years. After approximately a 2 weeks period the microbial population in vitro was able to consume O{sub 2} both at 30 deg C and 60 deg C. At 16 deg C no delay in O{sub 2} consumption was observed. Our results demonstrated that methanotrophs survive in deep groundwater and that they were induced by O{sub 2}. Some bacteria use Hg or CH{sub 4} as electron donor instead of organic matter, which means that microbial O{sub 2} reduction will occur also in deep groundwaters where the availability of organic carbon is limited. Specific CH{sub 4} oxidation rates ranged between 3.00 and 220 nM CH{sub 4} per litre per

  19. Silicon isotope separation utilizing infrared multiphoton dissociation of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser light

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishii, Takeshi; Ohya, Akio [Nuclear Development Corp., Tokai, Ibaraki (Japan); Arai, Shigeyoshi [Hill Research Co. Ltd., Tokyo (Japan)

    2002-08-01

    Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of {sup 28}Si was obtained at 49.63% dissociation of Si{sub 2}F{sub 6} after the simultaneous irradiation of 200 pulses with 966.23 cm{sup -1} photons (0.084 J/cm{sup 2}) and 954.55 cm{sup -1} photons (0.658 J/cm{sup 2}), while 2000 pulses were needed to obtain 99.35% of {sup 28}Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm{sup -1} (0.97 J/cm{sup 2}). (author)

  20. A 3d-4f complex constructed by the assembly of a cationic template, [Cu(en){sub 2}]{sup 2+}, and a 3D anionic coordination polymer, [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}(C{sub 5}O{sub 5})(H{sub 2}O){sub 2}]{sup 2-}

    Energy Technology Data Exchange (ETDEWEB)

    Ke, Szu-Yu; Yeh, Chang-Tsung; Wang, Chih-Chieh [Department of Chemistry, Soochow University, Taipei, Taiwan (China); Lee, Gene-Hsiang [Instrumentation Center, National Taiwan University, Taipei, Taiwan (China); Sheu, Hwo-Shuenn [National Synchrotron Radiation Research Center, Hsinchu, Taiwan (China)

    2017-05-18

    A three-dimensional (3D) 3d-4f complex, [Cu(en){sub 2}][Sm{sub 2}(C{sub 5}O{sub 5})(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 2}].8H{sub 2}O (1) (en = ethylenediamine, C{sub 5}O{sub 5}{sup 2-} = dianion of 4,5-dihydroxycyclopent-4-ene-1,2,3-trione), were prepared via the in-situ ring-opening oxidation reaction of croconate in the presence of the template-directed complex, [Cu(en){sub 2}]{sup 2+} cation. The structural characterization determined by X-ray diffraction determination reveals that the 3D anionic coordination polymer of [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}(C{sub 5}O{sub 5})(H{sub 2}O){sub 2}]{sup 2-} in 1 can be describe in terms of in-plane 2D honeycomb-like [Sm{sub 2}(C{sub 2}O{sub 4}){sub 3}] layered frameworks bridged by oxalate with bis-chelating mode, being mutually interlinked via the bridge of μ{sub 1,2,3,4}-croconate ligands with bis-chelating coordination mode to complete the 3D open framework, which gives rise to 1D channels with pore size of 14.023 x 11.893 Aa (longest atom-atom contact distances) along the b axis. The structure-directing complex, [Cu(en){sub 2}]{sup 2+}, and solvated water molecules are resided into these honeycomb-type hexagonal channels. The thermal stability of 1 was further studied by TGA and in-situ powder X-ray diffraction measurement. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. The influence of the iron content on the reductive decomposition of A{sub 3−x}Fe{sub x}Al{sub 2}Si{sub 3}O{sub 12} garnets (A = Mg, Mn; 0.47 ≤ x ≤ 2.85)

    Energy Technology Data Exchange (ETDEWEB)

    Aparicio, Claudia, E-mail: claudia.aparicio@upol.cz; Filip, Jan, E-mail: claudia.aparicio@upol.cz; Mashlan, Miroslav, E-mail: claudia.aparicio@upol.cz; Zboril, Radek, E-mail: claudia.aparicio@upol.cz [Regional Centre of Advanced Technologies and Materials, Departments of Experimental Physics and Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77146 Olomouc (Czech Republic)

    2014-10-27

    Thermally-induced reductive decomposition of natural iron-bearing garnets of the almandine-pyrope and almandine-spessartine series were studied at temperatures up to 1200 °C (heating rate of 10 °C/min) under atmosphere of forming gas (10% of H{sub 2} in N{sub 2}). Crystallochemical formula of the studied garnet was calculated as {sup VIII}(A{sub 3−x}Fe{sub x}{sup 2+}){sup VI}(Al,Fe{sup 3+}){sub 2}Si{sub 3}O{sub 12}, where the amount of Fe{sup 3+} in the octahedral sites is negligible with the exception of pyrope, A = Mg, Mn, and 0.47 ≤ x ≤ 2.85. The observed decomposition temperature, determined from differential scanning calorimetry and thermogravimetry, is greater than 1000 °C in all cases and showed almost linear dependence on the iron content in the dodecahedral sites of the studied garnets, with the exception of garnet with a near-pyrope composition (Prp{sub 80}Alm{sub 20}). The initial garnet samples and decomposition products were characterized in details by means of X-ray powder diffraction and {sup 57}Fe Mössbauer spectroscopy. We found that all studied garnets have common decomposition products such as metallic iron (in general, rounded particles below 4 μm) and Fe-spinel; the other identified decomposition products depend on starting chemical composition of the garnet: Fe-cordierite, olivine (fayalite or tephroite), cristobalite, pyroxene (enstatite or pigeonite), and anorthite. Anorthite and pigeonite were only present in garnets with Ca in the dodecahedral site. All the identified phases were usually well crystallized.

  2. Preparation and characterization of Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide formed by cathodic electroplating and anodizing

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Joo-Hee; Kim, Tae-Yoo; Kim, Nam-Jeong; Lee, Chang-Hyoung; Park, Eun-Mi [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Park, Chan [Division of Materials Science and Engineering, Pukyong National University, Busan 608-739 (Korea, Republic of); Suh, Su-Jeong, E-mail: suhsj@skku.ac.kr [School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Advanced Materials and Process Research Center for IT, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2011-11-15

    Highlights: > We fabricate Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3}/Al film for high performance thin film capacitor. > The optimum condition of electrolyte composition will coat NbO{sub x} on Al without corrosion of Al during the cathodic electroplating. > Increasing annealing temperature will form Nb{sub 2}O{sub 5} crystalline. > The Al{sub 2}O{sub 3} layer will form between Nb{sub 2}O{sub 5} layer and metal Al after anodizing and the thin film capacitor with Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3}/Al improve dielectric properties. - Abstract: Al foil was coated with niobium oxide by cathodic electroplating and anodized in a neutral boric acid solution to achieve high capacitance in a thin film capacitor. X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) revealed the niobium oxide layer on Al to be a hydroxide-rich amorphous phase. The film was crystalline and had stoichiometric stability after annealing at temperatures up to 600 deg. C followed by anodizing at 500 V, and the specific capacitance of the Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide was approximately 27% higher than that of Al{sub 2}O{sub 3} without a Nb{sub 2}O{sub 5} layer. The capacitance was quite stable to the resonance frequency. Overall, the Nb{sub 2}O{sub 5}-Al{sub 2}O{sub 3} composite oxide film is a suitable material for thin film capacitors.

  3. Photochemical degradation of diethyl phthalate with UV/H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xu Bin [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Gao Naiyun [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)]. E-mail: gaonaiyun@mail.tongji.edu.cn; Sun Xiaofeng [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Xia Shengji [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Rui Min [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Simonnot, Marie-Odile [Laboratory of Chemical Engineering Science, CNRS-INPL, 1 rue Grandville, BP451, F-54001 Nancy Cedex (France); Causserand, Christel [Laboratory of Chemical Engineering, UMR 5503 CNRS INP, Universite Paul Sabatier, 31062 Toulouse Cedex 9 (France); Zhao Jianfu [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

    2007-01-02

    The decomposition of diethyl phthalate (DEP) in water using UV-H{sub 2}O{sub 2} process was investigated in this paper. DEP cannot be effectively removed by UV radiation and H{sub 2}O{sub 2} oxidation alone, while UV-H{sub 2}O{sub 2} combination process proved to be effective and could degrade this compound completely. With initial concentration about 1.0 mg/L, more than 98.6% of DEP can be removed at time of 60 min under intensity of UV radiation of 133.9 {mu}W/cm{sup 2} and H{sub 2}O{sub 2} dosage of 20 mg/L. The effects of applied H{sub 2}O{sub 2} dose, UV radiation intensity, water temperature and initial concentration of DEP on the degradation of DEP have been examined in this study. Degradation mechanisms of DEP with hydroxyl radicals oxidation also have been discussed. Removal rate of DEP was sensitive to the operational parameters. A simple kinetic model is proposed which confirms to pseudo-first order reaction. There is a linear relationship between rate constant k and UV intensity and H{sub 2}O{sub 2} concentration.

  4. Effect of efficient supply of pure O{sub 2} concentrated by PSA-type O{sub 2} separator on improvement of indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Han, Gi Bo; Jang, Jung Hee; Choi, Changsik [Institute for Advanced Engineering, Yongin (Korea, Republic of); Lee, Tae Jin [School of Chemical Engineering Yeungnam University, Gyeongsan (Korea, Republic of)

    2016-04-15

    To minimize the cost and loss rate of energy artificial room ventilation system, the O{sub 2} separator was suggested for the flow of the excessive ventilation amount between indoor and outdoor because the pure O{sub 2} separated and concentrated by the O{sub 2} separator can be supplied with the ventilation amount minimized. How the O{sub 2} separator applies to ventilation and its operation characteristics were investigated by controlling under various conditions as well as the operation conditions optimized required for indoor air quality such as the concentration of CO{sub 2} and O{sub 2}. Consequently, it was known that the O{sub 2} concentration was increased; however, the increase of the CO{sub 2} concentration was suppressed by the sufficient supply of O{sub 2} concentrated from the storage tank into the room despite the two persons’ breathing in the room having an inner volume of about 56m{sup 3}. Consequently, it was concluded that the supply system of the concentrated O{sub 2} which was stored into the tank after the production with the O{sub 2} separator can be applied to the room ventilation system for the improvement of the indoor air quality.

  5. Role of O radical on the formation of O{sub 2} gas plasma; O{sub 2} purazuma ni okeru O rajikaru no yakuwari

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, I. [Toshiba Reasearch and Development Ceter, Tokyo (Japan). Mechanical Systems Laboratory

    2000-11-10

    The effect of plasma formed gas on the plasma structure is investigated using a self consistent continuous fluid plasma model, which assumes that the local field approximation was attained in the RF plasma. The swarm parameter was obtained by Boltzmann analysis for O{sub 2} gas which contains various amounts of O radicals. Positive ion density, negative ion density, and electron density in the O{sub 2} RF plasma including O radical generation were calculated by self-consistent one dimensional continuous fluid plasma model. The calculation results show the dominant positive charged particle became O{sup +} from O{sub 2}{sup +} with increasing amount of O radical in O{sub 2}. The plasma positive densities are not greatly affected if O radical content did not exceed 1 % of O{sub 2}. It was concluded that O{sub 2} plasma structure can be evaluated by source gas plasma calculation neglecting radical formation, since O radical formation in the O{sub 2} plasma is estimated as less than 0.2 % of O{sub 2}. (author)

  6. Influence of chemical composition on the X-ray photoemission, thermopower, specific heat, and magnetic properties of CeNi{sub 2}(Si{sub 1-y}Ge{sub y}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tolinski, T.; Synoradzki, K. [Polish Academy of Sciences, Institute of Molecular Physics, Poznan (Poland); Bajorek, A.; Chelkowska, G. [Silesian University, Institute of Physics, Katowice (Poland); Koterlyn, M. [K. Wielkiego University, Institute of Physics, Bydgoszcz (Poland); Ivan Franko National University of L' viv, Faculty of Electronics, L' viv (Ukraine); Koterlyn, G. [National Academy of Sciences of Ukraine and Ministry of Education and Science of Ukraine, Western Scientific Center, L' viv (Ukraine); Yasnitskii, R. [Ivan Franko National University of L' viv, Faculty of Electronics, L' viv (Ukraine)

    2017-06-15

    We report our studies of the intermediate compositions between CeNi{sub 2}Si{sub 2} and CeNi{sub 2}Ge{sub 2}, i.e., the alloys CeNi{sub 2}(Si{sub 1-y}Ge{sub y}){sub 2} by means of the thermopower, electrical resistivity, specific heat, magnetic susceptibility, and X-ray photoemission measurements. CeNi{sub 2}Si{sub 2} is a fluctuating valence system and CeNi{sub 2}Ge{sub 2} is known to show the heavy fermion behaviour. The change of the temperature dependence of the resistivity towards the typical metallic behaviour occurs below y ∝ 0.25. The transition between CeNi{sub 2}Si{sub 2} and CeNi{sub 2}Ge{sub 2} is discussed in the frames of competition between the crystal electric field and Kondo interactions. It is found that valence stabilisation occurs for Ge content y > 0.25. The hybridization energy Δ determined from the XPS Ce 3d spectrum reflects well the behaviour of the parameter E{sub ex} obtained from the analysis of the magnetic susceptibility by the interconfiguration fluctuation model. It has been also shown that thermopower data can be successfully described employing the single ion model for 0.6 < y < 1.0 and two-band model including the crystal electric field splitting for y ≤ 0.25. (orig.)

  7. Preparation of Cu/La{sub 2}O{sub 3}-ZrO{sub 2}-Al{sub 2}O{sub 3} catalyst and its catalytic properties for selective reduction of NO

    Energy Technology Data Exchange (ETDEWEB)

    Xi-kun Guo; Ping-ping Xie; Shu-dong Lin [Shantou University, Shantou (China). Department of Chemistry

    2008-12-15

    An La{sub 2}O{sub 3}-ZrO{sub 2}-Al{sub 2}O{sub 3} composite support was prepared by co-precipitation with the mixed aqueous solution of La(NO{sub 3}{sub 3}, Al(NO{sub 3){sub 3}, and ZrOCl{sub 2} dropping into the precipitant of (NH{sub 4})2CO{sub 3} aqueous solution. The Cu/La{sub 2}O{sub 3}-ZrO{sub 2}-Al{sub 2}O{sub 3} catalyst was prepared by the impregnation of La{sub 2}O{sub 3}-ZrO{sub 2}-Al{sub 2}O{sub 3} with active component Cu{sup 2+} aqueous solution. The effects of the catalyst on the selective catalytic reduction of NO with propylene in excess oxygen were investigated. The relationships between the preparation method, structure and properties of the Cu/La{sub 2}O{sub 3}-ZrO{sub 2}-Al{sub 2}O{sub 3} catalyst were also explored by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), surface area measurements (BET), pyridine absorption infrared spectrum (Py-IR), thermal gravimetry (TG), and temperature-programmed reduction (TPR). The results indicate that the support {gamma}-Al{sub 2}O{sub 3} prepared by Al(NO{sub 3})3 dropping into (NH{sub 4}{sub 2} CO{sub 3} can remarkably enlarge the surface area; the addition of La{sub 2}O{sub 3} contributes mainly to the enhancement of the thermal stability; and the introduction of ZrO{sub 2} can increase the amount of Lewis and Broenstead acid. Consequently, the catalyst Cu/La{sub 2}O{sub 3}-ZrO{sub 2}-Al{sub 2}O{sub 3} has excellent activity for the selective reduction of NO with propylene in excess oxygen. NO conversion is up to 88.9% at 300{sup o}C and 81.9% even at the presence of 10% volume fraction of water vapor. 15 refs., 8 figs., 1 tab.

  8. Electronic structure and vibrational properties of KRbAl{sub 2}B{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Adichtchev, S.V. [Laboratory of Condensed Matter Spectroscopy, Institute of Automation and Electrometry, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Bazarov, B.G.; Bazarova, Zh.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation); Gavrilova, T.A. [Laboratory of Nanodiagnostics and Nanolithography, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Grossman, V.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation); Kesler, V.G. [Laboratory of Physical Principles for Integrated Microelectronics, Institute of Semiconductor Physics, Novosibirsk, 630090 (Russian Federation); Meng, G.S. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P.O. Box 2711, Beijing 100190 (China); Key Laboratory of Quantum Information, University of Science and Technology of China, Chinese Academy of Sciences, Hefei, Anhui 230026 (China); Lin, Z.S., E-mail: zslin@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, P.O. Box 2711, Beijing 100190 (China); Surovtsev, N.V. [Laboratory of Condensed Matter Spectroscopy, Institute of Automation and Electrometry, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2013-03-15

    Graphical abstract: With the KRbAl{sub 2}B{sub 2}O{sub 7} powder formed by solid state synthesis (left), Raman spectrum (right upper) and XPS valence electronic states (right lower) were measured, agreed with the first-principles results. Highlights: ► KRbAl{sub 2}B{sub 2}O{sub 7} powder was obtained by solid state synthesis. ► Vibrational properties of KRbAl{sub 2}B{sub 2}O{sub 7} were determined by unpolarized Raman spectrum. ► Electronic structures of KRbAl{sub 2}B{sub 2}O{sub 7} were measured by XPS. ► Experimental electronic structure is consistent with the first-principles result. ► KRbAl{sub 2}B{sub 2}O{sub 7} has a noticeable refractive indices increase and small NLO effects decrease compared to K{sub 2}Al{sub 2}B{sub 2}O{sub 7}. - Abstract: The physical properties of KRbAl{sub 2}B{sub 2}O{sub 7} have been considered in comparison with those of K{sub 2}Al{sub 2}B{sub 2}O{sub 7} and Rb{sub 2}Al{sub 2}B{sub 2}O{sub 7}. The vibrational parameters of KRbAl{sub 2}B{sub 2}O{sub 7} have been measured by Raman spectroscopy as very similar to those of K{sub 2}Al{sub 2}B{sub 2}O{sub 7}. The electronic structures of KRbAl{sub 2}B{sub 2}O{sub 7} have been evaluated by X-ray photoelectron spectroscopy and ab initio computations using CASTEP package. A noticeable refractive indices increase and small decrease of nonlinear optical properties have been found in KRbAl{sub 2}B{sub 2}O{sub 7} in reference to optical parameters of K{sub 2}Al{sub 2}B{sub 2}O{sub 7}.

  9. Nb{sub 2}OsB{sub 2}, with a new twofold superstructure of the U{sub 3}Si{sub 2} type: Synthesis, crystal chemistry and chemical bonding

    Energy Technology Data Exchange (ETDEWEB)

    Mbarki, Mohammed; Touzani, Rachid St.; Fokwa, Boniface P.T., E-mail: boniface.fokwa@ac.rwth-aachen.de

    2013-07-15

    The new ternary metal-rich boride, Nb{sub 2}OsB{sub 2}, was synthesized by arc-melting the elements in a water-cooled copper crucible under an argon atmosphere. The compound was characterized from single-crystal X-ray data and EDX measurements. It crystallizes as a new superstructure (space group P4/mnc, no. 128) of the tetragonal U{sub 3}Si{sub 2}-structure type with lattice parameters a=5.922(1) Å and c=6.879(2) Å. All of the B atoms are involved in B{sub 2} dumbbells with B–B distances of 1.89(4) Å. Structure relaxation using VASP (Vienna ab intio Simulation Package) has confirmed the space group and the lattice parameters. According to electronic structure calculations (TB–LMTO–ASA), the homoatomic B–B interactions are optimized and very strong, but relatively strong heteroatomic Os–B, Nb–B and Nb–Os bonds are also found: These interactions, which together build a three-dimensional network, are mainly responsible for the structural stability of this new phase. The density of state at the Fermi level predicts metallic behavior, as expected, from this metal-rich boride. - Graphical abstract: Nb{sub 2}OsB{sub 2} is, to the best of our knowledge, the first fully characterized phase in the ternary Nb–Os–B system. It crystallizes (space group P4/mnc, 128) with a new twofold superstructure of the U{sub 3}Si{sub 2} structure type (space group P4/mbm, 127), and is therefore the first boride in this structure family crystallizing with a superstructure of the U{sub 3}Si{sub 2} structure type. We show that the distortions leading to this superstructure occurs mainly in the Nb-layer, which tries to accommodate the large osmium atoms. The consequence of this puckering is the building osmium dumbbells instead of chains along [001]. - Highlights: • First compound in the Nb–Os–B system. • New twofold superstructure of U{sub 3}Si{sub 2} structure type. • Puckering of Nb-layer responsible for superstructure occurrence. • Chemical bonding studied

  10. Facile synthesis and characterization of ZnFe{sub 2}O{sub 4}/{alpha}-Fe{sub 2}O{sub 3} composite hollow nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yu [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); School of Environmental and Chemical Engineering, Dalian Jiaotong University, Dalian 116028 (China); Li, Xinyong, E-mail: xyli@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Department of Chemical Engineering, Curtin University, Perth, WA 6845 (Australia); Zhao, Qidong; Hou, Yang [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024 (China); Tade, Moses [Department of Chemical Engineering, Curtin University, Perth, WA 6845 (Australia); Liu, Shaomin, E-mail: Shaomin.Liu@curtin.edu.au [Department of Chemical Engineering, Curtin University, Perth, WA 6845 (Australia)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer ZnFe{sub 2}O{sub 4}/{alpha}-Fe{sub 2}O{sub 3} composite hollow nanospheres were successfully synthesized via a facile method. Black-Right-Pointing-Pointer Detailed structural, morphology and the phase composition were studied. Black-Right-Pointing-Pointer The incorporation of ZnFe{sub 2}O{sub 4} and {alpha}-Fe{sub 2}O{sub 3} gives an appropriate band gap value to utilize solar energy. -- Abstract: ZnFe{sub 2}O{sub 4}/{alpha}-Fe{sub 2}O{sub 3} composite hollow nanospheres were successfully fabricated via a facile one-pot solvothermal method, utilizing polyethylene glycol as soft template. X-ray diffraction and scanning electron microscopy analysis revealed that the prepared nanospheres with cubic spinel and rhombohedra composite structure had a uniform diameter of about 370 nm, and the hollow structure could be further confirmed by transmission electron microscopy. Energy dispersive X-ray, X-ray photoelectron spectroscopy and Fourier transform infrared techniques were also applied to characterize the elemental composition and chemical bonds in the hollow nanospheres. The ZnFe{sub 2}O{sub 4}/{alpha}-Fe{sub 2}O{sub 3} composite hollow nanospheres show attractive light absorption property for potential applications in electronics, optics, and catalysis.

  11. Thermoresponsive behaviour of AM{sub 2}O{sub 8} materials

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Simon

    2003-07-01

    This thesis investigates the synthesis and structural characterisation of AM{sub 2}O{sub 8} phases, many of which show negative thermal expansion (NTE); relevant literature is reviewed in Chapter One. Chapter Two describes the synthesis, structure solution, and mechanistic role of a new family of low-temperature (LT) orthorhombic AM{sub 2}O{sub 8} polymorphs (A{sup IV} = Zr, Hf; M{sup VI} = Mo, W). These materials are key intermediates in the preparation of cubic AM{sub 2}O{sub 8} phases from AM{sub 2}O{sub 7}(OH){sub 2}(H{sub 2}O){sub 2}. The structure of LT-AM{sub 2}O{sub 8} has been elucidated by combined laboratory X-ray and neutron powder diffraction. Variable temperature X-ray diffraction (VTXRD) studies have shown LT-AMo{sub 2}O{sub 8} phases exhibit anisotropic NTE. LT-ZrMo{sub 2}O{sub 8} has been shown to undergo spontaneous rehydration, allowing preparation of ZrMo{sub 2}O{sub 7}(OD){sub 2}(D{sub 2}O){sub 2} and assignment of D{sub 2}O/OD positions within the structure by neutron diffraction. Using this result, a reversible topotactic dehydration pathway from AM{sub 2}O{sub 7}(OH){sub 2}(H{sub 2}O){sub 2} to LT-AM{sub 2}O{sub 8} is proposed. Chapter Three investigates the order-disorder phase transition with concurrent oxygen mobility in cubic AM{sub 2}O{sub 8} materials; studies include comprehensive VT neutron diffraction of cubic ZrMo{sub 2}O{sub 8} to reveal a static to dynamic transition at 215 K, and novel quench-anneal/quench-warm variable temperature/time diffraction experiments on ZrWMoO{sub 8} which lead to an activation energy of 40 kJmol{sup -1} for oxygen migration. In Chapter Four {sup 17}O-labelled cubic ZrW{sub 2}O{sub 8} has been prepared to understand the oxygen migration process by VT MAS NMR. In situ hydrothermal studies of cubic ZrMo{sub 2}O{sub 8} using synchrotron radiation have shown direct hydration to ZrMo{sub 2}O{sub 7}(OH){sub 2}(H{sub 2}O){sub 2}. In Chapter Five VTXRD of trigonal {alpha}-AMo{sub 2}O{sub 8} phases reveals a

  12. Electron tunneling and the energy gap in Bi2Sr2CaCu2O/sub x/

    International Nuclear Information System (INIS)

    Lee, M.; Mitzi, D.B.; Kapitulnik, A.; Beasley, M.R.

    1989-01-01

    Results of electron tunneling on single crystals of the Bi 2 Sr 2 CaCu 2 O/sub x/ superconductor are reported. The junctions show a gap structure with Δ≅25 meV, whose temperature dependence exhibits a qualitatively Bardeen-Cooper-Schrieffer-like behavior with a gap-closing T/sub c/≅81--85 K. Comparisons of these tunneling spectra to those obtained on YBa 2 Cu 3 O/sub 7-//sub x/ are made. Evidence that 2Δ/kT/sub c/∼7 for both Ba 2 Sr 2 CaCu 2 O/sub x/ and YBa 2 Cu 3 O/sub 7-//sub x/ is also discussed

  13. ALD Produced B{sub 2}O{sub 3}, Al{sub 2}O{sub 3} and TiO{sub 2} Coatings on Gd{sub 2}O{sub 3} Burnable Poison Nanoparticles and Carbonaceous TRISO Coating Layers

    Energy Technology Data Exchange (ETDEWEB)

    Weimer, Alan

    2012-11-26

    This project will demonstrate the feasibility of using atomic layer deposition (ALD) to apply ultrathin neutron-absorbing, corrosion-resistant layers consisting of ceramics, metals, or combinations thereof, on particles for enhanced nuclear fuel pellets. Current pellet coating technology utilizes chemical vapor deposition (CVD) in a fluidized bed reactor to deposit thick, porous layers of C (or PyC) and SiC. These graphitic/carbide materials degrade over time owing to fission product bombardment, active oxidation, thermal management issues, and long-term irradiation effects. ALD can be used to deposit potential ceramic barrier materials of interest, including ZrO{sub 2}, Y{sub 2}O{sub 3}:ZrO{sub 2} (YSZ), Al{sub 2}O{sub 3}, and TiO{sub 2}, or neutron-absorbing materials, namely B (in BN or B{sub 2}O{sub 3}) and Gd (in Gd{sub 2}O{sub 3}). This project consists of a two-pronged approach to integrate ALD into the next-generation nuclear plant (NGNP) fuel pellet manufacturing process:

  14. Light emission efficiency and imaging performance of Lu{sub 2}O{sub 3}:Eu nanophosphor under X-ray radiography conditions: Comparison with Gd{sub 2}O{sub 2}S:Eu

    Energy Technology Data Exchange (ETDEWEB)

    Seferis, I. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Department of Medical Physics, Medical School, University of Patras, 265 00 Patras (Greece); Michail, C.; Valais, I. [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Zeler, J. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Liaparinos, P.; Fountos, G.; Kalyvas, N.; David, S. [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Stromatia, F. [Department of Radiology and Nuclear Medicine, “IASO” General Hospital, Mesogion 264, 15562 Holargos (Greece); Zych, E. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Kandarakis, I., E-mail: kandarakis@teiath.gr [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Panayiotakis, G. [Department of Medical Physics, Medical School, University of Patras, 265 00 Patras (Greece)

    2014-07-01

    Nanocrystallic europium-activated lutetium oxide (Lu{sub 2}O{sub 3}:Eu) is a strong candidate for use in digital medical imaging applications, due to its spectroscopic and structural properties. The aim of the present study was to investigate the imaging and efficiency properties of a 33.3 mg/cm{sup 2} Lu{sub 2}O{sub 3}:Eu scintillating screen coupled to a high resolution RadEye HR CMOS photodetector under radiographic imaging conditions. Since Lu{sub 2}O{sub 3}:Eu emits light in the red wavelength range, the light emission efficiency and the imaging performance were compared with results for a Gd{sub 2}O{sub 2}S:Eu phosphor screen. Parameters such as the Absolute Efficiency (AE), the X-ray Luminescence Efficiency (XLE), and the Detector Quantum Gain (DQG), were investigated. The imaging characteristics of Lu{sub 2}O{sub 3}:Eu nanophosphor screen were investigated in terms of the Modulation Transfer Function (MTF), the Normalized Noise Power Spectrum (NNPS) and the Detective Quantum Efficiency (DQE). It was found that Lu{sub 2}O{sub 3}:Eu nanophosphor has higher AE and XLE by a factor of 1.32 and 1.37 on average, respectively, in the whole radiographic energy range in comparison with the Gd{sub 2}O{sub 2}S:Eu screen. DQG was also found higher in the energy range from 50 kVp to 100 kVp and comparable thereafter. The imaging quality of Lu{sub 2}O{sub 3}:Eu nanophosphor coupled to the CMOS sensor was found to outmatch in any aspect in comparison with the Gd{sub 2}O{sub 2}S:Eu screen. These results indicate that Lu{sub 2}O{sub 3}:Eu nanophosphor could be considered for further research in order to be used in medical imaging applications. - Highlights: • AE and XLE of Lu{sub 2}O{sub 3}:Eu nanophosphor were higher by a factor of 1.32 and 1.37 than Gd{sub 2}O{sub 2}S:Eu. • DQG was higher from 50 to 100 kVp and comparable thereafter. • Imaging performance of Lu{sub 2}O{sub 3}:Eu/CMOS was better than that of Gd{sub 2}O{sub 2}S:Eu/CMOS.

  15. Syntheses and structural characterization of vanado-tellurites and vanadyl-selenites: SrVTeO{sub 5}(OH), Cd{sub 2}V{sub 2}Te{sub 2}O{sub 11}, Ca{sub 3}VSe{sub 4}O{sub 13}·H{sub 2}O and Ba{sub 2}VSe{sub 3}O{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Konatham, Satish; Vidyasagar, Kanamaluru, E-mail: kvsagar@iitm.ac.in

    2017-05-15

    Four new quaternary vanado-tellurites and vanadyl-selenites, namely, SrVTeO{sub 5}(OH)(1), Cd{sub 2}V{sub 2}Te{sub 2}O{sub 11}(2), Ca{sub 3}VSe{sub 4}O{sub 13}·H{sub 2}O(3) and Ba{sub 2}VSe{sub 3}O{sub 10}(4) have been synthesized and structurally characterized by single crystal X-ray diffraction. The oxidation state of vanadium is +5 in tellurites 1 and 2 and +4 in selenites 3 and 4. The structures of SrVTeO{sub 5}(OH)(1) and Cd{sub 2}V{sub 2}Te{sub 2}O{sub 11}(2) compounds consist of (VTeO{sub 5}(OH)){sup 2-} and (V{sub 2}Te{sub 2}O{sub 11}){sup 4-}anionic chains respectively, which are built from tetrahedral VO{sub 4} and disphenoidal TeO{sub 4} moieties. Similarly the structures of Ca{sub 3}VSe{sub 4}O{sub 13}·H{sub 2}O(3) and Ba{sub 2}VSe{sub 3}O{sub 10}(4) respectively contain (VSe{sub 2}O{sub 7}){sup 2-} and (VSe{sub 3}O{sub 10}){sup 4-} anionic chains, which are made up of octahedral VO{sub 6} and pyramidal SeO{sub 3} units. Compounds 1 and 3 have been characterized by thermogravimetric and infrared spectroscopic methods. Compounds 1 and 2 are wide band gap semiconductors. - Graphical abstract: Ca{sub 3}VSe{sub 4}O{sub 13}·H{sub 2}O and Ba{sub 2}VSe{sub 3}O{sub 10} compounds contain (VSe{sub 2}O{sub 7}){sup 2-} and (VSe{sub 3}O{sub 10}){sup 4-} chains. - Highlights: • Four new vanado-tellurites and vanadyl-selenites are synthesized. • Their structural features are different. • The vanado-tellurites are wide band gap semiconductors.

  16. Effect of As/sub 2/O/sub 3/ on gluconeogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Szinicz, L.; Forth, W.

    1988-06-01

    The effect of As/sub 2/O/sub 3/ and As/sub 2/O/sub 5/ on gluconeogenesis from various substrates in the liver and kidney of rats was investigated. A concentration-dependent inhibition by As/sub 2/O/sub 3/ was found. The highest degree of inhibition was observed in incubations with pyruvate. The inhibition of glucose formation was accompanied to a lesser extent by a diminution in O/sub 2/ consumption and ATP content. The effect was also dependent on the substrate used. Oleate, 0,5 mmol/l, increased gluconeogenesis from pyruvate. The effect was not abolished by As/sub 2/O/sub 3/. A decrease in the content of acetyl-CoA, 3-hydroxybutyrate, and reduced glutathione was found in suspensions of isolated rat kidney tubules or hepatocytes incubated with As/sub 2/O/sub 3/. About 10 times higher concentrations of As/sub 2/O/sub 5/ were necessary to induce a similar extent of inhibition of gluconeogenesis, decrease in O/sub 2/ consumption, and in ATP content as compared with As/sub 2/O/sub 3/. Gluconeogenesis from pyruvate exhibited highest sensitivity to As/sub 2/O/sub 5/. Starved rats were shown to be much more sensitive to As/sub 2/O/sub 3/ than animals with free access to food.

  17. Phase transition of the orthorhombic fluorite-related compounds Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, Eu)

    Energy Technology Data Exchange (ETDEWEB)

    Hinatsu, Yukio, E-mail: hinatsu@sci.hokudai.ac.j [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Doi, Yoshihiro; Nishimine, Hiroaki; Wakeshima, Makoto [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810 (Japan); Sato, Mineo [Department of Chemistry and Chemical Engineering, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-nocho, Niigata 950-2181 (Japan)

    2009-12-04

    Rare earth iridium oxides Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, and Eu) were prepared and their structures were determined by X-ray diffraction measurements. At room temperature, Pr{sub 3}IrO{sub 7} crystallized in an orthorhombic superstructure of cubic fluorite with space group Cmcm. The differential thermal analysis (DTA) and specific heat measurements for Ln{sub 3}IrO{sub 7} (Ln = Pr, Nd, Sm, and Eu) showed a phase transition at 262, 342, 420, and 485 K, respectively. At low temperatures, Ln{sub 3}IrO{sub 7} crystallized in a monoclinic structure with the space group P2{sub 1}/n. The transition temperatures increased with decreasing the ionic radius of rare earths, which indicates that the transition is stress-induced and occurs with the lattice contraction on cooling. These results for Ln{sub 3}IrO{sub 7} were compared with the phase transitions observed for Ln{sub 3}MoO{sub 7}, Ln{sub 3}RuO{sub 7}, Ln{sub 3}ReO{sub 7}, and Ln{sub 3}OsO{sub 7}.

  18. Hidden order and disorder effects in URu{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Bernal, O.O. [California State University, Los Angeles, CA (United States)]. E-mail: obernal@calstatela.edu; Moroz, M.E. [California State University, Los Angeles, CA (United States); Ishida, K. [Graduate School of Science, Kyoto University, Kyoto (Japan); Murakawa, H. [Graduate School of Science, Kyoto University, Kyoto (Japan); Reyes, A.P. [National High Magnetic Field Lab, Tallahassee, FL (United States); Kuhns, P.L. [National High Magnetic Field Lab, Tallahassee, FL (United States); MacLaughlin, D.E. [University of California, Riverside, CA (United States); Mydosh, J.A. [Max Planck Institute for Chemical Physics of Solids, Dresden (Germany); Gortenmulder, T.J. [Kamerlingh Onnes Lab, Leiden University (Netherlands)

    2006-05-01

    NMR experiments at ambient pressure in URu{sub 2}Si{sub 2} demonstrate a linewidth enhancement effect below the hidden order transition temperature T{sub 0}. We present single-crystal {sup 29}Si NMR parameters for various temperatures and for an applied magnetic field perpendicular to the crystal c-axis. By comparing oriented-powder and single-crystal data, we observe that the size of the linewidth enhancement below T{sub 0} correlates with the size of the high-T broadening. We measure a {sup 29}Si up-field line shift below T{sub 0} which indicates the presence of an internal-field average for the entire crystal. This shift also correlates with the high-temperature width. The {sup 101}Ru NQR frequency as a function of temperature was also measured. No strong effect on the NQR frequency is observed at T{sub 0}. Both NMR and NQR measurements suggest a connection between linewidth/disorder effects and the transition to hidden order.

  19. Photoluminescence in Pb{sup 2+} activated SrB{sub 4}O{sub 7} and SrB{sub 2}O{sub 4} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Gawande, A.B., E-mail: gawandeab@gmail.com [Department of Physics, SGB Amravati University, Amravati-444602, Maharashtra (India); Ingle, J.T. [J. D. Institute of Engineering and Technology, Yavatmal, Maharashtra (India); Sonekar, R.P., E-mail: sonekar_rp@yahoo.com [Department of Physics, G.S. College, Khamgaon District, Buldhana, Maharashtra (India); Omanwar, S.K. [Department of Physics, SGB Amravati University, Amravati-444602, Maharashtra (India)

    2014-05-01

    The powder samples of SrB{sub 4}O{sub 7}:Pb{sup 2+} and SrB{sub 2}O{sub 4}:Pb{sup 2+} were prepared by solution combustion synthesis method. The synthesis is based on the exothermic reaction between the fuel (Urea) and Oxidizer (Ammonium nitrate). The synthesized materials were characterized using TG–DTA, powder XRD, SEM and the photoluminescence properties were studied using a Hitachi F-7000 spectrophotometer at room temperature. Both the samples SrB{sub 4}O{sub 7}:Pb{sup 2+} and SrB{sub 2}O{sub 4}:Pb{sup 2+} show broad emission of Pb{sup 2+} respectively at 307 nm and 360 nm (corresponds to {sup 3}P{sub 1} to {sup 1}S{sub 0} transition). The optimum concentrations of Pb{sup 2+} in both the phosphors SrB{sub 4}O{sub 7}:Pb{sup 2+} and SrB{sub 2}O{sub 4}:Pb{sup 2+} were found to be 3 mol% (relative to Sr) and for this concentration the critical transfer distance R{sub 0} were calculated to be 10.21 Å and 12.22 Å respectively. The Stokes shifts were calculated to be respectively 4464 cm{sup −1} and 8454 cm{sup −1}. The emission bands of both the phosphors are in the UV region and the phosphors can be potential candidates for application in UV lamps. - Highlights: • SrB{sub 4}O{sub 7}:Pb{sup 2+} and SrB{sub 2}O{sub 4}:Pb{sup 2+} have been synthesized by Novel solution combustion synthesis technique. • The synthesized materials were characterized using TG–DTA, powder XRD and SEM. • Photoluminescence spectra of synthesized materials showed the characteristic transition in Pb{sup 2+}. • Stokes shift, optimum concentration and critical transfer distance R{sub 0} were determined.

  20. Moessbauer study in the glass system PbO. 2B/sub 2/O/sub 3/. Fe/sub 2/O/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Sekhon, S S; Kamal, R [Punjabi Univ., Patiala (India). Dept. of Physics

    1978-05-01

    The Moessbauer technique has been employed to study the structure and crystallite formation in the glass system PbO.2B/sub 2/O/sub 3/ containing upto 30 wt% Fe/sub 2/O/sub 3/. Like alkali borate glasses, this glass system also exhibits a broadened quadrupole doublet and iron ions are present in Fe/sup 3 +/ state. Above about 20 wt%, the crystallites of magnetically ordered states have been identified. Susceptibility variation with concentration suggests the formation of a superparamagnetic state.

  1. A contribution to the kinetic study of the metatectic reaction U+U{sub 3}Si{sub 2}{yields}U{sub 3}Si; Contribucion al Estudio cinetico de la Reaccion Metatectica U+U{sub 3}Si{sub 2} U{sub 3}Si

    Energy Technology Data Exchange (ETDEWEB)

    Arroyo Ruiperez, J; Esteban Hernandez, J A

    1962-07-01

    An experimental study has been made to decide upon the advantages and drawbacks of the different methods and reagents employed in the metallography of U-Si alloys. It has been observed that all samples thermally treated to form the epsilon-phase undergo from the beginning a coalescence of the U{sub 3}Si{sub 2} particles, which makes practically useless any fine state of dispersion that might be present originally, as recommended by some authors. The coalescence of the U{sub 3}Si{sub 2} particle decreases the surface available for reaction and consequently the reaction rate. (Author) 7 refs.

  2. Fe{sub 2} O{sub 3} addition influence on the Sn O{sub 2}.Co O.Nb{sub 2} O{sub 5} varistors system; Influencia da adicao de Fe{sub 2} O{sub 3} no sistema varistor Sn O{sub 2}.Co O.Nb{sub 2} O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Antunes, A.C.; Antunes, S.R.M. [Universidade Estadual de Ponta Grossa, PR (Brazil). Dept. de Quimica; Castilhos, J.G.R.; Pianaro, S.R.; Zara, J.A. [Universidade Estadual de Ponta Grossa, PR (Brazil). Dept. de Engenharia dos Materiais; Longo, E. [Sao Carlos Univ., SP (Brazil). Dept. de Quimica; Varela, J.A. [UNESP, Araraquara, SP (Brazil). Inst. de Quimica

    1997-12-31

    The effect 0.05 to 0.30 mol% Fe{sub 2} 0{sub 3} addition on the electrical and microstructural properties of ternary varistor system composed by tin oxide, niobium oxide and cobaltum oxide was studied in this work. The samples were sintered at 1300 deg C for two hours. The characterizations were performed by Vxi measurements, scanning electron microscopy and X - ray diffraction. The Fe{sub 2} O{sub 3} additions up to 0,10% increased the {alpha} values breakdown electric fields (E{sub r}) and it was observed that the barrier voltage (v{sub b}) depends on the chemical composition. The second phase had high concentration of iron that precipitated in the grain boundaries and inhibited the grain growth during sintering. Fe{sub 2} O{sub 3} concentrations upper 0,10 mol% were deleterious for electrical properties of the ceramics. (author) 7 refs., 3 figs., 4 tabs.

  3. Nitration of toluene with N[sub 2]O[sub 5

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, Kikuo.; Yoshizawa, Fujiroku.; Akutsu, Yoshiaki.; Arai, Mitsuru.; Tamura, Masamitsu. (The University of Tokyo, Tokyo (Japan). School of Engineering)

    1999-06-30

    In order to clarify the mechanism of aromatic nitration with N[sub 2]O[sub 5], the nitration of toluene with N[sub 2]O[sub 5] in CCl[sub 4] was carried out and was investigated the yields of the products and the isomer distributions. As a result, the reaction should be very rapid and should involve a typical electrophilic substitution. Moreover, in order to investigate the effect of the solvent, the nitration of toluene with N[sub 2]O[sub 5] powder without CCl[sub 4] was also carried out. The nitration of toluene with N[sub 2]O[sub 5]/N[sub 2]O[sub 4] was also carried out, and the dependence of the isomer distribution and the ratio of produced nitrotoluenes on the ratio of N[sub 2]O[sub 5] was showed. As a result, it is suggested that N[sub 2]O[sub 5] should be dissociated homolytically in CCl[sub 4] and that the aromatic nitration with N[sub 2]O[sub 5] in CCl[sub 4] should proceed with NO[sub 3] as the initial attacking species. The thermal decomposition of N[sub 2]O[sub 5] over 25 degree C should produce a large amount of N[sub 2]O[sub 4](2NO[sub 2]), and the attack of NO[sub 2] on the intermediate [Ar(H)(ONO[sub 2])] should form the intermediates [AR(H)(ONO[sub 2])(H)(NO[sub 2])] following the specific isomer distributions. (author)

  4. Nitration of toluene with N{sub 2}O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, Kikuo.; Yoshizawa, Fujiroku.; Akutsu, Yoshiaki.; Arai, Mitsuru.; Tamura, Masamitsu. [The University of Tokyo, Tokyo (Japan). School of Engineering

    1999-06-30

    In order to clarify the mechanism of aromatic nitration with N{sub 2}O{sub 5}, the nitration of toluene with N{sub 2}O{sub 5} in CCl{sub 4} was carried out and was investigated the yields of the products and the isomer distributions. As a result, the reaction should be very rapid and should involve a typical electrophilic substitution. Moreover, in order to investigate the effect of the solvent, the nitration of toluene with N{sub 2}O{sub 5} powder without CCl{sub 4} was also carried out. The nitration of toluene with N{sub 2}O{sub 5}/N{sub 2}O{sub 4} was also carried out, and the dependence of the isomer distribution and the ratio of produced nitrotoluenes on the ratio of N{sub 2}O{sub 5} was showed. As a result, it is suggested that N{sub 2}O{sub 5} should be dissociated homolytically in CCl{sub 4} and that the aromatic nitration with N{sub 2}O{sub 5} in CCl{sub 4} should proceed with NO{sub 3} as the initial attacking species. The thermal decomposition of N{sub 2}O{sub 5} over 25 degree C should produce a large amount of N{sub 2}O{sub 4}(2NO{sub 2}), and the attack of NO{sub 2} on the intermediate [Ar(H)(ONO{sub 2})] should form the intermediates [AR(H)(ONO{sub 2})(H)(NO{sub 2})] following the specific isomer distributions. (author)

  5. Assessment of coal combustion in O{sub 2}+CO{sub 2} by equilibrium calculations

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Ligang [Natural Resources Canada, CANMET Energy Technology Centre, 1 Haanel Drive, Nepean, ON (Canada); Furimsky, Edward [IMAF Group, 184 Marlborough Avenue, Ottawa, ON (Canada)

    2003-04-15

    The facility for analysis of chemical thermodynamics (F*A*C*T) method based on the Gibbs energy minimization principle was used for the environmental assessment of coal combustion in O{sub 2}+CO{sub 2} mixture compared with that in air. For the former case, the calculations predict higher emissions of CO and lower emissions of NO{sub x}. For both combustion media, SO{sub x} emissions are governed by O{sub 2} concentration, whereas distribution of trace metals was unaffected when O{sub 2} concentration in the O{sub 2}+CO{sub 2} mixture approached that in air. The effect of O{sub 2}+CO{sub 2} mixture on the distribution of chlorine- and alkali-containing compounds in the vapor phase was minor compared with that in air. In spite of the large excess of CO{sub 2} in combustion medium, sulfation was the predominant reaction occurring in ash.

  6. Kinetic control in the synthesis of metastable polymorphs: Bixbyite-to-Rh{sub 2}O{sub 3}(II)-to-corundum transition in In{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Bekheet, Maged F., E-mail: maged.bekheet@ceramics.tu-berlin.de [Fachbereich Material -und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Fachgebiet Keramische Werkstoffe, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin (Germany); Schwarz, Marcus R. [Freiberg High Pressure Research Centre, Institut für Anorganische Chemie, Technische Universität-Bergakademie Freiberg, Leipziger Straße 29, 09599 Freiberg (Germany); Kroll, Peter [Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 760019-0065 (United States); Gurlo, Aleksander [Fachbereich Material -und Geowissenschaften, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Fachgebiet Keramische Werkstoffe, Institut für Werkstoffwissenschaften und -technologien, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin (Germany)

    2015-09-15

    An example for kinetic control of a solid-state phase transformation, in which the system evolves via the path with the lowest activation barrier rather than ending in the thermodynamically most favorable state, has been demonstrated. As a case study, the phase transitions of indium sesquioxide (In{sub 2}O{sub 3}) have been guided by theoretical calculations and followed in situ under high-pressure high-temperature conditions in multi-anvil assemblies. The corundum-type rh-In{sub 2}O{sub 3} has been synthesized from stable bixbyite-type c-In{sub 2}O{sub 3} in two steps: first generating orthorhombic Rh{sub 2}O{sub 3}-II-type o′-In{sub 2}O{sub 3} which is thermodynamically stable at 8.5 GPa/850 °C and, thereafter, exploiting the preferred kinetics in the subsequent transformation to the rh-In{sub 2}O{sub 3} during decompression. This synthesis strategy of rh-In{sub 2}O{sub 3} was confirmed ex situ in a toroid-type high-pressure apparatus at 8 GPa and 1100 °C. The pressure–temperature phase diagrams have been constructed and the stability fields of In{sub 2}O{sub 3} polymorphs and the crystallographic relationship between them have been discussed. - Graphical abstract: In situ energy-dispersive XRD patterns in multi-anvil assemblies show the sequence of phase transition c-In{sub 2}O{sub 3}→o′-In{sub 2}O{sub 3}→rh-In{sub 2}O{sub 3} under particular pressure and temperature conditions. The tick marks refer to the calculated Bragg positions of bixbyite-type (c-In{sub 2}O{sub 3}), Rh{sub 2}O{sub 3}-II-type (o–-In2O{sub 3}) and corundum-type (rh-In{sub 2}O{sub 3}). - Highlights: • The solid-state synthesis methods can be employed for obtaining metastable phases. • The phase transition of In{sub 2}O{sub 3} was guided by DFT calculations. • The phase transition of In{sub 2}O{sub 3} was followed in situ under HP–HT conditions. • Orthorhombic o′-In{sub 2}O{sub 3} polymorph was synthesized from c-In{sub 2}O{sub 3} at 8.5 GPa/850 °C. • Metastable rh

  7. Controllable synthesis and field emission enhancement of Al{sub 2}O{sub 3} coated In{sub 2}O{sub 3} core-shell nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yang; Li Yawei; Yu Ke; Zhu Ziqiang, E-mail: yk5188@263.net [Key Laboratory of Polar Materials and Devices (Ministry of Education of China), Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)

    2011-03-16

    Four types of indium oxide (In{sub 2}O{sub 3}) nanostructures were synthesized on Au-catalysed silicon substrate via a VLS method. A rod-like In{sub 2}O{sub 3} nanostructure was chosen to fabricate In{sub 2}O{sub 3}-Al{sub 2}O{sub 3} core-shell nanostructures with different shell thicknesses via a two-step method. Core-shell nanostructures with shell thickness of 30 nm are reprocessed by annealing and H{sub 2} plasma treating. Field emission (FE) properties of all the samples were measured and compared. It is found that Al{sub 2}O{sub 3} coatings remarkably decrease the effective work function and improve the FE capabilities of In{sub 2}O{sub 3} nanostructures (turn-on field decreases from 1.34 to 1.26 V {mu}m{sup -1}, threshold field decreases from 3.60 to 2.64 V {mu}m{sup -1}). Annealing and H{sub 2} plasma treating can promote the improvement even further (turn-on field 1.23 V {mu}m{sup -1}, 1.21 V {mu}m{sup -1} and threshold field 2.50 V {mu}m{sup -1}, 2.14 V {mu}m{sup -1}, respectively). The FE enhancement is attributed to the electron accumulation in the insulating Al{sub 2}O{sub 3} nanostructure and the electron redistribution at the heterojunction.

  8. Nitration of benzene with N{sub 2}O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, Kikuo; Yoshizawa, FUjiroku; Akutsu, Yoshiaki; Arai, Mitsuru; Tamura, Masamitsu [The University of Tokyo, Tokyo (Japan). School of Engineering

    1999-08-31

    In order to clarify the mechanism of aromatic nitration with N{sub 2}O{sub 5}, the nitrations of benzene and of nitrobenzene with N{sub 2}O{sub 5} were carried out and the yield of the products and the isomer distribution of dinitrobenzenes were investigated. As a result, the isomer distribution of the dinitrobenzenes in the nitration of benzene was quite different from that in the nitration of nitrobenzene. Moreover, the ratio of [dinitrobenzenes]/[nitrobenzene] increased with the reaction temperature. The nitration of benzene with N{sub 2}O{sub 5}/N{sub 2}O{sub 4} was also carried out and showed the dependence of the ratio of [dinitrobenzenes]/[nitrobenzene] on the ratio of N{sub 2}O{sub 4}. As a result, it is suggested that N{sub 2}O{sub 5} should be dissociated homolytically in CCl{sub 4}, that the aromatic nitration with N{sub 2}O{sub 5} over 25 degree C should produce a large amount of N{sub 2}O{sub 4}(2NO{sub 2}) and the attack of NO{sub 2} on the intermediate [Ar(H)(ONO{sub 2})] should form the intermediates [Ar(H)(ONO{sub 2})(H)(NO{sub 2})] following the production of a large amount of dinitrobenzenes. (author)

  9. Characterisation of a tertiary mixture of {alpha}-Fe{sub 2}O{sub 3}, {gamma}-Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan, M.P.; Narasimhan, S.V. [Water and Steam Chemistry Laboratory (Chemistry Group, BARC) BARC Facilities, Kalpakkam, Tamil Nadu 603 102. (India)

    1998-12-31

    A method has been developed to quantify the individual components of a ternary mixture containing {alpha}-Fe{sub 2}O{sub 3}, {gamma}- Fe{sub 2}O{sub 3} and Fe{sub 3}O{sub 4} based on the preferential dissolution of the components at a fixed time (fixed time - depending on the strength of the chelating agent) in a dilute chemical formulation (containing a chelant and an organic acid) both in presence and absence of reductant. A ternary component diagram was constructed based on the percentage dissolution of the individual components in 2,6-Pyridine dicarboxylic acid (PDCA), Nitrilo triacetic acid (NTA) and EDTA based formulation at 60degC both in presence and absence of reductant. In these formulations, the observed behaviour that the {alpha}-Fe{sub 2}O{sub 3} dissolved very little both in presence and absence of reductant and {gamma}-Fe{sub 2}O{sub 3} dissolved very little in absence of reductant were used for resolving the ternary physical mixture composition. Physical mixtures of Fe{sub 3}O{sub 4}, {alpha}-Fe{sub 2}O{sub 3} and {gamma}-Fe{sub 2}O{sub 3} based on mole ratio were taken such that the total quantity of Fe present would be 1.37 mM for complete dissolution. In presence and absence of reductant, dissolution percentage of Fe observed at fixed time in these formulations, when fit into the already constructed three component phase diagram for each formulation at the same fixed duration, the experimentally resolved composition showed good agreement with that based on individual components. This method is useful to resolve different polymorphs of metal oxides having the metal ions in single and/or multiple oxidation states. (author)

  10. The selectivity of catalysts composed of V/sub 2/O/sub 5/ supported on ZrO/sub 2/-Y/sub 2/O/sub 3/ mixed oxides for methanol oxidation

    International Nuclear Information System (INIS)

    VanOmmen, J.G.; Gellings, P.J.; Ross, J.R.H.

    1988-01-01

    V/sub 2/O/sub 5/ monolayer catalysts were prepared on ZrO/sub 2/ and ZrO/sub 2/ doped with Y/sub 2/O/sub 3/ by two methods. The coverages obtained are only half a monolayer and did not depend on the preparation method or type of support. The selectivity for oxidation of methanol over these V/sub 2/O/sub 5/ catalysts changes from a predominance of formaldehyde to a predominance of methyl formate when the support is doped with Y/sub 2/C/sub 3/, independent of the amount of Y/sub 2/O/sub 3/

  11. The borosulfates K{sub 4}[BS{sub 4}O{sub 15}(OH)], Ba[B{sub 2}S{sub 3}O{sub 13}], and Gd{sub 2}[B{sub 2}S{sub 6}O{sub 24}

    Energy Technology Data Exchange (ETDEWEB)

    Gross, Peter; Kirchhain, Arno; Hoeppe, Henning A. [Universitaet Augsburg, Institut fuer Physik (Germany)

    2016-03-18

    K{sub 4}[BS{sub 4}O{sub 15}(OH)], Ba[B{sub 2}S{sub 3}O{sub 13}], and Gd{sub 2}[B{sub 2}S{sub 6}O{sub 24}] were obtained by a new synthetic approach. The strategy involves initially synthesizing the complex acid H[B(HSO{sub 4}){sub 4}] which is subsequently reacted in an open system with anhydrous chlorides of K, Ba, and Gd to the respective borosulfates and a volatile molecule (HCl). Furthermore, protonated borosulfates should be accessible by appropriate stoichiometry of the starting materials, particularly in closed systems, which inhibit deprotonation of H[B(HSO{sub 4}){sub 4}] via condensation and dehydration. This approach led to the successful synthesis of the first divalent and trivalent metal borosulfates (Ba[B{sub 2}S{sub 3}O{sub 13}] with band-silicate topology and Gd{sub 2}[B{sub 2}S{sub 6}O{sub 24}] with cyclosilicate topology) and the first hydrogen borosulfate K{sub 4}[BS{sub 4}O{sub 15}(OH)]. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Song, Taek Ho

    1994-02-15

    In connection with the safe storage of high level nuclear waste, effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H{sub 2}O{sub 2}. The experimental results show that H{sub 2}O{sub 2} increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H{sub 2}O{sub 2} concentration increased, indicating that pitting resistance was decreased by the existence of H{sub 2}O{sub 2} in the electrolyte. These effects of H{sub 2}O{sub 2} on corrosion of 304L stainless steel are considered to be similar to those of γ-irradiation. To compare the effects of H{sub 2}O{sub 2} with those of O{sub 2}, cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H{sub 2}O{sub 2} on the corrosion behavior were very similar to those of O{sub 2} such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. Further, H{sub 2}O{sub 2} played much greater role in controlling cathodic reaction rate in neutral water environment. In acid and alkaline media, potential shifts by H{sub 2}O{sub 2} were restricted by the large current density of proton reduction and by the le Chatelier's principle respectively.

  13. IDENTIFYING PLANETARY BIOSIGNATURE IMPOSTORS: SPECTRAL FEATURES OF CO AND O{sub 4} RESULTING FROM ABIOTIC O{sub 2}/O{sub 3} PRODUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Schwieterman, Edward W.; Meadows, Victoria S.; Arney, Giada N.; Luger, Rodrigo; Misra, Amit; Barnes, Rory [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195 (United States); Domagal-Goldman, Shawn D.; Deming, Drake; Harman, Chester E., E-mail: eschwiet@uw.edu [NASA Astrobiology Institute’s Virtual Planetary Laboratory, Seattle, WA 981195 (United States)

    2016-03-01

    O{sub 2} and O{sub 3} have been long considered the most robust individual biosignature gases in a planetary atmosphere, yet multiple mechanisms that may produce them in the absence of life have been described. However, these abiotic planetary mechanisms modify the environment in potentially identifiable ways. Here we briefly discuss two of the most detectable spectral discriminants for abiotic O{sub 2}/O{sub 3}: CO and O{sub 4}. We produce the first explicit self-consistent simulations of these spectral discriminants as they may be seen by James Webb Space Telescope (JWST). If JWST-NIRISS and/or NIRSpec observe CO (2.35, 4.6 μm) in conjunction with CO{sub 2} (1.6, 2.0, 4.3 μm) in the transmission spectrum of a terrestrial planet it could indicate robust CO{sub 2} photolysis and suggest that a future detection of O{sub 2} or O{sub 3} might not be biogenic. Strong O{sub 4} bands seen in transmission at 1.06 and 1.27 μm could be diagnostic of a post-runaway O{sub 2}-dominated atmosphere from massive H-escape. We find that for these false positive scenarios, CO at 2.35 μm, CO{sub 2} at 2.0 and 4.3 μm, and O{sub 4} at 1.27 μm are all stronger features in transmission than O{sub 2}/O{sub 3} and could be detected with S/Ns ≳ 3 for an Earth-size planet orbiting a nearby M dwarf star with as few as 10 transits, assuming photon-limited noise. O{sub 4} bands could also be sought in UV/VIS/NIR reflected light (at 0.345, 0.36, 0.38, 0.445, 0.475, 0.53, 0.57, 0.63, 1.06, and 1.27 μm) by a next generation direct-imaging telescope such as LUVOIR/HDST or HabEx and would indicate an oxygen atmosphere too massive to be biologically produced.

  14. Competition of Kondo spin fluctuations and RKKY interactions in CeRh/sub 2/Si/sub 2-x/Ge/sub x/ and CeM/sub 2/X/sub 2/ compounds: a Kondo necklace problem

    Energy Technology Data Exchange (ETDEWEB)

    Godart, C; Gupta, L C; Tomy, C V; Vijayaraghavan, R; Thompson, J D

    1989-02-15

    We present the results of our measurements of the lattice constants and magnetic susceptibility of the pseudo-ternary system which crystallizes in the tetragonal ThCr/sub 2/Si/sub 2/ structure. Both of the cell constants a and c increase linearly with x. The magnetic ordering temperature T/sub N/ exhibits initially an enhancement with the increase in x and then decreases as x continues to increase further. These results, along with those on the pressure dependence of T/sub N/ in CeRh/sub 2/Si/sub 2/, can be understood on the basis of the Doniach's model of a Kondo necklace. We discuss also the applicability of this model to describe the strong correlation between the structural aspects and the ground-state properties of the whole series of Ce-based ternaries CeM/sub 2/X/sub 2/ (M = 3d, 4d and 5d elements; X = Si, Ge).

  15. Diffusion Monte Carlo studies of MB-pol (H{sub 2}O){sub 2−6} and (D{sub 2}O){sub 2−6} clusters: Structures and binding energies

    Energy Technology Data Exchange (ETDEWEB)

    Mallory, Joel D.; Mandelshtam, Vladimir A. [Department of Chemistry, University of California, Irvine, California 92697 (United States)

    2016-08-14

    We employ the diffusion Monte Carlo (DMC) method in conjunction with the recently developed, ab initio-based MB-pol potential energy surface to characterize the ground states of small (H{sub 2}O){sub 2−6} clusters and their deuterated isotopomers. Observables, other than the ground state energies, are computed using the descendant weighting approach. Among those are various spatial correlation functions and relative isomer fractions. Interestingly, the ground states of all clusters considered in this study, except for the dimer, are delocalized over at least two conformations that differ by the orientation of one or more water monomers with the relative isomer populations being sensitive to the isotope substitution. Most remarkably, the ground state of the (H{sub 2}O){sub 6} hexamer is represented by four distinct cage structures, while that of (D{sub 2}O){sub 6} is dominated by the prism, i.e., the global minimum geometry, with a very small contribution from a prism-book geometry. In addition, for (H{sub 2}O){sub 6} and (D{sub 2}O){sub 6}, we performed DMC calculations to compute the ground states constrained to the cage and prism geometries. These calculations compared results for three different potentials, MB-pol, TTM3/F, and q-TIP4P/F.

  16. Non-isothermal crystallization kinetics of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass containing nucleation agent P{sub 2}O{sub 5}/TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bin, E-mail: stra-ceo@163.com; Wang, Yongya; Luo, Wenqin; Li, Jingfen [Huzhou University, Department of Material Chemistry (China); Li, Jianyou [Huzhou Central Hospital, Orthopedic Department (China)

    2017-03-15

    Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass ceramics containing nucleation agent P{sub 2}O{sub 5}/TiO{sub 2} were prepared by sol-gel method. The samples were characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The activation energy and kinetic parameters for crystallization of the samples were calculated by the Johnson-Mehi-Avrami (JMA) model and Augis-Bennett method according to the results of DSC. The results showed that the crystallization mechanism of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass, whose non-isothermal kinetic parameter n = 2.3, was consistent with surface crystallization of the JMA model. The kinetics model function of Fe{sub 2}O{sub 3}–CaO–SiO{sub 2} glass, f(α) = 2.3(1–α)[–ln(1–α)]{sup 0.57}, was also obtained. The addition of nucleation agent P{sub 2}O{sub 5}/TiO{sub 2} could reduce the activation energy, which made the crystal growth modes change from onedimensional to three-dimensional.

  17. Superconductivity induced by oxygen doping in Y{sub 2}O{sub 2}Bi

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Xiyue; Deng, Shuiquan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou (China); Gordon, Elijah E. [Department of Chemistry, North Carolina State University, Raleigh, NC (United States); Whangbo, Myung-Hwan [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter (FJIRSM), Chinese Academy of Sciences (CAS), Fuzhou (China); Department of Chemistry, North Carolina State University, Raleigh, NC (United States)

    2017-08-14

    When doped with oxygen, the layered Y{sub 2}O{sub 2}Bi phase becomes a superconductor. This finding raises questions about the sites for doped oxygen, the mechanism of superconductivity, and practical guidelines for discovering new superconductors. We probed these questions in terms of first-principles calculations for undoped and O-doped Y{sub 2}O{sub 2}Bi. The preferred sites for doped O atoms are the centers of Bi{sub 4} squares in the Bi square net. Several Bi 6p x/y bands of Y{sub 2}O{sub 2}Bi are raised in energy by oxygen doping because the 2p x/y orbitals of the doped oxygen make antibonding possible with the 6p x/y orbitals of surrounding Bi atoms. Consequently, the condition necessary for the ''flat/steep'' band model for superconductivity is satisfied in O-doped Y{sub 2}O{sub 2}Bi. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Song, Taek Hoh; Kim, In Sub [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Noh, Sung Kee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-08-01

    In connection with the safe storage of high level nuclear waste, effect of H{sub 2}O{sub 2} on the corrosion behavior of 304L stainless steel was examined. Open circuit potentials and polarization curves were measured with and without H{sub 2}O{sub 2}. The experimental results show that H{sub 2}O{sub 2} increased corrosion potential and decreased pitting potential. The passive range, therefore, decreased as H{sub 2}O{sub 2} concentration increased, indicating that pitting resistance was decreased by the existence of H{sub 2}O{sub 2} in the electrolyte. These effects of H{sub 2}O{sub 2} on corrosion of 304L stainless steel are considered to be similar to those of {gamma}-irradiation. To compare the effects of H{sub 2}O{sub 2} with those of O{sub 2}, cathodic and anodic polarization curves were made in three types of electrolyte such as aerated, deaerated, and stirred electrolyte. The experimental results show that the effects of H{sub 2}O{sub 2} on the corrosion behavior were very similar to those of O{sub 2} such as increase of corrosion potential, decrease of pitting resistance, and increase of repassivation potential. In acid and alkaline media, the corrosion potential shifts by H{sub 2}O{sub 2} were restricted by the large current density of proton reduction and by the le Chatelier`s principle respectively. 13 figs., 1 tabs., 17 refs. (Author).

  19. Microstructures and properties of TiN reinforced Co-based composite coatings modified with Y{sub 2}O{sub 3} by laser cladding on Ti–6Al–4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Weng, Fei, E-mail: wengfeisdu@126.com [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science and Engineering, Shandong University, Ji' nan 250061 (China); Shandong University, Suzhou Institute, Suzhou 215123 (China); Yu, Huijun, E-mail: yhj2001@sdu.edu.cn [Key Laboratory of High-efficiency and Clean Mechanical Manufacture (Ministry of Education), School of Mechanical Engineering, Shandong University, Ji' nan 250061 (China); Shandong University, Suzhou Institute, Suzhou 215123 (China); Chen, Chuanzhong, E-mail: czchen@sdu.edu.cn [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science and Engineering, Shandong University, Ji' nan 250061 (China); Shandong University, Suzhou Institute, Suzhou 215123 (China); Liu, Jianli, E-mail: jianli21s@163.com [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science and Engineering, Shandong University, Ji' nan 250061 (China); Shandong University, Suzhou Institute, Suzhou 215123 (China); Zhao, Longjie, E-mail: zhaoljsdu@sina.com [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science and Engineering, Shandong University, Ji' nan 250061 (China); Shandong University, Suzhou Institute, Suzhou 215123 (China)

    2015-11-25

    In this study, TiN reinforced composite coatings were fabricated on Ti–6Al–4V substrate by laser cladding with Co42 self-fluxing alloy, TiN and Y{sub 2}O{sub 3} mixed powders. Microstructures and wear resistance of the cladding coatings with and without Y{sub 2}O{sub 3} addition were investigated comparatively. Results showed that the coatings were mainly comprised of γ-Co/Ni, TiN, CoTi, CoTi{sub 2}, NiTi, TiC, Cr{sub 7}C{sub 3}, TiB, Ti{sub 5}Si{sub 3} and TiC{sub 0.3}N{sub 0.7} phases. The coatings showed metallurgical bonding free of pores and cracks with the substrate. Compared with the Ti–6Al–4V substrate, the microhardness and wear resistance of the coatings was enhanced by 3–4 times and 9.5–11.9 times, respectively. With 1.0 wt.% Y{sub 2}O{sub 3} addition, the microstructure of the coating was refined significantly, and the microhardness and dry sliding wear resistance were enhanced further. The effects of Y{sub 2}O{sub 3} were attributed to the residual Y{sub 2}O{sub 3} and decomposed Y atoms. - Graphical abstract: The diagram illustration for the action mechanism of Y{sub 2}O{sub 3}: (a) dissolution of Y{sub 2}O{sub 3} and TiN, (b) re-formation of TiN and in situ formation of TiC, (c) growth of TiN, TiC and the distribution of Y atoms. - Highlights: • Coatings showing metallurgical bonding with the substrate were fabricated. • The effect of Y{sub 2}O{sub 3} on the refinement of the microstructure is notable. • A kind of Y{sub 2}O{sub 3} centered core–shell structure was picked out in the coating. • Microhardness and wear resistance of the coatings was enhanced significantly.

  20. Microstructure studies of interdiffusion behavior of U{sub 3}Si{sub 2}/Zircaloy-4 at 800 and 1000 °C

    Energy Technology Data Exchange (ETDEWEB)

    He, Lingfeng, E-mail: Lingfeng.He@inl.gov; Harp, Jason M., E-mail: Jason.Harp@inl.gov; Hoggan, Rita E.; Wagner, Adrian R.

    2017-04-01

    Fuel swelling during normal reactor operations could lead to unfavorable chemical interactions when in contact with its cladding. As new fuel types are developed, it is crucial to understand the interaction behavior between fuel and its cladding. Diffusion experiments between U{sub 3}Si{sub 2} and Zricaloy-4 (Zry-4) were conducted at 800 and 1000 °C up to 100 h. The microstructure of pristine U{sub 3}Si{sub 2} and U{sub 3}Si{sub 2}/Zry-4 interdiffusion products were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) equipped with an energy dispersive X-ray spectroscopy (EDS) system. The primary interdiffusion product observed at 800 °C is ZrSi{sub 2}, with secondary phases of U-Zr in the Zry-4, and Fe-Cr-W-Zr-Si phases at Zry-4/ZrSi{sub 2} interface and Fe-Cr-U-Si phases at ZrSi{sub 2}/U-Si interface. The primary interdiffusion products at 1000 °C were Zr{sub 2}Si, U-Zr-Fe-Ni, U, U-Zr, and a low melting point phase U{sub 6}Fe.

  1. Studies on high-pressure reaction of Er/sub 2/O/sub 3/ or Yb/sub 2/O/sub 3/ with VO/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Shin-ike, T [Osaka Dental Coll., Hirakata (Japan); Adachi, G; Shiokawa, J; Shimada, M; Koizumi, M

    1980-12-01

    The reaction of erbium sesquioxide (Er/sub 2/O/sub 3/) or ytterbium sesquioxide (Yb/sub 2/O/sub 3/) with vanadium dioxide (VO/sub 2/) at 1400/sup 0/C and 50 kbar and 30 kbar pressures was studied. Quadrivalent vanadium ions were reduced to the trivalent state, erbium vanadate (ErVO/sub 3/) or ytterbium vanadate (YbVO/sub 3/) being obtained. The crystal structure of ErVO/sub 3/ obtained at 50 kbar pressure was vaterite-type isostructural with ErBO/sub 3/ belonging to a hexagonal system, and that obtained at 30 kbar calcite-type belonging to a rhombohedral (pseudo-hexagonal) system. In the reaction of Yb/sub 2/O/sub 3/ with VO/sub 2/ at high pressure, a perovskite-type crystal was obtained. The electrical and magnetic properties of the vaterite- and the calcite-type ErVO/sub 3/ were studied.

  2. Fabrication and microstructural analysis of UN-U{sub 3}Si{sub 2} composites for accident tolerant fuel applications

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kyle D., E-mail: kylej@kth.se; Raftery, Alicia M.; Lopes, Denise Adorno; Wallenius, Janne

    2016-08-15

    In this study, U{sub 3}Si{sub 2} was synthesized via the use of arc-melting and mixed with UN powders, which together were sintered using the SPS method. The study revealed a number of interesting conclusions regarding the stability of the system – namely the formation of a probable but as yet unidentified ternary phase coupled with the reduction of the stoichiometry in the nitride phase – as well as some insights into the mechanics of the sintering process itself. By milling the silicide powders and reducing its particle size ratio compared to UN, it was possible to form a high density UN-U{sub 3}Si{sub 2} composite, with desirable microstructural characteristics for accident tolerant fuel applications. - Highlights: • U{sub 3}Si{sub 2} fabricated from elemental uranium and silicon through arc melting. • Homogeneity of the silicides assessed through densitometry, XRD, SEM and EDS, chemical etching and optical microscopy. • UN powder fabricated using hydriding-nitriding method. • No phase transformations detected when sintering using silicide particle sizes less than UN particle size. • High density composite (98%TD) fabricated with silicide grain coating using spark plasma sintering at 1450 °C.

  3. Structural and optical properties of glancing angle deposited In{sub 2}O{sub 3} columnar arrays and Si/In{sub 2}O{sub 3} photodetector

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, A.; Shougaijam, B.; Goswami, T.; Dhar, J.C.; Singh, N.K. [National Institute of Technology, Department of Electronics and Communication Engineering, Agartala (India); Choudhury, S. [North Eastern Hill University, Department of Electronics and Communication Engineering, Shillong (India); Chattopadhay, K.K. [Jadavpur University, Department of Physics, Kolkata (India)

    2014-04-15

    Ordered and perpendicular columnar arrays of In{sub 2}O{sub 3} were synthesized on conducting ITO electrode by a simple glancing angle deposition (GLAD) technique. The as-deposited In{sub 2}O{sub 3} columns were investigated by field emission gun-scanning electron microscope (FEG-SEM). The average length and diameter of the columns were estimated ∝400 nm and ∝100 nm, respectively. The morphology of the structure was examined by transmission electron microscopy (TEM). X-ray diffraction (XRD) analysis shows the polycrystalline nature of the sample which was verified by selective area electron diffraction (SAED) analysis. The growth mechanism and optical properties of the columns were also discussed. Optical absorption shows that In{sub 2}O{sub 3} columns have a high band to band transition at ∝3.75 eV. The ultraviolet and green emissions were obtained from the In{sub 2}O{sub 3} columnar arrays. The P-N junction was formed between In{sub 2}O{sub 3} and P-type Si substrate. The GLAD synthesized In{sub 2}O{sub 3} film exhibits low current conduction compared to In{sub 2}O{sub 3} TF. However, the Si/GLAD-In{sub 2}O{sub 3} detector shows ∝1.5 times enhanced photoresponsivity than that of Si/In{sub 2}O{sub 3} TF. (orig.)

  4. Enrichment of Sc{sub 2}O{sub 3} and TiO{sub 2} from bauxite ore residues

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Bona; Li, Guanghui, E-mail: liguangh@csu.edu.cn; Luo, Jun; Ye, Qing; Liu, Mingxia; Peng, Zhiwei; Jiang, Tao

    2017-06-05

    Highlights: • Sc{sub 2}O{sub 3} and TiO{sub 2} from bauxite ore residue were successfully enriched. • H{sub 3}PO{sub 4} and NaOH were efficient for enriching Sc{sub 2}O{sub 3} and TiO{sub 2} by removing SiO{sub 2}, Al{sub 2}O{sub 3}, and partial Fe{sub 2}O{sub 3} and CaO. • Enriching mechanism of Sc{sub 2}O{sub 3} and TiO{sub 2} was explicitly explained. - Abstract: As a major byproduct generated in the alumina industry, bauxite ore residue is an important reserve of scandium and titanium. In this study, the feasibility and mechanism of enriching Sc{sub 2}O{sub 3} and TiO{sub 2} from a non-magnetic material, which was obtained from carbothermal reductive roasting and magnetic separation of bauxite ore residue, were investigated based on a two-step (acidic and alkali) leaching process. It was revealed that approximately 78% SiO{sub 2} and 30–40% of CaO, FeO and Al{sub 2}O{sub 3} were removed from a non-magnetic material with 0.0134 wt.% Sc{sub 2}O{sub 3} and 7.64 wt.% TiO{sub 2} by phosphoric acidic leaching, while about 95% Al{sub 2}O{sub 3} and P{sub 2}O{sub 5} were further leached by subsequent sodium hydroxide leaching of the upper-stream leach residue. A Sc{sub 2}O{sub 3}-, TiO{sub 2}- rich material containing 0.044 wt.% Sc{sub 2}O{sub 3} and 25.5 wt.% TiO{sub 2} was obtained, the recovery and the enrichment factor of Sc{sub 2}O{sub 3} and TiO{sub 2} were about 85% and 5, respectively. The enrichment of Sc{sub 2}O{sub 3} was attributed to higher pH (>3.3) of phosphoric acid solution than its dissolution pH{sup 0}, and the enrichment of TiO{sub 2} was mainly associated with the insoluble perovskite (CaTiO{sub 3}) in the acidic solution at ambient temperature. As Sc{sub 2}O{sub 3} and TiO{sub 2} cannot be dissolved in the alkali solution, they were further enriched in the leach residue.

  5. NMR study of the paramagnetic state of low-dimensional magnets LiCu{sub 2}O{sub 2} and NaCu{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Sadykov, A. F., E-mail: sadykov@imp.uran.ru; Piskunov, Yu. V.; Gerashchenko, A. P.; Ogloblichev, V. V.; Smol’nikov, A. G.; Verkhovskii, S. V.; Arapova, I. Yu.; Volkova, Z. N.; Mikhalev, K. N. [Russian Academy of Sciences, Mikheev Institute of Metal Physics, Ural Branch (Russian Federation); Bush, A. A. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation)

    2017-02-15

    A comprehensive NMR study of the magnetic properties of single crystal LiCu{sub 2}O{sub 2} (LCO) and NaCu{sub 2}O{sub 2} (NCO) is carried out in the paramagnetic region of the compounds for various orientations of single crystals in an external magnetic field. The values of the electric-field gradient (EFG) tensor, as well as the dipole and transferred hyperfine magnetic fields for {sup 63,65}Cu, {sup 7}Li, and {sup 23}Na nuclei are determined. The results are compared with the data obtained in previous NMR studies of the magnetically ordered state of LCO/NCO cuprates.

  6. Resistance switching characteristics of core–shell γ-Fe{sub 2}O{sub 3}/Ni{sub 2}O{sub 3} nanoparticles in HfSiO matrix

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Guangdong [Guizhou Institute of Technology, Guiyang 550003 (China); Wu, Bo, E-mail: fqwubo@zync.edu.cn [Institute of Theoretical Physics, Zunyi Normal College, Zunyi 563002 (China); School of Marine Science and Technology, Northwestern Polytechnical University, Xian 710072 (China); Liu, Xiaoqin; Li, Zhiling; Zhang, Shuangju [Guizhou Institute of Technology, Guiyang 550003 (China); Zhou, Ankun [Kunming Institute of Botany, Chineses Academy Sciences, Kunming 650201 (China); Yang, Xiude [Institute of Theoretical Physics, Zunyi Normal College, Zunyi 563002 (China)

    2016-09-05

    Core–shell γ-Fe{sub 2}O{sub 3}/Ni{sub 2}O{sub 3} nanoparticles are synthesized by chemical co-precipitation method. Resistive switching memory behaviors, which have resistance ON/OFF ratio of ∼10{sup 2} and excellent retention property, are observed in the Au/HfSiO/γ-Fe{sub 2}O{sub 3}/Ni{sub 2}O{sub 3}/HfSiO/Pt structure. Space charge limited current (SCLC) mechanism, which is supported by the fitting current–voltage results, is employed to know the resistive switching memory effects. The transportation of Oxygen vacancy Vo{sup 2+}, oxygen ion O{sup 2−}, recombination of oxygen atom and drive of external electric field are responsible for the ON or OFF states observed in device. - Highlights: • Bipolar resistance switching effects are detected in core–shell of γ-Fe{sub 2}O{sub 3}@Ni{sub 2}O{sub 3}. • The Ohimc conduction and space-charge-limited current play an important role in Low/High field. • Rapture of filament assisted by Vo{sup 2+}, O{sup 2−} and O{sub 2} recombination is responsible for switching. • Resistance switching memory highlights excellent retention properties after stress 100 cycles.

  7. An experimental and mathematical modeling study comparing the reactivity and burnout of pulverized coal in air (O{sub 2}/N{sub 2}) and oxyfuel (O{sub 2}/CO{sub 2}) environments

    Energy Technology Data Exchange (ETDEWEB)

    Liza Elliott; Yinghui Liu; Bart Buhre; Jennifer Martin; Raj Gupta; Terry Wall [University of Newcastle, Callaghan, NSW (Australia). Cooperative Research Centre for Coal in Sustainable Development, Chemical Engineering

    2005-07-01

    Carbon dioxide in flue gas from conventional combustion processes is present as a dilute gas. CO{sub 2} capture is more easily achieved from a concentrated CO{sub 2} stream, which can be achieved by firing fuels with oxygen to obtain a sequestration ready gas stream, called oxy-fuel combustion. In this technology, the oxygen stream is usually diluted by recycled flue gas (RFG), so that the coal burns in an environment which is primarily O{sub 2}/CO{sub 2}. A size cut of a number of pulverised coals were devolatalised in N{sub 2} and CO{sub 2}. These sized coals were also combusted in a drop-tube furnace in an O{sub 2}/N{sub 2} environment simulating air combustion, and O{sub 2}/CO{sub 2} simulating oxyfuel combustion, with varying O{sub 2} levels from 3 to 30% v/v. Measurements of the extent of devolatilisation and coal burnout were completed. The detailed data provided for one coal indicated that the devolatilisation process in the O{sub 2}/CO{sub 2} environments is influenced by char gasification, and the char reaction rates are fitted better by a fractional order rate than first order in oxygen. Combustion rates in the oxyfuel environment were slightly higher. Estimates of the burnout for furnaces retrofitted from air to oxyfuel indicate that a better burnout can be expected. These trends were common for all coals. 14 refs., 4 figs., 5 tabs.

  8. A series of noncentrosymmetric antimony sulfides Ln{sub 8}Sb{sub 2}S{sub 15} (Ln = La, Pr, Nd) - syntheses, crystal and electronic structures, and NLO properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hua-Jun [Laboratory of Applied Research on the Characteristic Resources in the North of Guizhou Province, School of Chemistry and Chemical Engineering, Zunyi Normal College, Guizhou (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China); Zhou, Liu-Jiang [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou (China)

    2015-02-15

    A series of noncentrosymmetric sulfides Ln{sub 8}Sb{sub 2}S{sub 15} (Ln = La, Pr, Nd) were prepared from stoichiometric mixtures of the elements at 1223 K in an evacuated silica tube. The compounds Ln{sub 8}Sb{sub 2}S{sub 15} with Ln = La and Nd are isostructural to Pr{sub 8}Sb{sub 2}S{sub 15} and crystallize in the tetragonal noncentrosymmetric space group I4{sub 1}cd. Their structure contains discrete [SbS{sub 3}]{sup 3-} trigonal pyramids separated by Ln{sup 3+} cations and S{sup 2-} anions. La{sub 8}Sb{sub 2}S{sub 15} shows second harmonic generation with intensities 1.2 times that of the commercially used IR NLO (nonlinear optics) material AgGaS{sub 2} (at 2.05 μm laser). It exhibits excellent thermal stability up to 663 C. Studies with UV/Vis-NIR diffuse reflectance spectroscopy show that La{sub 8}Sb{sub 2}S{sub 15} has an optical gap of around 2.3 eV, and a DFT study indicates a direct band gap with an electronic transfer excitation of S 3p electrons to a La 5d orbital. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Interactions of a La{sub O.9}Sr{sub O.1}Ga{sub O.8}Mg{sub O.2}O{sub 3-{delta}} electrolyte with Fe{sub 2}O{sub 3}, Co{sub 2}O{sub 3} and NiO anode materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, X.; Ohara, S.; Okawa, H.; Maric, R.; Fukui, T. [Japan Fine Ceramics Center, 2-4-1 Mutsuo, Atsuta-ku, 456-8587 Nagoya (Japan)

    2001-01-02

    In this study, the interactions of a Sr- and Mg-doped lanthanum gallate (LSGM with composition La{sub O.9}Sr{sub O.1}Ga{sub O.8}Mg{sub O.2}O{sub 3-{delta}}) electrolyte with Fe{sub 2}O{sub 3}, Co{sub 2}O{sub 3} and NiO as the anode starting materials were investigated. It was found that the order of reactivity of the LSGM with the three oxides was Co{sub 2}O{sub 3}>NiO>Fe{sub 2}O{sub 3}, and La-containing oxides were detected in these binary powder mixtures after firing. The anode performance was greatly influenced by the interaction. The Fe{sub 2}O{sub 3}-LSGM anode, mixed with 40 vol.% LSGM powder and sintered at 1150C, exhibited the highest initial performance in comparison with NiO-LSGM and Co{sub 2}O{sub 3}-LSGM anodes. It seems that Fe{sub 2}O{sub 3} is a possible anode starting material for a LSGM-based solid oxide fuel cell.

  10. Study of conduction mechanism in Fe{sub 2}O{sub 3} doped Na{sub 2}O·Bi{sub 2}O{sub 3}·B{sub 2}O{sub 3} semiconducting glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ahlawat, Navneet [Matu Ram Institute of Engineering and Management, Rohtak 124001, Haryana (India); Aghamkar, Praveen [Department of Physics, Chaudhary Devi Lal University, Sirsa 125055, Haryana (India); Agarwal, Ashish [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Ahlawat, Neetu, E-mail: neetugju@yahoo.co.in [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India)

    2016-02-01

    Conduction mechanism in Fe{sub 2}O{sub 3} doped Na{sub 2}O·Bi{sub 2}O{sub 3}·B{sub 2}O{sub 3} semiconducting glass system was studied in frequency range 10 Hz to 1 MHz and at temperatures between room temperature and 663 K. The total conductivity spectrum follows universal power law with frequency exponent ‘s’ value less than unity and lies in the range 0.51≤s≤0.78. These ranges of ‘s’ values indicate that the carrier transport is predominately due to hopping electrons between charged defects and show temperature dependence as predicted by correlated barrier hopping (CBH) model. The change in activation energy of dc conductivity with temperature reveals the change in conduction mode from small polaron hopping (SPH) at high temperatures (T>θ{sub D}/2) to variable range hopping (VRH) at low temperatures (T<θ{sub D}/2). The range of density of states at Fermi level N (E{sub F})=7.25×10{sup 21}–1.32×10{sup 21} eV{sup −1} cm{sup −3} at temperatures below θ{sub D}/2 corresponds to localized states near Fermi level. The large values of activation energy W{sub 2} (0.067–0.155 eV) dominated the conduction may results in high range of temperature (T=503– 423 K) for variable-range hopping conduction in these glasses.

  11. Sintering of SiC ceramics, via liquid phase, with Al{sub 2}O{sub 3}-Yb{sub 2}O{sub 3} additives; Sinterizacao de ceramicas de SiC, via fase liquida, com aditivos de Al{sub 2}O{sub 3}-Yb{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Atilio, I.; Oliveira, M.R.; Garcia, G.C.R.; Ribeiro, S., E-mail: isabelaatilio@hotmail.com [Universidade de Sao Paulo (USP/EEL), Lorena, SP (Brazil). Escola de Engenharia. Dept. de Engenharia de Materiais

    2012-07-01

    The objective of this work was to study the sintering of SiC, through liquid phase, using the additive system Al{sub 2}O{sub 3} and Yb{sub 2}O{sub 3} for the first time. The samples were sintered at temperatures of 1900, 1950 and 2000 deg C for 60 minutes. The melting point of the system was determined according to DIN 51730. It has been found the ability of wetting of SiC in the system. The densification results were: 86,36% at 1900 deg C, 88,25% at 1950 deg C and 82,09% at 2000 deg C. The average linear shrinkage was approximately 17%. There was a conversion of β-SiC in α-SiC at all temperatures and sintering phase formation Yb{sub 3}Al{sub 5}O{sub 12}. The melting temperature was 1850 deg C for de system, consistent with the value in the phase diagram, and the wetting angle of 20 deg. The system (Yb{sub 2}O{sub 3}-Al{sub 2}O{sub 3}) is promising to make liquid phase sintering of SiC, for presenting a good result of wettability. (author)

  12. Hypoeutectic melting in the UO{sub 2-x}-Gd{sub 2}O{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Journeau, Christophe, E-mail: christophe.journeau@cea.fr [CEA, DEN, SMTA, LPMA, Cadarache, F13108 St Paul lez Durance (France); Fouquart, Pascal [CEA, DEN, SMTA, LPMA, Cadarache, F13108 St Paul lez Durance (France); Domenger, Renaud; Allegri, Patrick [CEA, DEN, SGCS, LMAC, Marcoule, F30207 Bagnols sur Cèze (France)

    2017-05-15

    Gadolinium is one of the best neutron absorber materials and its use can be considered as a sacrificial material in a Sodium Fast Reactor core catcher in view of preventing recriticallity. A series of experiments have been conducted in the VITI induction-heated facility to study the melting in the UO{sub 2-x}-Gd{sub 2}O{sub 3} system with 60–87 mol% gadolinia. These experiments have indicated that the eutectic composition is around 92 mol% Gd{sub 2}O{sub 3} – 8 mol% UO{sub 2-x} and that the liquidus line is close to that of Popov et al. [Atom. Energ. 110 (2011) pp. 221–229] phase diagram. - Highlights: •Melting/Solidification experiments with UO{sub 2-x} and Gd{sub 2}O{sub 3} in reducing environment. •Eutectic composition around 92 mol% Gd{sub 2}O{sub 3}-8 mol% UO{sub 2-x}. •UO{sub 2-x} - Gd{sub 2}O{sub 3} liquidus line seems close to that of the pseudobinary phase diagram proposed by Popov et al. •Results will support the assessment of Gd{sub 2}O{sub 3} as a sacrificial material to mitigate criticality risk in SFR core catchers.

  13. Degradation of 5-FU by means of advanced (photo)oxidation processes: UV/H{sub 2}O{sub 2}, UV/Fe{sup 2+}/H{sub 2}O{sub 2} and UV/TiO{sub 2} — Comparison of transformation products, ready biodegradability and toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Lutterbeck, Carlos Alexandre, E-mail: lutterbeck@leuphana.de [Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg (Germany); Graduate Program in Environmental Technology, Universidade de Santa Cruz do Sul — UNISC, Av. Independência, 2293, CEP 96815-900 Santa Cruz do Sul, Rio Grande do Sul (Brazil); Wilde, Marcelo Luís, E-mail: wilde@leuphana.de [Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg (Germany); Baginska, Ewelina, E-mail: ewelina.baginska@leuphana.de [Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg (Germany); Leder, Christoph, E-mail: cleder@leuphana.de [Sustainable Chemistry and Material Resources, Institute of Sustainable and Environmental Chemistry, Faculty of Sustainability, Leuphana University of Lüneburg, Scharnhorststraße 1/C13, DE-21335 Lüneburg (Germany); Machado, Ênio Leandro, E-mail: enio@unisc.br [Graduate Program in Environmental Technology, Universidade de Santa Cruz do Sul — UNISC, Av. Independência, 2293, CEP 96815-900 Santa Cruz do Sul, Rio Grande do Sul (Brazil); and others

    2015-09-15

    The present study investigates the degradation of the antimetabolite 5-fluorouracil (5-FU) by three different advanced photo oxidation processes: UV/H{sub 2}O{sub 2}, UV/Fe{sup 2+}/H{sub 2}O{sub 2} and UV/TiO{sub 2}. Prescreening experiments varying the H{sub 2}O{sub 2} and TiO{sub 2} concentrations were performed in order to set the best catalyst concentrations in the UV/H{sub 2}O{sub 2} and UV/TiO{sub 2} experiments, whereas the UV/Fe{sup 2+}/H{sub 2}O{sub 2} process was optimized varying the pH, Fe{sup 2+} and H{sub 2}O{sub 2} concentrations by means of the Box–Behnken design (BBD). 5-FU was quickly removed in all the irradiation experiments. The UV/Fe{sup 2+}/H{sub 2}O{sub 2} and UV/TiO{sub 2} processes achieved the highest degree of mineralization, whereas the lowest one resulted from the UV/H{sub 2}O{sub 2} treatment. Six transformation products were formed during the advanced (photo)oxidation processes and identified using low and high resolution mass spectrometry. Most of them were formed and further eliminated during the reactions. The parent compound of 5-FU was not biodegraded, whereas the photolytic mixture formed in the UV/H{sub 2}O{sub 2} treatment after 256 min showed a noticeable improvement of the biodegradability in the closed bottle test (CBT) and was nontoxic towards Vibrio fischeri. In silico predictions showed positive alerts for mutagenic and genotoxic effects of 5-FU. In contrast, several of the transformation products (TPs) generated along the processes did not provide indications for mutagenic or genotoxic activity. One exception was TP with m/z 146 with positive alerts in several models of bacterial mutagenicity which could demand further experimental testing. Results demonstrate that advanced treatment can eliminate parent compounds and its toxicity. However, transformation products formed can still be toxic. Therefore toxicity screening after advanced treatment is recommendable. - Highlights: • Full primary elimination of 5-FU was

  14. Nanostructured Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction photoelectrode for efficient hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Dipika; Upadhyay, Sumant; Verma, Anuradha [Department of Chemistry, Dayalbagh Educational Institute, Agra-282 110 India (India); Satsangi, Vibha R. [Department of Physics Computer Sciences, Dayalbagh Educational Institute, Agra-282 110 India (India); Shrivastav, Rohit [Department of Chemistry, Dayalbagh Educational Institute, Agra-282 110 India (India); Dass, Sahab, E-mail: drsahabdas@gmail.com [Department of Chemistry, Dayalbagh Educational Institute, Agra-282 110 India (India)

    2015-01-01

    Nanostructured thin films of pristine Fe{sub 2}O{sub 3}, Ti-doped Fe{sub 2}O{sub 3}, Cu{sub 2}O, and Fe{sub 2}O{sub 3}/Cu{sub 2}O, and Ti-doped Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction were deposited on tin-doped indium oxide (Sn:In{sub 2}O{sub 3}) glass substrate using spray pyrolysis method. Ti doping is done to improve photoelectric conversion efficiency and electrical conductivity of hematite thin films. Further enhanced photocurrent is achieved for Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction electrodes. All samples were characterized using X-ray diffractometry, scanning electron microscopy, atomic force microscopy, and UV-Vis spectrometry. Photoelectrochemical properties were also investigated in a three-electrode cell system. UV-Vis absorption spectrum for pristine Fe{sub 2}O{sub 3}, Ti-Fe{sub 2}O{sub 3}, Cu{sub 2}O, Fe{sub 2}O{sub 3}/Cu{sub 2}O, and Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction thin films exhibited absorption in visible region. Nanostructured thin films as prepared were used as photoelectrode in the photoelectrochemical cell for water splitting reaction. Maximum photocurrent density of 2.60 mA/cm{sup 2} at 0.95 V/SCE was exhibited by 454 nm thick Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction photoelectrode. Increased photocurrent density and enhanced incident photon-to-electron conversion efficiency, offered by the heterojunction thin films may be attributed to improved conductivity and efficient separation of the photogenerated charge carriers at the Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O interface. - Highlights: • Heterojunction thin films were deposited using spray pyrolysis techniques. • Titanium doping in Fe{sub 2}O{sub 3} played a significant role in PEC response. • Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O heterojunction shows the absorption in visible range. • Improved charge separation and enhanced PEC response were achieved in Ti-Fe{sub 2}O{sub 3}/Cu{sub 2}O.

  15. Thermal stability of SiO{sub 2}–B{sub 2}O{sub 3}–Al{sub 2}O{sub 3}–Na{sub 2}O–CaO glasses with high Nd{sub 2}O{sub 3} and MoO{sub 3} concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Chouard, Nolwenn [Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 75005, Paris (France); Laboratoire d' Etude et Développement des Matrices de Conditionnement, CEA/DEN/DTCD/SECM, Marcoule, 30207, Bagnols-sur-Cèze (France); Caurant, Daniel, E-mail: daniel.caurant@chimie-paristech.fr [Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 75005, Paris (France); Majérus, Odile; Guezi-Hasni, Nadia [Chimie ParisTech, PSL Research University, CNRS, Institut de Recherche de Chimie Paris (IRCP), 75005, Paris (France); Dussossoy, Jean-Luc [Laboratoire des Matériaux et Procédés Actifs, CEA/DEN/DTCD/SECM/LMPA, Marcoule, 30207, Bagnols-sur-Cèze (France); Baddour-Hadjean, Rita; Pereira-Ramos, Jean-Pierre [Groupe Electrochimie et Spectroscopie des Matériaux (UMR CNRS 7182), Institut de Chimie et des Matériaux Paris-Est, 94320, Thiais (France)

    2016-06-25

    The incorporation of high MoO{sub 3} amounts in borosilicate glasses developed for the immobilization of radioactive waste may lead to the crystallization of Mo-rich phases that may induce a decrease of the long term performances of glasses. It is thus essential to understand their crystallization mechanisms and the possible effect of other abundant fission products present in the wastes (such as rare earths) in order to control or to avoid their formation during glass preparation. This paper presents a study, performed by X-ray diffraction, scanning electron microscopy, Raman and optical absorption spectroscopies of the stability as a function of the thermal treatment temperature T{sub C} of a simplified Mo-rich nuclear waste glass. The impact of the addition of a high amount of Nd{sub 2}O{sub 3} on the thermal stability of this glass is studied. For comparison, the thermal stability of a Nd{sub 2}O{sub 3}-rich glass without Mo is also presented. The crystallization range of all phases formed in these glasses (CaMoO{sub 4}, Na{sub 2}MoO{sub 4}, Ca{sub 2}Nd{sub 8}(SiO{sub 4}){sub 6}O{sub 2} (apatite)) and the evolution of their structure and microstructure as a function of T{sub C} are presented. The introduction of Nd{sub 2}O{sub 3} in the MoO{sub 3}-rich glass inhibits the crystallization of molybdates (increase of Mo solubility), as long as apatite does not form which suggests that [MoO{sub 4}]{sup 2-} entities and Nd{sup 3+} cations are close to each other in the glass structure. Besides, when a high density of apatite crystals form, for instance from glass surface, small Mo-rich partially crystallized globular heterogeneities are observed between these crystals that exacerbate the nucleation of new apatite crystals (nucleating effect). - Highlights: • Effect of MoO{sub 3} and Nd{sub 2}O{sub 3} separately or together on glass crystallization is studied. • The crystallization range of molybdates and apatite (Ca{sub 2}Nd{sub 8}(SiO{sub 4}){sub 6}O{sub 2}) was

  16. Phase relationships in the area of the beta aluminate of the system K{sub 2}O-MgO-AL{sub 2}O{sub 3}; Phasenbeziehungen im Bereich der Beta-Aluminate des Systems K{sub 2}O-MgO-Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kroon, P de

    1996-12-01

    The aim of this work was to be able to make statements about the thermodynamic stability of K-{beta}``-Al{sub 2}O{sub 3} in the pseudo-binary system K{sub 2}O-Al{sub 2}O{sub 3} and in the pseudo-ternary system K{sub 2}O-MgO-Al{sub 2}O{sub 3} relative to the adjacent phases of KAlO{sub 2} {alpha}-Al{sub 2}O{sub 3}, MgAl{sub 2}O{sub 4} and K-{beta}-Al{sub 2}O{sub 3}. (orig./MM) [Deutsch] Ziel dieser Arbeit war es, Aussagen ueber die thermodynamische Stabilitaet von K-{beta}``-Al{sub 2}O{sub 3} im pseudobinaeren System K{sub 2}O-Al{sub 2}O{sub 3} und im pseudoternaeren System K{sub 2}O-MgO-Al{sub 2}O{sub 3} relativ zu den benachbarten Phasen KAlO{sub 2}, {alpha}-Al{sub 2}O{sub 3}, MgAl{sub 2}O{sub 4} und K-{beta}-Al{sub 2}O{sub 3} machen zu koennen. (orig./MM)

  17. MnFe{sub 2}O{sub 4} as a gas sensor towards SO{sub 2} and NO{sub 2} gases

    Energy Technology Data Exchange (ETDEWEB)

    Rathore, Deepshikha, E-mail: deep.nano@gmail.com; Mitra, Supratim [Department of Natural Sciences, NIIT University, Neemrana, Rajasthan 301705 (India)

    2016-05-06

    The chemical co-precipitation method was used to synthesize MnFe{sub 2}O{sub 4} nanoparticles. Single cubic phase formation of nanoparticles was confirmed by X-ray diffraction technique. The average particle size of MnFe{sub 2}O{sub 4} nanoparticles was found to be 10.7 nm using Scherrer formula. The ultrafine powder of MnFe{sub 2}O{sub 4} nanoparticles was pressed to design pellet of 10 mm diameter and 1mm thickness. Copper electrodes have been deposited on the surface of pellet using silver paste in the form of capacitor. Fabricated gas sensing device of MnFe{sub 2}O{sub 4} nanoparticles was tested towards SO{sub 2} and NO{sub 2} gases. Cole-Cole plot of MnFe{sub 2}O{sub 4} was investigated with the help of electrochemical workstation. The performance of the sensors including sensitivity, response and recovery time was also determined. It was observed that the MnFe{sub 2}O{sub 4} nanoparticles are more sensible for NO{sub 2} gas as compared to SO{sub 2} gas.

  18. Interaction of Ce{sub 1−x}Er{sub x}O{sub 2−y} nanoparticles with SiO{sub 2}-effect of temperature and atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Kepinski, L., E-mail: L.Kepinski@int.pan.wroc.pl; Krajczyk, L.; Mista, W.

    2014-01-15

    Morphology, microstructure and phase evolution of homogeneous, nanocrystalline Ce{sub 1−x}Er{sub x}O{sub 2−x/2} mixed oxide (x=0.3 and 0.5), prepared by microemulsion method, supported on amorphous SiO{sub 2} was studied in oxidizing and reducing atmosphere by XRD, TEM, SEM-EDS and N{sub 2} adsorption. The system is structurally and chemically stable in the oxidizing atmosphere up to 1000 °C, exhibiting only a small increase of the mean crystallite size of the oxide to ∼4 nm. At 1100 °C formation of Er silicate with unusual structure isomorphic with y-Y{sub 2}Si{sub 2}O{sub 7} (yttrialite), stabilized by Ce{sup 4+} ions was observed. In the reducing atmosphere the Ce{sub 1−x}Er{sub x}O{sub 2−x/2} reacted with SiO{sub 2} already at 900 °C, due to high affinity of the reduced Ce{sup 3+} to form a silicate phase. At higher temperature the silicate crystallized into the tetragonal, low temperature A-(Ce{sub 1−x}Er{sub x}){sub 2}Si{sub 2}O{sub 7} polymorph. Such systems, containing nanocrystalline silicate particles with Er{sup 3+} ions placed in well defined sites embedded in silica matrix, may be interesting as highly efficient active components of optical waveguides amplifiers integrated with Si microelectronics. The nanocrystalline Ce–Er–O/SiO{sub 2} system prepared by the impregnation of the silica with the aqueous solution of nitrates appeared to be chemically inhomogeneous and less stable in both oxidising and reducing atmosphere. - Graphical abstract: Structure evolution of Ce{sub 0.5}Er{sub 0.5}O{sub 1.75} in air and in H{sub 2}. Display Omitted - Highlights: • Homogeneous 3 nm Ce{sub 1−x}Er{sub x}O{sub 2−y} particles were prepared and uniformly dispersed on SiO{sub 2}. • Er diffusion to SiO{sub 2} determines the stability of the mixed oxide in air to ∼1000 °C. • Spreading of Ce{sub 1−x}Er{sub x}O{sub 2−y} onto SiO{sub 2} occurs in hydrogen at 900 °C. • Nanocrystalline A-(Ce,Er){sub 2}Si{sub 2}O{sub 7} silicate forms in H

  19. A potential method using Ge{iPrNC[N(SiMe_3)_2]NiPr}{sub 2}, (Et{sub 3}Si){sub 2}Te and anhydrous hydrazine for germanium tellurides

    Energy Technology Data Exchange (ETDEWEB)

    Du, Liyong; Du, Shulei; Ding, Yuqiang [School of Chemical and Material Engineering, Jiangnan University, Wuxi (China)

    2017-12-29

    A germanium(II)-guanidine derivative of formula Ge{iPrNC[N(SiMe_3)_2]NiPr}{sub 2} (1) was synthesized and characterized by {sup 1}H NMR, {sup 13}C NMR, elemental analysis, and X-ray diffraction method. Thermal property was also studied to identify its thermal stability and volatility. More importantly, compound 1 was synthesized to develop a new method for germanium tellurides, where anhydrous hydrazine was introduced to prompt the activity of germanium(II) guanidines (or derivatives) towards (Et{sub 3}Si){sub 2}Te. Solution reaction of compound 1, (Et{sub 3}Si){sub 2}Te, and anhydrous hydrazine was investigated to pre-identify the feasibility of this combination for ALD process. The EDS data of the black precipitate from this reaction verified the potential of this method to manufacture germanium tellurides. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Effect of Y{sub 2}O{sub 3} addition to Rh/Al{sub 2}O{sub 3} catalysts on the autothermal reforming of methane; Efeito da adicao de Y{sub 2}O{sub 3} a catalisadores de Rh/Al{sub 2}O{sub 3} na reforma autotermica do metano

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Vanessa Monteiro; Cardoso, Gabriel Alexandre Lima; Coutinho, Ana Carla da S. Lomba S.; Passos, Fabio Barboza [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Quimica e de Petroleo. Lab. de Reatores, Cinetica e Catalise (RECAT)]. E-mail: vanessafisqui@yahoo.com.br

    2008-07-01

    In this work, the effect of the addition of Y{sub 2}O{sub 3} (with 2%, 5% and 10% weight content) on Rh/{alpha}-Al{sub 2}O{sub 3} catalysts in the autothermal reforming reaction of methane to the production of hydrogen for fuel cells was investigated. The catalysts were characterized by the following techniques: N{sub 2} adsorption, H{sub 2} chemisorption, X-ray diffraction (XRD) and cyclohexane dehydrogenation reaction. The catalysts were also evaluated in the reaction of autothermal reforming. The catalyst with higher Y{sub 2}O{sub 3} content showed the best results both in the cyclohexane dehydrogenation rate and in the conversion of methane. (author)

  1. The crystal structure of Cs{sub 2}S{sub 2}O{sub 3}.H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Winkler, Verena; Schlosser, Marc; Pfitzner, Arno [Regensburg Univ. (Germany). Inst. fuer Anorganische Chemie

    2016-08-01

    A reinvestigation of the alkali metal thiosulfates has led to the new phase Cs{sub 2}S{sub 2}O{sub 3}.H{sub 2}O. At first cesium thiosulfate monohydrate was obtained as a byproduct of the synthesis of Cs{sub 4}In{sub 2}S{sub 5}. Further investigations were carried out using the traditional synthesis reported by J. Meyer and H. Eggeling. Cs{sub 2}S{sub 2}O{sub 3}.H{sub 2}O crystallizes in transparent, colorless needles. The crystal structure of the title compound was determined by single crystal X-ray diffraction at room temperature: space group C2/m (No. 12), unit cell dimensions: a = 11.229(4), b = 5.851(2), c = 11.260(5) Aa, β = 95.89(2) , with Z = 4 and a cell volume of V = 735.9(5) Aa{sup 3}. The positions of all atoms including the hydrogen atoms were located in the structure refinement. Cs{sub 2}S{sub 2}O{sub 3}.H{sub 2}O is isotypic with Rb{sub 2}S{sub 2}O{sub 3}.H{sub 2}O. Isolated tetrahedra [S{sub 2}O{sub 3}]{sup 2-} are coordinated by the alkali metal cations, and in addition they serve as acceptors for hydrogen bonding. For both Cs atoms the shortest distances are observed to oxygen atoms of the S{sub 2}O{sub 3}{sup 2-} anions whereas the terminating sulfur atom has its shortest contacts to the water hydrogen atoms. Thus, an extended hydrogen bonding network is formed. The title compound has also been characterized by IR spectroscopy. IR spectroscopy reveals the vibrational bands of the water molecules at 3385 cm{sup -1}. They show a red shift in the OH stretching and bending modes as compared to free water. This is due both to the S..H hydrogen bonding and to the coordination of H{sub 2}O molecules to the cesium atoms.

  2. Crystal structure of lithium disulfate, Li{sub 2}[S{sub 2}O{sub 7}], Li{sub 2}O{sub 7}S{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Logemann, Christian; Witt, Julia; Wickleder, Mathias S. [Oldenburg Univ. (Germany). Inst. of Pure and Applied Chemistry

    2013-07-01

    Li{sub 2}O{sub 7}S{sub 2}, orthorhombic, Pnma (no. 62), a = 13.177(2) Aa, b = 8.2516(7) Aa, c = 4.8547(4) Aa, V = 527.8 Aa{sup 3}, Z = 4, R{sub gt}(F) = 0.0338, wR{sub ref}(F{sup 2}) = 0.1054, T = 153 K.

  3. Bi{sub 2}O{sub 3} cocatalyst improving photocatalytic hydrogen evolution performance of TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Difa; Hai, Yang; Zhang, Xiangchao; Zhang, Shiying; He, Rongan, E-mail: hslra@tom.com

    2017-04-01

    Highlights: • Bi-Bi{sub 2}O{sub 3}-anatase-rutile TiO{sub 2} multijunction photocatalyst was prepared. • Bi{sub 2}O{sub 3} quantum dots with size of 2–3 nm were uniformly distributed. • Improved H{sub 2} evolution was noticed in glycerol-water mixture. • Optimal amount of Bi{sub 2}O{sub 3} was found to be 0.89 mol%. - Abstract: Photocatalytic hydrogen production using water splitting is of potential importance from the viewpoint of renewable energy development. Herein, Bi{sub 2}O{sub 3}-TiO{sub 2} composite photocatalysts presented as Bi-Bi{sub 2}O{sub 3}-anatase-rutile TiO{sub 2} multijunction were first fabricated by a simple impregnation-calcination method using Bi{sub 2}O{sub 3} as H{sub 2}-production cocatalysts. The obtained multijunction samples exhibit an obvious enhancement in photocatalytic H{sub 2} evolution activity in the presence of glycerol. The effect of Bi{sub 2}O{sub 3} amount on H{sub 2}-evolution activity of TiO{sub 2} was investigated and the optimal Bi{sub 2}O{sub 3} content was found to be 0.89 mol%, achieving a H{sub 2}-production rate of 920 μmol h{sup −1}, exceeding that of pure TiO{sub 2} by more than 73 times. The enhanced mechanism of photocatalytic H{sub 2}-evolution activity is proposed. This study will provide new insight into the design and fabrication of TiO{sub 2}-based hydrogen-production photocatalysts using low-cost Bi{sub 2}O{sub 3} as cocatalyst.

  4. Atomic layer deposition of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/TiO{sub 2} barrier coatings to reduce the water vapour permeability of polyetheretherketone

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadzada, Tamkin, E-mail: tahm4852@uni.sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); McKenzie, David R.; James, Natalie L.; Yin, Yongbai [School of Physics, University of Sydney, NSW 2006 (Australia); Li, Qing [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia)

    2015-09-30

    We demonstrate significantly enhanced barrier properties of polyetheretherketone (PEEK) against water vapour penetration by depositing Al{sub 2}O{sub 3} or Al{sub 2}O{sub 3}/TiO{sub 2} nanofilms grown by atomic layer deposition (ALD). Nanoindentation analysis revealed good adhesion strength of a bilayer Al{sub 2}O{sub 3}/TiO{sub 2} coating to PEEK, while the single layer Al{sub 2}O{sub 3} coating displayed flaking and delamination. We identified three critical design parameters for achieving the optimum barrier properties of ALD Al{sub 2}O{sub 3}/TiO{sub 2} coatings on PEEK. These are a minimum total thickness dependent on the required water vapour transmission rate, the use of an Al{sub 2}O{sub 3}/TiO{sub 2} bilayer coating and the application of the coating to both sides of the PEEK film. Using these design parameters, we achieved a reduction in moisture permeability of PEEK of over two orders of magnitude while maintaining good adhesion strength of the polymer–thin film system. - Highlights: • Atomic layer deposition of Al{sub 2}O{sub 3}/TiO{sub 2} coatings reduced water vapour permeability. • Bilayer coatings reduced the permeability more than single layer coatings. • Bilayer coatings displayed higher adhesion strength than the single layer coatings. • Double-sided coatings performed better than single-sided coatings. • Correlation was found between total thickness and reduced water vapour permeability.

  5. Effect of B{sub 2}O{sub 3}/P{sub 2}O{sub 5} substitution on the properties and structure of tin boro-phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Akira, E-mail: asaito@ehime-u.ac.jp [Graduate School of Science and Engineering, Ehime University, Matsuyama, 3 Bunkyo-cho (Japan); Tricot, Grégory [LASIR UMR-CNRS 8516, Université de Lille 1, Villeneuve d' Ascq 59655 (France); UCCS UMR-CNRS 8181, Université de Lille 1, Villeneuve d' Ascq 59655 (France); Rajbhandari, Prashant [UCCS UMR-CNRS 8181, Université de Lille 1, Villeneuve d' Ascq 59655 (France); Anan, Shoji; Takebe, Hiromichi [Graduate School of Science and Engineering, Ehime University, Matsuyama, 3 Bunkyo-cho (Japan)

    2015-01-15

    Effect of B{sub 2}O{sub 3}/P{sub 2}O{sub 5} substitution on the properties and structure of the ternary 67SnO–(33–x)P{sub 2}O{sub 5}–xB{sub 2}O{sub 3} composition line (from x = 0–33 mol%) are examined in this contribution. We show that density and glass transition temperature increase while molar volume and thermal expansion coefficient decrease with increasing B{sub 2}O{sub 3} concentration. Density and thermal properties experience an original three-domain evolution with rapid (region I: 0 ≤ x < 5), substantial (II: 5 < x ≤ 15), and moderate (III: 15 < x ≤ 33) increase. In order to explain this unconventional behaviour, the glass structure has been investigated using high magnetic field 1 dimensional {sup 31}P and {sup 11}B MAS–NMR, micro-Raman and infrared spectroscopies. {sup 11}B MAS–NMR experiments allow to (i) monitor the 3- and 4-fold coordinated borate species proportion and (ii) highlight the presence of unreported 4-fold coordinated species in the region (III). Finally, it is shown that substitution of P{sub 2}O{sub 5} by B{sub 2}O{sub 3} induces an alteration of the dimeric phosphate network and formation of mixed anion structure that consists of Q{sup 0} phosphate units, 3- and 4-fold coordinated borate units and their combinations. - Highlights: • We examined B{sub 2}O{sub 3}/P{sub 2}O{sub 5} substitution effect on the ternary SnO–P{sub 2}O{sub 5}–B{sub 2}O{sub 3} glasses. • We show a three-domains evolution for density and thermal properties. • The structure was investigated by {sup 31}P and {sup 11}B NMR, Raman and IR spectroscopies. • 3 and 4-folded borate species and unreported 4-folded species are revealed. • Mixed anion structure consists of Q{sup 0} phosphate unit and 3- and 4-folded borate units.

  6. Current-voltage characteristics of SnO{sub 2}-Co{sub 3}O{sub 4}-Cr{sub 2}O{sub 3}-Sb{sub 2}O{sub 5} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar-Martinez, J A [Centro de Investigacion en Materiales Avanzados, S.C. (CIMAV), Alianza Norte 202, Parque de Investigacion e Innovacion Tecnologica (PIIT), Nueva Carretera Aeropuerto km. 10, Apodaca, Nuevo Leon, CP 66600 (Mexico); Glot, A B [Posgrado, Universidad Tecnologica de la Mixteca, Carretera Acatlima Km. 2.5, Huajuapan de Leon, Oaxaca, CP 69000 (Mexico); Gaponov, A V [Department of Radioelectronics, Dniepropetrovsk National University, Dniepropetrovsk 49050 (Ukraine); Hernandez, M B [Instituto de Mineria, Universidad Tecnologica de la Mixteca, Carretera Acatlima Km. 2.5, Huajuapan de Leon, Oaxaca, CP 69000 (Mexico); Guerrero-Paz, J, E-mail: josue.aguilar@cimav.edu.m [Particulate Materials Lab, Universidad Autonoma del Estado de Hidalgo, Pachuca, CP 42184 (Mexico)

    2009-10-21

    The effect of mechanical treatment in a planetary mill on the microstructure and electrical properties of tin dioxide based varistor ceramics in the system SnO{sub 2}-Co{sub 3}O{sub 4}-Cr{sub 2}O{sub 3}-Sb{sub 2}O{sub 5} sintered in the range 1150-1450 {sup 0}C was studied. The mechanical treatment leads to an increase in shrinkage, decrease in porosity, decrease in sample diameter, change in colour of the sintered samples from grey to black and enhancement of nonlinearity. For the sample sintered at 1350 {sup 0}C the mechanical treatment enhances the nonlinearity coefficient from 11 to 31 and decreases the electric field E{sub 1} (at 10{sup -3} A cm{sup -2}) from 3500 to 2800 V cm{sup -1}. The observed changes in physical properties are explained in terms of an additional size reduction of oxide particles and a better mixing of oxide powder followed by the formation of potential barriers at the grain boundaries throughout the whole sample. In spite of the low porosity, the low-field electrical conductivity of mechanically treated ceramics is significantly increased with the growth of relative humidity. A higher humidity sensitivity is found for mechanically treated ceramics with higher barrier height and higher nonlinearity coefficient.

  7. Gas sensing behaviour of Cr{sub 2}O{sub 3} and W{sup 6+}: Cr{sub 2}O{sub 3} nanoparticles towards acetone

    Energy Technology Data Exchange (ETDEWEB)

    Kohli, Nipin, E-mail: nipinkohli82@yahoo.com; Hastir, Anita; Singh, Ravi Chand [Department of Physics, Guru Nanak Dev University, Amritsar-143005 (India)

    2016-05-23

    This paper reports the acetone gas sensing properties of Cr{sub 2}O{sub 3} and 2% W{sup 6+} doped Cr{sub 2}O{sub 3} nanoparticles. The simple cost-effective hydrolysis assisted co-precipitation method was adopted. Synthesized samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) techniques. XRD revealed that synthesized nanoparticles have corundum structure. The lattice parameters have been calculated by Rietveld refinement; and strain and crystallite size have been calculated by using the Williamson-Hall plots. For acetone gas sensing properties, the nanoparticles were applied as thick film onto alumina substrate and tested at different operating temperatures. The results showed that the optimum operating temperature of both the gas sensors is 250°C. At optimum operating temperature, the response of Cr{sub 2}O{sub 3} and 2% W{sup 6+} doped Cr{sub 2}O{sub 3} gas sensor towards 100 ppm acetone was found to be 25.5 and 35.6 respectively. The investigations revealed that the addition of W{sup 6+} as a dopant enhanced the sensing response of Cr{sub 2}O{sub 3} nanoparticles appreciably.

  8. Interaction of Al with O{sub 2} exposed Mo{sub 2}BC

    Energy Technology Data Exchange (ETDEWEB)

    Bolvardi, Hamid; Music, Denis, E-mail: music@mch.rwth-aachen.de; Schneider, Jochen M.

    2015-03-30

    Highlights: • Al adheres to many surfaces. • Solid–solid interactions challenging for real (oxidized) surfaces. • Dissociative O{sub 2} adsorption on Mo{sub 2}BC(0 4 0). • Al nonamer is disrupted on oxidized Mo{sub 2}BC(0 4 0). • Adhesion of a residual Al on the native oxide. - Abstract: A Mo{sub 2}BC(0 4 0) surface was exposed to O{sub 2}. The gas interaction was investigated using ab initio molecular dynamics and X-ray photoelectron spectroscopy (XPS) of air exposed surfaces. The calculations suggest that the most dominating physical mechanism is dissociative O{sub 2} adsorption whereby Mo−O, O−Mo−O and Mo{sub 2}−C−O bond formation is observed. To validate these results, Mo{sub 2}BC thin films were synthesized utilizing high power pulsed magnetron sputtering and air exposed surfaces were probed by XPS. MoO{sub 2} and MoO{sub 3} bond formation is observed and is consistent with here obtained ab initio data. Additionally, the interfacial interactions of O{sub 2} exposed Mo{sub 2}BC(0 4 0) surface with an Al nonamer is studied with ab initio molecular dynamics to describe on the atomic scale the interaction between this surface and Al to mimic the interface present during cold forming processes of Al based alloys. The Al nonamer was disrupted and Al forms chemical bonds with oxygen contained in the O{sub 2} exposed Mo{sub 2}BC(0 4 0) surface. Based on the comparison of here calculated adsorption energy with literature data, Al−Al bonds are shown to be significantly weaker than the Al−O bonds formed across the interface. Hence, Al−Al bond rupture is expected for a mechanically loaded interface. Therefore the adhesion of a residual Al on the native oxide layer is predicted. This is consistent with experimental observations. The data presented here may also be relevant for other oxygen containing surfaces in a contact with Al or Al based alloys for example during forming operations.

  9. Comparative study of water reactivity with Mo{sub 2}O{sub y}{sup −} and W{sub 2}O{sub y}{sup −} clusters: A combined experimental and theoretical investigation

    Energy Technology Data Exchange (ETDEWEB)

    Ray, Manisha; Waller, Sarah E.; Saha, Arjun; Raghavachari, Krishnan; Jarrold, Caroline Chick, E-mail: cjarrold@indiana.edu [Department of Chemistry, Indiana University, Bloomington, Indiana 47405 (United States)

    2014-09-14

    A computational investigation of the Mo{sub 2}O{sub y}{sup −} + H{sub 2}O (y = 4, 5) reactions as well as a photoelectron spectroscopic probe of the deuterated Mo{sub 2}O{sub 6}D{sub 2}{sup −} product have been carried out to understand a puzzling question from a previous study: Why is the rate constant determined for the Mo{sub 2}O{sub 5}{sup −} + H{sub 2}O/D{sub 2}O reaction, the terminal reaction in the sequential oxidation of Mo{sub 2}O{sub y}{sup −} by water, higher than the W{sub 2}O{sub 5}{sup −} + H{sub 2}O/D{sub 2}O reaction? This disparity was intriguing because W{sub 3}O{sub y}{sup −} clusters were found to be more reactive toward water than their Mo{sub 3}O{sub y}{sup −} analogs. A comparison of molecular structures reveals that the lowest energy structure of Mo{sub 2}O{sub 5}{sup −} provides a less hindered water addition site than the W{sub 2}O{sub 5}{sup −} ground state structure. Several modes of water addition to the most stable molecular and electronic structures of Mo{sub 2}O{sub 4}{sup −} and Mo{sub 2}O{sub 5}{sup −} were explored computationally. The various modes are discussed and compared with previous computational studies on W{sub 2}O{sub y}{sup −} + H{sub 2}O reactions. Calculated free energy reaction profiles show lower barriers for the initial Mo{sub 2}O{sub y}{sup −} + H{sub 2}O addition, consistent with the higher observed rate constant. The terminal Mo{sub 2}O{sub y}{sup −} sequential oxidation product predicted computationally was verified by the anion photoelectron spectrum of Mo{sub 2}O{sub 6}D{sub 2}{sup −}. Based on the computational results, this anion is a trapped dihydroxide intermediate in the Mo{sub 2}O{sub 5}{sup −} + H{sub 2}O/D{sub 2}O → Mo{sub 2}O{sub 6}{sup −} + H{sub 2}/D{sub 2} reaction.

  10. Pressure-jump in heterogeneous catalysis--2. Dehydrogenation of propane over a Cr/sub 2/O/sub 3/-Al/sub 2/O/sub 3/-K/sub 2/O catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Y; Kaneko, I

    1979-05-01

    Dehydrogenation of propane over a Cr/sub 2/O/sub 3/-Al/sub 2/O/sub 3/-K/sub 2/O catalyst confirmed the previously derived Langmuir-Hinshelwood type equation with a rate constant for the rate-determining step of 1.81 x 10/sup 11/ molecules/sec/sq cm. The experiments were performed by monitoring the transient pressure change in a 3 l. vessel after hydrogen was admitted to an equilibrated mixture of propane/propylene/hydrogen at 443/sup 0/C.

  11. Microstructural morphologies of slag based glass-ceramics nucleated with 5 wt% Cr{sub 2}O{sub 3} and 5 wt% Cr{sub 2}O{sub 3} + 5 wt% TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Oevecoglu, M.L.; Oezkal, B. [Istanbul Technical Univ. (Turkey). Dept. of Metallurgical and Materials Enginering; Catakli, E. [Mimar Sinan Univ., Istanbul (Turkey). Faculty of Science and Literature; Erkmen, Z.E. [Istnabul Univ. (Turkey). Dept. of Metallurgical Engineering

    2002-07-01

    Glass-ceramic materials were developed from the blast-furnace slags by mixing 5 wt% Cr{sub 2}O{sub 3} and 5 wt% Cr{sub 2}O{sub 3} + 5 wt% TiO{sub 2}. The samples were nucleated for 18 h at 780 C and crystallized for 20 min. at 905 C, respectively. SEM and SEM/EDS investigations revealed the presence of clover-shaped TiO{sub 2} particles in the glassy matrix of the sample nucleated with 5 wt% Cr{sub 2}O{sub 3} + 5 wt% TiO{sub 2} and polygonal-shaped Cr{sub 2}O{sub 3} platelets for both samples. XRD scans revealed the presence of akermanite (2CaO.MgO.2SiO{sub 2}) and gehlenite (2CaO.Al{sub 2}O{sub 3}.SiO{sub 2}) peaks indicating the existence of the mellilite solid solution for the crystallized glass-ceramic samples. (orig.)

  12. Influence of H{sub 2}O{sub 2} on LPG fuel performance evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Muhammad Saad, E-mail: iqbalmouj@gmail.com; Ahmed, Iqbal, E-mail: iqbalmouj@gmail.com; Mutalib, Mohammad Ibrahim bin Abdul, E-mail: iqbalmouj@gmail.com; Nadeem, Saad, E-mail: iqbalmouj@gmail.com; Ali, Shahid, E-mail: iqbalmouj@gmail.com [Department of Chemical Engineering, Faculty of Engineering, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2014-10-24

    The objective of this mode of combustion is to insertion of hydrogen peroxide (H{sub 2}O{sub 2}) to the Liquefied Petroleum Gas (LPG) combustion on spark plug ignition engines. The addition of hydrogen peroxide may probably decrease the formation of NO{sub x}, CO{sub x} and unburned hydrocarbons. Hypothetically, Studies have shown that addition of hydrogen peroxide to examine the performance of LPG/H{sub 2}O{sub 2} mixture in numerous volumetric compositions starting from lean LPG until obtaining a better composition can reduce the LPG fuel consumption. The theory behind this idea is that, the addition of H{sub 2}O{sub 2} can cover the lean operation limit, increase the lean burn ability, diminution the burn duration along with controlling the exhaust emission by significantly reducing the greenhouse gaseous.

  13. O{sub 2} depletion in granitic media. The Rex project

    Energy Technology Data Exchange (ETDEWEB)

    Puigdomenech, I. [Royal Inst. of Technology, Stockholm (Sweden); Ambrosi, J.P.; Eisenlohr, L.; Lartigue, J.E. [CNRS, Aix-en-Provence (France); Banwart, S.A. [Univ. of Sheffield (United Kingdom); Bateman, K.; Milodowski, A.E.; West, J.M. [British Geological Survey, Nottingham (United Kingdom); Griffault, L. [ANDRA (France); Gustafsson, E. [Geosigma AB, Uppsala (Sweden); Hama, K.; Yoshida, H. [JNC, Gifu (Japan). Tono Geoscience Centre; Kotelnikova, S.; Pedersen, K. [Goeteborg Univ. (Sweden); Michaud, V.; Trotignon, L. [CEA, Cadarache (France); Rivas Perez, J. [Univ. of Bradford (United Kingdom); Tullborg, E.L. [Terralogica AB, Graabo (Sweden)

    2001-02-01

    The redox conditions are of consequence for the performance of nuclear repositories. The presence of molecular oxygen (O{sub 2}) would affect the corrosion of canisters and the migration of radionuclides eventually released from a damaged canister. The rate of disappearance of O{sub 2} left in voids at repository closure is therefore an important information when evaluating repository designs. The REX project (Redox Experiment in Detailed Scale) has been carried out within the frame of SKB Aespoe Hard Rock Laboratory in Sweden. The aim was to determine how O{sub 2} trapped in the closed repository would react with the rock minerals in the tunnel and deposition holes and in the water conducting fractures. The REX project consisted of the following sections: Field investigations at Aespoe: Microbial O{sub 2} consumption at several sites in the Aespoe tunnel. The in situ experiment: Injection of oxygen and monitoring of O{sub 2} uptake in a confined fracture surface. The Replica Experiment: a laboratory study using the other half of the fracture surface used for the in situ experiment. Laboratory experiments: needed to support the interpretation of the field and replica experiments. Conducted with groundwaters, bacteria, and mineral samples from Aespoe. The results from the in-situ experiment were confirmed by those of the replica experiment performed in the CEA laboratory in France. Both were concordant in showing time scales for O{sub 2} uptake in the order of days. The agreement was remarkable when taking into account the differences in experimental conditions. For example, different microbial processes took place in the two experiments. Laboratory studies with rock samples demonstrated that microbial activity induced increased chemical weathering, with the formation of clay minerals. Rates of O{sub 2} uptake by fracture filling minerals were determined under laboratory conditions. These rates were faster than those reported in literature studies of pure mineral

  14. Influence of Al{sub 2}O{sub 3} addition on microstructure and mechanical properties of 3YSZ-Al{sub 2}O{sub 3} composites

    Energy Technology Data Exchange (ETDEWEB)

    Abden, Md. Jaynul [International Islamic Univ., Chittagong (Bangladesh). Dept. of Electrical and Electronic Engineering; Afroze, Jannatul Dil [Noakhali Science and Technology Univ. (Bangladesh). Faculty of Science and Engineering; Gafur, Md. Abdul [Bangladesh Council of Scientific and Industrial Research, Dhaka (Bangladesh). Pilot Plant and Process Development Centre; Chowdhury, Faruque-Uz-Zaman [Chittagong University of Engineering and Technology (Bangladesh). Dept. of Physics

    2015-07-01

    The effect of the amount of Al{sub 2}O{sub 3} content on microstructure, tetragonal phase stability and mechanical properties of 3YSZ-Al{sub 2}O{sub 3} composites are investigated in this study. The ceramic composites are obtained by means of uniaxial compacting at 210 MPa and green compacts are sintered at 1550 C for 3 h in air. The monoclinic zirconia (m-ZrO{sub 2}) phase has completely been transformed into tetragonal zirconia (t-ZrO{sub 2}) phase with corresponding higher Al{sub 2}O{sub 3} content. The t-ZrO{sub 2} grains induce transgranular fracture mode that has contribution in improvement of fracture toughness. The maximum flexural strength of 340 MPa, Vickers hardness value of 14.31 GPa and fracture toughness of 5.1 MPa x m{sup 1/2} in the composition containing 40 wt.-% Al{sub 2}O{sub 3} is attributed to the microstructure with t-ZrO{sub 2} grains as inter- and intragranular particles in the Al{sub 2}O{sub 3} grains, which makes it suitable for dental applications.

  15. Preparation and characterization of sol-gel derived 4%La{sub 2}O{sub 3}-Al{sub 2}O{sub 3} ceramic membrane on clay-based supports

    Energy Technology Data Exchange (ETDEWEB)

    Ersoy, B. [Afyon Kocatepe Univ., Mining Engineering Dept., AFYON (Turkey); Gunay, V. [TUBITAK-MRC, MCTRI, Gebze-KOCAELI (Turkey)

    2004-07-01

    In this work, {gamma}-Al{sub 2}O{sub 3} membrane layer (4 wt% La{sub 2}O{sub 3}+96% Al{sub 2}O{sub 3}) was coated on the clay based porous support by using the sol-gel coating. The coating solution was prepared by using boehmite (AlOOH), La-nitrate (La{sub 2}(NO{sub 3}){sub 3}.6H{sub 2}O), PVA, distilled water and HNO{sub 3}. The thickness of the {gamma}-Al{sub 2}O{sub 3} membrane layer was between 5-7 {mu}m. Two unprocessed clay samples which were supplied from Kutahya and Balikesir regions, were used to produce supports for the membranes. Porosities of the supports were varied from 25 to 40% depending on sintering temperatures. Mean pore diameter of the supports were between 0.01-1{mu}m. The mean pore diameter of 4wt%La{sub 2}O{sub 3} - Al{sub 2}O{sub 3} membrane layer was around 11 nm and total pore area was 113 m{sup 2} / g at 1000 C for 1 hour. (orig.)

  16. Controlled synthesis and photoluminescence properties of In{sub 2}O{sub 3} rods with dodecahedron In{sub 2}O{sub 3} microcrystals on top

    Energy Technology Data Exchange (ETDEWEB)

    Ouacha, Hassan [King Abdullah Institute for Nanotechnology, King Saud University, Riyadh (Saudi Arabia); Hendaoui, Ali [Department of Physics, College of Science and General Studies, Alfaisal University, Riyadh (Saudi Arabia); Kleineberg, Ulf [Faculty of Physics, Ludwig Maximilian University of Munich, Garching (Germany); Albrithen, Hamad; Azzeer, Abdallah [Physics and Astronomy Department, King Saud University, Riyadh (Saudi Arabia)

    2017-10-15

    In{sub 2}O{sub 3} rods with dodecahedron In{sub 2}O{sub 3} microcrystals on top were synthesized in an electrical furnace via Au-catalyzed vapor transport process. A catalyst-assisted selective vapor-solid (VS) growth was proposed to explain the formation of the dodecahedron In{sub 2}O{sub 3} microcrystal, while the self-catalytic VS growth mechanism dominated the subsequent one-dimensional (1D) growth of the In{sub 2}O{sub 3} rod underneath the In{sub 2}O{sub 3} microcrystal. The structural evolution of these structures was carefully examined during the synthesis process by controlling the growth parameters. The morphologies, crystalline structures and surface chemistry were characterized by scanning electron microscopy (SEM), X-ray diffraction technique (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. The photoluminescence (PL) spectrum at room temperature of the as-grown In{sub 2}O{sub 3} structures exhibited both UV and blue luminescence emission under one excitation at 260 nm, which may be related to the existence of oxygen vacancies. The synthesized multifaceted In{sub 2}O{sub 3} microcrystal has shown to contain a large number of vertices and may find many applications in developing three-dimensional (3D) resonators. This work will not only enrich the synthesis science but also will open doors for applications of such structures in optical devices. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Thermochemistry of rare earth doped uranium oxides Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} (Ln = La, Y, Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei; Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.edu

    2015-10-15

    Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10–50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO{sub 1.5}, UO{sub 2} and UO{sub 3} in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} is similar to that of UO{sub 2} to UO{sub 3} for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U{sup 5+}, U{sup 6+}, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements. - Highlights: • We synthesize, characterize Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} solid solutions (Ln = La, Y, Nd). • Formation enthalpies become more exothermic with increasing rare earth content. • Oxidation enthalpy of Ln{sub x}U{sub 1−x}O{sub 2−0.5x+y} is similar to that of UO{sub 2} to UO{sub 3}. • Direct calorimetric measurements are in good agreement with free energy data.

  18. Synthesis and crystallographic study of the compounds in the system Cs{sub 2}O - Al{sub 2}O{sub 3} - SiO{sub 2}; Synthese et etude cristallographique des composes du systeme Cs{sub 2}O - Al{sub 2}O{sub 3} - SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Langlet, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-05-01

    A study has been made on the preparation, structure and thermal evolution of some definite compounds in the system: Cs{sub 2}O - Al{sub 2}O{sub 3} - SiO{sub 2}. Precise details are given about the structure of the following compounds: CsAlO{sub 2}, RbAlO{sub 2}, KAlO{sub 2} and NaAlO{sub 2}; CsAlO{sub 2}, 2 H{sub 2}O; Cs{sub 2}O, 11 Al{sub 2}O{sub 3}; Cs{sub 2}O, 2 SiO{sub 2}; Cs{sub 2}O, 4 SiO{sub 2} and Rb{sub 2}O, 4 SiO{sub 2}; CsAlSiO{sub 4}; CsAlSi{sub 2}O{sub 6}; Cs{sub 4}Ge{sub 11}O{sub 24} and Rb{sub 4}Ge{sub 11}O{sub 24}. The long term purpose of this work was to find a compound which would be insoluble, refractory and at the same time able to contain radioactive isotopes of cesium and thus suitable as radiation sources. The knowledge of the properties and structure of aluminates, silicates and aluminosilicates is a necessary stage before the elaboration of ceramic caesium sources. The compound which seems quite convenient for this use, Cs{sub 2}AlSi{sub 2}O{sub 6}, is closely related to the natural mineral 'pollucite', and offers interesting properties. (author) [French] Ce travail constitue une etude de la preparation, de la structure et de l'evolution thermique des composes definis du systeme: Cs{sub 2}O - Al{sub 2}O{sub 3} - SiO{sub 2} et de quelques homologues. Des precisions sont donnees sur la structure des composes suivants: CsAlO{sub 2}, RbAlO{sub 2}, KAlO{sub 2} et NaAlO{sub 2}; CsAlO{sub 2}, 2 H{sub 2}O; Cs{sub 2}O, 11 Al{sub 2}O{sub 3}; Cs{sub 2}O, 2 SiO{sub 2}; Cs{sub 2}O, 4 SiO{sub 2} et Rb{sub 2}O, 4 SiO{sub 2}; CsAlSiO{sub 4}; CsAlSi{sub 2}O{sub 6}; Cs{sub 4}Ge{sub 11}O{sub 24} et Rb{sub 4}Ge{sub 11}O{sub 24}. Le but a long terme de cette etude consistait a obtenir un compose a la fois refractaire et insoluble, susceptible de contenir un isotope radioactif du caesium, et d'etre utilise comme source de rayonnement. La connaissance des proprietes et de la structure des aluminates, silicates et aluminosilicates represente une etape necessaire

  19. Luminescence, scintillation, and energy transfer in SiO{sub 2}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-Gd{sub 2}O{sub 3}:Ce{sup 3+},Pr{sup 3+} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lertloypanyachai, Prapon; Chewpraditkul, Weerapong; Pattanaboonmee, Nakarin [Department of Physics, King Mongkut' s University of Technology Thonburi, Bangkok (Thailand); Chen, Danping [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai (China); Babin, Vladimir; Beitlerova, Alena; Nikl, Martin [Institute of Physics, AS CR, Prague (Czech Republic)

    2017-09-15

    Ce{sup 3+},Pr{sup 3+}-codoped SiO{sub 2}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-Gd{sub 2}O{sub 3} glasses (SABG:Ce,Pr) were prepared by melt quenching under a CO reducing atmosphere. Luminescence properties were investigated under UV and X-ray excitations. A dominant emission band at 430 nm belonging to the Ce{sup 3+}:5d{sub 1} → 4f transition was observed in the photo- and radio-luminescence spectra. The energy transfer occurs from this Ce{sup 3+} band toward the {sup 3}P{sub J} levels of Pr{sup 3+} with an efficiency of up to 24%, followed by the reduction of integrated luminescence intensity with an increasing Pr{sup 3+} concentration. This result is attributed to the increase in the reabsorption of Ce{sup 3+} luminescence and the non-radiative energy transfer toward the {sup 3}P{sub J} levels of Pr{sup 3+}. The cross-relaxation process within the Pr{sup 3+} pairs can further diminish the total luminescence yield at high Pr{sup 3+} concentrations. The integral scintillation efficiency and light yield measurements were carried out and compared to the reference Bi{sub 4}Ge{sub 3}O{sub 12} (BGO) crystal. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Degradation kinetics and mechanism of β-lactam antibiotics by the activation of H{sub 2}O{sub 2} and Na{sub 2}S{sub 2}O{sub 8} under UV-254 nm irradiation

    Energy Technology Data Exchange (ETDEWEB)

    He, Xuexiang [Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Department of Civil and Environmental Engineering and Nireas-International Water Research Centre, School of Engineering, University of Cyprus, PO Box 20537, 1678 Nicosia (Cyprus); Mezyk, Stephen P. [Department of Chemistry and Biochemistry, California State University Long Beach, 1250 Bellflower Blvd., Long Beach, CA 90840 (United States); Michael, Irene; Fatta-Kassinos, Despo [Department of Civil and Environmental Engineering and Nireas-International Water Research Centre, School of Engineering, University of Cyprus, PO Box 20537, 1678 Nicosia (Cyprus); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Department of Civil and Environmental Engineering and Nireas-International Water Research Centre, School of Engineering, University of Cyprus, PO Box 20537, 1678 Nicosia (Cyprus)

    2014-08-30

    Graphical abstract: - Highlights: • Removal efficiency was comparable at different UV fluence rates but same fluence. • Reducing pH to 3 or 2 did not inhibit the removal of nitrobenzene by UV/S{sub 2}O{sub 8}{sup 2−}. • 1.84 × 10{sup −14} M [HO{sup •} ]{sub ss} and 3.10 × 10{sup −13} M [SO{sub 4}{sup •} {sup −}]{sub ss} in UV/S{sub 2}O{sub 8}{sup 2−} were estimated. • HO{sup •} reacted faster with the β-lactams than SO{sub 4}{sup •} {sup −} but sharing similar byproducts. • Transformation pathways included hydroxylation, hydrolysis and decarboxylation. - Abstract: The extensive production and usage of antibiotics have led to an increasing occurrence of antibiotic residuals in various aquatic compartments, presenting a significant threat to both ecosystem and human health. This study investigated the degradation of selected β-lactam antibiotics (penicillins: ampicillin, penicillin V, and piperacillin; cephalosporin: cephalothin) by UV-254 nm activated H{sub 2}O{sub 2} and S{sub 2}O{sub 8}{sup 2−} photochemical processes. The UV irradiation alone resulted in various degrees of direct photolysis of the antibiotics; while the addition of the oxidants improved significantly the removal efficiency. The steady-state radical concentrations were estimated, revealing a non-negligible contribution of hydroxyl radicals in the UV/S{sub 2}O{sub 8}{sup 2−} system. Mineralization of the β-lactams could be achieved at high UV fluence, with a slow formation of SO{sub 4}{sup 2−} and a much lower elimination of total organic carbon (TOC). The transformation mechanisms were also investigated showing the main reaction pathways of hydroxylation (+16 Da) at the aromatic ring and/or the sulfur atom, hydrolysis (+18 Da) at the β-lactam ring and decarboxylation (–44 Da) for the three penicillins. Oxidation of amine group was also observed for ampicillin. This study suggests that UV/H{sub 2}O{sub 2} and UV/S{sub 2}O{sub 8}{sup 2−} advanced

  1. Exchange coupling behavior in bimagnetic CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Leite, G.C.P. [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Chagas, E.F., E-mail: efchagas@fisica.ufmt.br [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Pereira, R.; Prado, R.J. [Instituto de Fisica, Universidade Federal de Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Terezo, A.J. [Departamento de Quimica, Universidade Federal do Mato Grosso, 78060-900 Cuiaba-MT (Brazil); Alzamora, M.; Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Fisicas, Rua Xavier Sigaud 150 Urca, Rio de Janeiro (Brazil)

    2012-09-15

    In this work we report a study of the magnetic behavior of ferrimagnetic oxide CoFe{sub 2}O{sub 4} and ferrimagnetic oxide/ferromagnetic metal CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite. The latter compound is a good system to study hard ferrimagnet/soft ferromagnet exchange coupled. Two steps were followed to synthesize the bimagnetic CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite: (i) first, preparation of CoFe{sub 2}O{sub 4} nanoparticles using a simple hydrothermal method, and (ii) second, reduction reaction of cobalt ferrite nanoparticles using activated charcoal in inert atmosphere and high temperature. The phase structures, particle sizes, morphology, and magnetic properties of CoFe{sub 2}O{sub 4} nanoparticles were investigated by X-Ray diffraction (XRD), Mossbauer spectroscopy (MS), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) with applied field up to 3.0 kOe at room temperature and 50 K. The mean diameter of CoFe{sub 2}O{sub 4} particles is about 16 nm. Mossbauer spectra revealed two sites for Fe{sup 3+}. One site is related to Fe in an octahedral coordination and the other one to the Fe{sup 3+} in a tetrahedral coordination, as expected for a spinel crystal structure of CoFe{sub 2}O{sub 4}. TEM measurements of nanocomposite showed the formation of a thin shell of CoFe{sub 2} on the cobalt ferrite and indicate that the nanoparticles increase to about 100 nm. The magnetization of the nanocomposite showed a hysteresis loop that is characteristic of exchange coupled systems. A maximum energy product (BH){sub max} of 1.22 MGOe was achieved at room temperature for CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposites, which is about 115% higher than the value obtained for CoFe{sub 2}O{sub 4} precursor. The exchange coupling interaction and the enhancement of product (BH){sub max} in nanocomposite CoFe{sub 2}O{sub 4}/CoFe{sub 2} are discussed. - Highlights: Black-Right-Pointing-Pointer CoFe{sub 2}O{sub 4}/CoFe{sub 2} nanocomposite

  2. New compounds bearing [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions (M = Si, Ge, Sn): Syntheses and characterization of A{sub 2}[Si(S{sub 2}O{sub 7}){sub 3}] (A = Na, K, Rb), A{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}] (A = Li, Na, K, Rb, Cs), A{sub 2}[Sn(S{sub 2}O{sub 7}){sub 3}] (A = Na, K), and the unique germanate Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} with cationic {sup 1}{sub ∞}[HgCl{sub 2/2}]{sup +} chains

    Energy Technology Data Exchange (ETDEWEB)

    Logemann, Christian; Witt, Julia; Wickleder, Mathias S. [Universitaet Oldenburg, Institut fuer Reine und Angewandte Chemie (Germany); Gunzelmann, Daniel; Senker, Juergen [Universitaet Bayreuth, Lehrstuhl fuer Anorganische Chemie III (Germany)

    2012-10-15

    The reaction of the group 14 tetrachlorides MCl{sub 4} (M = Si, Ge, Sn) with oleum (65 % SO{sub 3}) at elevated temperatures led to the unique anionic complexes [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} that show the central M atoms in coordination of three chelating S{sub 2}O{sub 7}{sup 2-} groups. The mean distances M-O within the complexes increase from 175 pm (M = Si) via 186 pm (M = Ge) up to 200 pm (M = Sn). The charge balance for the [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions is achieved by alkaline metal ions A{sup +} (A = Li, Na, K, Rb, Cs) which were implemented in the syntheses in form of their sulfates. The size of the A{sup +} ions, i.e. their coordination requirement causes the crystallographic differences in the crystal structures, while the structure of the complex [M(S{sub 2}O{sub 7}){sub 3}]{sup 2-} anions remains essentially unaffected. Furthermore, we were able to characterize the unique germanate Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} which forms when HgCl{sub 2} is added as a source for the counter cation. The Hg{sup 2+} and the Cl{sup -} ions form infinite cationic chains according to {sup 1}{sub ∞}[HgCl{sub 2/2}]{sup +} which take care for the charge compensation. For selected examples of the compounds the thermal behavior has been monitored by means of thermal analyses and X-ray powder diffraction. For A being an alkaline metal the decomposition product is a mixture of the sulfates A{sub 2}SO{sub 4} and the dioxides MO{sub 2}, whereas Hg{sub 2}[Ge(S{sub 2}O{sub 7}){sub 3}]Cl{sub 2} shows a more complicated decomposition. The tris-(disulfato)-silicate Na{sub 2}[Si(S{sub 2}O{sub 7}){sub 3}] has additionally been examined by solid state {sup 29}Si and {sup 23}Na NMR spectroscopic measurements. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Synthesis of nanocrystalline Gd{sub 2}O{sub 2}NCN from a versatile single-source precursor

    Energy Technology Data Exchange (ETDEWEB)

    Ionescu, Emanuel; Wiehl, Leonore; Mera, Gabriela; Riedel, Ralf [Fachbereich Material- und Geowissenschaften, Technische Universitaet Darmstadt (Germany); Li, Wenjie [Fachbereich Material- und Geowissenschaften, Technische Universitaet Darmstadt (Germany); Center for Energy Harvesting Materials and Systems, Mechanical Engineering Department, Virginia Polytechnic Institute and State University, Blacksburg, VA (United States)

    2017-11-17

    Nanocrystalline Gd{sub 2}O{sub 2}NCN (P anti 3m1, crystallite size 30-40 nm) was synthesized upon ammonolysis of bis[[(N-carboxymethyl,N-carboxy-κO-methyl)amino-κN-ethyl]-glycinato( 3-)-κN,κO]gadolinium(III) (diethylenetriamine pentaacetic acid gadolinium(III) dihydrogen salt or gadopentetic acid, Gd-H{sub 2}DTPA hereafter) at 900 C. The conversion of Gd-H{sub 2}DTPA into Gd{sub 2}O{sub 2}NCN takes place in several steps, probably via transient formation of iminodiacetate-, glycinate-, and carbamate-containing complexes of Gd. Thermal treatment in air of Gd-H{sub 2}DTPA at 750 and 1300 C delivers nanocrystalline bixbyite-type Gd{sub 2}O{sub 3} (Ia anti 3, crystallite size 30-70 nm); in an argon or nitrogen atmosphere the formation of monoclinic Gd{sub 2}O{sub 3} (C2/m) was observed at 1300 C. The synthesized Gd{sub 2}O{sub 2}NCN converts upon thermal treatment in air, nitrogen, or argon atmosphere into monoclinic Gd{sub 2}O{sub 3} (C2/m). In ammonia atmosphere, Gd{sub 2}O{sub 2}NCN seems to be stable against decomposition, even upon prolonged exposure to 1000 C. This study indicates that Gd-H{sub 2}DTPA may be a robust, low-cost, and flexible precursor for nanoscaled Gd-based nanopowders. Moreover, precursor approaches based on metal complexes using H{sub 5}DTPA as a ligand are suggested as promising access pathways towards nanocrystalline materials in the M/O/C/N system. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. O{sub 2}(X{sup 3}Σ{sub g}{sup −}) and O{sub 2}(a{sup 1}Δ{sub g}) charge exchange with simple ions

    Energy Technology Data Exchange (ETDEWEB)

    Ziółkowski, Marcin; Schatz, George C., E-mail: schatz@chem.northwestern.edu [Department of Chemistry, Northwestern University, Evanston, Illinois 60208-3113 (United States); Viggiano, A. A.; Midey, Anthony [Air Force Research Laboratory, Space Vehicles Directorate, 3500 Aberdeen Ave, Kirtland AFB, New Mexico 87117 (United States); Dotan, Itzhak [Air Force Research Laboratory, Space Vehicles Directorate, 3500 Aberdeen Ave, Kirtland AFB, New Mexico 87117 (United States); Open University of Israel, 108 Ravutski St., Raanana 43107 (Israel)

    2014-06-07

    We present theory and experiments which describe charge transfer from the X{sup 3}Σ{sub g}{sup −} and a{sup 1}Δ{sub g} states of molecular oxygen and atomic and molecular cations. Included in this work are new experimental results for O{sub 2}(a{sup 1}Δ{sub g}) and the cations O{sup +}, CO{sup +}, Ar{sup +}, and N{sub 2}{sup +}, and new theory based on complete active space self-consistent field method calculations and an extended Langevin model to calculate rate constants for ground and excited O{sub 2} reacting with the atomic ions Ar{sup +}, Kr{sup +}, Xe{sup +}, Cl{sup +}, and Br{sup +}. The T-shaped orientation of the (X − O{sub 2}){sup +} potential surface is used for the calculations, including all the low lying states up to the second singlet state of the oxygen molecule b{sup 1}Σ{sub g}{sup +}. The calculated rate constants for both O{sub 2}(X{sup 3}Σ{sub g}{sup −}) and O{sub 2}(a{sup 1}Δ{sub g}) show consistent trends with the experimental results, with a significant dependence of rate constant on charge transfer exothermicity that does not depend strongly on the nature of the cation. The comparisons with theory show that partners with exothermicities of about 1 eV have stronger interactions with O{sub 2}, leading to larger Langevin radii, and also that more of the electronic states are attractive rather than repulsive, leading to larger rate constants. Rate constants for charge transfer involving O{sub 2}(a{sup 1}Δ{sub g}) are similar to those for O{sub 2}(X{sup 3}Σ{sub g}{sup −}) for a given exothermicity ignoring the electronic excitation of the O{sub 2}(a{sup 1}Δ{sub g}) state. This means (and the electronic structure calculations support) that the ground and excited states of O{sub 2} have about the same attractive interactions with ions.

  5. Characterization of magnetic nano particles of CoFe{sub 2}O{sub 4} and CoZnFe{sub 2}O{sub 4} prepared by the chemical co-precipitation method; Caracterizacion de nanoparticulas magneticas de CoFe{sub 2}O{sub 4} y CoZnFe{sub 2}O{sub 4} preparadas por el metodo de coprecipitacion quimica

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, J.; Zambrano, G.; Gomez, M. E. [Universidad del Valle, Departamento de Fisica, Laboratorio de Peliculas Delgadas, Ciudad Universitaria Melendez, 25360 Cali (Colombia); Prieto, P. [Universidad del Valle, Centro de Excelencia en Nuevos Materiales, Ciudad Universitaria Melendez, 25360 Cali (Colombia); Espinoza B, F. J., E-mail: javierlo21@gmail.com [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Queretaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, 76230 Queretaro (Mexico)

    2012-07-01

    Magnetic cobalt ferrite nanoparticles of CoFe{sub 2}O{sub 4} and CoZnFe{sub 2}O{sub 4} were prepared by co-precipitation technique from aqueous salt solutions of Co (II), ZnSO{sub 4} and Fe (III), in an alkaline medium. CoFe{sub 2}O{sub 4} powder samples were structurally characterized by X-ray diffraction, showing the presence of the most intense peat at 2{theta} = 413928{sup o} (Co K{alpha}1) corresponding to the (311) crystallographic orientation of the CoFe{sub 2}O{sub 4} spinel phase. The mean size of the crystalline of CoFe{sub 2}O{sub 4} and CoZnFe{sub 2}O{sub 4} nanoparticles determined from the full width at half maximum of the strongest reflection of the (311) peak by using the Scherrer approximation was calculated to be 11.4 and 7.0 ({+-} o.2) nm, respectively. Transmission electron microscopy studies permitted determining nanoparticle size of CoZnFe{sub 2}O{sub 4}. Fourier transform infrared spectroscopy was used to confirm the formation of Fe-O bonds, allowing identifying the presence of ferrite spinel structure. Magnetic properties were investigated with the aid of a vibrating sample magnetometer at room temperature Herein, the sample showed superparamagnetic behavior, determined by the hysteresis loop finally, due to the hysteresis loop of the CoZnFe{sub 2}O{sub 4} is very small, our magnetic nanoparticles can be considered as a soft magnetic material. These magnetic nanoparticles have interesting technological applications in biomedicine given their biocompatibility, in nano technology, and in ferro fluid preparation. (Author)

  6. Effects of Fe{sub 2}O{sub 3} content on ionic conductivity of Li{sub 2}O-TiO{sub 2}-P{sub 2}O{sub 5} glasses and glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Mohaghegh, E., E-mail: elnaz.mohaghegh@gmail.com [Department of Materials Science and Engineering, Sharif University of Technology, Tehran, 11155-9466 (Iran, Islamic Republic of); Nemati, A. [Department of Materials Science and Engineering, Sharif University of Technology, Tehran, 11155-9466 (Iran, Islamic Republic of); Eftekhari Yekta, B. [Ceramic Division, School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, 16846-13114 (Iran, Islamic Republic of); Banijamali, S. [Ceramic Division, Materials & Energy Research Center, Alborz, 31787-316 (Iran, Islamic Republic of)

    2017-04-01

    In this study, Li{sub 2}O-TiO{sub 2}-P{sub 2}O{sub 5}-x(Fe{sub 2}O{sub 3}) (x = 0, 2.5, 5 and 7.5 weight part) glass and glass-ceramics were synthesized through conventional melt-quenching method and subsequently heat treatment. Glass samples were studied by UV–visible spectroscopy and crystallized samples were characterized by differential thermal analysis, X-ray diffractometry and field emission scanning electron microscopy. Besides, electrical properties were examined according to the electrochemical impedance spectroscopy techniques. Experimental optical spectra of the Fe{sub 2}O{sub 3}-doped glasses revealed strong UV absorption band in the range of 330–370 nm, which were attributed to the presence of Fe{sup 3+} ions. The major crystalline phase of the fabricated glass-ceramics was LiTi{sub 2}(PO{sub 4}){sub 3}. However, Li{sub 3}PO{sub 4} was also identified as the minor one. Considering the impedance spectroscopy studies, ionic conductivity of Fe{sub 2}O{sub 3} containing glasses was higher than that of the base glass. Additionally, the maximum bulk ionic conductivity of 1.38 × 10{sup −3} S/cm was achieved as well as activation energy as low as 0.26 eV at room temperature for x = 5. - Highlights: • Bulk and total ionic conductivity was extracted by using impedance spectroscopy. • Ionic conductivity of the studied glasses and glass-ceramics increased with increasing Fe{sub 2}O{sub 3} content. • The highest bulk ionic conductivity at room temperature was found to be 1.38 × 10{sup −3} S/cm for GC{sub 5}.

  7. Perovskite-type La{sub 2}Ti{sub 2}O{sub 7} mesoporous photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Onozuka, K.; Kawakami, Y.; Imai, H.; Yokoi, T.; Tatsumi, T. [Chemical Resources Laboratory, Tokyo Institute of Technology, R1-10, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Kondo, J.N., E-mail: jnomura@res.titech.ac.jp [Chemical Resources Laboratory, Tokyo Institute of Technology, R1-10, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan)

    2012-08-15

    Crystalline particles of mesoporous La{sub 2}Ti{sub 2}O{sub 7}, a perovskite-type material, were prepared by hydrothermal synthesis at 210 Degree-Sign C in the presence of structure directing agent. Crystallization and simultaneous sintering occurred in the time course of the hydrothermal treatment, resulting in the improvement in crystallinity with a sacrifice of the decrease in surface area. The photocatalytic property was evaluated by hydrogen evolution from water with methanol sacrificial agent. The increase and the decrease of the material in crystallinity and surface area were responsible for the photocatalytic activity: the activity was improved by crystallization but the concurrent decrease in surface area (increase in size) of crystalline particles was disadvantageous. - Graphical abstract: A homogeneous mixture of La and Ti oxide with amorphous inorganic network was hydrothermally crystallized at low temperatures to a perovskite-type La{sub 2}Ti{sub 2}O{sub 7}. The small La{sub 2}Ti{sub 2}O{sub 7} particles with high crystallinity showed a potential as a photocatalyst for H{sub 2} evolution. Highlights: Black-Right-Pointing-Pointer Crystalline mesopourous La{sub 2}Ti{sub 2}O{sub 7} was prepared. Black-Right-Pointing-Pointer Hydrothermal treatment encouraged low temperature crystallization. Black-Right-Pointing-Pointer Small crystalline domain was advantageous to a photocatalytic reaction.

  8. Synthesis, characterization, photocatalytic activity and ethanol-sensing properties of In{sub 2}O{sub 3} and Eu{sup 3+}:In{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Anand, Kanica; Thangaraj, R., E-mail: rthangaraj@rediffmail.com [Semiconductors Laboratory, Department of Physics, GND University, Amritsar (India); Kumar, Praveen [Department of Physics, DAV University, Jalandhar (India); Kaur, Jasmeet; Singh, R. C. [Laboratory for sensors and physical education, Department of Physics, GND University, Amritsar (India)

    2015-05-15

    In the present endeavor, Indium oxide (In{sub 2}O{sub 3}) and Europium doped In{sub 2}O{sub 3} (In{sub 2}O{sub 3}:0.5%Eu{sup 3+} and In{sub 2}O{sub 3}:5%Eu{sup 3+}) nanoparticles were prepared by co-precipitation method. Synthesized nanoparticles were characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and UV-Visible spectrophotometry (UV-vis). XRD revealed that nanoparticles were of pure bixbyite-type cubic phase and the crystallite size decreased with the Eu{sup 3+} doping. SEM micrographs showed that particles were spherical in shape. Synthesized nanoparticles were used for photo degradation of methylene blue (MB) dye under sunlight and the results clearly showed that In{sub 2}O{sub 3}:5%Eu{sup 3+} nanoparticles exhibited higher activity than pure In{sub 2}O{sub 3} nanoparticles. For gas sensing characteristics, the nanoparticles were applied as thick film onto alumina substrate and tested at different operating temperatures. The results showed that the optimum operating temperature of the gas sensors prepared from synthesized nanoparticles is 300°C. The investigations revealed that the addition of Eu{sup 3+} as a dopant enhanced the sensing response of In{sub 2}O{sub 3} nanoparticles appreciably.

  9. Preparation of transparent Cu{sub 2}Y{sub 2}O{sub 5} thin films by RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Te-Wei, E-mail: tewei@ntut.edu.tw; Chang, Chih-Hao; Yang, Li-Wei; Wang, Yung-Po

    2015-11-01

    Highlights: • Cu{sub 2}Y{sub 2}O{sub 5} thin films were prepared by RF magnetron sputtering. • Cu{sub 2}Y{sub 2}O{sub 5} thin films have high transmittance and antibacterial properties. • Mechanical properties of Cu{sub 2}Y{sub 2}O{sub 5} thin films were investigated. - Abstract: Cu{sub 2}Y{sub 2}O{sub 5} thin films were deposited on non-alkali glass substrates by RF magnetron sputtering. Its crystal structure, microstructure, optical property, mechanical property, and antibacterial activity were investigated by grazing-incidence X-ray diffraction, transmittance spectra, nanoindenter, and antibiotics test, respectively. A single-phase of Cu{sub 2}Y{sub 2}O{sub 5} was obtained while annealing at 700 °C in air and its optical transparency was >80% in the visible region. The hardness and elastic modulus of the film were 6.7 GPa and 82 GPa, respectively. Antibiotics testing result revealed that Cu{sub 2}Y{sub 2}O{sub 5} surface had a superior antibacterial performance even at a dark environment. Therefore, Cu{sub 2}Y{sub 2}O{sub 5} is a promising novel transparent antibacterial hard coating material.

  10. High temperature oxidation-sulfidation behavior of Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composites densified by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Saucedo-Acuna, R.A. [Instituto e Ingenieria y Tecnologia, Universidad Autonoma de Cd. Juarez, Av. Del Charro 450 Norte, Col. Partido Romero, C.P. 32310, Cd. Juarez, Chihuahua (Mexico); Monreal-Romero, H.; Martinez-Villafane, A. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); Chacon-Nava, J.G. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico)], E-mail: jose.chacon@cimav.edu.mx; Arce-Colunga, U. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); Universidad Autonoma de Tamaulipas, Matamoros 8 y 9 Col. Centro C.P. 87110, Cd. Victoria, Tamaulipas (Mexico); Gaona-Tiburcio, C. [Centro de Investigacion en Materiales Avanzados, Departamento de Fisica de Materiales, Miguel de Cervantes 120, Complejo Industrial Chihuahua, C.P. 31109, Chihuahua (Mexico); De la Torre, S.D. [Centro de Investigacion e Innovacion Tecnologica (CIITEC)-IPN, D.F. Mexico (Mexico)

    2007-12-15

    The high temperature oxidation-sulfidation behavior of Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composites prepared by mechanical alloying (MA) and spark plasma sintering (SPS) has been studied. These composite powders have a particular metal-ceramic interpenetrating network and excellent mechanical properties. Oxidation-sulfidation tests were carried out at 900 deg. C, in a 2.5%SO{sub 2} + 3.6%O{sub 2} + N{sub 2}(balance) atmosphere for 48 h. The results revealed the influence of the sintering conditions on the specimens corrosion resistance, i.e. the Cr-Al{sub 2}O{sub 3} and Nb-Al{sub 2}O{sub 3} composite sintered at 1310 deg. C/4 min showed better corrosion resistance (lower weight gains) compared with those found for the 1440 deg. C/5 min conditions. For the former composite, a protective Cr{sub 2}O{sub 3} layer immediately forms upon heating, whereas for the later pest disintegration was noted. Thus, under the same sintering conditions the Nb-Al{sub 2}O{sub 3} composites showed the highest weight gains. The oxidation products were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy.

  11. Creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates to strengthen the Fe-14Cr-3Al-2W steels by adding Ti hydride and Y{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Linbo; Bai, Zhonglian; Shen, Hailong; Wang, Chenxi; Liu, Tong, E-mail: tongliu@buaa.edu.cn

    2017-05-15

    In order to prohibit the formation of large Y-Al-O precipitates, Ti hydride nanoparticles (NPs) were prepared and used to replace Ti as raw particles to fabricate the oxide dispersion strengthened (ODS) Fe-14Cr-3Al-2W-0.35Y{sub 2}O{sub 3} steels by mechanical alloying (MA) and hot isostatic pressing (HIP). As the content of Ti hydride increases from 0.1 to 0.5 and 1.0 wt%, the oxide nanoprecipitates in the ODS steels changes from Y{sub 3}Al{sub 5}O{sub 12} phase to Y{sub 2}Ti{sub 2}O{sub 7} phase (semicoherent with the matrix), and the particle size is successfully reduced. The tensile strength of the ODS steel increases remarkably with increasing Ti hydride content. The sample with 1.0 wt% Ti hydride exhibits a high strength of 1049 MPa at 25 °C and 278 MPa at 700 °C. The creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates by adding Ti hydride NPs opens a new way to control the structure and size of the oxide precipitates in the ODS steels. - Graphical abstract: The creation of Y{sub 2}Ti{sub 2}O{sub 7} nanoprecipitates by adding Ti hydride nanoparticles remarkably increases the mechanical properties of the Al-containing ODS steels. - Highlights: •TiH{sub 1.971} reacts with Y{sub 2}O{sub 3} to form Y{sub 2}Ti{sub 2}O{sub 7} in the Al-containing ODS steel. •Addition of TiH{sub 1.971} nanoparticles can prevent the formation of Y-Al-O phases. •Y{sub 2}Ti{sub 2}O{sub 7} nanoparticles share semicoherent interface with the ferrite matrix. •The mean size of oxide dispersion is reduced to 11.2 ± 7.1 nm with 1.0 wt% TiH{sub 1.971}. •The tensile strength of the ODS steel enlarges with increasing TiH{sub 1.971} content.

  12. Effect of Fe{sub 2}O{sub 3} in Fe{sub 2}O{sub 3}/AP composite particles on thermal decomposition of AP and on burning rate of the composite propellant

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Zhenye [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing, 210094 (China); Nanjing University of Technology, Nanjing (China); Li, Fengsheng; Bai, Huaping [National Special Superfine Powder Engineering Research Center, Nanjing University of Science and Technology, Nanjing, 210094 (China)

    2006-12-15

    A technique of composite processing of Fe{sub 2}O{sub 3} and ammonium perchlorate (AP) was employed in making the propellant. The effects of composite processing of Fe{sub 2}O{sub 3} on catalytic activity, on the thermal decomposition of AP, and on the burning rate of the composite propellant were investigated in this paper. Fe{sub 2}O{sub 3}/AP composite particles were prepared by a novel solvent-nonsolvent method. The results show that AP is successfully coated on the surface of Fe{sub 2}O{sub 3}. Composite processing of Fe{sub 2}O{sub 3} and AP can improve the catalytic activity of Fe{sub 2}O{sub 3}. Fe{sub 2}O{sub 3} exhibits better catalytic effect with increasing Fe{sub 2}O{sub 3} content. The larger interface between Fe{sub 2}O{sub 3} and AP and lower density of composite propellant (with the added Fe{sub 2}O{sub 3}/AP composite particles) are responsible for the enhancement of the catalytic activity of Fe{sub 2}O{sub 3}. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  13. Structural and magnetic properties of CoFe{sub 2}O{sub 4}/NiFe{sub 2}O{sub 4} core/shell nanocomposite prepared by the hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Sattar, A.A. [Department of Physics, Faculty of Science, Ain Shams University, 11566 Abbasia, Cairo (Egypt); EL-Sayed, H.M., E-mail: h_m_elsaid@hotmail.com [Department of Physics, Faculty of Science, Ain Shams University, 11566 Abbasia, Cairo (Egypt); ALsuqia, Ibrahim [Department of Physics, Faculty of Education and Applied Science, Hajjah University, Alshahli, Hajjah (Yemen)

    2015-12-01

    CoFe{sub 2}O{sub 4}/NiFe{sub 2}O{sub 4} core/shell magnetic nanocomposite was synthesized by using hydrothermal method.The analysis of XRD indicated the coexistence of CoFe{sub 2}O{sub 4}, NiFe{sub 2}O{sub 4}as core/shell composite. The core/shell structure of the composite sample has been confirmed by HR-TEM images, EDX and FT-IR measurements. The size of obtained core/shell nanoparticles was 17 nm in core diameter and about 3 nm in shell thickness. The magnetization measurements showed that both the coercive field and the saturation magnetization of the resulting core/shell nanocomposite were slightly decreased compared to those of the CoFe{sub 2}O{sub 4} core but the thermal stability is of the magnetization parameter was enhanced. Furthermore, superparamagnetic phase is established at temperatures higher than the room temperature. The results were discussed in terms of the surface pinning and the magnetic interaction at the interface between the core and shell. - Highlights: • CoFe{sub 2}O{sub 4}/NiFe{sub 2}O{sub 4} core/shell could be prepared by hydrothermal method. • The structural analysis proved the formation of NiFe{sub 2}O{sub 4} shell with thickness 3 nm. • The thermal stability of M{sub s} and H{sub c} is enhanced due to the presence of NiFe{sub 2}O{sub 4} as a shell. • Super paramagnetic transition is confirmed and the effective magnetic anisotropy was calculated.

  14. Microstructure of a commercial W–1% La{sub 2}O{sub 3} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Yinzhong, E-mail: shenyz@sjtu.edu.cn; Xu, Zhiqiang; Cui, Kai; Yu, Jie

    2014-12-15

    W–1% La{sub 2}O{sub 3} alloy is considered as the most promising material for plasma-facing components of fusion reactors. The microstructure of a commercial W–1% La{sub 2}O{sub 3} alloy was investigated using optical and transmission electron microscopes. The microstructure of pure tungsten can be improved significantly by fabrication of W–1% La{sub 2}O{sub 3} alloys. W–1% La{sub 2}O{sub 3} alloys can be produced with no porosities and cracks, and with various oxide phases dispersed in alloy matrix. La{sub 2}O{sub 3} with different crystal structures, La{sub 6}W{sub 2}O{sub 15}, WO{sub 2}, WO{sub 3} and W{sub 3}O{sub 8} phases were identified in as-forged W–1% La{sub 2}O{sub 3} alloy. Long strip-like La{sub 2}O{sub 3} has a very large size, whereas spherical La{sub 6}W{sub 2}O{sub 15}, navicular WO{sub 3}, hexagonal W{sub 3}O{sub 8} and short rod-like La{sub 2}O{sub 3} are smaller particles. Most identified phases have a heterogeneous distribution. Forging leads to a more dispersive distribution of large-sized La{sub 2}O{sub 3} particles but not of fine WO{sub 3} particles compared with rolling. The mechanical properties of the alloys are also discussed.

  15. Epitaxial growth of Sc{sub 2}O{sub 3} films on Gd{sub 2}O{sub 3}-buffered Si substrates by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Paulraj, Joseph; Wang, Rongping; Sellars, Matthew; Luther-Davies, Barry [Australian National University, Laser Physics Centre, Research School of Physics and Engineering, Acton, Canberra, ACT (Australia)

    2016-04-15

    We investigated the optimal conditions to prepare high-quality Sc{sub 2}O{sub 3} films on Gd{sub 2}O{sub 3}-buffered Si wafers using pulsed laser deposition technique with an aim at developing waveguide devices that can transform the performance of the gradient echo quantum memory based on bulk crystals. Under the optimal conditions, only oxide and Si (2 2 2) peaks appeared in the X-ray diffraction pattern. The Sc{sub 2}O{sub 3} (2 2 2) diffraction peak was located at 2θ=31.5 with a full width at half maxima (FWHM) of 0.16 , and its rocking curve had a FWHM of 0.10 . In-plane epitaxial relationship was confirmed by X-ray pole figure where Sc{sub 2}O{sub 3} (1 1 1) was parallel to Si (1 1 1). High-resolution TEM images indicated clear interfaces and perfect lattice images with sharp electron diffraction dots. All these results confirm that the oxide films on Si were single crystalline with high quality. (orig.)

  16. Preparation mechanism of (Bi{sub 2}O{sub 3}){sub 0.75}(Dy{sub 2}O{sub 3}){sub 0.25} nano-crystalline solid electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Li Rong [Nano-science and Nano-technology Research Center, School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); UCCS: Unite de Catalyse et de Chimie du Solide - UMR CNRS 8181, ENSCL, Batiment C7, BP 90108, 59652 Villeneuve d' Ascq Cedex (France); Zhen Qiang, E-mail: zhenqiang@263.ne [Nano-science and Nano-technology Research Center, School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Drache, Michel; Rubbens, Annick; Vannier, Rose-Noelle [UCCS: Unite de Catalyse et de Chimie du Solide - UMR CNRS 8181, ENSCL, Batiment C7, BP 90108, 59652 Villeneuve d' Ascq Cedex (France)

    2010-04-02

    (Bi{sub 2}O{sub 3}){sub 0.75}(Dy{sub 2}O{sub 3}){sub 0.25} nanopowder was prepared by reverse chemical titration co-precipitation method. The reaction mechanism during the precipitation process was discussed by thermodynamic analysis. Thermal decomposition behavior of the precursor was investigated using X-ray diffractometry and TG-MS analysis. The precursor was calcined at 500 {sup o}C for 3 h to obtain (Bi{sub 2}O{sub 3}){sub 0.75}(Dy{sub 2}O{sub 3}){sub 0.25} nanopowder. Using the nanopowder, pellets with relative density higher than 94% were obtained at 700 {sup o}C for 2 h by pressureless sintering, and the grains remained at the nano-scale with size of 72 nm.

  17. Stability of fluorite-type La{sub 2}Ce{sub 2}O{sub 7} under extreme conditions

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, F.X., E-mail: zhangfx@umich.edu [Department of Earth and Environmental Sciences, The University of Michigan, Ann Arbor, MI 48109 (United States); State Key Laboratory of Metastable Materials Science & Technology, Yanshan University, Qinhuangdao, Hebei 066004 (China); Tracy, C.L. [Department of Materials Science and Engineering, The University of Michigan, Ann Arbor, MI 48109 (United States); Lang, M. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37966 (United States); Ewing, R.C. [Department of Geological Sciences, Stanford University, Stanford, CA 94305 (United States)

    2016-07-25

    The structural stability of fluorite-type La{sub 2}Ce{sub 2}O{sub 7} was studied at pressure up to ∼40 GPa and under hydrothermal conditions of ∼1 GPa and up to 350 °C, respectively, using synchrotron X-ray diffraction (XRD) and Raman scattering measurements. XRD measurements indicated that the fluorite-type La{sub 2}Ce{sub 2}O{sub 7} is not stable at pressures greater than 22.6 GPa and gradually transformed to a high-pressure phase. The high-pressure phase is not stable and changed back to the fluorite-type structure when pressure is released. The La{sub 2}Ce{sub 2}O{sub 7} fluorite is also not stable under hydrothermal conditions and began to react with water at 200–250 °C. Both Raman and XRD results suggest that lanthanum hydroxide La(OH){sub 3} and La{sup 3+}-doped CeO{sub 2} fluorite are the dominant products after hydrothermal treatment. - Graphical abstract: The fluorite-type La{sub 2}Ce{sub 2}O{sub 7} reacted with water at hydrothermal condition (1 GPa, and above 200 °C), and formed rare earth hydroxides. - Highlights: • La{sub 2}Ce{sub 2}O{sub 7} transforms to a metastable phase at pressure higher than 21 GPa. • La{sub 2}Ce{sub 2}O{sub 7} reacts with water at ∼1 GPa and above 200 °C. • The pressure-induced phase transition is reversible.

  18. Oxygen redistribution in (UCe)Osub(2-x)

    International Nuclear Information System (INIS)

    Guedeney, Philippe.

    1983-01-01

    Redistribution of oxygen has been investigated in (Usub(0,7)Cesub(0,3))Osub(2-x) mixed oxide subjected to a temperature gradient in laboratory experiments, in order to apply the results to the nuclear fuel (UPu)Osub(2-x). Cylindrical sintered oxide specimens were exposed to temperature up to 1300 0 C with a longitudinal thermal gradient of about 400 0 C/cm. The most interesting feature of the experimental set-up is a solid-state electrochemical gauge (ThO 2 - Y 2 O 3 ), placed in the cold part of the sample which allows a continuous measurement of the oxygen activity. The experiments showed a fast oxygen migration down the thermal gradient. The calculations performed with a model based on solid-state thermodiffusion are in good agreement with experimental results. The heat of transport Q measured for bare samples reaches (7.2+-0.5)-kcal/mole. When the sample is coated with a tight fitting metallic cladding, an extra term Qe has to be added to the heat of transport Qe. This was interpreted as an electrotransport phenomena. On the same basis, calculations applied to radial oxygen redistribution in (UPu)Osub(2-x) seem to be adequate at least during the first stage of irradiation, taking Q=(20+-5)kcal/mole [fr

  19. Electrical resistivity of YbRh{sub 2}Si{sub 2} and EuT{sub 2}Ge{sub 2} (T=Co,Cu) at extreme conditions of pressure and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dionicio, G.A.

    2006-07-01

    This investigation addresses the effect that pressure, p, and temperature, T, have on 4f states of the rare-earth elements in the isostructural YbRh{sub 2}Si{sub 2}, EuCo{sub 2}Ge{sub 2}, and EuCu{sub 2}Ge{sub 2} compounds. Upon applying pressure the volume of the unit cell reduces, enforcing either the enhancement of the hybridization of the 4f localized electrons with the ligand or a change in the valence state of the rare-earth ions. Here, we probe the effect of a pressure-induced lattice contraction on these system by means of electrical-resistivity measurements, {rho}(T), from room temperature down to 100 mK. (orig.)

  20. The single crystal structure determination of Ln{sub 6}MnSb{sub 15} (Ln=La, Ce), Ln{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), and Ln{sub 6}ZnSb{sub 15} (Ln=La-Pr)

    Energy Technology Data Exchange (ETDEWEB)

    Benavides, Katherine A.; McCandless, Gregory T.; Chan, Julia Y. [Texas Univ., Dallas, Richardson, TX (United States). Dept. of Chemistry and Biochemistry

    2017-09-01

    Single crystals of Ln{sub 6}MnSb{sub 15} (Ln=La, Ce), Ln{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), and Ln{sub 6}ZnSb{sub 15} (Ln=La-Pr) have been successfully grown and the compounds adopt the orthorhombic Ln{sub 6}MnSb{sub 15} structure type (space group Immm), with a∝4.3 Aa, b∝15 Aa, and c∝19 Aa. This structure is comprised of antimony nets and antimony ribbons which exhibit positional disorder at connecting points between antimony substructures, in addition to two partially occupied transition metal sites. The unit cell volumes of the La analogs displayed a systematic decrease upon Zn substitution. However, for the Ce{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} and Pr{sub 6}Mn{sub 1-x}Zn{sub x}Sb{sub 15} (x∝0.5), the volumes deviate from linearity as observed in the parent compounds.

  1. Lu{sub 2}O{sub 3}:Tb,Hf storage phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kulesza, Dagmara; Trojan-Piegza, Joanna [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw (Poland); Zych, Eugeniusz, E-mail: zych@wchuwr.p [Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw (Poland)

    2010-03-15

    Lu{sub 2}O{sub 3}:Tb,Hf ceramics containing 0.1% of Tb and 0-1.5% of Hf were prepared in reducing atmosphere at 1700 {sup o}C and their thermoluminescence properties were systematically studied. For comparison Tb,Ca co-doped specimen was also fabricated and investigated. The Tb,Hf ceramics shows basically a single TL band located around 180 {sup o}C as found with heating rate of 15 {sup o}C/min. Ceramics singly doped with Tb show complex TL glow curves indicating the presence of traps of very different depths. On the other hand Tb,Ca co-doping is beneficial for the development of shallow traps with the main TL band around 70 {sup o}C. Hence, the aliovalent impurities, Ca{sup 2+} and Hf{sup 4+}, strongly influenced the traps structure in Lu{sub 2}O{sub 3}:Tb ceramics, each of them in its own specific way. Isothermal decay of Lu{sub 2}O{sub 3}:Tb,Hf at 185 {sup o}C was recorded and its shape suggest that multiple hole trapping occurs in the Lu{sub 2}O{sub 3}:Tb,Hf ceramics. Due to the different traps depths the Lu{sub 2}O{sub 3}:Tb,Hf ceramics possess properties typical for storage phosphors, while Lu{sub 2}O{sub 3}:Tb,Ca is a persistent luminescent material rather.

  2. Lithium insertion in V{sub 2}O{sub 5}, M{sub x}V{sub 2}O{sub 5} (M = Fe, Cr, Al, La) mixed oxides; Insertion du lithium dans les oxydes mixtes de V{sub 2}O{sub 5}, M{sub x}V{sub 2}O{sub 5} (M = Fe, Cr, Al, La)

    Energy Technology Data Exchange (ETDEWEB)

    Gregoire, G.; Pecquenard, B.; Baffier, N. [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France). Laboratoire de Chimie Appliquee de l`Etat Solide; Soudan, P.; Farcy, J.; Pereira-Ramos, J.P. [Centre National de la Recherche Scientifique (CNRS), 94 - Ivry-sur-Seine (France). Laboratoire d`Electrochimie Catalyse et Synthese Organique

    1996-12-31

    V{sub 2}O{sub 5} based compounds are interesting low potential materials for rechargeable cathodes of lithium electrochemical generators. However, the ionic conductivity and the reversibility of electrochemical cycling of V{sub 2}O{sub 5} are limited by the possibilities of lithium insertion. This work shows that the doping of vanadium pentoxide by a M{sup 3+} trivalent transition element (M Fe, Al, Cr or La) allows to intercalate a more important amount of lithium and to improve the behaviour of the material during cycling. These materials of M{sub 0.11}V{sub 2}O{sub 5.16} formula are obtained by sol-gel synthesis. the electrochemical study of the Fe compound has shown that it is a mixed oxide with a behaviour similar to V{sub 2}O{sub 5}. The maximum capacity is of about 2 F/mole in the case of Fe, Al and Cr compounds and of about 1.7 F/mole in the case of La. The structural evolution of the Fe compound has been followed during the chemical insertion of Li and the same succession of phases ({alpha}, {epsilon}, {delta} and {gamma}) is observed as in Li{sub x}V{sub 2}O{sub 5} compounds but with a delay. The occurrence of the {gamma} phase, in particular, which is involved in recharging problems is delayed thanks to the (Fe-O){sub n} chains perpendicular to the (V{sub 2}O{sub 5}){sub n} layers. Abstract only. (J.S.) 3 refs.

  3. Lithium insertion in V{sub 2}O{sub 5}, M{sub x}V{sub 2}O{sub 5} (M = Fe, Cr, Al, La) mixed oxides; Insertion du lithium dans les oxydes mixtes de V{sub 2}O{sub 5}, M{sub x}V{sub 2}O{sub 5} (M = Fe, Cr, Al, La)

    Energy Technology Data Exchange (ETDEWEB)

    Gregoire, G; Pecquenard, B; Baffier, N [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France). Laboratoire de Chimie Appliquee de l` Etat Solide; Soudan, P; Farcy, J; Pereira-Ramos, J P [Centre National de la Recherche Scientifique (CNRS), 94 - Ivry-sur-Seine (France). Laboratoire d` Electrochimie Catalyse et Synthese Organique

    1997-12-31

    V{sub 2}O{sub 5} based compounds are interesting low potential materials for rechargeable cathodes of lithium electrochemical generators. However, the ionic conductivity and the reversibility of electrochemical cycling of V{sub 2}O{sub 5} are limited by the possibilities of lithium insertion. This work shows that the doping of vanadium pentoxide by a M{sup 3+} trivalent transition element (M Fe, Al, Cr or La) allows to intercalate a more important amount of lithium and to improve the behaviour of the material during cycling. These materials of M{sub 0.11}V{sub 2}O{sub 5.16} formula are obtained by sol-gel synthesis. the electrochemical study of the Fe compound has shown that it is a mixed oxide with a behaviour similar to V{sub 2}O{sub 5}. The maximum capacity is of about 2 F/mole in the case of Fe, Al and Cr compounds and of about 1.7 F/mole in the case of La. The structural evolution of the Fe compound has been followed during the chemical insertion of Li and the same succession of phases ({alpha}, {epsilon}, {delta} and {gamma}) is observed as in Li{sub x}V{sub 2}O{sub 5} compounds but with a delay. The occurrence of the {gamma} phase, in particular, which is involved in recharging problems is delayed thanks to the (Fe-O){sub n} chains perpendicular to the (V{sub 2}O{sub 5}){sub n} layers. Abstract only. (J.S.) 3 refs.

  4. Interpretation of the Raman spectra of the glassy states of Si{sub x}S{sub 1−x} and Si{sub x}Se{sub 1−x}

    Energy Technology Data Exchange (ETDEWEB)

    Devi, V. Radhika [M.L.R. Institute of Technology, Affiliated to Jawaharlal Nehru Technological University, Dundigal, Hyderabad 500043 (India); Zabidi, Noriza Ahmad [Department of Physics, Centre for Defence Foundation Studies, National Defence University of Malaysia, Kem Sungai Besi, Kuala Lumpur 57000 (Malaysia); Shrivastava, Keshav N., E-mail: keshav1001@yahoo.com [School of Physics, University of Hyderabad, Hyderabad 50046 (India); Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia)

    2013-09-16

    We use the density-functional theory to make models of Si{sub x}S{sub y} and Si{sub x}Se{sub y} for the values of x,y = 1–6. The vibrational frequencies are calculated for each model. The stable clusters are selected on the basis of positive vibrational frequencies. In the case of Si{sub x}S{sub 1−x}, the values of the vibrational frequencies calculated from the first principles for Si{sub 2}S(triangular)cluster of atoms, 364.1 cm{sup −1} and 380.8 cm{sup −1}, agree with the experimentally measured values of 367 cm{sup −1} and 381 cm{sup −1}, indicating that Si{sub 2}S clusters occur in the glassy state of SiS. The calculated values of the vibrational frequencies of SiSe{sub 4} (pyramidal) which agree with the experimental Raman frequencies of glassy Si{sub x}Se{sub 1−x} are 114, 166 and 361 cm{sup −1}. The calculated values for Si{sub 2}Se{sub 4} (bipyramidal) which agree with the experimental data of Si{sub x}Se{sub 1−x} are 166 and 464 cm{sup −1}. In Si{sub 4}Se (pyramidal) the values 246 and 304 cm{sup −1} agree with the measured values. In Si{sub 4}Se{sub 2} (bipyramidal), the calculated values 162, 196 and 304 cm{sup −1} agree with the measured values. The calculated values of 473 cm{sup −1} for Si{sub 6}Se{sub 2} (bipyramidal) also agree with the experimentally measured values. We thus find that pyramidal structures are present in the amorphous Si{sub x}Se{sub 1−x} glassy state. - Highlights: • A first principles calculation is performed to calculate the vibrational frequencies. • The calculated frequencies of clusters agree with measured Raman values. • The structures, bond lengths and symmetries are determined. • The importance of Jahn–Teller effect in SiS and in SiSe is clearly seen. • The clusters of SiS and SiSe are found to stabilize in different symmetries.

  5. Subsolidus phase relationships of the {beta}-sialon solid solution in the oxygen-rich part of the Nd-Si-Al-O-N system

    Energy Technology Data Exchange (ETDEWEB)

    Kaiser, A.; Telle, R. [Rheinisch Westfaelische Technische Hochschule Aachen (Germany). Inst. fuer Gesteinshuettenkunde; Herrmann, M.; Richter, H.J.; Hermel, W. [Fraunhofer Inst. Keramische Technologien und Sinterwerkstoffe, Dresden (Germany)

    2001-10-01

    The subsolidus phase relationships in the Nd{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2} system and in the Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z} (0 {<=} z {<=} 4)-''Al{sub 2}O{sub 3}:AlN''-Al{sub 2}O{sub 3}-Nd{sub 2}O{sub 3}-SiO{sub 2}-range of the Nd-Si-Al-O-N system have been determined. 50 three- and four-phase equilibria were established in this phase region. The phase equilibria define the regions of stable coexistence between {beta}-sialon Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z} (0 {<=} z {<=} 4) and oxide or oxynitride compounds, which are potential grain boundary phases for silicon nitride ceramics. {beta}-Si{sub 3}N{sub 4} coexists with N-melilite (Nd{sub 2}Si{sub 3-x}Al{sub x}N{sub 4-x} (0 {<=} x {<=} 1)), N-{alpha}-wollastonite NdSi{sub 2}ON, a nitrogen-rich (Al, N)-apatite solid solution and Nd{sub 2}Si{sub 2}O{sub 7}. Between 0 {<=} z {<=} 0.8 {beta}-sialon (Si{sub 6-z}Al{sub z}O{sub z}N{sub 8-z}) is compatible with N-melilite (Nd{sub 2}Si{sub 3-x}Al{sub x}N{sub 4-x} (x = 1)), an (Al,N)-apatite of intermediate composition and Nd{sub 2}Si{sub 2}O{sub 7}. The equilibrium phases between z = 0.8 to z = 4 are NdAlO{sub 3} and the U-phase (Nd{sub 3}Si{sub 3-x}Al{sub 3+x}O{sub 12+x}N{sub 2-x}) as well as NdAl{sub 11+x}O{sub 18}N{sub x} (x = 1) and corundum at the Al-rich terminal composition (z = 4). (orig.)

  6. Pt-doped In{sub 2}O{sub 3} nanoparticles prepared by flame spray pyrolysis for NO{sub 2} sensing

    Energy Technology Data Exchange (ETDEWEB)

    Inyawilert, K. [Chiang Mai University, Department of Physics and Materials Science, Faculty of Science (Thailand); Channei, D. [Naresuan University, Department of Chemistry, Faculty of Science (Thailand); Tamaekong, N. [Maejo University, Program in Materials Science, Faculty of Science (Thailand); Liewhiran, C. [Chiang Mai University, Department of Physics and Materials Science, Faculty of Science (Thailand); Wisitsoraat, A.; Tuantranont, A. [National Electronics and Computer Technology Center (NECTEC), Nanoelectronics and MEMS Laboratory (Thailand); Phanichphant, S., E-mail: sphanichphant@gmail.com [Chiang Mai University, Faculty of Science, Materials Science Research Center (Thailand)

    2016-02-15

    Undoped In{sub 2}O{sub 3} and 0.25–1.00 wt% M (M=Pt, Nb, and Ru)-doped/loaded In{sub 2}O{sub 3} nanoparticles were successfully synthesized in a single-step flame spray pyrolysis technique using indium nitrate, platinum (II) acetylacetonate, niobium ethoxide, and ruthenium (III) acetylacetonate precursors. The undoped In{sub 2}O{sub 3} and M-doped In{sub 2}O{sub 3} nanoparticles were characterized by Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM & TEM). The BET average diameter of spherical nanoparticles was found to be in the range of 10.2–15.2 nm under 5/5 (precursor/oxygen) flame conditions. All XRD peaks were confirmed to correspond to the cubic structure of In{sub 2}O{sub 3}. TEM images showed that there is no Pt nanoparticle loaded on In{sub 2}O{sub 3} surface, suggesting that Pt should form solid solution with the In{sub 2}O{sub 3} lattice. Gas sensing studies showed that 0.5 wt% Pt doping in In{sub 2}O{sub 3} nanoparticles gave a significant enhancement of NO{sub 2} sensing performances in terms of sensor response and selectivity. 0.5 wt% Pt/In{sub 2}O{sub 3} exhibited a high NO{sub 2} response of ∼1904 to 5 ppm NO{sub 2} at 250 °C and good NO{sub 2} selectivity against NO, H{sub 2}S, H{sub 2}, and C{sub 2}H{sub 5}OH. In contrast, Nb and Ru loading resulted in deteriorated NO{sub 2} response. Therefore, Pt is demonstrated to be an effective additive to enhance NO{sub 2} sensing performances of In{sub 2}O{sub 3}-based sensors.

  7. Ferromagnetic glass ceramics and glass fibers based on the composition of SiO{sub 2}-CaO-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-Fe{sub 2}O{sub 3} glass system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jianan, E-mail: lja@qlu.edu.cn; Zhu, Chaofeng; Zhang, Meimei; Zhang, Yanfei; Yang, Xuena

    2017-03-15

    Ferromagnetic glass-ceramics and glass fibers were obtained by the melt-method from the glass system SiO{sub 2}-CaO-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-Fe{sub 2}O{sub 3} without performing any nucleation and crystallization heat treatments. Glass-ceramics and glass fibers were characterized by x-ray diffraction, scanning and transmission electron microscopy, magnetic measurements, and thermal expansion instrument. The influence of alumina content on the spontaneous crystallization of magnetite, magnetism properties and thermal expansion performances in glass were investigated. We examined the crystallization behavior of the glasses and found that the spontaneous crystallization capacity of magnetite and magnetism properties in base glass increases with increasing the content of alumina. The ferromagnetic glass fibers containing magnetite nano-crystals are also obtained. - Highlights: • Magnetite nano-crystals are formed spontaneously in the investigated glass systems. • The crystallization behavior of the glasses with the alumina content is examined. • Ferromagnetic glass fibers containing magnetite nano-crystals are obtained.

  8. Structural influence of aluminium, gallium and indium metal oxides by means of dielectric and spectroscopic properties of CaO-Sb{sub 2}O{sub 3}-B{sub 2}O{sub 3} glass system

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasa Reddy, M. [Department of Physics, Acharya Nagarjuna University P.G. Centre, Nuzvid 521 201, AP (India); Naga Raju, G. [Department of Physics, Acharya Nagarjuna University P.G. Centre, Nuzvid 521 201, AP (India); Nagarjuna, G. [Department of Chemistry, Acharya Nagarjuna University, Nagarjunanagar, AP (India); Veeraiah, N. [Department of Physics, Acharya Nagarjuna University P.G. Centre, Nuzvid 521 201, AP (India)]. E-mail: nvr8@rediffmail.com

    2007-07-12

    Dielectric constant ({epsilon}'), loss (tan {delta}), ac conductivity ({sigma}) of CaO-Sb{sub 2}O{sub 3}-B{sub 2}O{sub 3}:M{sub 2}O{sub 3} (Al{sub 2}O{sub 3}, Ga{sub 2}O{sub 3} and In{sub 2}O{sub 3}) glasses with varying concentrations of M{sub 2}O{sub 3} (0-5 mol%), were measured as a function of frequency and temperature over moderately wide ranges. The analysis of results of these studies along with IR, Raman and optical absorption spectra and also DTA studies indicated that in the concentration ranges, 0 {<=} Al{sub 2}O{sub 3} {<=} 4, 0 {<=} Ga{sub 2}O{sub 3} {<=} 2 and 1 {<=} In{sub 2}O{sub 3} {<=} 5, Al{sup 3+}, Ga{sup 3+} ions occupy tetrahedral positions whereas In{sup 3+} ions take up octahedral substitutional positions, cross-link with the other structural units in the glass network and increase the rigidity of the glass network.

  9. Optimization of α-Fe{sub 2}O{sub 3}@Fe{sub 3}O{sub 4} incorporated N-TiO{sub 2} as super effective photocatalysts under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, Mohamed Mokhtar, E-mail: mohmok2000@yahoo.com [Benha University, Faculty of Science, Chemistry Department, Benha (Egypt); Bayoumy, W.A. [Benha University, Faculty of Science, Chemistry Department, Benha (Egypt); Goher, M.E. [National Institute of Oceanography & Fisheries, Environmental Chemistry, Cairo (Egypt); Abdo, M.H., E-mail: mh_omr@yahoo.com [National Institute of Oceanography & Fisheries, Environmental Chemistry, Cairo (Egypt); Mansour El-Ashkar, T.Y. [National Institute of Oceanography & Fisheries, Environmental Chemistry, Cairo (Egypt)

    2017-08-01

    Highlights: • The α-Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4} doped n-TiO{sub 2} was synthesized via deposition-self assembly technique. • The photocatalyst 1%α-Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4}/n-TiO{sub 2} show a remarkable performance while MB degradation. • The strong interaction between α-Fe{sub 2}O{sub 3}/Fe{sub 3}O{sub 4} and n-TiO{sub 2} plays an important role. • It exhibits a unique textural, optical and charge transfer properties. - Abstract: Well dispersed α-Fe{sub 2}O{sub 3}@Fe{sub 3}O{sub 4} nanoparticles (7 nm) supported on mesoporous nitrogen doped titanium dioxide (N-TiO{sub 2}) are synthesized by deposition self-assembly route and their performances as photocatalysts toward methylene blue (MB) degradation are evaluated. The results illustrate that the spherical yolk-shell structure of α-Fe{sub 2}O{sub 3}@Fe{sub 3}O{sub 4}@N-TiO{sub 2} at the loading of 1%; of excellent S{sub BET} (187 m{sup 2} g{sup −1}) and pore volume (0.50 cm{sup 3} g{sup −1}), achieved high photocatalytic performance for the MB degradation (20 ppm, λ > 420 nm, lamp power = 160 W) under visible light illumination (k = 0.059 min{sup −1}). The influence of the interface formation between α-Fe{sub 2}O{sub 3}@Fe{sub 3}O{sub 4} and n-TiO{sub 2} affects severely the charges separation efficiency and enhances the electron transfer to keep on the existence of Fe{sup 3+}/Fe{sup 2+} moieties; those take significant role in the reaction mechanism. The existence of the latter junction is affirmed via XRD, TEM-SAED, Raman and FTIR techniques whereas, the photogenerated charges, their separation together with their transport and recombination rates are depicted via photoluminescence, electrical conductivity, incident photon to current efficiency (IPCE), cyclic voltammetry (CV) and impedance (EIS) measurements. The catalyst loading, zero point charge, pH variation, total organic carbon (TOC%) and the effect of lamps power are thoroughly investigated. The 1%α-Fe{sub 2}O{sub 3

  10. Microstructures and mechanical properties of Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Lei [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning 110819 (China); Key Laboratory for Advanced Ceramics and Application of Shenyang, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142 (China); Ma, Weimin, E-mail: maleisy2003@163.com [Key Laboratory for Advanced Ceramics and Application of Shenyang, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142 (China); Sun, Xudong, E-mail: xdsun@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, Liaoning 110819 (China); Ji, Lianyong; Liu, Jianan; Hang, Kai [Key Laboratory for Advanced Ceramics and Application of Shenyang, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142 (China)

    2015-09-25

    Highlights: • Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) composites were prepared using vacuum sintering. • The phase composition and microstructure are studied. • Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) materials show superior mechanical properties. • The solid solution strengthening and stress-induced phase transformation toughening mechanism are proposed. • Two kinds of mechanisms explain the improvement of mechanical properties. - Abstract: Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) composite ceramics were prepared by vacuum sintering using Gd{sub 2}Zr{sub 2}O{sub 7} and ZrO{sub 2}(3Y) nanoparticles. The ceramics were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), the three-point-bending technique and single-edge-notched-beam tests. The effect of various proportions of ZrO{sub 2}(3Y) on the phase composition, microstructure, bending strength and fracture toughness of the final Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) composite ceramics was also analyzed. The change from m-ZrO{sub 2} to t-ZrO{sub 2} phase contents, before and after fracture, was measured using XRD quantitative phase analysis. The results confirm that, with the increasing content of ZrO{sub 2}(3Y), a phase transition from solid solution to saturated precipitation occurs and the bending strength and fracture toughness of the samples increase gradually. When the content of ZrO{sub 2}(3Y) reached 95 vol.%, the Gd{sub 2}Zr{sub 2}O{sub 7}/ZrO{sub 2}(3Y) composite ceramics had a bending strength of 547 MPa and a fracture toughness of 5.5 MPa m{sup 1/2}, indicating that stress-induced phase transformation toughening was an efficient way to increase the mechanical properties of the Gd{sub 2}Zr{sub 2}O{sub 7} ceramics.

  11. Investigation of the fabrication processes of AlGaN/AlN/GaN HEMTs with in situ Si{sub 3}N{sub 4} passivation

    Energy Technology Data Exchange (ETDEWEB)

    Tomosh, K. N., E-mail: sky77781@mail.ru; Pavlov, A. Yu.; Pavlov, V. Yu.; Khabibullin, R. A.; Arutyunyan, S. S.; Maltsev, P. P. [Russian Academy of Sciences, Institute of Ultra-High-Frequency Semiconductor Electronics (Russian Federation)

    2016-10-15

    The optimum mode of the in situ plasma-chemical etching of a Si{sub 3}N{sub 4} passivating layer in C{sub 3}F{sub 8}/O{sub 2} medium is chosen for the case of fabricating AlGaN/AlN/GaN HEMTs. It is found that a bias of 40–50 V at a high-frequency electrode provides anisotropic etching of the insulator through a resist mask and introduces no appreciable radiation-induced defects upon overetching of the insulator films in the region of gate-metallization formation. To estimate the effect of in situ Si{sub 3}N{sub 4} growth together with the heterostructure in one process on the AlGaN/AlN/GaN HEMT characteristics, transistors with gates without the insulator and with gates through Si{sub 3}N{sub 4} slits are fabricated. The highest drain current of the AlGaN/AlN/GaN HEMT at 0 V at the gate is shown to be 1.5 times higher in the presence of Si{sub 3}N{sub 4} than without it.

  12. Novel oxide buffer approach for GaN integration on Si(111) platform through Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} bi-layer

    Energy Technology Data Exchange (ETDEWEB)

    Tarnawska, Lidia

    2012-12-19

    Motivation: Preparation of GaN virtual substrates on large-scale Si wafers is intensively pursued as a cost-effective approach for high power/high frequency electronics (HEMT's etc.) and optoelectronic applications (LED, LASER). However, the growth of high quality GaN layers on Si is hampered by several difficulties mainly related to a large lattice mismatch (-17%) and a huge difference in the thermal expansion coefficient (56%). As a consequence, GaN epitaxial layers grown on Si substrates show a high number of defects (threading dislocations etc.), which severely deteriorate the overall quality of the GaN films. Additionally, due to the different thermal expansion coefficients of the substrate and the film, um-thick GaN layers crack during post-growth cooling. To solve these integration problems, different semiconducting (e.g. AlN, GaAs, ZnO, HfN) and insulating (e.g. Al{sub 2}O{sub 3}, MgO, LiGaO{sub 2}) buffer layers, separating the Si substrate from the GaN film, are applied. Goal: In this thesis, a novel buffer approach for the integration of GaN on Si is proposed and investigated. The new approach employs Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3} bilayer templates as a step-graded buffer to reduce the lattice mismatch between GaN and the Si(111) substrate. According to the bulk crystal lattices, since the Y{sub 2}O{sub 3} has an in-plane lattice misfit of -2% to Si, Sc{sub 2}O{sub 3} -7% to Y{sub 2}O{sub 3}, the lattice misfit between GaN and the substrate can be theoretically reduced by about 50% from -17% (GaN/Si) to -8% (GaN/Sc{sub 2}O{sub 3}). Experimental: The GaN/Sc{sub 2}O{sub 3}/Y{sub 2}O{sub 3}/Si(111) heterostructures are prepared in a multichamber molecular beam epitaxy system on 4 inch Si(111) wafers. In order to obtain complete information on the structural quality of the oxide buffer as well as the GaN layer, synchrotron- and laboratory-based X-ray diffraction, transmission electron microscopy and photoluminescence measurements are performed. The

  13. Structure of RbAlAs[sub 2]O[sub 7]. Structure de RbAlAs[sub 2]O[sub 7

    Energy Technology Data Exchange (ETDEWEB)

    Boughzala, H. (Dept. de Chimie, Faculte des Sciences, Tunis (Tunisia)); Driss, A. (Dept. de Chimie, Faculte des Sciences, Tunis (Tunisia)); Jouini, T. (Dept. de Chimie, Faculte des Sciences, Tunis (Tunisia))

    1993-03-15

    Rubidium aluminium pyroarsenate, M[sub r]=374.29, triclinic, P anti 1, a=8.233(5), b=6.34(2), c=6.241(5) A, [alpha]=102.6(1), [beta]=103.89(7), [gamma]=96.7(1) , V=303.9 A[sup 3], Z=2, D[sub m]=3.9(3) (pycnometry), D[sub x]=4.09 g cm[sup -3], [lambda](Ag K anti [alpha])=0.5608 A, [mu]=108.14 cm[sup -1], F(000)=344, T=296 K, R=0.049, wR=0.053 for 2193 reflections. The first structural investigation on a pyroarsenate is reported. It is built from AlAs[sub 2]O[sub 11] units comprising one AlO[sub 6] octahedron and one As[sub 2]O[sub 7] pyroarsenate group in which two AsO[sub 4] tetrahedra point in opposite directions. These units are connected by heteropolyhedral linkages to form a three-dimensional framework having intersecting tunnels where the Rb[sup +] ions are located. Although this structure is not isotypic with the phosphate analogues, it is closely related to that of the pyrophosphates of type I represented by KAlP[sub 2]O[sub 7]. (orig.).

  14. Kinetics of dissolution of {alpha}-Fe{sub 2}O{sub 3} and {gamma}-Fe{sub 2}O{sub 3} in EDTA and NTA-based formulations

    Energy Technology Data Exchange (ETDEWEB)

    Ranganathan, S. [Dept. of Chemical Engineering, Univ. of New Brunswick, Fredericton, N.B. (Canada); Srinivasan, M.P. [Water and Steam Chemistry Lab. of Bhabha Atomic Research Centre (BARC) (India); Narasimhan, S.V. [Bhabha Atomic Research Centre (India); Raghavan, P.S. [Madras Christian Coll., Chennai (India); Gopalan, R. [Dept. of Chemistry, Madras Christian Coll., Chennai (India)

    2004-06-01

    The dissolution studies were carried out on haematite ({alpha}-Fe{sub 2}O{sub 3}) and maghemite ({gamma}-Fe{sub 2}O{sub 3}) in two different formulations of ethylenediaminetetraacetic acid (EDTA) and nitrilotriaceticacid (NTA). The rate constants were calculated using the ''inverse cubic rate law.'' The leaching of the metal ions from the oxide is controlled partly by the Fe(II)-L{sub n} (L is a complexing ligand and n is the number of ligands attached to Fe{sup 2+}), a dissolution product arising from the oxides having Fe{sup 2+} in the lattice. The addition of Fe(II)-L{sub n} along with the formulation greatly increased the initial rate of dissolution. The effect of the addition of Fe(II)-L as a reductant on the dissolution of {alpha}-Fe{sub 2}O{sub 3} was not the same as in the case of {gamma}-Fe{sub 2}O{sub 3}. The rate constants (k{sub obs}) for the dissolution of {alpha}-Fe{sub 2}O{sub 3} and {gamma}-Fe{sub 2}O{sub 3} in the presence of ascorbic acid were less in the EDTA formulation than in the NTA formulation. The studies using Fe(II)-NTA and Fe(II)-EDTA with varying compositions of citric acid and ascorbic acid revealed that a minimum quantity of the chelant is sufficient to initiate the dissolution process, which can be further controlled by the reductants and weaker chelants such as citric acid. (orig.)

  15. Removal of elemental mercury by bamboo charcoal impregnated with H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zengqiang Tan; Jianrong Qiu; Hancai Zeng; Hao Liu; Jun Xiang [Huazhong University of Science and Technology, Wuhan (China). Key Laboratory of Coal Combustion

    2011-04-15

    Mercury emission from coal combustion is an increasing environmental concern due to its high volatility and toxicity, and activated carbon (AC) adsorption has been proven an effective mercury-control method, with high-cost limit. The renewable bioresource of bamboo constitutes an important precursor for activated carbon, and the bamboo charcoal (BC) may act as low-cost sorbent used in the mercury-control. The adsorptive potential of BC and modified BC using H{sub 2}O{sub 2} for elemental mercury was investigated for the first time through a parametric study conducted with a bench-scale bed. The effects of pore structure and surface chemistry were investigated based on BET, XPS. Which suggest that BC materials have excellent adsorption potential for elemental mercury, especially after modified by H{sub 2}O{sub 2}. The modification using H{sub 2}O{sub 2} altered the physical and chemical properties of BC materials, making the sorbents more effective in mercury adsorption even at a relative higher temperature, and the enhancing-effect was more obvious with increasing H{sub 2}O{sub 2}. 32 refs., 6 figs., 5 tabs.

  16. Vaporization study on nonstoichiometric NbOsub(2+-x) by mass-spectrometric method

    International Nuclear Information System (INIS)

    Matsui, T.; Naito, K.

    1981-01-01

    The vapor pressures over nonstoichiometric NbOsub(2+-x)(s) (1.972 2 (g) and NbO(g) over nonstoichiometric NbOsub(2+-x), from which the partial molar enthalpies and entropies of oxygen were calculated as a function of O/Nb composition. The composition dependence of the partial molar enthalpy and entropy obtained suggested the existence of some kind of short-range ordering in the nonstoichiometric Nbsub(2+-x) (s) phase. The enthalpies of formation of nonstoichiometric NbOsub(2+-x) (s) were also determined as a function of composition by combining the partial molar enthalpies of oxygen with the enthalpy of formation of stoichiometric NbOsub(2.000) (s). The phase diagram around NbOsub(2+-x) at high temperatures was determined from the vaporization study. (orig.)

  17. Hydrothermal synthesis and characterization of the praseodymium borate-nitrate Pr[B{sub 5}O{sub 8}(OH)(H{sub 2}O){sub 0.87}]NO{sub 3}.2H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Ortner, Teresa S.; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2017-10-01

    The praseodymium borate-nitrate Pr[B{sub 5}O{sub 8}(OH)(H{sub 2}O){sub 0.87}]NO{sub 3}.2H{sub 2}O was obtained in a hydrothermal synthesis. It crystallizes monoclinically in the space group P2{sub 1}/n (no. 14) with four formula units (Z=4) and unit cell parameters of a=641.9(3), b=1551.8(7), c=1068.4(5) pm, with β=90.54(2) yielding V=1.0643(8) nm{sup 3}. The defect variant constitutes the missing member in the series of isostructural, early rare earth borate-nitrates of the composition RE[B{sub 5}O{sub 8}(OH)(H{sub 2}O){sub x}]NO{sub 3}.2H{sub 2}O [RE=La (x=0; 1), Ce (x=1), Nd (x=0.85), Sm (x=0)]. In addition to powder and single-crystal X-ray diffraction data, the novel borate-nitrate was characterized through IR and Raman spectroscopy.

  18. Synthesis and characterization of physical properties of Gd{sub 2}O{sub 2}S:Pr{sup 3+} semi-nanoflower phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, A.; Rezaee Ebrahim Saraee, Kh.; Shakur, H.R. [University of Isfahan, Department of Nuclear Engineering, Faculty of Advance Sciences and Technologies, Isfahan (Iran, Islamic Republic of); Zamani Zeinali, H. [Nuclear Science and Technology Research Institute, Agriculture, Medical and Industrial Research School, Karaj (Iran, Islamic Republic of)

    2016-05-15

    Pure gadolinium oxysulfide phosphor (Gd{sub 2}O{sub 2}S) and trivalent praseodymium-doped gadolinium oxysulfide phosphor (Gd{sub 2}O{sub 2}S:Pr{sup 3+}) scintillators with semi-nanoflower crystalline structures were successfully synthesized through a precipitation method and subsequent calcination treatment as a converter for X-ray imaging detectors. The characterization such as the crystal structures and nanostructure of Gd{sub 2}O{sub 2}S:Pr{sup 3+} scintillator measured by XRD and FeE-SEM experiment. The optical properties of Gd{sub 2}O{sub 2}S:Pr{sup 3+} scintillator were studied. Luminescence spectra of Gd{sub 2}O{sub 2}S:Pr{sup 3+} under 320 nm UV excitation show a green emission at near 511 nm corresponding to the {sup 3}P{sub 0}-{sup 3}H{sub 4} of Pr ions. After scintillation properties of synthesized Gd{sub 2}O{sub 2}S:Pr{sup 3+} scintillator investigated, Gd{sub 2}O{sub 2}S:Pr{sup 3+} scintillating film fabricated on a glass substrate by a sedimentation method. X-ray imaging of the fabricated scintillators confirmed that the Gd{sub 2}O{sub 2}S:Pr{sup 3+} scintillator could be used for radiography applications in which good spatial resolution is needed. (orig.)

  19. MgFe{sub 2}O{sub 4}/ZrO{sub 2} composite nanoparticles for hyperthermia applications

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, Amin ur [Magnetism Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Department of Applied Physical and Material Sciences, University of Swat, Khyber Pakhtunkhwa (Pakistan); Humayun, Asif [Magnetism Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Manzoor, Sadia, E-mail: sadia_manzoor@comsats.edu.pk [Magnetism Laboratory, Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)

    2017-04-15

    MgFe{sub 2}O{sub 4}/ZrO{sub 2} composites containing ZrO{sub 2} in different weight percentages from 0% to 80% were prepared via the citrate gel technique as potential candidate materials for magnetic hyperthermia. The biocompatible ceramic ZrO{sub 2} was introduced to prevent MgFe{sub 2}O{sub 4} nanoparticles from aggregation and to reduce their dipolar interactions in order to enhance the specific absorption rate (SAR). Structural and magnetic properties of the samples were studied using powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and a vibrating sample magnetometer (VSM). Magnetically induced heating in radio frequency (RF) magnetic fields was observed in all samples. Most significantly, the sample with only 20 wt% MgFe{sub 2}O{sub 4} has been found to have a SAR that is larger than that of pure MgFe{sub 2}O{sub 4}. This is an important finding from the point of view of biomedical applications, because ZrO{sub 2} in known to have low toxicity and a higher biocompatibility as compared to ferrites. - Highlights: • MgFe{sub 2}O{sub 4} and ZrO{sub 2} composite nanoparticles with different weight percentages of ZrO{sub 2} were prepared via the citrate gel technique. • Significant variation in magnetic properties was observed with increasing the weight % of ZrO{sub 2}. • Magnetically induced heating was observed when the composites were subjected to RF magnetic field. • Most significantly, the sample 80 wt% ZrO{sub 2} has been found to have SAR that is larger than that of pure MgFe{sub 2}O{sub 4}. • The SAR was found to have a strong dependence on magnetic dipolar interactions.

  20. First-principles calculation on electronic structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Zhi-Fang, E-mail: tongzhifang1998@126.com; Wei, Zhan-Long; Xiao, Cheng

    2017-04-15

    The crystal structure, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} with varying Eu doping concentrations are computed by the density functional theory (DFT) and compared with experimental results. The results show that the lattice parameters of primitive cells of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} become smaller and Eu–N bond length shortens as Eu concentration increases. The band structure of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x} exhibits a direct optical band gap and it's propitious to luminescence. The energy differences from the lowest Eu 5d state to the lowest Eu 4f state decrease with increasing Eu concentrations. The analysis of simulative absorption spectra indicates that the electron transition from Eu 4f states to 5d states of both Eu and Ba atoms contributes to the absorption of Ba{sub 1−x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sub x}. Under the coupling effect between Eu and Ba, Ba in BaSi{sub 2}O{sub 2}N{sub 2} exhibits longer wavelength absorption and increases absorption efficiency. The emission wavelength is deduced by measuring energy differences from the lowest Eu 5d state to the lowest Eu 4f state, and the result is in good agreement with experimental value within experimental Eu{sup 2+} doping range. - Graphical abstract: The structure and optical property of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT and its absorption mechanism is analysed. Results show that absorption peak α is from the host lattice absorption. The absorption peaks β, γ and δ are from Eu 4f to Eu 5d and Ba 6s 5d states. The absorption is attributed to the coupling effect of Eu and Ba atom. - Highlights: • The crystal, electronic structure and optical properties of BaSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} are computed by DFT. • The lattice parameters of primitive cells reduces and Eu–N bond length shortens as Eu{sup 2+} increases. • The energy gap from Eu 5d state to Eu 4f state

  1. Effect of molar ratios of MgO/Al{sub 2}O{sub 3} on the sintering behavior and thermal shock resistance of MgOAl{sub 2}O{sub 3}SiO{sub 2} composite ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Dong, E-mail: 1078155409@qq.com [School of High Temperature Materials and Magnesium Resource Engineering, University of Science and Technology Liaoning, Anshan 114051 (China); Luo, Xudong, E-mail: luoxudongs@aliyun.com [School of High Temperature Materials and Magnesium Resource Engineering, University of Science and Technology Liaoning, Anshan 114051 (China); Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhang, Guodong [School of High Temperature Materials and Magnesium Resource Engineering, University of Science and Technology Liaoning, Anshan 114051 (China); Xie, Zhipeng [Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2017-01-01

    In order to determine the relationship between the property of MgOAl{sub 2}O{sub 3}SiO{sub 2} composite ceramics and molar ratios of MgO/Al{sub 2}O{sub 3}, especially the sintering behavior and thermal shock resistance, the MgOAl{sub 2}O{sub 3}SiO{sub 2} composite ceramics were fabricated with micro-size MgO, Al{sub 2}O{sub 3} powder and nano-size SiO{sub 2} as main raw materials. The sample was characterized by phase analysis, densification and thermal shock times. Moreover, field emission scanning electron microscope was also conducted to study microstructure of the samples before and after thermal shock. Effect of different molar ratios of MgO/Al{sub 2}O{sub 3} on the sintering behavior and thermal shock resistance of composite ceramics were investigated. The results showed that the sample possess better sintering behavior and thermal shock resistance with the molar ratio of MgO/Al{sub 2}O{sub 3} equal to 2/1. Grains of periclase and spinel were directly bonded together, resulting in a dense and compact microstructure, and the bulk density of obtained sample reached 3.4 g/cm{sup 3}. The microstructure of sample after thermal shock revealed that the crack propagation path was deflected and bifurcated, the main-crack propagation was restricted and more fracture energy was consumed, the thermal shock resistance of composite ceramics was greatly improved. - Highlights: • Effect of MgO/Al{sub 2}O{sub 3} on the composite ceramic was firstly researched with 1 mol% SiO{sub 2}. • Microcracks for a short distance by interlinking can eliminate the crack propagation. • The composite ceramic have optimal synthetic property with MgO/Al{sub 2}O{sub 3} was 2/1.

  2. Enhancement of photoluminescence properties and modification of crystal structures of Si{sub 3}N{sub 4} doping Li{sub 2}Sr{sub 0.995}SiO{sub 4}:0.005Eu{sup 2+} phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Song, Kaixin, E-mail: kxsong@hdu.edu.cn [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Zhang, Fangfang [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Chen, Daqin [College of Materials Sciences and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wu, Song; Zheng, Peng [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Huang, Qingming [Instrument Analysis and Testing Center, Fuzhou University, Fuzhou 350002 (China); Jiang, Jun [Ningbo Institute of Materials Technologies and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Xu, Junming; Qin, Huibin [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2015-10-15

    Highlights: • Si{sub 3}N{sub 4} modified Li{sub 2}Sr{sub 0.995}SiO{sub 4}:0.005Eu{sup 2+} phosphors were prepared. • The luminescence intensity of Li{sub 2}Sr{sub 0.995}SiO{sub 4}:Eu{sup 2+} was enhanced by doping Si{sub 3}N{sub 4}. • The fluorescence decay times and thermal stability were enhanced by doping Si{sub 3}N{sub 4}. - Abstract: Si{sub 3}N{sub 4} modified Li{sub 2}Sr{sub 0.995}SiO{sub 4}:0.005Eu{sup 2+} (Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+}) phosphors were synthesized with the conventional solid-state reaction in the reduced atmosphere. The crystal structure and vibrational modes were analyzed by X-ray diffraction, Raman scattering spectroscopy and Rietveld crystal structure refinement. Photoluminescence (PL) and photoluminescence excitation (PLE) spectra showed that Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} powder exhibited a broad yellow emission band centered at 560 nm under the excitation of 460 nm visible light, due to the 4f{sup 6}5d{sup 1} → 4f{sup 7} transition of Eu{sup 2+}. The partial nitridation of Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} (x = 0.01) phosphors led to a large enhancement in the luminescence intensity, as much as 190%. At the same time, the fluorescence decay behavior curves further showed that the photoluminescence efficiencies of Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} phosphors were enhanced by addition of Si{sub 3}N{sub 4}. The temperature quenching characteristics confirmed that the oxynitride based Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} showed slightly higher stability. It is implied that Li{sub 2}Sr{sub 0.995}SiO{sub 4−3x/2}N{sub x}:0.005Eu{sup 2+} phosphors had a possible potential application on white LEDs to match blue light chips.

  3. Fuel densification study about uranium- 7% nanostructured gadolinium (Gd{sub 2}O{sub 3}); Estudo da densificacao do combustivel uranio - 7% gadolinio (Gd{sub 2}O{sub 3}) nanoestruturado

    Energy Technology Data Exchange (ETDEWEB)

    Serafim, Antonio da Costa

    2016-11-01

    The sintering process of UO{sub 2}-Gd{sub 2}O{sub 3} pellets has been investigated in this work for its importance in the nuclear industry and for its complex behavior during sintering. Sintering blockage occurs from 1300 deg C upwards, when densification is shifted toward higher temperatures and the final density obtained is decreased. This research includes the development of nuclear fuel for power reactors in order to increase its efficiency inside the reactor core by raising the burnup. The use of nanosized Gd{sub 2}O{sub 3} was studied in the range from 10 to 30nm, which was added to UO{sub 2}, trying to verify the occurrence of characteristic sintering blockage due to Kirkendall sintering effect observed in previous research. The samples were produced by dry mechanical mixture of UO{sub 2} powder and 7% Gd{sub 2}O{sub 3} (macro- and nanostructured). The powders were compacted and the pellets were sintered at 1700 deg C under H{sub 2} atmosphere. These results indicate that the characteristic blockage during sintering in macrostructured system UO{sub 2}-Gd{sub 2}O{sub 3} occurred in the temperature range of 1300-1500 deg C, which slows down the densification. It was observed a less intense effect when using the nanostructured Gd{sub 2}O{sub 3}; it took place at the temperature of 900 deg C, then facilitating to get an additional densification. The dilatometric tests indicated shrinkage of 22, 18 and 20% respectively in UO{sub 2} pellets, macrostructured UO{sub 2}-7% Gd{sub 2}O{sub 3} and nanostructured UO{sub 2}-7%Gd{sub 2}O{sub 3}. We detected 2% higher shrinkage, when nanostructured Gd{sub 2}O{sub 3} was used instead of macrostructured Gd{sub 2}O{sub 3}, which is used commercially. Then, the nanostructured results showed more adequate density for nuclear fuel usage. (author)

  4. Laser-joined Al{sub 2}O{sub 3} and ZrO{sub 2} ceramics for high-temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Boerner, Floriana-Dana, E-mail: floriana.boerner@tu-dresden.d [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3, D-01062 Dresden (Germany); Lippmann, Wolfgang, E-mail: wolfgang.lippmann@tu-dresden.d [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3, D-01062 Dresden (Germany); Hurtado, Antonio, E-mail: antonio.hurtado@tu-dresden.d [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3, D-01062 Dresden (Germany)

    2010-10-01

    A laser process is presented that has been specially developed for joining oxide ceramics such as zirconium oxide (ZrO{sub 2}) and aluminium oxide (Al{sub 2}O{sub 3}). It details, by way of example, the design of the laser process applied for to producing both Al{sub 2}O{sub 3}-Al{sub 2}O{sub 3} and ZrO{sub 2}-ZrO{sub 2} joints using siliceous glasses as fillers. The heat source used was a continuous wave diode laser with a wavelength range of 808-1010 nm. Glasses of the SiO{sub 2}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-MeO system were developed as high-temperature resistant brazing fillers whose expansion coefficients, in particular, were optimally adapted to those of the ceramics to be joined. Specially designed measuring devices help to determine both the temperature-dependent emission coefficients and the synchronously determined proportions of reflection and transmission. The glass-ceramic joints produced are free from gas inclusions and macroscopic defects and exhibit a homogenous structure. The average strength values achieved were 158 MPa for the Al{sub 2}O{sub 3} system and 190 MPa for the ZrO{sub 2} system, respectively.

  5. A simple method for the determination of residual amount of Hsub(2)Osub(2) a preservative present in the milk

    International Nuclear Information System (INIS)

    Srinivas, B.; Rao, V.R.S.; Kuriacose, J.C.

    1986-01-01

    A new method for the continuous determination of Hsub(2)Osub(2) is described based on the catalytic decomposition of Hsub(2)Osub(2) by LaCoOsub(3). The liberated oxygen is measured by a gas measuring burette. γ-irradiated catalyst enhances the catalytic activity and decreases the time required for complete decomposition. The procedure is suitable for microdetermination of Hsub(2)Osub(2) in various food products. (author)

  6. Synthesis and characterization of In{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ayeshamariam, A. [KhadirMohideen College, Adirampattinam (India); Kashif, M. [Universiti Malaysia Perlis, Perlis (Malaysia); Raja, S. Muthu [Vellore Institute of Technology, Vellore (India); Sivaranjani, S. [SBM College of Engineering and technology, Dindigul (India); Sanjeeviraja, C. [Alagappa University, Karaikudi (India); Bououdina, M. [University of Bahrain, Bahrain (Bahrain)

    2014-01-15

    Metal-oxide nanostructures have elicited increasing interest in both fundamental and applied sciences. Among metal oxide nanostructures, In{sub 2}O{sub 3} has the potential for use asa semiconductor material. This article provides details on studies carried out thus far for the synthesis and the characterization of In{sub 2}O{sub 3} nanostructures. In this research, various techniques were investigated for the fabrication of diverse and fascinating spherical shaped In{sub 2}O{sub 3} nanostructures. BrunauerEmmett-Teller (BET) analyses of the In{sub 2}O{sub 3} nanostructures through detailed refinements of the structure of the In{sub 2}O{sub 3} nanoparticles by using the Rietveld method, followed by microstructural analyses using scanning electron microscopy/ transmission electron microscopy (SEM/TEM) and a chemical composition analysis are presented and discussed. Decreasing crystallinity with an improvement in specific surface area was observed from the structural characterization. The energy dispersive analysis results showed that the as-prepared In{sub 2}O{sub 3} powder sample was stoichiometric, containing almost equal proportions of indium and oxygen. The microstructural analysis (TEM and SEM) demonstrated precise control over the diameters of the nanoparticles, which is an important advantage of the solution combustion approach.

  7. Alternative route for the synthesis of high surface-area η-Al{sub 2}O{sub 3}/Nb{sub 2}O{sub 5} catalyst from aluminum waste

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, Francisco G.E. [Departamento de Engenharia Química, Universidade Federal de São Carlos, CEP 13565-905, São Carlos, SP (Brazil); Asencios, Yvan J.O. [Departamento de Ciências do Mar, Universidade Federal de São Paulo, Av. Alm. Saldanha da Gama, 89, 11030-400, Santos, SP (Brazil); Rodella, Cristiane B. [Laboratório Nacional de Luz Sincrotron, Rua Giuseppe Máximo Scolfaro, 10.000 Polo II de Alta Tecnologia, 13083-970, Campinas, SP (Brazil); Porto, André L.M. [Departamento de Engenharia Química, Universidade Federal de São Carlos, CEP 13565-905, São Carlos, SP (Brazil); Assaf, Elisabete M., E-mail: eassaf@iqsc.usp.br [Instituto de Química de São Carlos, Universidade de São Paulo, Av. Trabalhador São Carlense, 400, 13560-970, São Carlos, SP (Brazil)

    2016-12-01

    This paper describes an alternative route for the production of a high-surface-area η-Al{sub 2}O{sub 3}/Nb{sub 2}O{sub 5} catalyst synthesized from aluminum waste and niobium ammonium oxalate (NH{sub 4}H{sub 2}[NbO−(C{sub 2}O{sub 4}){sub 3}]·3H{sub 2}O). The effects of thermal treatment on the morphology and crystal structure were examined by X-ray powder diffraction (XPD), surface area measurements (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence, dynamic scanning calorimetry (DSC) and thermogravimetry (TG) measurement. The catalysts were evaluated in the glycerol dehydration reaction. Catalytic tests were carried out with reactants in gas-phase with a fixed-bed reactor at 300° and 400 °C. - Highlights: • Alternative route for the production of a high-surface-area Al{sub 2}O{sub 3}/Nb{sub 2}O{sub 5} catalyst. • The catalyst was synthesized from aluminum waste and ammonium oxalato-niobate. • NbAl catalyst obtained showed high specific surface area (330 m{sup 2}/g). • The catalyst produced by this method showed promise in the dehydration of glycerol.

  8. Synthesis, structure, and luminescence properties of In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sunghoon; An, Soyeon; Jin, Changhyun; Lee, Chongmu [Inha University, Incheon (Korea, Republic of)

    2012-09-15

    In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires were synthesized by using a two-step process: thermal evaporation of a mixture of In and Ge powders and atomic layer deposition of SnO{sub 2}. The core-shell nanowires were characterized using by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and photoluminescence spectroscopy. The In{sub 2}Ge{sub 2}O{sub 7} cores in these core-shell nanowires varied from 50 to 100 nanometers in diameter and up to a few hundreds of micrometers in length, and the SnO{sub 2} shell layer thickness ranged from 5 to 15 nm. Photoluminescence measurements showed that the In{sub 2}Ge{sub 2}O{sub 7} nanowires had a weak broad violet emission band centered at approximately 405 nm. In contrast, the In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires had a taller blue-violet emission peak at approximately 440 nm. The optimum shell layer thickness of the In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires for the highest PL intensity was found to be 15 nm. Our results also showed that the intensity of the blue-violet emission was increased further by thermal annealing in an Ar atmosphere. The origins of the change on and the enhancement of the luminescence of the In{sub 2}Ge{sub 2}O{sub 7} nanowires by SnO{sub 2} coating and annealing are discussed.

  9. Interfacial microstructure of Si{sub 3}N{sub 4}/Si{sub 3}N{sub 4} brazing joint with Cu-Zn-Ti filler alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: hitzhangjie@hit.edu.cn; Zhang, X.M.; Zhou, Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Naka, M. [Joining and Welding Research Institute, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Svetlana, Atroshenko [Faculty of Mathematics and Mechanics, Saint-Petersburg State University (Russian Federation)

    2008-11-15

    In this study, Si{sub 3}N{sub 4} ceramic was jointed by a brazing technique with a Cu-Zn-Ti filler alloy. The interfacial microstructure between Si{sub 3}N{sub 4} ceramic and filler alloy in the Si{sub 3}N{sub 4}/Si{sub 3}N{sub 4} joint was observed and analyzed by using electron-probe microanalysis, X-ray diffraction and transmission electron microscopy. The results indicate that there are two reaction layers at the ceramic/filler interface in the joint, which was obtained by brazing at a temperature and holding time of 1223 K and 15 min, respectively. The layer nearby the Si{sub 3}N{sub 4} ceramic is a TiN layer with an average grain size of 100 nm, and the layer nearby the filler alloy is a Ti{sub 5}Si{sub 3}N{sub x} layer with an average grain size of 1-2 {mu}m. Thickness of the TiN and Ti{sub 5}Si{sub 3}N{sub x} layers is about 1 {mu}m and 10 {mu}m, respectively. The formation mechanism of the reaction layers was discussed. A model showing the microstructure from Si{sub 3}N{sub 4} ceramic to filler alloy in the Si{sub 3}N{sub 4}/Si{sub 3}N{sub 4} joint was provided as: Si{sub 3}N{sub 4} ceramic/TiN reaction layer/Ti{sub 5}Si{sub 3}N{sub x} reaction layer/Cu-Zn solution.

  10. Doping of low-T{sub g} phosphate glass with Al{sub 2}O{sub 3}, B{sub 2}O{sub 3} and SiO{sub 2}: Part I- effect on glass property and stability

    Energy Technology Data Exchange (ETDEWEB)

    Rajbhandari, P., E-mail: p.rajbhandari@sheffield.ac.uk [UCCS UMR-CNRS 8181, Universite de Lille1, Villeneuve d' Ascq (France); Montagne, L. [UCCS UMR-CNRS 8181, Universite de Lille1, Villeneuve d' Ascq (France); Tricot, G. [UCCS UMR-CNRS 8181, Universite de Lille1, Villeneuve d' Ascq (France); LASIR UMR-CNRS 8516, Universite de Lille1, Villeneuve d' Ascq (France)

    2016-11-01

    A zinc alkali pyrophosphate system 46.6ZnO-20Na{sub 2}O-33.5P{sub 2}O{sub 5} presenting low-T{sub g} (339 °C) and good thermal stability has been doped with (1–4) mol% of Al{sub 2}O{sub 3}, B{sub 2}O{sub 3} and SiO{sub 2} to improve the stability of the glass with a minimal increase in glass transition temperature (T{sub g}). XRD and 1D {sup 31}P solid state NMR were used to monitor the isothermal crystallization process occurring at 130 °C above T{sub g}. If the Al{sub 2}O{sub 3} and B{sub 2}O{sub 3} doping significantly improved thermal stability, this property was marginally affected by SiO{sub 2} doping. Viscosity measurements were performed to observe the crystallization effects induced by the doping. It is noteworthy that the T{sub g} values of all the doped compositions with improved stability presented in this work are below 400 °C. Raman spectroscopy, 1D {sup 31}P, {sup 27}Al, {sup 11}B and {sup 29}Si solid state NMR were carried out to determine the structural modifications and coordination states of the doping elements all along the composition line. - Highlights: • Low-Tg phosphate glasses doped with Al{sub 2}O{sub 3}, B{sub 2}O{sub 3} and SiO{sub 2} have been formulated. • Thermal stability of the glass has been improved significantly. • The structural modification induced by doping elements has been studied by employing solid state NMR technique.

  11. Preparation, characterization, and antibacterial activity of NiFe{sub 2}O{sub 4}/PAMA/Ag–TiO{sub 2} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Allafchian, Alireza, E-mail: Allafchian@cc.iut.ac.ir [Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan 84156–83111 (Iran, Islamic Republic of); Jalali, Seyed Amir Hossein [Institute of Biotechnology and Bioengineering, Isfahan University of Technology, Isfahan 84156–83111 (Iran, Islamic Republic of); Department of Natural Resources, Isfahan University of Technology, Isfahan 84156–83111 (Iran, Islamic Republic of); Bahramian, Hamid; Ahmadvand, Hossein [Department of physics, Isfahan University of Technology, Isfahan 84156–83111 (Iran, Islamic Republic of)

    2016-04-15

    We have described a facile fabrication of silver deposited on the TiO{sub 2}, Poly Acrylonitrile Co Maleic Anhydride (PAMA) polymer and nickel ferrite composite (NiFe{sub 2}O{sub 4}/PAMA/Ag–TiO{sub 2}) through a three-step procedure. A pre-synthesized NiFe{sub 2}O{sub 4} was first coated with PAMA polymer and then Ag–TiO{sub 2} was deposited on the surface of PAMA polymer shell. After the characterization of this three-component composite by various techniques, such as FTIR, XRD, FESEM, BET, TEM and VSM, it was impregnated in standard antibiotic discs. The antibacterial activity of NiFe{sub 2}O{sub 4}/PAMA/Ag–TiO{sub 2} nanocomposite was investigated against some gram positive and gram negative bacteria by employing disc diffusion assay and then compared with that of naked NiFe{sub 2}O{sub 4}, NiFe{sub 2}O{sub 4}/Ag, AgNPs and NiFe{sub 2}O{sub 4}/PAMA. The results demonstrated that the AgNPs, when embedded in TiO{sub 2} and combined with NiFe{sub 2}O{sub 4}/PAMA, became an excellent antibacterial agent. The NiFe{sub 2}O{sub 4}/PAMA/Ag–TiO{sub 2} nanocomposite could be readily separated from water solution after the disinfection process by applying an external magnetic field. - Highlights: • A novel NiFe{sub 2}O{sub 4}/PAMA/Ag–TiO{sub 2} magnetic nanocomposite has been prepared. • This nanocomposite displays potent antimicrobial activity. • The antibacterial effect was evaluated by the disk diffusion method. • Recyclable antibacterial activity of NiFe{sub 2}O{sub 4}/PAMA/Ag–TiO{sub 2} was studied.

  12. Supercurrents in HgBa{sub 2}CaCu{sub 2}O{sub 6+{delta}} and TlBa{sub 2}CaCu{sub 2}O{sub 7} epitaxial thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gapud, A.A.; Wu, J.Z.; Fang, L.; Yan, S.L.; Xie, Y.Y. [Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045-2151 (United States); Siegal, M.P.; Overmyer, D.L. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    1999-06-01

    The availability of high-quality epitaxial thin films of HgBa{sub 2}CaCu{sub 2}O{sub 6+{delta}} (Hg-1212) and TlBa{sub 2}CaCu{sub 2}O{sub 7} (Tl-1212) with high critical current densities (J{sub c}) has made it possible to examine and compare the J{sub c} of these species. Results reveal that the J{sub c} of 1212 species have very similar temperature behavior at low fields, strongly suggesting that the 30 K shift in critical temperature (T{sub c}) induced by the exchange of Hg and Tl in the 1212 structure is due largely to a change in charge carrier density and/or electronic band structure. {copyright} {ital 1999 American Institute of Physics.}

  13. Electric-field gradients at {sup 181}Ta impurity sites in Ho{sub 2}O{sub 3} and Eu{sub 2}O{sub 3} bixbyites

    Energy Technology Data Exchange (ETDEWEB)

    Errico, Leonardo A. [Departamento de Fisica-IFLP(CONICET), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Renteria, Mario [Departamento de Fisica-IFLP(CONICET), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina)]. E-mail: renteria@fisica.unlp.edu.ar; Bibiloni, Anibal G. [Departamento de Fisica-CONICET, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Freitag, Kristian [Helmholtz-Institut fuer Strahlen-und Kernphysik (H-ISKP) der Universitaet Bonn, Nussallee 14-16, D 53115 Bonn (Germany)

    2007-02-01

    The time-differential {gamma}-{gamma} perturbed-angular-correlation (PAC) technique with ion-implanted {sup 181}Hf tracers has been applied to study the hyperfine interactions of {sup 181}Ta impurities in the cubic bixbyite structure of Ho{sub 2}O{sub 3} and Eu{sub 2}O{sub 3}. The PAC experiments were performed in air in the temperature range 300-1373 K (in the case of Ho{sub 2}O{sub 3}) and 77-1273 K (in the case of Eu{sub 2}O{sub 3}). For both oxides, two electric-quadrupole interactions were found and attributed to the electric-field gradients (EFGs) acting on {sup 181}Ta probes substitutionally located at the two free-of-defects nonequivalent cation sites of the bixbyite structure. In the case of Ho{sub 2}O{sub 3}, two additional interactions were found in the temperature range 300-573 K. These results, as well as previous characterizations of the EFG at {sup 181}Ta sites in bixbyites, were compared to those obtained in experiments using {sup 111}Cd as probe, and to point-charge model calculations. Very recent ab initio predictions for the EFG tensor at impurities sites in binary oxides are also discussed. All these results enable us to discuss the validity of the widely used ionic model to describe the EFG in these highly ionic compounds.

  14. Potential rare-earth modified CeO{sub 2} catalysts for soot oxidation. Part III. Effect of dopant loading and calcination temperature on catalytic activity with O{sub 2} and NO + O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, K.; Bueno-Lopez, A.; Makkee, M.; Moulijn, J.A. [Catalysis Engineering, DelftChemTech, Delft University of Technology, Julianalaan 136, NL 2628 BL Delft (Netherlands)

    2007-09-26

    CeO{sub 2} and CeReO{sub xy} catalysts are prepared by the calcination at different temperatures (y = 500-1000 C) and having a different composition (Re = La{sup 3+} or Pr{sup 3+/4+}{sub ,} 0-90 wt.%). The catalysts are characterised by XRD, H{sub 2}-TPR, Raman, and BET surface area. The soot oxidation is studied with O{sub 2} and NO + O{sub 2} in the tight and loose contact conditions, respectively. CeO{sub 2} sinters between 800-900 C due to a grain growth, leading to an increased crystallite size and a decreased BET surface area. La{sup 3+} or Pr{sup 3+/4+} hinders the grain growth of CeO{sub 2} and, thereby, improving the surface catalytic properties. Using O{sub 2} as an oxidant, an improved soot oxidation is observed over CeLaO{sub xy} and CePrO{sub xy} in the whole dopant weight loading and calcination temperature range studied, compared with CeO{sub 2}. Using NO + O{sub 2}, the soot conversion decreased over CeLaO{sub xy} catalysts calcined below 800 C compared with the soot oxidation over CeO{sub 2y}. CePrO{sub xy}, on the other hand, showed a superior soot oxidation activity in the whole composition and calcination temperature range using NO + O{sub 2}. The improvement in the soot oxidation activity over the various catalysts with O{sub 2} can be explained based on an improvement in the external surface area. The superior soot oxidation activity of CePrO{sub xy} with NO + O{sub 2} is explained by the changes in the redox properties of the catalyst as well as surface area. CePrO{sub xy}, having 50 wt.% of dopant, is found to be the best catalyst due to synergism between cerium and praseodymium compared to pure components. NO into NO{sub 2} oxidation activity, that determines soot oxidation activity, is improved over all CePrO{sub x} catalysts. (author)

  15. Effect of MnCuFe{sub 2}O{sub 4} content on magnetic and dielectric properties of poly (O-Phenylenediamine)/MnCuFe{sub 2}O{sub 4} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Kannapiran, Nagarajan [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Muthusamy, Athianna, E-mail: muthusrkv@gmail.com [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Chitra, Palanisamy [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India)

    2016-03-01

    Poly o-phenylenediamine (PoPD)/MnCuFe{sub 2}O{sub 4} nanocomposites with three different ratios of MnCuFe{sub 2}O{sub 4} (10%, 20%, 30% w/w) were synthesized by in-situ oxidative chemical polymerization method ammonium persulphate used as oxidant, while MnCuFe{sub 2}O{sub 4} nanoparticles was prepared by auto-combustion method. The structure, morphology and magnetic properties of synthesized PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites were characterized by FT-IR, UV–visible absorption spectra, X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA) and Vibrating sample magnetometer (VSM). FTIR spectra and XRD were confirmed the formation of the PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites. The morphology of PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites is visualized through SEM and TEM. The spherical morphology of the PoPD was confirmed using SEM analysis. Dielectric properties of PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites at different temperatures have been performed in the frequency range of 50 Hz–5 MHz. The optical absorption experiments of PoPD/MnCuFe{sub 2}O{sub 4} nanocomposites reveal that the direct transition with an energy band gap is around 2 eV. - Highlights: • Green synthesis of PoPD (the polymerization carried out only in aqueous medium) by in-situ chemical polymerization method. • For the first time, PoPD incorporated with MnCuFe{sub 2}O{sub 4} with lesser particle size. • The auto combustion reaction, support to achieve less particle size. • Ferrite content affects the magnetic properties of the nanocomposites.

  16. Photoluminescence and cathodoluminescence properties of Sr{sub 2}Gd{sub 8}Si{sub 6}O{sub 26}:RE{sup 3+}(RE{sup 3+}=Tb{sup 3+}or Sm{sup 3+}) phosphors

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, Sk. Khaja [Department of Electronics and Radio Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Rao, Gattupalli Manikya [Department of Physics, College of Science and Technology, Andhra University, Visakhapatanam, Andhra Pradesh 53003 (India); Raju, G. Seeta Rama; Krishna Bharat, L. [Department of Electronics and Radio Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Subba Rao, P.S.V., E-mail: raopsvs@rediffmail.com [Department of Physics, College of Science and Technology, Andhra University, Visakhapatanam, Andhra Pradesh 53003 (India); Yu, Jae Su, E-mail: jsyu@khu.ac.kr [Department of Electronics and Radio Engineering, Kyung Hee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

    2016-10-15

    Trivalent terbium (Tb{sup 3+}) or samarium (Sm{sup 3+}) ions individually activated green and orange emitting Sr{sub 2}Gd{sub 8}Si{sub 6}O{sub 26} (SGSO) phosphors were synthesized by a citrate sol–gel method. The X-ray diffraction patterns of SGSO:Tb{sup 3+} and SGSO:Sm{sup 3+} phosphors exhibited the characteristic diffraction peaks of oxyapatite in a hexagonal lattice structure. The photoluminescence (PL) properties at ultraviolet (UV) or near-UV excitation wavelengths were measured for Tb{sup 3+} or Sm{sup 3+} ions doped SGSO phosphors as a function of its respective concentration. The PL spectra of SGSO:Tb{sup 3+} phosphors revealed the characteristic emission peaks of both Gd{sup 3+} and Tb{sup 3+} ions which are associated with 4f–4f transitions under 274 nm of excitation wavelength. When the concentration of Tb{sup 3+} ions increased over 0.05 mol (5 mol%), the emission intensities of {sup 5}D{sub 3} transitions decreased due to the well-known cross-relaxation process. However, based on the intensities of {sup 5}D{sub 4} transitions, the optimum concentration of Tb{sup 3+} ions was found to be 0.05 mol. Under 404 nm of excitation wavelength, the SGSO:Sm{sup 3+} phosphors exhibited the characteristic orange emission at 600 nm due to the {sup 4}G{sub 5/2}→{sup 6}H{sub 7/2} electronic transition. The optimum concentration of SGSO:Sm{sup 3+} phosphors was found to be 0.02 mol. The decay curves of the optimized SGSO:Tb{sup 3+} and SGSO:Sm{sup 3+} phosphors were well fitted to single exponential functions and their lifetimes were calculated. Furthermore, the optimized phosphor samples showed good thermal stability. Likewise, cathodoluminescence properties were also studied for the optimized samples as a function of filament current and accelerating voltage. The Commission International de I-Eclairage chromaticity coordinates were calculated for the SGSO:Tb{sup 3+} and SGSO:Sm{sup 3+} phosphors.

  17. Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}: A new telluro-phosphate with S=1/2 Heisenberg chain

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Mingjun [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Shen, Shipeng; Lu, Jun; Sun, Young [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, R.K., E-mail: rkli@mail.ipc.ac.cn [Beijing Center for Crystal Research and Development, Key Laboratory of Functional Crystals and Laser Technology, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-10-15

    A new telluro-phosphate compound Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} with S=1/2 Heisenberg chain has been successfully synthesized by solid state reaction and grown by flux method. Single crystal X-ray diffraction reveals that Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} crystallizes into a monoclinic space group C2/c and cell parameters of a=17.647(3) Å, b=7.255(2) Å, c=9.191(2) Å and β=100.16 (3)°. In the structure of Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, one dimensional [CuTePO{sub 7}]{sup 3−} chains are formed by tetrahedral PO{sub 4} and trigonal bi-pyramidal TeO{sub 4} joining square planar CuO{sub 4} groups. Those [CuTePO{sub 7}]{sup 3−} chains are inter-connected by sharing one oxygen atom from the TeO{sub 4} group to form two dimensional layers. Magnetic susceptibility and specific heat measurements confirm that the title compound is a model one dimensional Heisenberg antiferromagnetic chain system. - Graphical abstract: Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, containing (CuTePO{sub 7}){sup 3−} chains formed by PO{sub 4} and TeO{sub 4} joining CuO{sub 4} groups, shows typical 1D Heisenberg antiferromagnetic chain model behavior as confirmed by magnetic measurements. - Highlights: • New telluro-phosphate Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} has been grown. • It features layered structure composed of [CuTePO{sub 7}]{sup 3−} chains and TeO{sub 4} groups. • It shows the Heisenberg antiferromagnetic chain behavior. • It is transparent in the range of 1000–2500 nm with a UV absorption edge of 393 nm.

  18. Luminescent properties of phosphor converted LED using an orange-emitting Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hee Jo; Yim, Dong Kyun [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Cho, In-Sun [Department of Mechanical Engineering, Stanford University, CA 94305 (United States); Roh, Hee-Suk; Kim, Ju Seong [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kim, Dong-Wan, E-mail: dwkim@ajou.ac.kr [Department of Materials Science and Engineering, Ajou University, Woncheon-dong, San 5, Yeongtong-gu, Suwon 443-749 (Korea, Republic of); Hong, Kug Sun, E-mail: kshongss@plaza.snu.ac.kr [Department of Materials Science and Engineering, College of Engineering, Seoul National University, Daehak-dong, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Phase-pure Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} powders were synthesized by a solid state reaction process. ► The optimum emission intensity was observed at the Eu{sup 2+} ion concentration of 0.006. ► The dipole–dipole interaction was the major concentration quenching mechanism. ► The pc-LED coated with Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} had higher CRI than commercial red phosphor. -- Abstract: A series of orange-emitting Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphors were synthesized by a conventional solid-state reaction method. The as-prepared phosphors were characterized by X-ray powder diffraction (XRD), fluorescence spectroscopy, and spectroradiometry. XRD showed that all prepared samples exhibited a monoclinic Rb{sub 2}CaP{sub 2}O{sub 7} phase. Fluorescence spectroscopy showed that the photoluminescence efficiency of Rb{sub 2}Ca{sub 1−x}P{sub 2}O{sub 7}:Eu{sub x}{sup 2+} phosphors increased with increasing Eu{sup 2+} concentration until x = 0.006, then decreased at higher concentrations, due to a concentration quenching effect. The thermal activation energy was also measured to be 0.40 eV. Furthermore, a phosphor-converted LED (pc-LED) coated with Rb{sub 2}Ca{sub 0.994}P{sub 2}O{sub 7}:Eu{sub 0.006}{sup 2+} was fabricated, which exhibited bright orange emission under a forward bias, from 200 to 300 mA. The color rendering index (CRI) of pc-LED coated with Rb{sub 2}Ca{sub 0.994}P{sub 2}O{sub 7}:Eu{sub 0.006}{sup 2+} was higher than the CRI of pc-LED coated with commercial red phosphor, due to the broad emission band of Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor. In applying with three-band pc-LEDs, moreover, white pc-LED using Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor had a higher CRI, than using commercial phosphor. These results indicated that Rb{sub 2}CaP{sub 2}O{sub 7}:Eu{sup 2+} phosphor could be a good candidate for a near-UV based w-LED.

  19. Optoelectronic and magnetic properties of Eu{sub 2}Si{sub 5}N{sub 8}. An ab-initio study

    Energy Technology Data Exchange (ETDEWEB)

    Azam, Sikander; Khan, Saleem Ayaz [West Bohemia Univ., Pilsen (Czech Republic). New Technologies Research Center; Khenata, R. [Univ. de Mascara (Algeria). Lab. de Physique Quantique et de Modelisation Mathematique (LPQ3M); Murtaza, G. [Islamia College Univ., Peshawar (Pakistan). Materials Modeling Lab.; Bin Omran, S. [King Saud Univ., Riyadh (Saudi Arabia). Dept. of Physics and Astronomy; Muhammad, Saleh [Hazara Univ., Mansehra (Pakistan). Materials Modeling Lab.

    2015-07-01

    Eu{sub 2}Si{sub 5}N{sub 8} is considered the most important compound in the development of inorganic materials with high potential and performance. Therefore, the electronic, magnetic and optical properties of Eu{sub 2}Si{sub 5}N{sub 8} are investigated here using density functional theory. The electronic interactions are described within the generalised gradient approximation, GGA+U (where U is the Hubbard Coulomb energy term). The calculated energy gap was 3.5 eV for the investigated compound, resulting in a direct band gap semiconductor. The optical constants, including the dielectric function, refractive index, absorption coefficient, reflectivity, and energy loss function were calculated for radiation up to 14 eV. The optical properties demonstrate that the main differences in absorption, reflectivity, energy-loss function and refractive index occur in the infrared and visible regions for the spin-up and spin-down states, which makes this material an excellent candidate for optical memory devices.

  20. Thermal analysis and prediction of phase equilibria in the TiO{sub 2}-Bi{sub 2}O{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Martinez, Jaqueline, E-mail: jacky-411@hotmail.com [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Romero-Serrano, Antonio, E-mail: romeroipn@hotmail.com [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Hernandez-Ramirez, Aurelio, E-mail: aurelioh@hotmail.com [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Zeifert, Beatriz, E-mail: bzeifert@yahoo.com [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Gomez-Yanez, Carlos, E-mail: cgomezy@ipn.mx [Metallurgy and Materials Department, Instituto Politecnico Nacional-ESIQIE, Apdo. P. 118-431, 07051 Mexico D.F (Mexico); Martinez-Sanchez, Roberto, E-mail: roberto.martinez@cimav.edu.mx [CIMAV, Av. Miguel de Cervantes 120, Chihuahua C.P.31109 (Mexico)

    2011-03-20

    A thermodynamic study on the TiO{sub 2}-Bi{sub 2}O{sub 3} system was carried out using differential thermal analysis (DTA) and X-Ray diffraction (XRD) techniques covering the composition range from 65 to 90 mol% Bi{sub 2}O{sub 3}. From the XRD results the only two intermediate compounds in the Bi{sub 2}O{sub 3} rich region were Bi{sub 4}Ti{sub 3}O{sub 12} and Bi{sub 12}TiO{sub 20}. The Bi{sub 4}Ti{sub 3}O{sub 12} phase presents the well known plate-like morphology. The experimentally determined phase transition temperatures with DTA technique were compared with thermodynamic calculated results and good agreement was obtained. The DTA results also showed that the limit of the peritectic reaction between liquid and Bi{sub 4}Ti{sub 3}O{sub 12} occurs approximately at 90 mol% Bi{sub 2}O{sub 3}. The phase diagram of the TiO{sub 2}-Bi{sub 2}O{sub 3} system was calculated using a quasichemical model for the liquid phase. The thermodynamic properties of the intermediate compounds were estimated from the data of TiO{sub 2} and Bi{sub 2}O{sub 3} pure solids. In this manner, data for this binary system have been analysed and represented with a small adjustable parameter for the liquid phase.

  1. Growth of Gd{sub 2}O{sub 3} coherent layers on UO{sub 2} microsphere surface via sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Luciana S.; Silva, Edilaine F.; Oliveira, Felipe W.F.; Pereira, Yara S.; Brandão, Alisson F.C.; Santos, Ana Maria M.; Lameiras, Fernando S.; Reis, Sergio C.; Pedrosa, Tércio A.; Santos, Armindo, E-mail: santosa@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2017-07-01

    In this work, we synthesized and characterized UO{sub 2}-Gd{sub 2}O{sub 3} nuclear fuel via three routes, aiming to solve the problems arising from the addition of Gd{sub 2}O{sub 3} in UO{sub 2} matrix. By the industrial route, the mixture of powders (UO{sub 2}, <90 μ and 6 wt% Gd{sub 2}O{sub 3} <10 μm) results in pellets with 91% TD at 1677 °C/H{sub 2}/4 h. By the mixed route, the formation of Gd{sub 2}O{sub 3} coherent layers on UO{sub 2} powder (particles <90 μ) and microsphere (225 μm) surface produced UO{sub 2} - 6 wt% Gd{sub 2}O{sub 3} pellets with 95% (powder; 1625 °C/H{sub 2}/4 hr) and 83% (microsphere; 1677°C/H{sub 2}/4 hr) TD. By the sol-gel route, we obtained UO{sub 2} - 6 wt% Gd{sub 2}O{sub 3} in a deagglomerated (powder; <70 μm) or agglomerated microsphere 232 μm) form whose pellets reached > 97% (powder) and >98% (microsphere) TI) at 1677 °C/H{sub 2}/4h. According to XRD, OM, and SEM/EDS analysis, the referred three routes do not form a complete solid solution of UO{sub 2}-Gd{sub 2}O{sub 3} at the temperatures and time of sintering used; Gd{sub 2}O{sub 3} granule islands are present in the pellets originating from these routes. The obtained results suggest that the topological arrangement and the deficient nanostructuring of UO{sub 2} and Gd{sub 2}O{sub 3} phases, either in the raw material (powder and microsphere) as in their compacts, are the cause of low densification and irregular distribution of Gd{sub 2}O{sub 3} in UO{sub 2} matrix; mixing of U and Gd at the molecular level does not form a solid solution; and the mixed route is a good alternative to the industrial route. (author)

  2. The behavior of ZrO{sub 2}/20%Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3} coatings deposited on aluminum alloys at high temperature regime

    Energy Technology Data Exchange (ETDEWEB)

    Pintilei, G.L., E-mail: laura_rares082008@yahoo.com [Pitesti University, Faculty of Mechanics and Technology, Str. Targu din Vale nr.1, 110040 Pitesti, Arges (Romania); Technical University “Gheorghe Asachi” of Iasi, Faculty of Mechanics, Bld D. Mangeron nr. 61, 700050 Iasi (Romania); Crismaru, V.I. [Technical University “Gheorghe Asachi” of Iasi, Faculty of Mechanics, Bld D. Mangeron nr. 61, 700050 Iasi (Romania); Abrudeanu, M. [Pitesti University, Faculty of Mechanics and Technology, Str. Targu din Vale nr.1, 110040 Pitesti, Arges (Romania); Munteanu, C. [Technical University “Gheorghe Asachi” of Iasi, Faculty of Mechanics, Bld D. Mangeron nr. 61, 700050 Iasi (Romania); Baciu, E.R. [University of Medicine and Pharmacy “Gr.T.Popa”, Department Implantology, Removable Restorations, Technology, Str. Universitatii nr. 16, 700115 Iasi (Romania); Istrate, B.; Basescu, N. [Technical University “Gheorghe Asachi” of Iasi, Faculty of Mechanics, Bld D. Mangeron nr. 61, 700050 Iasi (Romania)

    2015-10-15

    Highlights: • In both the ZrO{sub 2}/20%Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3} coatings the high temperature caused a decrease of pores volume and a lower thickness of the interface between successive splats. • The NiCr bond layer in the sample with a ZrO{sub 2}/20%Y{sub 2}O{sub 3} suffered a fragmentation due to high temperature exposure and thermal expansion which can lead to coating exfoliation. • The NiCr bond layer in the sample with an Al{sub 2}O{sub 3} coating showed an increase of pore volume due to high temperature. - Abstract: Aluminum alloy present numerous advantages like lightness, high specific strength and diversity which recommend them to a high number of applications from different fields. In extreme environments the protection of aluminum alloys is difficult and requires a high number of requirements like high temperature resistance, thermal fatigue resistance, corrosion fatigue resistance and galvanic corrosion resistance. To obtain these characteristics coatings can be applied to the surfaces so they can enhance the mechanical and chemical properties of the parts. In this paper two coatings were considered for deposition on an AA2024 aluminum alloy, ZrO{sub 2}/20%Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3}. To obtain a better adherence of the coating to the base material an additional bond layer of NiCr is used. Both the coatings and bond layer were deposited by atmospheric plasma spraying on the samples. The samples were subjected to a temperature of 500 °C and after that slowly cooled to room temperature. The samples were analyzed by electron microscopy and X-ray diffraction to determine the morphological and phase changes that occurred during the temperature exposure. To determine the stress level in the parts due to thermal expansion a finite element analysis was performed in the same conditions as the tests.

  3. Facile hydrothermal synthesis of polyhedral Fe{sub 3}O{sub 4} nanocrystals, influencing factors and application in the electrochemical detection of H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Kefeng [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China); Ni Yonghong, E-mail: niyh@mail.ahnu.edu.cn [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China); Zhang Li [College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000 (China)

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Fe{sub 3}O{sub 4} polyhedra had been successfully synthesized by a facile hydrothermal technology. Black-Right-Pointing-Pointer The as-obtained product exhibited the room-temperature ferrimagnetic property. Black-Right-Pointing-Pointer The final product could be prepared into an electrochemical sensor for the detection of H{sub 2}O{sub 2}. - Abstract: Polyhedral Fe{sub 3}O{sub 4} nanocrystals have been successfully synthesized by a facile hydrothermal technique, employing FeSO{sub 4}{center_dot}7H{sub 2}O, N{sub 2}H{sub 4} and NH{sub 3}{center_dot}H{sub 2}O as the reactants without the assistance of any surfactant. The phase of the as-obtained Fe{sub 3}O{sub 4} was characterized by X-ray powder diffraction (XRD) and further proved by Rietveld refinement of XRD data. Energy dispersive spectrometry (EDS) and scanning electron microscopy (SEM) were used for the composition and morphology analyses of the final product. Some factors influencing the formation of polyhedral Fe{sub 3}O{sub 4} nanocrystals were systematically investigated, including the reaction temperature and time, and the original volume ratio of NH{sub 3}{center_dot}H{sub 2}O/N{sub 2}H{sub 4}{center_dot}H{sub 2}O. It was found that the as-prepared Fe{sub 3}O{sub 4} polyhedra exhibited a good electrochemical property in 0.1 M phosphate buffer solution (PBS) with pH 7.0 and could be prepared into an electrochemical sensor for the detection of H{sub 2}O{sub 2}. The linear response range of the sensor was 10.0 Multiplication-Sign 10{sup -6} to 140.0 Multiplication-Sign 10{sup -6} M and a sensitivity was 11.05 {mu}A/mM. Furthermore, the room-temperature magnetic property of the product was also investigated.

  4. Phase separation, crystallization and polyamorphism in the Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3} system

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Lawrie B; Barnes, Adrian C [H H Wills Physics Laboratory, Royal Fort, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Salmon, Philip S [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom); Crichton, Wilson A [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, Grenoble Cedex, F-38043 (France)], E-mail: a.c.barnes@bristol.ac.uk

    2008-05-21

    A detailed study of glass formation from aerodynamically levitated liquids in the (Y{sub 2}O{sub 3}){sub x}(Al{sub 2}O{sub 3}){sub 1-x} system for the composition range 0.21{<=}x{<=}0.41 was undertaken by using pyrometric, optical imaging and x-ray diffraction methods. Homogeneous and clear single-phase glasses were produced over the composition range 0.27{<=}x{<=}0.33. For Y{sub 2}O{sub 3}-rich compositions (0.33{<=}x{<=}0.375), cloudy materials were produced which contain inclusions of crystalline yttrium aluminium garnet (YAG) of diameter up to 40 {mu}m in a glassy matrix. For Y{sub 2}O{sub 3}-poor compositions around x = 0.24, cloudy materials were also produced, but it was not possible to deduce whether this resulted from (i) sub-micron inclusions of a nano-crystalline or glassy material in a glassy matrix or (ii) a glass formed by spinodal decomposition. For x = 0.21, however, the sample cloudiness results from crystallization into at least two phases comprising yttrium aluminium perovskite and alumina. The associated pyrometric cooling curve shows slow recalescence events with a continuous and slow evolution of excess heat which contrasts with the sharp recalescence events observed for the crystallization of YAG at compositions near x = 0.375. The materials that are the most likely candidates for demonstrating homogeneous nucleation of a second liquid phase occur around x = 0.25, which corresponds to the limit for formation of a continuous random network of corner-shared AlO{sub 4} tetrahedra.

  5. Electronic properties of metal-In{sub 2}O{sub 3} interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Nazarzadehmoafi, Maryam

    2017-02-22

    The behavior of the electronic properties of as-cleaved melt-grown In{sub 2}O{sub 3} (111) single crystals was studied upon noble metals, In and Sn deposition using angle-resolved photoemission spectroscopy. The stoichiometry, structural quality and crystal orientation, surface morphology, and the electron concentration were examined by energy dispersive X-ray spectroscopy, Laue diffraction, scanning tunneling microscopy (STM), and Hall-effect measurement, respectively. The similarity of the measured-fundamental and surface-band gaps reveals the nearly flat behavior of the bands at the as-cleaved surface of the crystals. Ag and Au/In{sub 2}O{sub 3} interfaces show Schottky behavior, while an ohmic one was observed in Cu, In, and Sn/In{sub 2}O{sub 3} contacts. From agreement of the bulk and surface band gaps, rectifying contact formation as well as the occurrence of photovoltage effect at the pristine surface of the crystals, it can be deduced that SEAL is not an intrinsic property of the as-cleaved surface of the studied crystals. Moreover, for thick Au and Cu overlayer regime at room temperature, Shockley-like surface states were observed. Additionally, the initial stage of Cu and In growth on In{sub 2}O{sub 3} was accompanied by the formation of a two dimensional electron gas (2DEG) fading away for higher coverages which are not associated with the earlier-detected 2DEG at the surface of In{sub 2}O{sub 3} thin films. The application of the Schottky-Mott rule, using in situ-measured work functions of In{sub 2}O{sub 3} and the metals, showed a strong disagreement for all the interfaces except for Ag/In{sub 2}O{sub 3}. The experimental data also disagree with more advanced theories based on the electronegativity concept and metal-induced gap states models.

  6. Synthesis, crystal structure, and vibrational spectroscopic and UV-visible studies of Cs{sub 2}MnP{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Kaoua, Saida; Krimi, Saida [LPCMI, Faculte des Sciences Aien Chok, UH2C, Casablanca (Morocco); Pechev, Stanislav; Gravereau, Pierre; Chaminade, Jean-Pierre [CNRS, Universite de Bordeaux, ICMCB, 87, Avenue du Dr. A. Schweitzer, Pessac (France); Couzi, Michel [CNRS, Universite de Bordeaux, ISM, UMR 5255, F-33400 Talence (France); El Jazouli, Abdelaziz, E-mail: eljazouli_abdelaziz@yahoo.fr [LCMS, URAC 17, Faculte des Sciences Ben M' Sik, UH2MC, Casablanca (Morocco)

    2013-02-15

    A new member of the A{sub 2}MP{sub 2}O{sub 7} diphosphate family, Cs{sub 2}MnP{sub 2}O{sub 7}, has been synthesized and structurally characterized. The crystal structure was determined by single crystal X-Ray diffraction. Cs{sub 2}MnP{sub 2}O{sub 7} crystallizes in the orthorhombic system, space group Pnma ( Music-Sharp-Sign 62), with the unit cell parameters a=16.3398(3), b=5.3872(1), c=9.8872(2) A, Z=4 and V=870.33(3) A{sup 3}. The structure parameters were refined to a final R{sub 1}/wR{sub 2}=0.0194/0.0441 for 1650 observed reflections. The 2D framework of Cs{sub 2}MnP{sub 2}O{sub 7} structure consists of P{sub 2}O{sub 7} and MnO{sub 5} units. The corner-shared MnO{sub 5} and P{sub 2}O{sub 7} units are alternately arranged along the b axis to form [(MnO)P{sub 2}O{sub 7}]{sub {infinity}} chains. These chains are interconnected by an oxygen atom to form sheets parallel to the (b, c) plane. The cesium atoms are located between the sheets in 9- and 10-fold coordinated sites. The infrared and Raman vibrational spectra have been investigated. A factor group analysis leads to the determination of internal modes of (P{sub 2}O{sub 7}) groups. UV-visible spectrum consists of weak bands, between 340 and 700 nm, assigned to the forbidden d-d transitions of Mn{sup 2+} ion, and of a strong band around 250 nm, attributed to the O--Mn charge transfer. - Graphical abstract: Structure of Cs{sub 2}MnP{sub 2}O{sub 7}: The 2D structure of Cs{sub 2}MnP{sub 2}O{sub 7} is built from P{sub 2}O{sub 7} diphosphate groups and MnO{sub 5} square pyramids which share corners and form [(MnO)P{sub 2}O{sub 7}]{sub {infinity}} chains along b axis. These chains are interconnected by an oxygen atom to form wavy (MnP{sub 2}O{sub 7}){sup 2-} sheets parallel to the (b, c) plane. The cesium ions are located between these sheets in the inter-layers space, in zigzag positions. Highlights: Black-Right-Pointing-Pointer A new diphosphate, Cs{sub 2}MnP{sub 2}O{sub 7}, has been synthesized and structurally

  7. Chemical interaction between Ba{sub 2}YCu{sub 3}O{sub 6+x} and CeO{sub 2} at pO{sub 2}=100 Pa

    Energy Technology Data Exchange (ETDEWEB)

    Wong-Ng, W.; Yang, Z.; Cook, L.P.; Huang, Q.; Frank, J. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, MD (United States); Kaduk, J.A. [BP-Amoco Research, Naperville, IL (United States)

    2005-07-01

    Chemical interaction between the Ba{sub 2}YCu{sub 3}O{sub 6+x} superconductor and the CeO{sub 2} buffer layers employed in coated conductor architectures has been modeled experimentally by investigating phase equilibria on the Ba{sub 2}YCu{sub 3}O{sub 6+x}-CeO{sub 2} join at pO{sub 2}=100 Pa. This join is actually a non-binary join within the BaOY{sub 2}O{sub 3}CeO{sub 2}CuO{sub x} quaternary system. At an approximate mole ratio of Ba{sub 2}YCu{sub 3}O{sub 6+x}:CeO{sub 2} = 40:60, a phase boundary was found to separate two four-phase regions. At the Ba{sub 2}YCu{sub 3}O{sub 6+x}-rich side of the join, the four-phase region consists of Ba{sub 2}YCu{sub 3}O{sub 6+x}, Ba(Ce{sub 1-z}Y{sub z})O{sub 3-x}, BaY{sub 2}CuO{sub 5}, and Cu{sub 2}O; at the CeO{sub 2} rich side, the four phases were determined to be Ba(Ce{sub 1-z}Y{sub z})O{sub 3-x}, BaY{sub 2}CuO{sub 5}, Cu{sub 2}O and CeO{sub 2}. At 810 C and pO{sub 2}=100 Pa, there appears to be negligible solid solution formation of the types Y{sub 1-z}Ce{sub z}O{sub 3-x} and Ce{sub 1-z}Y{sub z}O{sub 2-x}. The minimum melting temperature along the Ba{sub 2}YCu{sub 3}O{sub 6+x}-CeO{sub 2} join was determined to be {approx} 860 C. As part of this study, phase diagrams of the subsystems CeO{sub 2}-Y{sub 2}O{sub 3}-CuO{sub x}, BaO-CeO{sub 2}-CuO{sub x}, and BaO-Y{sub 2}O{sub 3}-CeO{sub 2} were also determined at 810 C under 100 Pa pO{sub 2}. The Y{sub 2}O{sub 3}-CeO{sub 2}-CuO{sub x} diagram does not contain ternary phases and shows a tie-line from Y{sub 2}O{sub 3} to the binary phase Y{sub 2}Cu{sub 2}O{sub 5-x}. Similarly, the BaO-CeO{sub 2}-CuO{sub x} diagram contains no ternary phases, but has four tie-lines originating from BaCeO{sub 3} to Ba{sub 2}CuO{sub 3+x}, BaCuO{sub 2+x}, BaCu{sub 2}O{sub 2+x} and CuO{sub x}. The BaO-Y{sub 2}O{sub 3}-CeO{sub 2} system contains one ternary phase, the solid solution Ba(Ce{sub 1-z}Y{sub z})O{sub 3-x} (0{<=}z{<=}0.13), which crystallizes with the orthorhombic space group Pmcn (No. 62

  8. Al{sub 2} O{sub 3}:Cr,Ni: a possible thermoluminescent dosemeter; Al{sub 2} O{sub 3}: Cr, Ni un posible dosimetro termoluminiscente

    Energy Technology Data Exchange (ETDEWEB)

    Mariani R, Francisco; Roman B, Alvaro; Saavedra S, Renato [Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Ibarra S, Angel [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain). Seccion Materiales para Fusion

    1997-12-31

    Results from a study on the thermoluminescent (Tl) emission from Al{sub 2} O{sub 3}:Cr,Ni are presented. The measurements were obtained for evaluation of the Al{sub 2} O{sub 3}:Cr,Ni dosimetric properties. Different crystal batches were exposed to two kind of ionizing radiation (X-ray and {beta}{sup -}). The Tl spectrum has a main peak with high thermal and optical stability, deviating from linearity for doses lower than 3.6 Gy. Furthermore, this material shows advantages (thermal resistance, reusability, multiple heating cycles) compared to TLD-100. Measured Al{sub 2} O{sub 3}:Cr,Ni properties indicate that it could be used as a dosemeter. (author). 5 refs., 4 figs.

  9. New insight into electrochemical-induced synthesis of NiAl{sub 2}O{sub 4}/Al{sub 2}O{sub 3}: Synergistic effect of surface hydroxyl groups and magnetism for enhanced adsorptivity of Pd(II)

    Energy Technology Data Exchange (ETDEWEB)

    Salleh, N.F.M. [Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Jalil, A.A., E-mail: aishah@cheme.utm.my [Department of Chemical Engineering, Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Centre of Hydrogen Energy, Institute of Future Energy, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Triwahyono, S. [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia); Efendi, J. [Department of Chemistry, Universitas Negeri Padang, Jl. Prof. Hamka, Air Tawar, Padang, West Sumatera (Indonesia); Mukti, R.R. [Division of Inorganic and Physical Chemistry, Faculty of Mathematics and Natural Science, Institut Teknologi Bandung, Jl Ganesha No 10, Bandung 40132 (Indonesia); Hameed, B.H. [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2015-09-15

    Graphical abstract: - Highlights: • The introduction of Ni to γ-Al{sub 2}O{sub 3} by electrolysis formed NiAl{sub 2}O{sub 4} spinels and NiO. • Physical mixed of NiO with γ-Al{sub 2}O{sub 3} only produced agglomerated NiO-Ni{sup 0}. • Ni/Al{sub 2}O{sub 3}-E has remarkably higher degree of magnetism than Ni/Al{sub 2}O{sub 3}-PM. • Ni/Al{sub 2}O{sub 3}-E adsorbed Pd{sup 2+} ions more effectively (q{sub m} = 40.3 mg/g) than Ni/Al{sub 2}O{sub 3}-PM. • Pd{sup 2+} ions were adsorbed to both samples via magnetic attraction and ion exchange. - Abstract: A new promising adsorbent, Ni supported on γ-Al{sub 2}O{sub 3} was prepared in a simple electrolysis system (Ni/Al{sub 2}O{sub 3}-E) in minutes and was compared with the sample prepared by a physical mixing method (Ni/Al{sub 2}O{sub 3}-PM). The adsorbents were characterized by XRD, TEM, FTIR, {sup 27}Al MAS NMR, XPS, and VSM. The results showed that besides NiO nanoparticles, a NiAl{sub 2}O{sub 4} spinel was also formed in Ni/Al{sub 2}O{sub 3}-E during the electrolysis via the dealumination and isomorphous substitution of Ni{sup 2+} ions. In contrast, only agglomerated NiO was found in the Ni/Al{sub 2}O{sub 3}-PM. Adsorption test on removal of Pd{sup 2+} ions from aqueous solution showed that the Pd{sup 2+} ions were exchanged with the hydrogen atoms of the surface–OH groups of both adsorbents. Significantly, the Ni/Al{sub 2}O{sub 3}-E demonstrated a higher adsorption towards Pd{sup 2+} ions than Ni/Al{sub 2}O{sub 3}-PM due to its remarkably higher degree of magnetism, which came from the NiAl{sub 2}O{sub 4}. The use of 0.1 g L{sup −1} Ni/Al{sub 2}O{sub 3}-E gave the maximum monolayer adsorption capacity (q{sub m}) of 40.3 mg g{sup −1} at 303 K and pH 5. The Ni/Al{sub 2}O{sub 3}-E showed high potential for simultaneous removal of various noble and transition metal ions and could be also used repetitively without affecting the high adsorptivity for Pd{sup 2+} ions. This work may provide promising

  10. Method for generating O.sub.2-rich gas from air using water

    Science.gov (United States)

    Nakano, Anna; Nakano, Jinichiro; Bennett, James P.

    2018-01-30

    The present disclosure is directed to a method for enriching an inlet air stream utilizing a number of enrichment sub-units connected in series, where each enrichment sub-unit conducts both a dissolution and degasification cycle. Each enrichment sub-unit comprises a compressor, an aeration unit, a deaeration unit, and a pump for the recirculation of water between the aeration and deaeration units. The methodology provides a manner in which the relationship between the respective Henry's coefficients of the oxygen and nitrogen in water may be exploited to enrich the O.sub.2 volume percent and diminish the N.sub.2 volume percent over repeated dissolution and degasification cycles. By utilizing a number of enrichment sub-units connected in series, the water contained in each enrichment sub-unit acts to progressively increase the O.sub.2 volume percent. Additional enrichment sub-units may be added and utilized until the O.sub.2 volume percent equals or exceeds a target O.sub.2 volume percent. In a particular embodiment, air having a general composition of about 78 vol. % N.sub.2 and 21 vol. % O.sub.2 is progressively enriched to provide a final mixture of about 92% vol. % O.sub.2 and 8% vol. % N.sub.2.

  11. Method for generating O.sub.2-rich gas from air using water

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Anna; Nakano, Jinichiro; Bennett, James P.

    2018-01-30

    The present disclosure is directed to a method for enriching an inlet air stream utilizing a number of enrichment sub-units connected in series, where each enrichment sub-unit conducts both a dissolution and degasification cycle. Each enrichment sub-unit comprises a compressor, an aeration unit, a deaeration unit, and a pump for the recirculation of water between the aeration and deaeration units. The methodology provides a manner in which the relationship between the respective Henry's coefficients of the oxygen and nitrogen in water may be exploited to enrich the O.sub.2 volume percent and diminish the N.sub.2 volume percent over repeated dissolution and degasification cycles. By utilizing a number of enrichment sub-units connected in series, the water contained in each enrichment sub-unit acts to progressively increase the O.sub.2 volume percent. Additional enrichment sub-units may be added and utilized until the O.sub.2 volume percent equals or exceeds a target O.sub.2 volume percent. In a particular embodiment, air having a general composition of about 78 vol. % N.sub.2 and 21 vol. % O.sub.2 is progressively enriched to provide a final mixture of about 92% vol. % O.sub.2 and 8% vol. % N.sub.2.

  12. Synthesis of SrBi{sub 2}Ta{sub 2}O{sub 9} by combustion synthesis; Obtencao do SrBi{sub 2}Ta{sub 2}O{sub 9} utilizando a sintese por combustao

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, F.F.; Bergmann, C.P. [Universidade Federal do Rio Grande do Sul (LACER/UFRGS), Porto Alegre, RS (Brazil). Dept. de Materiais. Lab. de Materiais Ceramicos; Sousa, V.C. [Universidade Federal do Rio Grande do Sul (LABIOMAT/UFRGS), Porto Alegre, RS (Brazil). Dept. de Materiais. Lab. de Materiais de Biomateriais

    2009-07-01

    The combustion synthesis is a low cost technique for obtaining homogeneous nanostructured compounds with high purity. The ferroelectric memory devices have been widely studied by the electronics industry by presenting high-speed recording, read and rewrite. The PZT, in the form of thin films, is the ceramic materials most used for this purpose, but it presents ferroelectric fatigue. The SrBi{sub 2}Ta{sub 2}O{sub 9} has a high cycle enables the recording which is good applicability in the PZT. Therefore, this work aims to obtain the SrBi{sub 2}Ta{sub 2}O{sub 9} using the combustion synthesis and urea as a reducing agent. The characterization of the powder was realized used the technique of x-ray diffraction (XRD) to determine the phases present and to evaluate surface area by the BET method. The powder obtained after synthesis showed low crystallinity presenting just the BiOCl like the crystalline phase present, but heat treatment at 800 deg C for 2 hours was sufficient for the formation of SrBi{sub 2}Ta{sub 2}O{sub 9} . (author)

  13. Piezoelectrically-induced stress-luminescence phenomenon in CaAl{sub 2}O{sub 4}:Eu{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Yongbin [Department of Physics, Zhejiang Normal University, Jinhua 321004 (China); Wu, Zheng, E-mail: wuzheng@zjnu.cn [College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004 (China); Jia, Yanmin, E-mail: ymjia@zjnu.edu.cn [Department of Physics, Zhejiang Normal University, Jinhua 321004 (China); Liu, Yongsheng [Department of Physics, Shanghai University of Electric Power, Shanghai 200090 (China)

    2015-10-15

    Piezoelectrically-induced stress-luminescence in the CaAl{sub 2}O{sub 4}:Eu{sup 2+} was investigated. Blue light that was visible to the naked eye could be observed in the dark when a pulse force of ∼7.7 kN was applied to the sample. The intensity of the stress-luminescence strongly depended on the magnitude of the applied force during a pulse cycle. The intensity decreased with repetitive application of pulse stress and was completely recovered after irradiation with ultraviolet light. It is suggested that the stress-luminescence effect in CaAl{sub 2}O{sub 4}:Eu{sup 2+} arises from the piezoelectrically-induced de-trapping of the charge carriers. A CaAl{sub 2}O{sub 4}:Eu{sup 2+} ceramic that exhibits a stress-luminescence effect has potential applications in smart stress optically-sensing devices. - Highlights: • The strong induced stress-luminescence in CaAl{sub 2}O{sub 4}:Eu{sup 2+} was observed. • The stress-luminescent intensity strongly depends on the magnitude of force. • The stress-luminescence could be completely recovered after the UV irradiation. • The strong stress-luminescent effect is potential in stress-light sensors.

  14. Processing and characterisation of novel metal-reinforced Al{sub 2}O{sub 3}-composites; Herstellung und Charakterisierung neuartiger metallverstaerkter Al{sub 2}O{sub 3}-Verbundwerkstoffe

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, R. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Werkstofforschung

    1999-07-01

    Using a new processing route, Al{sub 2}O{sub 3}-based ceramic composites have been prepared, that consist of 3-d networks of the ceramic and different metallic phases. The damage tolerance of these composites could be significantly improved over monolithic Al{sub 2}O{sub 3}: fracture strength and fracture toughness were increased by a factor of 4 up to 1393 MPa and 11.8 MPa {radical}(m), respectively. Similarly, resistance against abrasive wear was successfully improved by a factor of two over monolithic Al{sub 2}O{sub 3}. In combination with the good electrical and thermal conductivity, these superior mechanical properties are of great interest for automotive and biomedical industries. (orig.) [German] Mit einem neu entwickelten Verfahren werden keramische Al{sub 2}O{sub 3}-Verbundwerkstoffe hergestellt, die sich durch eine dreidimensionale Vernetzung der (inter)metallischen und der keramischen Phase auszeichnen. Die Schadenstoleranz derartiger Verbundwerkstoffe konnte im Vergleich zu monolithischer Al{sub 2}O{sub 3}-Keramik deutlich gesteigert werden: Die Bruchfestigkeit und die Bruchzaehigkeit wurden jeweils um einen Faktor 4 auf 1393 MPa bzw. 11,8 MPa {radical}(m) erhoeht, die Abriebfestigkeit um einen Faktor 2 verbessert. In Kombination mit der elektrischen und thermischen Leitfaehigkeit sind diese aussergewoehnlichen mechanischen Eigenschaften in Automobilbau und in der Medizintechnik von grossem Interesse. (orig.)

  15. Preparation and structural properties of nonlinear optical borates K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7}, 0 < x < 0.75

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Bazarov, B.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation); Gavrilova, T.A. [Laboratory of Nanodiagnostics and Nanolithography, Institute of Semiconductor Physics, SB RAS, Novosibirsk 630090 (Russian Federation); Grossman, V.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation); Molokeev, M.S. [Laboratory of Crystal Physics, Institute of Physics, SB RAS, Krasnoyarsk 660036 (Russian Federation); Bazarova, Zh.G. [Laboratory of Oxide Systems, Baikal Institute of Nature Management, SB RAS, Ulan-Ude 47, 670047 (Russian Federation)

    2012-02-25

    Highlights: Black-Right-Pointing-Pointer Solid solutions K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7} are synthesized over wide composition range up to x {approx} 0.83. Black-Right-Pointing-Pointer Crystal structure of K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7} solutions is determined in space group P321. Black-Right-Pointing-Pointer Second harmonic generation is observed in KRbAl{sub 2}B{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Drastic variation of cell parameters is found over KABO-type crystal family. - Abstract: The structures of K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7}, x = 0.25, 0.5, 0.75, have been determined in space group P321 through Rietveld analysis of X-ray powder diffraction data. The solubility limit in K{sub 2(1-x)}Rb{sub 2x}Al{sub 2}B{sub 2}O{sub 7} crystals has been estimated as x {approx} 0.83-0.9. Nonlinear optical properties of KRbAl{sub 2}B{sub 2}O{sub 7} have been verified by powder Kurtz-Perry method. Mechanisms of structural parameter variation in K{sub 2}Al{sub 2}B{sub 2}O{sub 7} crystal family have been discussed.

  16. Spectroscopic and dielectric properties of titanium doped MgO-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3} glass system

    Energy Technology Data Exchange (ETDEWEB)

    Raju, G Naga; Ramesh, N Ch; Naresh, P; Krishna, T L; Srinivasulu, K; Sudhkar, K S V; Rao, P Venkateswara, E-mail: gnag_9@rediffmail.com [Department of Physics, Acharya Nagarjuna University-Nuzvid Campus, Nuzvid - 521 201 (India)

    2009-07-15

    In this paper we have reported the influence of titanium ions on different spectroscopic and dielectric properties of MgO-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses. The analysis of result of all these studies has indicated that as the concentration of TiO{sub 2} increased in the glass matrix, there is a gradual transformation of titanium ions from octahedral position to tetrahedral positions and cause to increase the rigidity of glass network.

  17. Structural, dielectric and magnetic properties of SnO{sub 2}-CuFe{sub 2}O{sub 4} nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Kashif [Department of Physics, International Islamic University, Islamabad (Pakistan); Iqbal, Javed, E-mail: javed.saggu@qau.edu.pk [Laboratory of Nanoscience and Technology (LNT), Department of Physics, Qaid-i-Azam University, Islamabad (Pakistan); Jan, Tariq [Department of Physics, University of Lahore, Sargodha Campus, Sargodha (Pakistan); Wan, Dongyun [School of Materials Science and Engineering, Shanghai University, Shanghai 200444 (China); Ahmad, Naeem [Department of Physics, International Islamic University, Islamabad (Pakistan); Ahamd, Ishaq [Experimental Physics Labs, National Center for Physics, Islamabad (Pakistan); Ilyas, Syed Zafar [Department of Physics, Allama Iqbal Open University, Islamabad (Pakistan)

    2017-04-15

    The nanocomposites of (SnO{sub 2}){sub x}(CuFe{sub 2}O{sub 4}){sub (1−x)} (where x=0–100 wt%) have been successfully synthesized via two steps chemical method. XRD pattern has revealed the formation of inverse spinal phases with tetragonal crystal structure without any impurity phases for CuFe{sub 2}O{sub 4} sample. The thermodynamic solubility limit of SnO{sub 2} in CuFe{sub 2}O{sub 4} matrix has been found to be 30 wt% and above this percentage crystal phases related to SnO{sub 2} started to appear. The average particle size and shape of CuFe{sub 2}O{sub 4} nanoparticles have been strongly influenced by addition of SnO{sub 2} as depicted by TEM results. FTIR results have confirmed the existence of cation vibration bands at tetrahedral and octahedral sites along with Sn-O vibration band at higher concentrations, which also validates the formation of nanocomposites. Furthermore, the dielectric constant, tangent loss and conductivity of CuFe{sub 2}O{sub 4} nanoparticles have been found to increase up to 30 wt% addition of SnO{sub 2} and then decreases with further increase which is attributed to variations in resistivity and space charge carriers. Magnetic measurements have shown that saturation magnetization decreases from 35.68 emu/gm to 10.26 emu/gm with the addition of SnO{sub 2} content. - Highlights: • SnO{sub 2}-CuFe{sub 2}O{sub 4} nanocomposites with varying SnO{sub 2} concentrations were synthesized. • The thermodynamic solubility limit for SnO{sub 2} into CuFe{sub 2}O{sub 4} matrix by employing current method was found to be ≤30 wt%. • At higher concentrations, structural phases related to SnO{sub 2} started to appear. • FTIR results corroborated well with the XRD results. • It has been observed that the addition of SnO{sub 2} significantly influence the morphology, dielectric and magnetic properties of CuFe{sub 2}O{sub 4} nanoparticles.

  18. LiCa{sub 4}Si{sub 4}N{sub 8}F and LiSr{sub 4}Si{sub 4}N{sub 8}F. Nitridosilicate fluorides with a BCT-zeolite-type network structure

    Energy Technology Data Exchange (ETDEWEB)

    Horky, Katrin; Schnick, Wolfgang [Department of Chemistry, Inorganic Solid-State, Chemistry, University of Munich (LMU), Butenandtstrasse 5-13, 81377, Munich (Germany)

    2017-02-17

    LiCa{sub 4}Si{sub 4}N{sub 8}F and LiSr{sub 4}Si{sub 4}N{sub 8}F were synthesized from Si{sub 3}N{sub 4}, LiNH{sub 2}, CaH{sub 2}/SrH{sub 2}, and LiF through a metathesis reaction in a radiofrequency furnace. The crystal structures of both compounds were solved and refined on the basis of single-crystal X-ray diffraction data [LiCa{sub 4}Si{sub 4}N{sub 8}F: P2{sub 1}/c (no. 14), a = 10.5108(3), b = 9.0217(3), c = 10.3574(3) Aa, β = 117.0152(10) , R{sub 1} = 0.0422, wR{sub 2} = 0.0724, Z = 4; LiSr{sub 4}Si{sub 4}N{sub 8}F: P4nc (no. 104), a = 9.3118(4), b = 9.3118(4), c = 5.5216(2) Aa, R{sub 1} = 0.0160, wR{sub 2} = 0.0388, Z = 2]. The silicate substructure of both compounds is built up of vertex-sharing SiN{sub 4} tetrahedra, thereby forming a structure analogous to the BCT zeolite with Ca{sup 2+}/Sr{sup 2+}, Li{sup +}, and F{sup -} ions filling the voids. The crystal structure of LiSr{sub 4}Si{sub 4}N{sub 8}F is homeotypic with that of Li{sub 2}Sr{sub 4}Si{sub 4}N{sub 8}O as it exhibits the same zeolite-type [SiN{sub 2}]{sup 2-} framework, but incorporates LiF instead of Li{sub 2}O. In contrast to the respective Sr compound, LiCa{sub 4}Si{sub 4}N{sub 8}F shows a distortion of the BCT-zeolite-type network as well as an additional site for F. Both F sites in LiCa{sub 4}Si{sub 4}N{sub 8}F exhibit different coordination spheres to LiSr{sub 4}Si{sub 4}N{sub 8}F. The title compounds are the first reported lithium alkaline-earth nitridosilicates containing fluorine. The crystal structures were confirmed by lattice-energy calculations (MAPLE), energy-dispersive X-ray spectroscopy (EDX) measurements, and powder X-ray diffraction. IR spectra confirmed the absence of N-H bonds. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Enhanced photocatalytic activity of Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xinjuan, E-mail: lxj669635@126.com [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Liu, Junying [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Chu, Haipeng [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Li, Jinliang; Yu, Wei [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Zhu, Guang [Anhui Key Laboratory of Spin Electron and Nanomaterials, Suzhou University, Suzhou 234000 (China); Niu, Lengyuan [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Sun, Zhuo [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Pan, Likun, E-mail: lkpan@phy.ecnu.edu.cn [Engineering Research Center for Nanophotonics & Advanced Instrument, Ministry of Education, Department of Physics, East China Normal University, Shanghai 200062 China (China); Sun, Chang Q. [Institute of Coordination Bond Metrology and Engineering, College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China)

    2015-08-30

    Graphical abstract: Bi{sub 2}O{sub 3}–Ag{sub 2}O composites were fabricated for visible light photocatalytic degradation of phenol with a high degradation rate of 92% for 60 min. - Highlights: • Bi{sub 2}O{sub 3}–Ag{sub 2}O composites were synthesized via a co-precipitation method. • The photocatalytic activity for the degradation of phenol is investigated. • A high degradation rate of 92% for 60 min is achieved under visible light irradiation. - Abstract: Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts were successfully synthesized via a co-precipitation method. The morphology, structure and photocatalytic performance in the degradation of phenol were characterized by using scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, electrochemical impedance spectra and UV–vis absorption spectroscopy, respectively. The results show that Bi{sub 2}O{sub 3}–Ag{sub 2}O hybrid photocatalysts exhibit enhanced photocatalytic performance in the degradation of phenol with a maximum degradation rate of 92% for 60 min under visible light irradiation compared with pure Bi{sub 2}O{sub 3} (57%), which is ascribed to the increase in light adsorption and the reduction in electron–hole pair recombination with the introduction of Ag{sub 2}O.

  20. Thermal cycling behavior of La{sub 2}Zr{sub 2}O{sub 7} coating with the addition of Y{sub 2}O{sub 3} by EB-PVD

    Energy Technology Data Exchange (ETDEWEB)

    Xu Zhenhua [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); He Limin, E-mail: he_limin@yahoo.co [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Chen Xiaolong; Zhao Yu [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Mu Rende; He Shimei [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Cao Xueqiang, E-mail: xcao@ciac.jl.c [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2010-10-15

    Thermal barrier coatings (TBCs) of La{sub 2}Zr{sub 2}O{sub 7} (LZ) with the addition of 3 wt.% Y{sub 2}O{sub 3} (LZ3Y) were deposited by electron beam-physical vapor deposition (EB-PVD). The phase structures, surface and cross-sectional morphologies, cyclic oxidation behaviors of these coatings were studied in detail. The thermal cycling test at 1373 K in an air furnace indicates that the LZ3Y coating has a lifetime of 617 cycles which is about 10% longer than that of LZ coating. The improvement of chemical homogeneity of the coating, the superior growth behavior of columns and the favorable mechanical properties are all very helpful to the prolongation of thermal cycling life of LZ3Y coating. The failure of LZ and LZ3Y coatings is mainly a result of the excess La{sub 2}O{sub 3}, the chemical incompatibility of ceramic coatings with TGO layer, the thermal expansion mismatch between ceramic coatings and bond coat, and the outward diffusion of alloying elements into the ceramic coatings.

  1. Direct synthesis of Sb{sub 2}O{sub 3} nanoparticles via hydrolysis-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yuehua [Department of Inorganic Materials, School of Resources Processing and Bioengineering, Central South University, Changsha 410083 (China); Zhang, Huihui [Department of Inorganic Materials, School of Resources Processing and Bioengineering, Central South University, Changsha 410083 (China); Yang, Huaming [Department of Inorganic Materials, School of Resources Processing and Bioengineering, Central South University, Changsha 410083 (China)]. E-mail: hmyang@mail.csu.edu.cn

    2007-01-31

    Antimony oxide (Sb{sub 2}O{sub 3}) has wide applications as conductive materials, effective catalyst, functional filler and optical materials. Nanocrystalline Sb{sub 2}O{sub 3} has been successfully synthesized by hydrolysis-precipitation method. The samples were characterized by means of transmission electron microscopy (TEM), high-resolution TEM (HRTEM) images, X-ray diffraction (XRD) and differential thermal analysis (DTA). The average crystal size of the Sb{sub 2}O{sub 3} nanoparticles increases with increasing the reaction temperature. TEM image of the as-synthesized nanocrystalline Sb{sub 2}O{sub 3} shows rod-like structure. HRTEM images indicate a preferred directional growth of the Sb{sub 2}O{sub 3} nanoparticles. The electrochemical behaviors of Sb{sub 2}O{sub 3} electrodes have been primarily investigated by cyclic voltammetry (CV) in lithium hexafluorophosphate (LiPF{sub 6}) solution. Sb{sub 2}O{sub 3} nanocrystallite phase has prominent effect on the electrochemical properties. The results indicate that nanocrystalline Sb{sub 2}O{sub 3} synthesized by hydrolysis-precipitation method shows potential application in the field of the electrode materials.

  2. Optical properties of the Na{sub 2}O-B{sub 2}O{sub 3}-Bi{sub 2}O{sub 3}-MoO{sub 3} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Saddeek, Yasser B. [Physics Department, Faculty of Science, Al-Azhar University, P.O. 71452, Assiut (Egypt); Aly, K.A., E-mail: kamalaly2001@gmail.co [Physics Department, Faculty of Science, Al-Azhar University, P.O. 71452, Assiut (Egypt); Dahshan, A., E-mail: adahshan73@gmail.co [Department of Physics, Faculty of Science, Suez Canal University, Port Said (Egypt); Kashef, I.M.El. [Department of Physics, Faculty of Education, Suez Canal University, Al Arish (Egypt)

    2010-04-02

    Glasses with compositions (100 - x)Na{sub 2}B{sub 4}O{sub 7}-0.5Bi{sub 2}O{sub 3}-0.5MoO{sub 3}, with 0 {<=} x {<=} 40 mol% have been prepared using the melt quenching technique. The optical transmittance and reflectance spectrum of the glasses have been recorded in the wavelength range 300-1100 nm. The values of the optical band gap E{sub g}{sup opt} for indirect transition and refractive index have been determined for 0 {<=} x {<=} 40 mol%. The average electronic polarizability of the oxide ion {alpha}{sub O{sup 2-}} and the optical basicity have been estimated from the calculated values of the refractive indices. The variations in the different physical parameters such as the optical band gap, the refractive index, the average electronic polarizability of the oxide ion and the optical basicity with Bi{sub 2}O{sub 3} and MoO{sub 3} content have been analyzed and discussed in terms of the changes in the glass structure. The results are interpreted in terms of the increase in the number of non-bridging oxygen atoms, substitution of longer bond-lengths of Bi-O, and Mo-O in place of shorter B-O bond and the change in Na{sup +} ion concentration.

  3. Stabilization/Solidification of Radioactive LiCl-KCl Waste Salt by Using SiO{sub 2}-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}(SAP) Inorganic Composite: Part 2. The Effect of SAP Composition on Stabilization/Solidification

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Soo Na; Park, Hwan Seo; Cho, In Hak; Kim, In Tae; Cho, Yong Zun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-03-15

    Metal chloride waste is generated as a main waste streams in a series of electrolytic processes of a pyrochemical process. Different from carbonate or nitrate salt, metal chloride is not decomposed into oxide and chlorine but it is just vaporized. Also, it has low compatibility with conventional silicate glasses. Our research group adapted the dechlorination approach for the immobilization of waste salt. In this study, the composition of SAP (SiO{sub 2}-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}) was adjusted to enhance the reactivity and to simplify the solidification process as a subsequent research. The addition of Fe{sub 2}O{sub 3} into the basic SAP decreased the SAP/Salt ratio in weight from 3 for SAP 1071 to 2.25 for M-SAP(Fe=0.1). The experimental results indicated that the addition of Fe{sub 2}O{sub 3} increased the reactivity of M-SAP with LiCl-KCl but the reactivity gradually decreased above Fe=0.1. Also, introducing B{sub 2}O{sub 3} into M-SAP requires no glass binder for the consolidation of reaction products. U-SAP (SiO{sub 2}-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}) could effectively dechlorinate the LiCl-KCl waste and its reaction product could be consolidated as a monolithic form without a glass binder. The leaching test result indicated that U-SAP 1071 was more durable than other SAPs wasteform. By using U-SAP, 1 g of waste salt could generated 3 - 4 g of wasteform for final disposal. The final volume would be about 3 - 4 times lower than the glass-bonded sodalite. From these results, it could be concluded that the dechlorination approach using U-SAP would be one of prospective methods to manage the volatile waste salt.

  4. RE{sub 2}B{sub 8}O{sub 15} (RE = La, Pr, Nd). Syntheses of three new rare earth borates isotypic to Ce{sub 2}B{sub 8}O{sub 15}

    Energy Technology Data Exchange (ETDEWEB)

    Glaetzle, Matthias; Hoerder, Gregor J.; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2016-08-01

    The rare earth borates RE{sub 2}B{sub 8}O{sub 15} (RE = La, Pr, Nd) were synthesized in a Walker-type multianvil apparatus under conditions of 5.5 GPa and 1100 C. Starting from the corresponding rare earth oxides and boron oxide, the syntheses yielded crystalline products of all new compounds that allowed crystal structure analyses based on single-crystal X-ray diffraction data for La{sub 2}B{sub 8}O{sub 15} and Nd{sub 2}B{sub 8}O{sub 15}. The compound Pr{sub 2}B{sub 8}O{sub 15} could be characterized via X-ray powder diffractometry. The results show that the new compounds crystallize isotypically to Ce{sub 2}B{sub 8}O{sub 15} in the monoclinic space group P2/c. The infrared spectra of RE{sub 2}B{sub 8}O{sub 15} (RE = La, Pr, Nd) have also been studied.

  5. Dechlorination Reaction of Metal Chloride Wastes with Inorganic Composite (SiO{sub 2}-Al{sub 2}O{sub 3}- P{sub 2}O{sub 5}) at 650 .deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Soo Na; Park, Hwan Seo; Cho, In Hak; Kim, In Tae; Cho, Yong Zun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2011-05-15

    Pyrochemical process to recover uranium and transuranic elements from the spent nuclear fuel indispensably generates radioactive metal chlorides waste containing fission products. These wastes are difficult to solidify and stabilize by conventional method due to their volatility and low comparability with silicate glass. Our research group is under development of dechlorination method to remove Clinduced problems. For dechlorination of metal chloride waste, an inorganic composite, SiO{sub 2}-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5} (SAP), has been investigated as dechlorination agent. The composite reacts with metal chloride to produce aluminosilicates, alumino phosphate and orthophosphate. The products are thermally stable up to 1200 .deg. C and compatible with silicate glass. In this study, modified SAP containing Fe{sub 2}O{sub 3} as another component was investigated to enhance the dechlorination reaction and characterize the reaction behavior of LiCl

  6. Thiol-PEG-carboxyl-stabilized Fe{sub 2}O{sub 3}/Au nanoparticles targeted to CD105: Synthesis, characterization and application in MR imaging of tumor angiogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Song; Gong, Mingfu; Zhang, Dong; Yang, Hua [Department of Radiology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037 (China); Gao, Fabao [Department of Radiology, West China Hospital, Sichuan University, Chengdu 610041 (China); Zou, Liguang, E-mail: zlgxqyy@163.com [Department of Radiology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037 (China)

    2014-07-15

    Objective: To detect tumor angiogenesis in tumor-bearing mice using thiol-PEG-carboxyl-stabilized Fe{sub 2}O{sub 3}/Au nanoparticles targeted to CD105 on magnetic resonance imaging (MRI). Methods: Fe{sub 2}O{sub 3}/Au nanoparticles (hybrids) were prepared by reducing Au{sup 3+} on the surface of Fe{sub 2}O{sub 3} nanoparticles. Hybrids were stabilized with thiol-PEG-carboxyl via the Au–S covalent bond, and further conjugated with anti-CD105 antibodies through amide linkages. Characteristics of the hybrid-PEG-CD105 nanoparticles were evaluated. Using these nanoparticles, the labeling specificity of human umbilical vein endothelial cells (HUVECs) was evaluated in vitro. MRI T2*-weighted images were obtained at different time points after intravenous administration of the hybrid-PEG-CD105 nanoparticles in the tumor-bearing mice. After MR imaging, the breast cancer xenografts were immediately resected for immunohistochemistry staining and Prussian blue staining to measure the tumor microvessel density (MVD) and evaluate the labeling of blood microvessels by the hybrid-PEG-CD105 nanoparticles in vivo. Results: The mean diameter of the hybrid-PEG-CD105 nanoparticles was 56.6 ± 8.0 nm, as measured by transmission electron microscopy (TEM). Immune activity of the hybrid-PEG-CD105 nanoparticles was 53% of that of the anti-CD105 antibody, as detected by enzyme-linked immunosorbent assay (ELISA). The specific binding of HUVECs with the hybrid-PEG-CD105 nanoparticles was proved by immunostaining and Prussian blue staining in vitro. For breast cancer xenografts, the combination of the hybrid-PEG-CD105 nanoparticles with blood microvessels was detectable by MRI after 60 min administration of the contrast agent. The T2* relative signal intensity (SI{sub R}) was positively correlated with the tumor MVD (R{sup 2} = 0.8972). Conclusion: Anti-CD105 antibody-coupled, thiol-PEG-carboxyl-stabilized core–shell Fe{sub 2}O{sub 3}/Au nanoparticles can efficiently target CD105 expressed

  7. Synthesis, surface properties and photocatalytic abilities of semiconductor In{sub 2}Cu{sub 2}O{sub 5} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jian; Wan, Yingpeng; Huang, Yanlin [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Wang, Yaorong, E-mail: yrwang@suda.edu.cn [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Qin, Lin [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2016-12-15

    Highlights: • In{sub 2}Cu{sub 2}O{sub 5} has high absorption in the UV-green and red wavelength region. • The nanoparticles present efficient photocatalytsis under visible light. • The photochemical properties were elucidated on its structure properties. - Abstract: In{sub 2}Cu{sub 2}O{sub 5} photocatalyst was prepared by the sol-gel method which produced worm-like nanoparticles. The X-ray powder diffraction (XRD) measurement and Rietveld structural refinement were applied to elucidate the phase formation and structural properties. The morphological properties of the surfaces were measured by scanning electron microscope (SEM), energy dispersive spectrum (EDS), and transmission electron microscopy (TEM). The nanoparticles present optical absorption from both the host lattices and the d–d transitions of distorted Cu{sup 2+} octahedra in UV–vis light wavelength region. The band-gap of In{sub 2}Cu{sub 2}O{sub 5} photocatalyst is about 2.31 eV. The photocatalytic abilities of In{sub 2}Cu{sub 2}O{sub 5} nanoparticles were verified by photo-degradation of methylene blue (MB) solutions irradiated by visible light. The energy potential and bad structure were discussed. In{sub 2}Cu{sub 2}O{sub 5} nanoparticles have the potential application for the efficient photocatalysis on MB dye solutions.

  8. Determination of Gd concentration profile in UO{sub 2}–Gd{sub 2}O{sub 3} fuel pellets

    Energy Technology Data Exchange (ETDEWEB)

    Tobia, D., E-mail: dina.tobia@cab.cnea.gov.ar [Laboratorio de Resonancias Magnéticas, Centro Atómico Bariloche – CNEA and CONICET, 8400 S.C. de Bariloche (Argentina); Winkler, E.L.; Milano, J.; Butera, A. [Laboratorio de Resonancias Magnéticas, Centro Atómico Bariloche – CNEA and CONICET, 8400 S.C. de Bariloche (Argentina); Kempf, R. [División Caracterización de Combustibles Avanzados, Gerencia Ciclo Combustible Nuclear, Centro Atómico Constituyentes – CNEA, 1650 San Martín, Pcia. de Buenos Aires (Argentina); Bianchi, L.; Kaufmann, F. [Departamento de Combustibles Avanzados, Gerencia Ciclo Combustible Nuclear, Centro Atómico Constituyentes – CNEA, 1650 San Martín, Pcia. de Buenos Aires (Argentina)

    2014-08-01

    A transversal mapping of the Gd concentration was measured in UO{sub 2}–Gd{sub 2}O{sub 3} nuclear fuel pellets by electron paramagnetic resonance spectroscopy (EPR). The quantification was made from the comparison with a Gd{sub 2}O{sub 3} reference sample. The nominal concentration in the pellets is UO{sub 2}: 7.5% Gd{sub 2}O{sub 3}. A concentration gradient was found, which indicates that the Gd{sub 2}O{sub 3} amount diminishes towards the edges of the pellets. The concentration varies from (9.3 ± 0.5)% in the center to (5.8 ± 0.3)% in one of the edges. The method was found to be particularly suitable for the precise mapping of the distribution of Gd{sup 3+} ions in the UO{sub 2} matrix.

  9. High-pressure synthesis and single-crystal structure elucidation of the indium oxide-borate In{sub 4}O{sub 2}B{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Ortner, Teresa S.; Vitzthum, Daniela; Heymann, Gunter; Huppertz, Hubert [Department of General, Inorganic and Theoretical Chemistry, Centre of Chemistry and Biomedicine (CCB), Leopold-Franzens-University Innsbruck (Austria)

    2017-12-29

    The indium oxide-borate In{sub 4}O{sub 2}B{sub 2}O{sub 7} was synthesized under high-pressure/high-temperature conditions at 12.5 GPa/1420 K using a Walker-type multianvil apparatus. Single-crystal X-ray structure elucidation showed edge-sharing OIn{sub 4} tetrahedra and B{sub 2}O{sub 7} units building up the oxide-borate. It crystallizes with Z = 8 in the monoclinic space group P2{sub 1}/n (no. 14) with a = 1016.54(3), b = 964.55(3), c = 1382.66(4) pm, and β = 109.7(1) . The compound was also characterized by powder X-ray diffraction and vibrational spectroscopy. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. A comparative study of dissolution of {alpha}-Fe{sub 2}O{sub 3} and {gamma}-Fe{sub 2}O{sub 3} in DCD formulations

    Energy Technology Data Exchange (ETDEWEB)

    Ranganathan, S.; Raghavan, P.S.; Gopalan, R. [Madras Christian Coll. (India). Dept. of Chemistry; Srinivasan, M.P.; Narasimhan, S.V.

    1998-12-31

    The important corrosion products deposited on the surfaces of structural materials such as stainless steel in the primary coolant system of BWRs are haematite in the outer layers and ferrites such as magnetite, nickel ferrite, cobalt ferrite, etc., in the inner layers. Magnetite dissolution by 2, 6 Pyridinedicarboxylic acid (PDCA), Ethylenediaminetetraacetic acid (EDTA) and Nitrolotriacetic acid (NTA) showed that there is an optimum pH of dissolution for each ligand. The leaching of the metal ions from the oxides is controlled in part by reductive dissolution; this is due to the presence of Fe(II)-L complexes generated from the released Fe{sup 2+} ions. The addition of Fe(II)-L with the formulation greatly increases the rate of dissolution. In order to understand the role of Fe{sup 2+} arising from the spinel lattice of Fe{sub 3}O{sub 4} in aiding the dissolution of magnetite, it is appropriate to study the dissolution behaviour of the system like Fe{sub 2}O{sub 3} which is not containing any Fe{sup 2+} in the crystal lattice. The present study has been carried out with {alpha}-Fe{sub 2}O{sub 3} and {gamma}-Fe{sub 2}O{sub 3} in DCD formulation in the presence of ascorbic acid and with the addition of Fe(II)-L as a reductant. (author)

  11. First-principles insights on electron transport in V{sub 2}O{sub 5} nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Anurag [Advanced Materials Research Group, Computational Nanoscience and Technology Laboratory, Atal Bihari Vajpayee-Indian Institute of Information Technology and Management, Gwalior, Madhya Pradesh 474015 (India); Chandiramouli, R., E-mail: rcmoulii@gmail.com [School of Electrical and Electronics Engineering, Shanmugha Arts Science Technology and Research Academy (SASTRA) University, Tirumalaisamudram, Thanjavur, Tamil Nadu 613 401 (India)

    2015-11-15

    Graphical abstract: - Highlights: • Band structure and electron transport in V{sub 2}O{sub 5} nanostructure are investigated using density functional theory. • V{sub 2}O{sub 5} nanostructure exhibits semiconducting behavior. • The electron density is observed to be more in oxygen sites than in vanadium sites. • The electron transport in V{sub 2}O{sub 5} molecular device can be tuned with the applied bias voltage. - Abstract: The present report is on the electron transport properties of V{sub 2}O{sub 5} nanostructures, investigated using density functional theory. As the band structure of V{sub 2}O{sub 5} exhibits semiconducting nature, the V{sub 2}O{sub 5} nanostructures are designed as molecular device and the transport properties are studied. The density of electrons is found to be more in the oxygen sites than in vanadium sites. The device density of states shows that the density of electrons in the energy intervals depends on the applied bias voltage. The transmission spectrum gives the insight on the transport property of V{sub 2}O{sub 5} molecular device. The bias voltage drives the electrons across V{sub 2}O{sub 5} scattering region, where the transmission along V{sub 2}O{sub 5} molecular device mainly depends on the bias voltage. The findings of the present work give insights to fine-tune the transport property of V{sub 2}O{sub 5} molecular device upon varying the bias voltage.

  12. Order-disorder reactions in the ferroelectric perovskites Pb(Sc/sub 1/2/Nb/sub 1/2/)O/sub 3/ and Pb(Sc/sub 1/2/Ta/sub 1/2/)O/sub 3/. 2. Relation between ordering and properties

    Energy Technology Data Exchange (ETDEWEB)

    Stenger, C G.F.; Burggraaf, A J [Technische Hogeschool Twente, Enschede (Netherlands)

    1980-10-16

    The ordering of the trivalent and pentavalent cations in the pervoskites Pb(Sc/sub 1/2/Nb/sub 1/2/)O/sub 3/ and Pb(Sc/sub 1/2/Ta/sub 1/2/)O/sub 3/ can be varied by suitable heat treatments. The degree as well as the kind of order strongly affects the character of the FE ..-->.. PE phase transition. A spatially homogeneous disorder leads to a diffuse phase transition whereas a hybrid crystal with a nonhomogeneous disorder shows a sequence of two FE ..-->.. PE transitions.

  13. Photodegradation and toxicity changes of antibiotics in UV and UV/H{sub 2}O{sub 2} process

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yuan [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Hu Chun, E-mail: huchun@rcees.ac.cn [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China); Xuexiang, Hu; Dongbin, Wei; Yong, Chen; Jiuhui, Qu [State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085 (China)

    2011-01-30

    The photodegradation of three antibiotics, oxytetracycline (OTC), doxycycline (DTC), and ciprofloxacin (CIP) in UV and UV/H{sub 2}O{sub 2} process was investigated with a low-pressure UV lamp system. Experiments were performed in buffered ultrapure water (UW), local surface water (SW), and treated water from local municipal drinking water treatment plant (DW) and wastewater treatment plant (WW). The efficiency of UV/H{sub 2}O{sub 2} process was affected by water quality. For all of the three selected antibiotics, the fastest degradation was observed in DW, and the slowest degradation occurred in WW. This phenomenon can be explained by R{sub OH,UV}, defined as the experimentally determined {center_dot}OH radical exposure per UV fluence. The R{sub OH,UV} values represent the background {center_dot}OH radical scavenging in water matrix, obtained by the degradation of para-chlorobenzoic acid (pCBA), a probe compound. In natural water, the indirect degradation of CIP did not significantly increase with the addition of H{sub 2}O{sub 2} due to its effective degradation by UV direct photolysis. Moreover, the formation of several photoproducts and oxidation products of antibiotics in UV/H{sub 2}O{sub 2} process was identified using GC-MS. Toxicity assessed by Vibrio fischer (V. fischer), was increased in UV photolysis, for the photoproducts still preserving the characteristic structure of the parent compounds. While in UV/H{sub 2}O{sub 2} process, toxicity increased first, and then decreased; nontoxic products were formed by the oxidation of {center_dot}OH radical. In this process, detoxification was much easier than mineralization for the tested antibiotics, and the optimal time for the degradation of pollutants in UV/H{sub 2}O{sub 2} process would be determined by parent compound degradation and toxicity changes.

  14. Influence of P{sub 2}O{sub 5} and Al{sub 2}O{sub 3} content on the structure of erbium-doped borosilicate glasses and on their physical, thermal, optical and luminescence properties

    Energy Technology Data Exchange (ETDEWEB)

    Bourhis, Kevin, E-mail: k.bourhis@argolight.com [Politecnico di Torino, DISAT, Istituto di Ingegneria e Fisica dei Materiali, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy); Massera, Jonathan [Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Turku (Finland); Petit, Laeticia; Ihalainen, Heikki [nLIGHT Corporation, Sorronrinne 9, FI-08500 Lohja (Finland); Fargues, Alexandre; Cardinal, Thierry [CNRS, Université de Bordeaux, ISM, 351Cours de la Libération, F-33405 Talence (France); Hupa, Leena; Hupa, Mikko [Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Turku (Finland); Dussauze, Marc; Rodriguez, Vincent [CNRS, Université de Bordeaux, ICMCB, 87 Avenue du Dr Schweitzer, F-33608 Pessac (France); Boussard-Plédel, Catherine; Bureau, Bruno; Roiland, Claire [Equipe Verres et Céramiques, UMR-CNRS 6226, Inst. des Sciences chimiques de Rennes, Université de Rennes 1, 35042 Rennes CEDEX (France); Ferraris, Monica [Politecnico di Torino, DISAT, Istituto di Ingegneria e Fisica dei Materiali, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy)

    2015-03-15

    Highlights: • Reorganization of the glass structure induced by the addition of P{sub 2}O{sub 5} or Al{sub 2}O{sub 3}. • Emission properties related to the presence of P or Al in the Er{sup 3+} coordination shell. • Declustering observed upon addition of P{sub 2}O{sub 5}. • No declustering upon addition of Al{sub 2}O{sub 3}. - Abstract: The effect of P{sub 2}O{sub 5} and/or Al{sub 2}O{sub 3} addition in Er-doped borosilicate glasses on the physical, thermal, optical, and luminescence properties is investigated. The changes in these glass properties are related to the glass structure modifications induced by the addition of P{sub 2}O{sub 5} and/or Al{sub 2}O{sub 3}, which were probed by FTIR, {sup 11}B MAS NMR and X-ray photoelectron spectroscopies. Variations of the polymerization degree of the silicate tetrahedra and modifications in the {sup [3]}B/{sup [4]}B ratio are explained by a charge compensation mechanism due to the formation of AlO{sub 4}, PO{sub 4} groups and the formation of Al-O-P linkages in the glass network. From the absorption and luminescence properties of the Er{sup 3+} ions at 980 nm and 1530 nm, declustering is suspected for the highest P{sub 2}O{sub 5} concentrations while for the highest Al{sub 2}O{sub 3} concentrations no declustering is observed.

  15. Effect of coagulation on treatment of municipal wastewater reverse osmosis concentrate by UVC/H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Umar, Muhammad; Roddick, Felicity, E-mail: felicity.roddick@rmit.edu.au; Fan, Linhua

    2014-02-15

    Highlights: • Alum coagulation is an effective pre-treatment for UVC/H{sub 2}O{sub 2} treatment of high salinity ROC. • Comparable DOC in samples but different coagulation success due to different nature of organics. • Comparable mineralization obtained for two different ROCs with UVC/H{sub 2}O{sub 2} only treatment. • UVC/H{sub 2}O{sub 2} treatment led to increased biodegradability with and without coagulation. • Significant reduction in energy consumption obtained after pre- and biological post-treatment. -- Abstract: Disposal of reverse osmosis concentrate (ROC) is a growing concern due to potential health and ecological risks. Alum coagulation was investigated as pre-treatment for the UVC/H{sub 2}O{sub 2} treatment of two high salinity ROC samples (ROC A and B) of comparable organic and inorganic content. Coagulation removed a greater fraction of the organic content for ROC B (29%) than ROC A (16%) which correlated well with the reductions of colour and A{sub 254}. Although the total reductions after 60 min UVC/H{sub 2}O{sub 2} treatment with and without coagulation were comparable, large differences in the trends of reduction were observed which were attributed to the different nature of the organic content (humic-like) of the samples as indicated by the LC-OCD analyses and different initial (5% and 16%) biodegradability. Coagulation and UVC/H{sub 2}O{sub 2} treatment preferentially removed humic-like compounds which resulted in low reaction rates after UVC/H{sub 2}O{sub 2} treatment of the coagulated samples. The improvement in biodegradability was greater (2–3-fold) during UVC/H{sub 2}O{sub 2} treatment of the pre-treated samples than without pre-treatment. The target DOC residual (≤15 mg/L) was obtained after 30 and 20 min irradiation of pre-treated ROC A and ROC B with downstream biological treatment, corresponding to reductions of 55% and 62%, respectively.

  16. Atomic disorder in Gd{sub 2}Zr{sub 2}O{sub 7} pyrochlore

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, F. X. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004 (China); Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lang, M. [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Ewing, R. C. [Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305 (United States)

    2015-05-11

    Gd{sub 2}Zr{sub 2}O{sub 7} pyrochlore with different degrees of cation disorder were synthesized by isothermal annealing at various temperatures (1100–1550 °C), and the related changes in the structure were investigated by ambient and high pressure x-ray diffraction (XRD) measurements. Unit cell parameters increase almost linearly with increasing treatment temperature. The degree of cation order in pyrochlore also increases with the increase of temperature, but saturates at ∼60%. The compressibility of the pyrochlore structures decreases when the degree of cation order increases. High pressure XRD measurements also indicate that the phase stability of Gd{sub 2}Zr{sub 2}O{sub 7} is not very sensitive to the degree of atomic disorder in the pyrochlore structure.

  17. Synthesis of Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} via combustion route: Effects of Al{sub 2}O{sub 3} nanoparticles on superconducting properties

    Energy Technology Data Exchange (ETDEWEB)

    Mohd Suan, Mohd Shahadan, E-mail: mohdshahadan@utem.edu.my [Department of Engineering Materials, Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, 76100 Durian Tunggal, Melaka (Malaysia); Johan, Mohd Rafie [Nanomaterial Engineering Research Group, Advanced Materials Research Laboratory, Department of Mechanical Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2017-02-01

    Combustion reaction was used to synthesis Al{sub 2}O{sub 3} nanoparticles embedded Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} simultaneously. The effects of Al{sub 2}O{sub 3} nanoparticles with nominal molar mass (x{sub mol}) of 0.02, 0.04, 0.06, 0.08 and 0.10 towards the critical current density J{sub C} of Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} were verified by magnetic measurement. Resulted XRD patterns revealed that the calcined samples consist of pure Al{sub 2}O{sub 3} and Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} phases which had been confirmed by EDX results. The SEM images showed that Al{sub 2}O{sub 3} nanoparticles (~10 nm) were distributed in polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-δ} grains and grain boundaries. The presence of higher concentration of Al{sub 2}O{sub 3} nanoparticles has developed Al{sup 3+} rich spots which diffused within the YBa{sub 2}Cu{sub 3}O{sub 7-δ} superconducting matrix to form Y{sub 1-x}Al{sub x}Ba{sub 2}Cu{sub 3}O{sub 7-δ} and was confirmed by EDX analysis. The samples were electrically superconducting at temperature above 85 K as measured by using standard four-probe technique. The magnetic field (H) dependent magnetization (M), M-H hysteresis loops measured at 77 K for x{sub mol}≤0.06 samples are significantly improved attributed to the increase of trapped fluxes in the samples. Remarkable increase of magnetic J{sub C} (H) in Al{sub 2}O{sub 3} nanoparticles added samples compared to the as prepared polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-δ} sample indicating strong pinning effect. It is suggested that well-distributed Al{sub 2}O{sub 3} nanoparticles in the polycrystalline YBa{sub 2}Cu{sub 3}O{sub 7-δ} matrix achieved via auto-combustion reaction has efficiently pin the magnetic vortex. The magnetic J{sub C} was optimized to ~6 kAcm{sup -2} in x{sub mol}=0.06 sample. On the other hand, insignificant magnetic J{sub C} improvement in x{sub mol}≥0.08 samples is probably resulted from the

  18. The catalytic activity of Ag{sub 2}S-montmorillonites as peroxidase mimetic toward colorimetric detection of H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qingyun, E-mail: qyliu@sdust.edu.cn [School of Chemistry and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510 (China); Jiang, Yanling; Zhang, Leyou; Zhou, Xinpei [School of Chemistry and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510 (China); Lv, Xintian [School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252000 (China); Ding, Yanyuan; Sun, Lifang; Chen, Pengpeng [School of Chemistry and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266510 (China); Yin, Hailiang [Academy of Science & Technology, China University of Petroleum, Dongying 257061 (China)

    2016-08-01

    Nanocomposites based on silver sulfide (Ag{sub 2}S) and Ca-montmorillonite (Ca{sup 2+}-MMT) were synthesized by a simple hydrothermal method. The nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectra (FTIR). The as-prepared Ag{sub 2}S-MMT nanocomposites were firstly demonstrated to possess intrinsic peroxidase-like activity and could rapidly catalytically oxidize the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H{sub 2}O{sub 2} to produce a blue product which can be seen by the naked eye in only one minute. The experimental results revealed that the Ag{sub 2}S-MMT nanocomposites exhibit higher thermal durance. Based on the TMB–H{sub 2}O{sub 2} catalyzed color reaction, the Ag{sub 2}S-MMT nanocomposites were exploited as a new type of biosensor for detection and estimation of H{sub 2}O{sub 2} through a simple, cheap and selective colorimetric method. - Highlights: • Ag{sub 2}S – montmorillonites (MMT) was synthesized by a facile one step method. • The as-prepared Ag{sub 2}S-MMT nanocomposites firstly demonstrate to possess intrinsic peroxidase-like activity. • Ag{sub 2}S-MMT nanocomposites showed highly catalytic activity. • Ag{sub 2}S-MMT could rapidly catalytically oxidize substrates TMB in the presence of H{sub 2}O{sub 2} in 1 min. • The catalytic mechanism is from the generation of hydroxyl radical (·OH) decomposed from H{sub 2}O{sub 2}.

  19. Effect of calcination temperature on the H{sub 2}O{sub 2} decomposition activity of nano-crystalline Co{sub 3}O{sub 4} prepared by combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Makhlouf, M.Th. [Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut (Egypt); Abu-Zied, B.M., E-mail: babuzied@aun.edu.eg [Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut (Egypt); Mansoure, T.H. [Chemistry Department, Faculty of Science, Assiut University, 71516 Assiut (Egypt)

    2013-06-01

    Cobalt oxide nano-particles were prepared by combustion method using urea as a combustion fuel. The effects of calcination temperature, 350–1000 °C, on the physicochemical, surface and catalytic properties of the prepared Co{sub 3}O{sub 4} nano-particles were studied. The products were characterized by thermal analyses (TGA and DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. Textural features of the obtained catalysts were investigated using nitrogen adsorption at −196 °C. X-ray diffraction confirmed that the resulting oxide was pure single-crystalline Co{sub 3}O{sub 4} nano-particles. Transmission electron microscopy indicating that, the crystallite size of Co{sub 3}O{sub 4} nano-crystals was in the range of 8–34 nm. The catalytic activities of prepared nano-crystalline Co{sub 3}O{sub 4} catalysts were tested for H{sub 2}O{sub 2} decomposition at 35–50 °C temperature range. Experimental results revealed that, the catalytic decomposition of H{sub 2}O{sub 2} decreases with increasing the calcination temperature. This was correlated with the observed particle size increase accompanying the calcination temperature rise.

  20. Photocatalytic performance of nano-photocatalyst from TiO{sub 2} and Fe{sub 2}O{sub 3} by mechanochemical synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Ghorai, Tanmay K., E-mail: tanmay_ghorai@yahoo.co.in [Department of Chemistry, West Bengal State University, Barasat, North 24 Pgs, Kolkata 700126 (India); Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India); Chakraborty, Mukut [Department of Chemistry, West Bengal State University, Barasat, North 24 Pgs, Kolkata 700126 (India); Pramanik, Panchanan [Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302 (India)

    2011-08-11

    Graphical abstract: Nano-particles of homogeneous solution between TiO{sub 2} and Fe{sub 2}O{sub 3} (up to 5 mol%) have been prepared by mechanochemical milling. The results show that the alloy of TiO{sub 2} with 5 mol% of Fe{sub 2}O{sub 3} (YFT1) exhibit photocatalytic activity 3-5 times higher than that of P25 TiO{sub 2} for oxidation of various dyes (RB, MO, TB and BG) under visible light irradiation. The average particle size and crystallite size of YFT1 were found to be 30 {+-} 5 nm and 12 nm measured from TEM and XRD. Optical adsorption edge is found to be 2.26 eV. Tentative schematic diagram of reaction mechanism of YFT/RFT photocatalysts under visible light irradiation. Highlights: > Synthesis of nano-sized homogeneous solid solution between Fe{sub 2}O{sub 3} and TiO{sub 2} with high photocatalytic activity for oxidative degradation of different dyes was successfully obtained through mechanochemical synthesis. XRD data shows the formation of solid solution having anatase structure with no free Fe{sub 2}O{sub 3} up to 5 mol% of Fe{sub 2}O{sub 3}. Fe{sub 2}O{sub 3}/TiO{sub 2} catalyst have crystallite size about 12-13 nm measured from XRD and particle size about 30 {+-} 5 nm measured from TEM. FT-IR of all Fe{sub 2}O{sub 3}/TiO{sub 2} prepared catalysts is similar to pure TiO{sub 2}. The maximum solubility of Fe{sub 2}O{sub 3} in TiO{sub 2} is 5 mol% of Fe{sub 2}O{sub 3} irrespective of source and this composition has highest photocatalytic activity that is 3-5 times higher than P25 TiO{sub 2} for the oxidation of different dyes. We also observed that the rate of degradation of Rhodamine B is faster among all the four dyes under prepared catalyst and visible light. - Abstract: Nano-particles of homogeneous solid solution between TiO{sub 2} and Fe{sub 2}O{sub 3} (up to 10 mol%) have been prepared by mechanochemical milling of TiO{sub 2} and yellow Fe{sub 2}O{sub 3}/red Fe{sub 2}O{sub 3}/precipitated Fe (OH){sub 3} using a planetary ball mill. Such novel solid

  1. Sol–gel hybrid membranes loaded with meso/macroporous SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} materials with high proton conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Yolanda, E-mail: castro@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Mosa, Jadra, E-mail: jmosa@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Aparicio, Mario [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Pérez-Carrillo, Lourdes A.; Vílchez, Susana; Esquena, Jordi [Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona (Spain); Durán, Alicia [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain)

    2015-01-15

    In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m{sup 2}/g (TiO{sub 2}–P{sub 2}O{sub 5}) and 300 m{sup 2}/g (SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5}). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion{sup ®} at higher temperatures (120 °C) (2·10{sup −2} S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure. - Highlights: • Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel. • Depositions of hybrid solutions by spraying onto glass substrates were performed. • Proton conductivity was evaluated as a function of composition and porous structure.

  2. Synthesis and luminescent properties of Eu{sup 3+}/Eu{sup 2+} co-doped calcium aluminosilicate glass–ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Bouchouicha, H. [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Panczer, G., E-mail: gerard.panczer@univ-lyon1.fr [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Ligny, D. de [Universität Erlangen-Nürnberg, Department Werkstoffwissenschaften, Lehrstuhl für Glas und Keramik, D-91058 Erlangen (Germany); Guyot, Y. [Institut Lumière Matière, UMR5306 Université Lyon 1-CNRS, Université de Lyon, 69622 Villeurbanne Cedex (France); Baesso, M.L. [Departemento de Fisica, Universidade Estadual de Maringa, 87020-900 Maringa, PR (Brazil); Andrade, L.H.C.; Lima, S.M. [Grupo de Espectroscopia Óptica e Fototérmica, Universidade Estadual de Mato Grosso do Sul – UEMS, C.P. 351, Dourados, MS (Brazil); Ternane, R. [Laboratoire d' Application de la Chimie aux Ressources et Substances Naturelles et à l' Environnement (LACReSNE), Université de Carthage, Faculté des Sciences de Bizerte, 7021 Zarzouna, Bizerte (Tunisia)

    2016-01-15

    Eu{sup 3+} and Eu{sup 2+} co-doped calcium aluminosilicate glass–ceramics have been prepared by devitrification of calcium aluminosilicate glass using heat-treatment. Control of crystallization in the glass–ceramics was studied by X-ray diffraction (XRD) and Raman spectroscopy. The results showed that crystalline phases in glass–ceramic belong to the family of melilite Ca{sub 2}Mg{sub 0.25}Al{sub 1.5}Si{sub 1.25}O{sub 7} as the major phase and anorthite CaAl{sub 2}Si{sub 2}O{sub 8} as the minor phase. Luminescent properties were investigated by emission; lifetime and the color points were calculated. Emission spectra showed that Eu{sup 2+} entered into the crystalline phase in a two steps mechanism: first as Eu{sup 3+} which is then reduced to Eu{sup 2+}. This incorporation in the crystal enhanced Eu{sup 2+} emission with increasing time of heat-treatment and therefore crystallization. - Highlights: • Crystallization of doped glass–ceramics by heat-treatment controlled by microRaman. • Crystalline phases consist of melilite and anorthite. • Eu{sup 3+} and Eu{sup 2+} emissions characterized by their lifetime and color indexes. • Crystallization process modified efficiently the emission color point.

  3. Conversion of green emission into white light in Gd{sub 2}O{sub 3} nanophosphors

    Energy Technology Data Exchange (ETDEWEB)

    Jayasimhadri, M.; Ratnam, B.V. [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Jang, Kiwan, E-mail: kwjang@changwon.ac.k [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Lee, Ho Sueb [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Yi, Soung-Soo [Department of Photonics, Silla University, Busan (Korea, Republic of); Jeong, Jung-Hyun [Department of Physics, Pukyong National University, Busan (Korea, Republic of)

    2010-09-01

    Gd{sub 2}O{sub 3} nanophosphors were prepared by combustion synthesis with and without doping of Dy{sup 3+} ions. The X-ray powder diffraction patterns indicate that as-prepared Gd{sub 2}O{sub 3} and 0.1 mol% Dy{sub 2}O{sub 3} doped Gd{sub 2}O{sub 3} nanophosphors have monoclinic structures. The transmission electron microscope (TEM) studies revealed that the as-prepared phosphors had an average crystallite sizes around 37 nm. The excitation and emission properties have been investigated for Dy{sup 3+} doped and undoped Gd{sub 2}O{sub 3} nanophosphors. New emission bands were observed in the visible region for Gd{sub 2}O{sub 3} nanophosphors without any rare earth ion doping under different excitations. A tentative mechanism for the origin of luminescence from Gd{sub 2}O{sub 3} host was discussed. Emission properties also measured for 0.1 mol% Dy{sup 3+} doped Gd{sub 2}O{sub 3} nanophosphors and found the characteristic Dy{sup 3+} visible emissions at 489 and 580 nm due to {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 15/2} and {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 13/2} transitions, respectively. The chromaticity coordinates were calculated based on the emission spectra of Dy{sup 3+} doped and undoped Gd{sub 2}O{sub 3} nanophosphors and analyzed with Commission Internationale de l'Eclairage (CIE) chromaticity diagram. These nanophosphors exhibit green color in undoped Gd{sub 2}O{sub 3} and white color after adding 0.1 mol% Dy{sub 2}O{sub 3} to Gd{sub 2}O{sub 3} nanophosphors under UV excitation. These phosphors could be a promising phosphor for applications in flat panel displays.

  4. Static susceptibility and heat capacity studies on V{sub 3}O{sub 7}.H{sub 2}O{sub 7} nanobelts

    Energy Technology Data Exchange (ETDEWEB)

    Hellmann, I., E-mail: i.hellmann@ifw-dresden.d [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Zakharova, G.S.; Volkov, V.L. [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620219 (Russian Federation); Taeschner, C.; Leonhardt, A.; Buechner, B.; Klingeler, R. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2010-04-15

    V{sub 3}O{sub 7}.H{sub 2}O nanobelts were prepared by a hydrothermal method at 190 deg. C using V{sub 2}O{sub 5}.nH{sub 2}O gel and H{sub 2}C{sub 2}O{sub 4}.2H{sub 2}O as starting agents. The obtained nanobelts have diameters ranging from 40 to 70 nm with lengths up to several micrometers. Measurements of the static magnetic susceptibility and the specific heat show a discontinuous phase transition at around T=145 K, which separates two regions of paramagnetic behavior.

  5. SiO{sub 2} effect on spectral and colorimetric properties of europium doped SrO{sub 2}-MgO-xSiO{sub 2} (0.8 {<=} x {<=} 1.6) phosphor for white LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Chen, B J; Jang, K W; Lee, H S; Jayasimhadri, M; Cho, E J [Department of Physics, Changwon National University, Changwon, 641-773 (Korea, Republic of); Yi, S S [Department of Photonics, Silla University, Pusan 617-736 (Korea, Republic of); Jeong, J H [Department of Physics, Pukyong National University, Pusan 608-737 (Korea, Republic of)], E-mail: kwjang@changwon.ac.kr

    2009-05-21

    Silicate phosphors with compositions 1.99 SrO{sub 2}-1.0 MgO-xSiO{sub 2}-0.01 Eu{sub 2}O{sub 3} (x = 0.8, 1.0, 1.2, 1.4 and 1.6) were prepared in a reducing atmosphere via a solid state reaction. The resultant phosphors were examined by using x-ray diffraction and confirmed to be a mixture of monoclinic Sr{sub 2}SiO{sub 4} and orthorhombic Mg{sub 2}(Si{sub 2}O{sub 4}). The scanning electron microscope images revealed that SiO{sub 2} content does not influence the morphology of the resultant phosphors. It was also observed that the excitation spectra are dependent on the monitored emission wavelength, and the emission spectra are dependent on the excitation wavelength and the SiO{sub 2} content. The energy transfer between Eu{sup 2+} ions occupying different Sr{sup 2+} sites was discussed. The colour coordinates for these phosphors are tunable based on both the excitation wavelength and the SiO{sub 2} content.

  6. Effects of Y{sub 2}O{sub 3}/CeO{sub 2} co-doping on microwave dielectric properties of Ba(Co{sub 0.6}Zn{sub 38}){sub 1/3}Nb{sub 2/3}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuqin; Zhou, Xiaohua, E-mail: 1250590698@qq.com; Yang, Xinshi; Sun, Chengli; Yang, Fan; Chen, Hetuo

    2016-09-15

    The effects of CeO{sub 2}/Y{sub 2}O{sub 3} co-doping on the microstructure and microwave dielectric properties of Ba(Co{sub 0.6}Zn{sub 0.38}){sub 1/3}Nb{sub 2/3}O{sub 3}-xA-xB (x = 0,1,2,3,4,6; A = 0.1204 wt%Y{sub 2}O{sub 3}; B = 0.1 wt%CeO{sub 2}) ceramics prepared by the conventional solid-state route technique were investigated. The X-ray diffraction (XRD) results presented that all the well sintered samples exhibited the main phase BaZn{sub 0.33}Nb{sub 0.67}O{sub 3}−Ba{sub 3}CoNb{sub 2}O{sub 9}. A certain amount of Ba{sub 8}CoNb{sub 6}O{sub 24} surface secondary phase and minority phase of Ba{sub 5}Nb{sub 4}O{sub 15} were also observed in all sintered ceramics. The 1:2 B-site cation ordering degree was found to influenced by the substitution of Y{sup 3+} and Ce{sup 4+} in the crystal lattice, especially for x = 0.02. Then the scanning electron microscopy (SEM) picture of the optimally well-sintered (1350 °C for 20 h) ceramic has shown a dense microstructure. Although the ε{sub r} almost kept unchanged, appropriate doping content would greatly improve the Q × f value. Meanwhile, the τ{sub f} value first declined and then increased with increasing x. At last, the excellent microwave dielectric properties of ε{sub r} = 36.09, Q × f = 72006 GHz, τ{sub f} = 3.35 ppm/ºC were obtained for the ceramic with x = 0.02 sintered in air at 1350 °C for 20 h. - Graphical abstract: Fig. SEM images of as-sintered Ba(Co{sub 0.6}Zn{sub 0.38}){sub 1/3}Nb{sub 2/3}O{sub 3}-xA-Xb (A = 0.1204 wt%Y{sub 2}O{sub 3}; B = 0.1 wt%CeO{sub 2)}ceramics: (a) x = 0,(b) x = 0.01,(c) x = 0.02,(d) x = 0.03, (e) x = 0.04,(f) x = 0.06. The images confirmed the presences of two phases on the surface of the ceramics, plate-shaped grains (Ba{sub 8}(C{sub O},Zn){sub 1}Nb{sub 6}O{sub 24}phase) and needle-shaped grains (Ba{sub 3}(Co{sub 0.6}Zn{sub 0.38}){sub 1}Nb{sub 2}O{sub 9} phase). As a small content of CeO{sub 2}/Y{sub 2}O{sub 3} (x = 0.01–0.04) was codoped into the BCZN ceramics, the

  7. Densification and mechanical properties of sintered Al{sub 2}O{sub 3}-Y{sub 3}Al{sub 5}O{sub 12} ceramic composite

    Energy Technology Data Exchange (ETDEWEB)

    Paneto, Flavio Jose; Pereira, Joaquim Lopes; Oliveira, Jean de Lima; Jesus Filho, Edson de; Silva, Leandro Anselmo da; Cabral, Ricardo de Freitas; Santos, Claudinei dos [Centro Universitario de Volta Redonda (UNIFOA), Volta Redonda, RJ (Brazil); Lima, Eduardo de Sousa [Institutlo Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil)

    2014-06-15

    In this work, Al{sub 2}O{sub 3}-Y{sub 3}Al{sub 5}O{sub 12} ceramic composites were developed with different proportions of Al{sub 2}O{sub 3}-Y{sub 3}Al{sub 5}O{sub 12}, which were mixed and compacted at different pressures of 40MPa to 100MPa, being consequently sintered at 1600 deg C-2h. The sintered samples were characterized by X-ray diffraction presenting α-Al{sub 2}O{sub 3} and Y{sub 3}Al{sub 5}O{sub 12} as crystalline phases. Samples with relative densities ranging from 78 to 80% and 87 to 91% were obtained depending on the composition and the compaction pressure used. The hardness values obtained were of 1010 to 1080HV and 370- 470HV, for mixes Al{sub 2}O{sub 3}-Y{sub 3}Al{sub 5}O{sub 12} having the composition with levels of 20 and 36.5wt.%, respectively. (author)

  8. Microwave dielectric properties of CaCu{sub 3}Ti{sub 4}O{sub 12}-Al{sub 2}O{sub 3} composite

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Mohd Fariz Ab; Abu, Mohamad Johari; Zaman, Rosyaini Afindi; Ahmad, Zainal Arifin [School of Materials and Mineral Resources Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Karim, Saniah Ab; Mohamed, Julie Juliewatty, E-mail: juliewatty.m@umk.edu.my [Advance Materials Research Cluster, Faculty of Earth Sciences, Universiti Malaysia Kelantan, Jeli Campus, 17600 Jeli, Kelantan (Malaysia); Ain, Mohd Fadzil [School of Electrical and Electronic Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2016-07-19

    (1-x)CaCu{sub 3}Ti{sub 4}O{sub 12} + (x)Al{sub 2}O{sub 3} composite (0 ≤ x ≤0.25) was prepared via conventional solid-state reaction method. The fabrication of sample was started with synthesizing stoichiometric CCTO from CaCO{sub 3}, CuO and TiO{sub 2} powders, then wet-mixed in deionized water for 24 h. The process was continued with calcined CCTO powder at 900 °C for 12 h before sintered at 1040 °C for 10 h. Next, the calcined CCTO powder with different amount of Al{sub 2}O{sub 3} were mixed for 24 h, then palletized and sintered at 1040 °C for 10. X-ray diffraction analysis on the sintered samples showed that CCTO powder was in a single phase, meanwhile the trace of secondary peaks which belong to CaAl{sub 2}O{sub 4} and Corundum (Al{sub 2}O{sub 3}) could be observed in the other samples Scanning electron microscopy analysis showed that the grain size of the sample is firstly increased with addition of Al{sub 2}O{sub 3} (x = 0.01), then become smaller with the x > 0.01. Microwave dielectric properties showed that the addition of Al{sub 2}O{sub 3} (x = 0.01) was remarkably reduced the dielectric loss while slightly increased the dielectric permittivity. However, further addition of Al{sub 2}O{sub 3} was reduced both dielectric loss and permittivity at least for an order of magnitude.

  9. Rhodium-rich silicides RERh{sub 6}Si{sub 4} (RE=La, Nd, Tb, Dy, Er, Yb)

    Energy Technology Data Exchange (ETDEWEB)

    Vosswinkel, Daniel; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2017-07-01

    Polycrystalline RERh{sub 6}Si{sub 4} (RE=La, Nd, Tb, Dy, Er, Yb) samples can be synthesized by arc-melting of the elements. Single crystals of LaRh{sub 6}Si{sub 4}, NdRh{sub 6}Si{sub 4} and YbRh{sub 6}Si{sub 4} were synthesized from the elements in bismuth fluxes (non-reactive flux medium). The structures were refined on the basis of single-crystal X-ray diffractometer data: LiCo{sub 6}P{sub 4} type, P anti 6m2, a=700.56(3), c=380.55(1) pm, wR2=0.0257, 317 F{sup 2} values, 19 variables for LaRh{sub 6}Si{sub 4}, a=698.4(5), c=377.7(2) pm, wR2=0.0578, 219 F{sup 2} values, 19 variables for NdRh{sub 6}Si{sub 4} and a=696.00(3), c=371.97(1) pm, wR2=0.0440, 309 F{sup 2} values, 19 variables for YbRh{sub 6}Si{sub 4}. The rhodium and silicon atoms build up three-dimensional, covalently bonded [Rh{sub 6}Si{sub 4}]{sup δ-} polyanionic networks with Rh-Si distances ranging from 239 to 249 pm. The rare earth atoms fill larger cavities within channels of these networks and they are coordinated by six silicon and twelve rhodium atoms in the form of hexa-capped hexagonal prisms.

  10. Development of a high-performance nanostructured V(sub2)O(sub5)/SnO(sub2)catalyst for efficient benzene hydroxylation

    CSIR Research Space (South Africa)

    Makgwane, PR

    2015-02-01

    Full Text Available Nanostructured vanadium-tin oxide (V(sub2)O(sub5)/SnO(sub2)) catalysts with V(sub2)O(sub5) loading in a range of 5–20 wt% have been synthesized. The V(sub2)O(sub5)/SnO(sub2) nanostructures exhibited effective catalytic performance...

  11. Synthesis, characterization, and comparative gas-sensing properties of Fe{sub 2}O{sub 3} prepared from Fe{sub 3}O{sub 4} and Fe{sub 3}O{sub 4}-chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Cuong, Nguyen Duc [Faculty of Hospitality and Tourism, Hue University, 22 Lam Hoang, Vy Da Ward, Hue City (Viet Nam); College of Sciences, Hue University, 77 Nguyen Hue, Phu Nhuan Ward, Hue City (Viet Nam); International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), Hanoi (Viet Nam); Hoa, Tran Thai; Khieu, Dinh Quang [College of Sciences, Hue University, 77 Nguyen Hue, Phu Nhuan Ward, Hue City (Viet Nam); Lam, Tran Dai [Institute of Materials Science, Vietnamese Academy of Science and Technology, Hanoi (Viet Nam); Hoa, Nguyen Duc [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), Hanoi (Viet Nam); Van Hieu, Nguyen, E-mail: hieu@itims.edu.vn [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology (HUST), Hanoi (Viet Nam)

    2012-05-15

    Highlights: Black-Right-Pointing-Pointer We have demonstrated a facile method to prepare Fe{sub 3}O{sub 4} nanoparticles and chitosan-coated Fe{sub 3}O{sub 4} nanoparticles. Black-Right-Pointing-Pointer {alpha}-Fe{sub 2}O{sub 3} sensors prepared from those Fe{sub 3}O{sub 4} materials have been investigated and compared. Black-Right-Pointing-Pointer The results show potential application of {alpha}-Fe{sub 2}O{sub 3} for CO sensors in environmental monitoring. - Abstract: In this paper, Fe{sub 3}O{sub 4} and chitosan (CS)-coated Fe{sub 3}O{sub 4} nanoparticles were synthesized via co-precipitation method and subsequent covalent binding of CS onto the surface for functionalization, respectively. Characterization of the crystal structures and morphologies of as-synthesized nanoparticles by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy demonstrated that Fe{sub 3}O{sub 4} had a cubic spinal structure with irregular shapes and average diameters of 10-20 nm. The surface states and magnetic properties of Fe{sub 3}O{sub 4}-CS nanoparticles were characterized by Fourier transform infrared spectra and vibrating sample magnetometry. Results showed that Fe{sub 3}O{sub 4}-CS nanoparticles possessed super-paramagnetic properties, with saturated magnetization up to 60 emu/g. In addition, Fe{sub 3}O{sub 4} and CS-coated Fe{sub 3}O{sub 4} nanoparticles were used in the fabrication of {alpha}-Fe{sub 2}O{sub 3} based gas sensors. Gas sensing measurements revealed that the {alpha}-Fe{sub 2}O{sub 3} gas sensor prepared from Fe{sub 3}O{sub 4}-CS had a better response to H{sub 2}, CO, C{sub 2}H{sub 5}OH, and NH{sub 3} compared with the device prepared from pristine Fe{sub 3}O{sub 4}. Furthermore, the {alpha}-Fe{sub 2}O{sub 3} sensor prepared from Fe{sub 3}O{sub 4}-CS nanoparticles exhibited the highest response to CO among the test gases, suggesting that it has great potential for practical applications in environmental monitoring.

  12. Compressive strain-dependent bending strength property of Al{sub 2}O{sub 3}-ZrO{sub 2} (1.5 mol% Y{sub 2}O{sub 3}) composites performance by HIP

    Energy Technology Data Exchange (ETDEWEB)

    Reyes-Rojas, A. [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico)], E-mail: armando_reyesmx@yahoo.com.mx; Esparza-Ponce, H. [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico); De la Torre, S.D. [Centro de Investigacion e Innovacion Tecnologica (CIITEC)-IPN, D.F. Mexico (Mexico); Torres-Moye, E. [Centro de Investigacion en Materiales Avanzados S.C. (CIMAV), Miguel de Cervantes 120, Complejo Industrial Chihuahua, Cd. de Chihuahua, Chihuahua (Mexico)

    2009-04-15

    Nanometric powders and sintered ceramics of Al{sub 2}O{sub 3}-ZrO{sub 2} (1.5 mol% Y{sub 2}O{sub 3}) prepared by hot isostatic pressing HIP have been studied. A detailed crystallographic study has been performed through X-ray diffraction, Williamson-Hall method, Rietveld method and high-resolution electron microscopy HREM analysis. The crystallographic structure data, such as domain size, lattice parameters, wt% phase, and micro-strain direction have been obtained using Rietveld refinement and Williamson-Hall methods. The results revealed that the compressive strain ({epsilon}) increased from 0.56 to 1.18 (10{sup -3}) as the t-ZrO{sub 2} content increased too. The HREM interface study conducted along the [0 0 0 1]Al{sub 2}O{sub 3}||[0 0 1]ZrO{sub 2} zone axis revealed a micro-strain lattice distortion accumulated at the grain boundary due to the ZrO{sub 2} martensitic phase transformation on cooling, t-ZrO{sub 2} grains coalescence and to the grain growth of {alpha}-Al{sub 2}O{sub 3} which cause elongated tetragonal crystals. Micro-strain lattice distortion is adjusted by the shear displacements of the planes (1 1 0) and (11-bar0) along [1-bar10] and [1-bar1-bar0] crystallographic directions, respectively; these planes are arrested by the (101-bar0) alumina plane. In this case, semi-coherent interfaces were observed along the grain boundary. It is verified that the bending strength increased in connection with the strain accumulation and amount of tetragonal structure.

  13. Au and Pd nanoparticles supported on CeO{sub 2}, TiO{sub 2}, and Mn{sub 2}O{sub 3} oxides

    Energy Technology Data Exchange (ETDEWEB)

    Nascente, P.A.P., E-mail: nascente@ufscar.br [Federal University of Sao Carlos, Department of Materials Engineering, Sao Carlos, SP (Brazil); Maluf, S.S.; Afonso, C.R.M. [Federal University of Sao Carlos, Department of Materials Engineering, Sao Carlos, SP (Brazil); Landers, R. [State University of Campinas, Institute of Physics, Department of Applied Physics, Campinas, SP (Brazil); Pinheiro, A.N.; Leite, E.R. [Federal University of Sao Carlos, Department of Chemistry, Sao Carlos, SP (Brazil)

    2014-10-01

    Highlights: • CeO{sub 2}, TiO{sub 2}, and Mn{sub 2}O{sub 3} supported Au and Pd nanoparticles. • Additions of 0.5 wt% of Au and Pd onto CeO{sub 2}, TiO{sub 2}, and Mn{sub 2}O{sub 3} supports. • Characterization by XRD, XPS, EDS, TEM, HRTEM, STEM, and EFTEM. - Abstract: Gold and palladium nanoparticles were incorporated on CeO{sub 2}, TiO{sub 2}, and Mn{sub 2}O{sub 3} supports prepared by a sol–gel method. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), high resolution TEM (HRTEM), scanning TEM (STEM) in high angle annular dark field mode (HAADF), and energy filtered TEM (EFTEM) using electron energy loss spectroscopy (EELS). The XRD diffractograms presented sharp and intense peaks indicating that the samples are highly crystalline, but it did not detected any peak corresponding to Au or Pd phases. This indicates that the Au and Pd NPs were incorporated into the structures of the oxides. It was not possible to obtain an Au 4f spectrum for Au/Mn{sub 2}O{sub 3} due to an overlap with the Mn 3p spectrum. The XPS Au 4f spectra for Au/CeO{sub 2} and Au/TiO{sub 2} present negative chemical shifts that could be attributed to particle-size-related properties. The XPS Pd 3d spectra indicate that for both CeO{sub 2} and TiO{sub 2} substrates, the Pd NPs were in the metallic state, while for the Mn{sub 2}O{sub 3} substrate, the Pd NPs were oxidized. The HRTEM results show the formation of nanocrystalline oxides having particles sizes between 50 and 200 nm. TEM micrographs show that the addition of Au caused the formation of Au clusters in between the CeO{sub 2} NPS, formation of Au NPs for the TiO{sub 2} support, and homogeneous distribution of Au clusters for the Mn{sub 2}O{sub 3} support. The addition of Pd yielded a homogeneous dispersion throughout the CeO{sub 2} and TiO{sub 2}, but caused the formation of Pd clusters for the Mn{sub 2}O{sub

  14. Solvothermal syntheses, crystal structures, and properties of lanthanide(III) thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln==Sm, Eu, Gd) and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln==Tb, Dy, Ho)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fang; Tang, Chunying; Chen, Ruihong; Zhang, Yong; Jia, Dingxian, E-mail: jiadingxian@suda.edu.cn

    2013-10-15

    Solvothermal reactions of Ln{sub 2}O{sub 3}, As and S in diethylenetriamine (dien) at 170 °C for 6 days afforded two structural types of lanthanide thioarsenates with the general formulae [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} [Ln=Sm(1), Eu(2), Gd(3)] and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] [Ln=Tb(4), Dy(5), Ho(6)]. The Ln{sub 2}O{sub 3} oxides were converted to [Ln(dien){sub 2}]{sup 3+} complex units in the solvothermal reactions. The As atom binds four S atoms, forming a tetrahedral AsS{sub 4} unit. In 1−3, the AsS{sub 4} units interconnect the [Ln(dien){sub 2}]{sup 3+} cations via Ln−S bonds as tridentate μ-1κ,2κ{sup 2}-AsS{sub 4} bridging ligands, resulting in the neutral coordination polymers [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} (Ln1). In 4−6, the AsS{sub 4} units coordinate with the Ln{sup 3+} ion of [Ln(dien){sub 2}]{sup 3+} as 1κ{sup 2}-AsS{sub 4} chelating ligands to form neutral coordination compounds [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] (Ln2). The Ln{sup 3+} ions are in nine- and eight-coordinated environments in Ln1 and Ln2, respectively. The formation of Ln1 and Ln2 is related with ionic size of the Ln{sup 3+} ions. Optical absorption spectra showed that 1−6 have potential use as semiconductors with the band gaps in the range 2.18−3.21 eV. - Graphical abstract: Two types of Ln-thioarsenates [Ln(dien){sub 2}(μ-1κ,2κ{sup 2}-AsS{sub 4})]{sub n} and [Ln(dien){sub 2}(1κ{sup 2}-AsS{sub 4})] were prepared by solvothermal methods and the soft Lewis basic AsS{sub 4}{sup 3–} ligand to Ln(III) centers with polyamine co-ligand was obtained. Display Omitted - Highlights: • Lanthanide thioarsenates were prepared by solvothermal methods. • The soft Lewis basic AsS{sub 4} ligand coordinate Ln{sup 3+} ions with coexistence polyamine ligands. • Two structural types of Ln-thioarsenates with structural turnover at Tb were obtained along Ln series. • The Ln-thioarsenates are potential semiconductors

  15. Electronic structure and optical properties of ABP{sub 2}O{sub 7} double phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Hizhnyi, Yu. [Faculty of Physics, Kyiv National Taras Shevchenko University, 2, Block 1, Acad. Hlushkova Ave., 03680 Kyiv (Ukraine)], E-mail: hizhnyi@univ.kiev.ua; Gomenyuk, O.; Nedilko, S.; Oliynyk, A.; Okhrimenko, B. [Faculty of Physics, Kyiv National Taras Shevchenko University, 2, Block 1, Acad. Hlushkova Ave., 03680 Kyiv (Ukraine); Bojko, V. [National Agriculture University, 5 Geroiv Oborony Str., 03041 Kyiv (Ukraine)

    2007-04-15

    Luminescence and luminescence excitation under VUV radiation of ABP{sub 2}O{sub 7} (A=Na, K, Cs; B=Al, In) double phosphates are studied. Two emission bands peaking near 330 and 420 nm are common for investigated ABP{sub 2}O{sub 7} crystals. The band structure and partial densities of electronic states of perfect KAlP{sub 2}O{sub 7}, LiInP{sub 2}O{sub 7} and NaTiP{sub 2}O{sub 7} crystals are calculated by the full-potential linear-augmented-plane-wave (FLAPW) method. It is found that the structures of the conduction bands of ABP{sub 2}O{sub 7} crystals, which have different B cations, are appreciably different. Experimental results are compared with results of calculations of the electronic structure. Assumptions concerning the origin of luminescence in double phosphates are made.

  16. Hydrogen permeation on Al{sub 2}O{sub 3}-based nickel/cobalt composite membranes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jihee; Jung, Miewon [Department of Chemistry/Institute of Basic Science, Sungshin Women' s University, Seoul 136-742 (Korea, Republic of); Hong, Tae-Whan [Department of Materials Science and Engineering/Research Center for Sustainable Eco-Devices and Materials(ReSEM), Chungju National University, Chungju 380-702 (Korea, Republic of)

    2010-12-15

    Al{sub 2}O{sub 3} was synthesized using the sol-gel process with aluminum isopropoxide as the precursor and primary distilled water as the solvent. Nickel and cobalt metal powders were used to increase the strength of the membranes. The Al{sub 2}O{sub 3}-based membranes were prepared using HPS following a mechanical alloying process. The phase transformation, thermal evolution, surface and cross-section morphology of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}-based membranes were characterized by XRD, TG-DTA and FE-SEM. The hydrogen permeation of Al{sub 2}O{sub 3}-based membranes was examined at 300-473 K under increasing pressure. Hydrogen permeation flux through an Al{sub 2}O{sub 3}-20wt%Co membrane was obtained to 2.36 mol m{sup -2} s{sup -1}. Reaction enthalpy was calculated to 4.5 kJ/mol using a Van't Hoff's plot. (author)

  17. Defect luminescence and lattice strain in Mn{sup 2+} doped ZnGa{sub 2}O{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Somasundaram, K.; Abhilash, K.P. [Department of Physics, Nallamuthu Gounder Mahalingam College, Pollachi, 642001 Coimbatore (India); Sudarsan, V., E-mail: vsudar@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Christopher Selvin, P., E-mail: pcsphyngmc@rediffmail.com [Department of Physics, Nallamuthu Gounder Mahalingam College, Pollachi, 642001 Coimbatore (India); Kadam, R.M. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2016-06-15

    Undoped and Mn{sup 2+} doped ZnGa{sub 2}O{sub 4} phosphors were prepared by solution combustion method and characterized by XRD, SEM, luminescence and electron paramagnetic resonance (EPR) techniques. Based on XRD results, it is inferred that, strain in ZnGa{sub 2}O{sub 4} host lattice increases with incorporation of Mn{sup 2+} ions in the lattice. Mn{sup 2+} doping at concentration levels investigated, lead to significant reduction in the defect emission and this has been attributed to the formation of higher oxidation states of Mn ions in the lattice. Electron Paramagnetic Resonance studies confirmed that majority of Mn ions exist as Mn{sup 2+} species and they occupy tetrahedral Zn{sup 2+} site in ZnGa{sub 2}O{sub 4} lattice with an average hyperfine coupling constant, A{sub iso}∼82 G.

  18. In situ DRIFTS study of O{sub 3} adsorption on CaO, γ-Al{sub 2}O{sub 3}, CuO, α-Fe{sub 2}O{sub 3} and ZnO at room temperature for the catalytic ozonation of cinnamaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jianfeng; Su, Tongming; Jiang, Yuexiu; Xie, Xinling [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Qin, Zuzeng, E-mail: qinzuzeng@gmail.com [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Ji, Hongbing, E-mail: jihb@mail.sysu.edu.cn [School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); School of Chemistry, Sun Yat-sen University, Guangzhou 510275 (China)

    2017-08-01

    Highlights: • In situ DRIFTS study of O{sub 3} adsorption on metal oxides at room temperature. • Using acidic probe molecules (DRIFTS) characterization of surface basicity. • Correlation between basic strength of metal oxides and O{sub 3} adsorption. • Study on the competitive adsorption of O{sub 3} and CO{sub 2}. • DRIFTS study of cinnamaldehyde ozonation and benzaldehyde excessive oxidation. - Abstract: In situ DRIFTS were conducted to identify adsorbed ozone and/or adsorbed oxygen species on CaO, ZnO, γ-Al{sub 2}O{sub 3}, CuO and α-Fe{sub 2}O{sub 3} surfaces at room temperature. Samples were characterized by means of TG, XRD, N{sub 2} adsorption–desorption, pyridine-IR, nitrobenzene-IR, chloroform-IR, and CO{sub 2}-TPD. Pyridine-DRIFTS measurements evidence two kinds of acid sites in all the samples. Nitrobenzene, chloroform-DRIFTS, and CO{sub 2}-TPD reveal that there are large amounts of medium-strength base sites on all the metal oxides, and only CaO, ZnO, and γ-Al{sub 2}O{sub 3} have strong base sites. And the benzaldehyde selectivity was increased in the same order of the alkalinity of the metal oxides. With weaker sites, ozone molecules form coordinative complexes bound via the terminal oxygen atom, observed by vibrational frequencies at 2095–2122 and 1026–1054 cm{sup −1}. The formation of ozonide O{sub 3}{sup −} at 790 cm{sup −1}, atomic oxygen at 1317 cm{sup −1}, and superoxide O{sub 2}{sup −} at 1124 cm{sup −1} was detected; these species are believed to be intermediates of O{sub 3} decomposition on strong acid/base sites. The adsorption of ozone on metal oxides is a weak adsorption, and other gases, such as CO{sub 2}, will compete with O{sub 3} adsorption. The mechanism of cinnamaldehyde ozonation at room temperature over CaO shows that cinnamaldehyde can not only be oxidized into cinnamic acid, but also be further oxidized into benzaldehyde, benzoic acid, maleic anhydride, and ultimately mineralized to CO{sub 2} in the

  19. Removal of UO{sup 2+}{sub 2} from aqueous solution using halloysite nanotube-Fe{sub 3}O{sub 4} composite

    Energy Technology Data Exchange (ETDEWEB)

    He, Wenfang; Chen, Yuantao; Zhang, Wei; Hu, Chunlian; Wang, Jian; Wang, Pingping [Qinghai Normal University, Xining (China)

    2016-01-15

    Halloysite nanotubes (HNTs) were modified with Fe{sub 3}O{sub 4} to form novel magnetic HNTs-Fe{sub 3}O{sub 4} composites, and the composites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM). The as-obtained results indicated that Fe{sub 3}O{sub 4} nanoparticles were successfully installed on the surface of HNTs. The adsorption of UO{sup 2+}{sub 2} on HNTs-Fe{sub 3}O{sub 4} was investigated as a function of solid content, contact time, pH, ionic strength and temperature by batch experiments. The consequences revealed that the adsorption of UO{sup 2+}{sub 2} onto HNTs-Fe{sub 3}O{sub 4} was strongly dependent on pH and ionic strength. Equilibrium data fitted well with the Langmuir isotherm. The experimental results demonstrated that the adsorbents with HNTs-Fe{sub 3}O{sub 4} had the largest adsorption capacity of 88.32mg/g for UO{sup 2+}{sub 2}.

  20. Structural and photoluminescence study of Er-Yb codoped nanocrystalline ZrO{sub 2}-B{sub 2}O{sub 3} solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro 76000 (Mexico); Borja-Urby, R. [Grupo de Espectroscopia de Materiales Avanzados y nanoestructurados (EMANA), Centro de Investigaciones en Optica, A. C., Loma del Bosque 115, Col. Lomas del Campestre, C.P. 37150 Leon, Gto. (Mexico); Diaz-Torres, L.A., E-mail: ditlacio@cio.mx [Grupo de Espectroscopia de Materiales Avanzados y nanoestructurados (EMANA), Centro de Investigaciones en Optica, A. C., Loma del Bosque 115, Col. Lomas del Campestre, C.P. 37150 Leon, Gto. (Mexico); Rodriguez, G. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro 76000 (Mexico); Vega, M. [Centro de Geociencias, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro 76000 (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas 152, A.P. 14-805, 07730 Mexico, DF (Mexico)

    2012-09-20

    Codoped Er{sup 3+} and Yb{sup 3+} nanocrystalline ZrO{sub 2}-B{sub 2}O{sub 3} phosphor obtained by a modified sol-gel method is demonstrated. The addition of up to 2.5 mol% B{sub 2}O{sub 3} to nanocrystalline ZrO{sub 2}:Yb(2%), Er(1%) keep the tetragonal rare-earth stabilized ZrO{sub 2} phase; whereas higher B{sub 2}O{sub 3} content destabilize the tetragonal phase, leading to the tetragonal to monoclinic transition with no tetragonal ZrO{sub 2} phase segregation. Visible upconversion of the luminescent active ions, Er{sup 3+} and Yb{sup 3+}, depend strongly on B{sub 2}O{sub 3} content. The PL intensity is strongly quenched for high B{sub 2}O{sub 3} content due to increasing multiphonon relaxation processes related to B-O and B-O-B vibronic modes.

  1. Fast response of sprayed vanadium pentoxide (V{sub 2}O{sub 5}) nanorods towards nitrogen dioxide (NO{sub 2}) gas detection

    Energy Technology Data Exchange (ETDEWEB)

    Mane, A.A. [Thin Film Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); General Science and Humanities Department, Sant Gajanan Maharaj College of Engineering, Mahagaon, 416 503 (India); Suryawanshi, M.P. [Optoelectronics Convergence Research Center, Department of Materials Science and Engineering, Chonnam National University, 300, Yongbong-Dong, Buk-Gu, Gwangju 500-757 (Korea, Republic of); Kim, J.H., E-mail: jinhyeok@chonnam.ac.kr [Optoelectronics Convergence Research Center, Department of Materials Science and Engineering, Chonnam National University, 300, Yongbong-Dong, Buk-Gu, Gwangju 500-757 (Korea, Republic of); Moholkar, A.V., E-mail: avmoholkar@gmail.com [Thin Film Nanomaterials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India)

    2017-05-01

    Highlights: • Effect of solution concentration on physicochemical properties of sprayed V{sub 2}O{sub 5} nanorods is studied. • Good response and short response-recovery times of V{sub 2}O{sub 5} nanorods towards NO{sub 2} gas show it is potential material for fabrication of NO{sub 2} sensor. • The chemisorption mechanism of NO{sub 2} gas on the V{sub 2}O{sub 5} nanorods is discussed. - Abstract: The V{sub 2}O{sub 5} nanorods have been successfully spray deposited at optimized substrate temperature of 400 °C onto the glass substrates using vanadium trichloride (VCl{sub 3}) solution of different concentrations. The effect of solution concentration on the physicochemical and NO{sub 2} gas sensing properties of sprayed V{sub 2}O{sub 5} nanorods is studied at different operating temperatures and gas concentrations. The XRD study reveals the formation of V{sub 2}O{sub 5} having an orthorhombic symmetry. The FE-SEM micrographs show the nanorods-like morphology of V{sub 2}O{sub 5}. The AFM micrographs exhibit a well covered granular surface topography. For direct allowed transition, the band gap energy values are found to be decreased from 2.45 eV to 2.42 eV. The nanorods deposited with 30 mM solution concentration shows the maximum response of 24.2% for 100 ppm NO{sub 2} gas concentration at an operating temperature of 200 °C with response and recovery times of 13 s and 140 s, respectively. Finally, the chemisorption mechanism of NO{sub 2} gas on the V{sub 2}O{sub 5} nanorods is discussed.

  2. Pressure and temperature phase diagram of Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Catillon, G. [Université Paris-Est, G2I, EA4119, 5 Blvd. Descartes, F-77454 Marne la Vallée Cedex 2 (France); Chartier, A., E-mail: alain.chartier@cea.fr [CEA, DEN, DMN, SCCME, F-91191 Gif-Sur-Yvette Cedex (France)

    2014-11-21

    The pressure and temperature phase diagram of Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation are calculated by means of molecular dynamics calculations. The critical temperature for amorphization obeys a linear law with pressure. Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation transits towards the fluorite above this temperature and amorphizes below. The configuration of the Ti interstitial reveals to be the key of the amorphizability of Gd{sub 2}Ti{sub 2}O{sub 7}. Its stability depends upon disorder and pressure. Low pressure promotes the stabilization of Ti linked-polyhedra that drive the system to the amorphous state under irradiation. Conversely, high pressure activates its destabilization to interstitials that recombine with vacancies, driving the system to the fluorite structure under irradiation.

  3. Collinear order in the frustrated spin-(1)/(2) antiferromagnet Li{sub 2}CuW{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Tsirlin, Alexander A. [NICPB, Tallinn (Estonia); Nath, Ramesh; Ranjith, Kumar [Indian Institute of Science Education and Research, Trivandrum (India); Kasinathan, Deepa [MPI CPfS, Dresden (Germany); Skoulatos, Markos [Laboratory of Neutron Scattering, PSI, Villigen (Switzerland)

    2015-07-01

    Li{sub 2}CuW{sub 2}O{sub 8} is a three-dimensional spin-(1)/(2) antiferromagnet that features collinear spin order despite abundant magnetic frustration that would normally trigger a non-collinear incommensurate order, at least on the classical level. Using density-functional calculations, we establish the spin lattice comprising two non-coplanar triangular networks that introduce frustration along all three crystallographic directions. Magnetic susceptibility and heat capacity reveal a 1D-like magnetic response, which is, however, inconsistent with the naive spin-chain model. Moreover, the high saturation field of 29 T compared to the susceptibility maximum at as low as 8.5 K give strong evidence for the importance of interchain couplings and the magnetic frustration. Below T{sub N} ≅ 3.9 K, Li{sub 2}CuW{sub 2}O{sub 8} develops collinear magnetic order with parallel spins along a and c and antiparallel spins along b. The ordered moment is about 0.7 μ{sub B} according to neutron powder diffraction. This qualifies Li{sub 2}CuW{sub 2}O{sub 8} as a unique three-dimensional spin-(1)/(2) antiferromagnet, where collinear magnetic order is stabilized by quantum fluctuations.

  4. Effect of Er-doping on the structural and optical properties of Cd{sub 2}V{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Lozada-Morales, R.; Cid-Garcia, A.; Palomino-Merino, R. [Benemerita Universidad Autonoma de Puebla, Postgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico); Lopez-Calzada, G.; Jimenez-Sandoval, S. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Apartado Postal 1-798, Queretaro, Qro. 76001 (Mexico); Zayas, Ma.E. [Departamento de Investigacion en Fisica de la Universidad de Sonora, Edificio 3I, Blvd. Edificio 5 E, Luis Encinas s/n, Col. Centro, 83000 Hermosillo, Sonora (Mexico); Zelaya-Angel, O. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados, P.O. Box 14-740, Mexico D. F. 07360 (Mexico); Carmona-Rodriguez, J. [Instituto Tecnologico Superior de Poza Rica, Calle Luis Donaldo Colosio S/N, Col. Arroyo del Maiz, C.P. 93230, Poza Rica, Veracruz (Mexico); Rubio-Rosas, E. [Centro de Vinculacion Universitaria, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico); Portillo-Moreno, O. [Facultad de Ciencias Quimicas, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico)

    2012-11-15

    The melt-quenching method was used to prepare two groups of samples using CdO and V{sub 2}O{sub 5} as starting materials. Taking into account that a crystalline-amorphous phase transition would be expected for the CdO-V{sub 2}O{sub 5} system, a first batch was prepared varying the proportions of CdO and V{sub 2}O{sub 5} in the intervals 60-95 and 40-5 wt%, respectively. With the aim of investigating the effect of erbium in the phase transition and crystalline quality of the first group of samples, a second batch was fabricated with the same proportions of CdO and V{sub 2}O{sub 5}, with the addition of 5 wt% of Er(NO{sub 3})5H{sub 2}O as source of Er{sup 3+} ions. It was found that crystalline or amorphous samples could be obtained depending on the relative concentrations of CdO and V{sub 2}O{sub 5}, and that the borderline between amorphous and crystalline samples was affected by the incorporation of Er. From X-ray diffraction, it was possible to identify the formation of the ternary compound Cd{sub 2}V{sub 2}O{sub 7} in the crystalline cases. The Raman and infrared bands in these samples were in agreement with the lattice modes of Cd{sub 2}V{sub 2}O{sub 7}. Additionally, an improvement in the crystalline quality of Cd{sub 2}V{sub 2}O{sub 7} was obtained for the Er-doped samples. The effect of the local environment around the Er{sup 3+} ions on the room temperature photoluminescence was also investigated for the amorphous and crystalline samples. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. ZnFe{sub 2}O{sub 4} antiferromagnetic structure redetermination

    Energy Technology Data Exchange (ETDEWEB)

    Kremenović, Aleksandar, E-mail: akremenovic@rgf.bg.ac.rs [Laboratory for Crystallography, Faculty of Mining and Geology, University of Belgrade, Đušina 7, Belgrade 11000 (Serbia); Antić, Bratislav [Condensed Matter Physics Laboratory, Institute of Nuclear Sciences “Vinča”, University of Belgrade, P.O. Box 522, Belgrade 11001 (Serbia); Vulić, Predrag [Laboratory for Crystallography, Faculty of Mining and Geology, University of Belgrade, Đušina 7, Belgrade 11000 (Serbia); Blanuša, Jovan [Condensed Matter Physics Laboratory, Institute of Nuclear Sciences “Vinča”, University of Belgrade, P.O. Box 522, Belgrade 11001 (Serbia); Tomic, Aleksandra [Condensed Matter Physics Laboratory, Institute of Nuclear Sciences “Vinča”, University of Belgrade, P.O. Box 522, Belgrade 11001 (Serbia); Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY, 10027 (United States)

    2017-03-15

    Magnetic structure of ZnFe{sub 2}O{sub 4} normal spinel is re-examined. Antiferromagnetic structure non-collinear model is established within C{sub a}2 space group having four different crystallographic/magnetic sites for 32 Fe{sup 3+} spins within magnetic unit cell. - Highlights: • Magnetic structure of ZnFe{sub 2}O{sub 4} normal spinel is re-examined. • Antiferromagnetic non-collinear structure model is established within C{sub a}2 space group. • Four different crystallographic/magnetic sites contain 32 Fe{sup 3+} spins within magnetic unit cell.

  6. Electrospun ZnFe{sub 2}O{sub 4}-based nanofiber composites with enhanced supercapacitive properties

    Energy Technology Data Exchange (ETDEWEB)

    Agyemang, Frank Ofori; Kim, Hern, E-mail: hernkim@mju.ac.kr

    2016-09-15

    Highlights: • Electrospun ZnFe{sub 2}O{sub 4}-based nanofibers were successfully fabricated. • The electrochemical properties of ZnFe{sub 2}O{sub 4} were enhanced by addition of ZnO and Fe{sub 2}O{sub 3.} • A specific capacitance of 590 F g{sup −1} was achieved from a CV curve at a scan rate of 5 mV s{sup −1.} • The electrode materials poses excellent cycling stability even after 3000 cycles. - Abstract: Herein, we are reporting a facile method to synthesis ZnFe{sub 2}O{sub 4}-based nanofibers (ZnFe{sub 2}O{sub 4}, ZnO–ZnFe{sub 2}O{sub 4} and Fe{sub 2}O{sub 3}–ZnFe{sub 2}O{sub 4}) via the electrospinning technique using zinc acetonate and ferric acetonate as the metal oxide precursor and polyvinyl pyrrolidone (PVP) as the polymer. The as-prepared electrospun nanofiber composites were calcined at 500 °C to obtain crystalline porous nanofibers. The effect of different compositions on the morphology of each sample as well as their electrochemical properties when employed as electrode materials was studied. The results show that the as-prepared electrodes exhibited excellent performance with their specific capacitances calculated from the CV curves as 590, 490 and 450 F g{sup −1} for Fe{sub 2}O{sub 3}–ZnFe{sub 2}O{sub 4}, ZnO–ZnFe{sub 2}O{sub 4} and ZnFe{sub 2}O{sub 4} respectively at a scan rate of 5 mV s{sup −1}. Excellent stability of the electrodes was also observed even after 3000 cycles. The results obtained suggest these electrode materials might be promising candidates for supercapacitor application.

  7. The effect of different annealing temperatures on the structure and luminescence properties of Y{sub 2}O{sub 3}:Bi{sup 3+} thin films fabricated by spin coating

    Energy Technology Data Exchange (ETDEWEB)

    Yousif, A.; Jafer, R.M.; Som, S. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Department of Physics, Faculty of Education, University of Khartoum, P.O. Box 321, 11115 Omdurman (Sudan); Duvenhage, M.M.; Coetsee, E. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA 9300 (South Africa)

    2016-03-01

    Graphical abstract: - Highlights: • Y{sub 2−x}O{sub 3}:Bi{sub x=0.005} thin films were successfully fabricated by the spin coating method. • The Y{sub 2−x}O{sub 3}:Bi{sub x=0.005} thin films were converted into Y{sub 2}Si{sub 2}O{sub 7}:Bi films after annealing. • The conversion affected the PL properties of the Bi{sup +} ion in the newly formed host. • A blue shift in emission colour was observed. - Abstract: This paper reports on the structural, morphology and optical properties of Y{sub 2−x}O{sub 3}:Bi{sub x=0.005} micro-and nanophosphors synthesized via the spin coating method. The influence of different annealing temperatures (900–1200 °C) on the morphology, crystal structure and the photoluminescence (PL) properties of the synthesized films were studied in detail. The crystal structure of the films was investigated with X-ray diffraction. The presence of the three major diffraction peaks with Miller indexes (2 1 1), (2 2 2) and (4 0 0) indicated that the Y{sub 2−x}O{sub 3}:Bi{sub x=0.005} thin films were well-crystallized at 900 °C, 1000 °C, 1100 °C and 1200 °C. Additionally, extra diffraction peaks were observed for the sample that was annealed at 1200 °C. Those extra peaks were due to the formation of the Y{sub 2}Si{sub 2}O{sub 7} phase owing to the annealing induced changes in the crystal structure and chemical composition of the Y{sub 2−x}O{sub 3}:Bi{sub x=0.005} thin film. This may also be attributed to inter diffusion of atomic species between the Si substrate and the Y{sub 2−x}O{sub 3}:Bi{sub x=0.005} thin film at the high annealing temperature. Due to structure-sensitive properties of the Bi{sup 3+} ions, a blue shift of the centre PL emission band from 495 nm to 410 nm was clearly observed and explained in detail. The time-of-flight secondary ion mass spectroscopy results show the Si diffusion from the Si substrate, whereas, the scanning electron microscopy and the atomic force microscopy were used for the morphology

  8. Structural and magnetic properties of SiO{sub 2}-CaO-Na{sub 2}O-P{sub 2}O{sub 5} containing BaO-Fe{sub 2}O{sub 3} glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Leenakul, W.; Kantha, P.; Pisitpipathsin, N. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Rujijanagul, G.; Eitssayeam, S. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Pengpat, K., E-mail: kamonpan.p@cmu.ac.th [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2013-01-15

    The incorporation method was employed to produce bioactive glass-ceramics from the BaFe{sub 12}O{sub 19}-SiO{sub 2}-CaO-Na{sub 2}O-P{sub 2}O{sub 5} glass system. The ferrimagnetic BaFe{sub 12}O{sub 19} was first prepared using a simple mixed oxide method, where the oxide precursors of 45S5 bioglass were initially mixed and then melted to form glass. The devitrification of Na{sub 3}Ca{sub 6}(PO{sub 4}){sub 5} and Fe{sub 3}O{sub 4} was observed in all of the quenched glass samples. The glass samples were then subjected to a heat treatment schedule for further crystallization. It was found that the small traces of BaFe{sub 12}O{sub 19} phases started to crystallize in high BF content samples of 20 and 40 wt%. These samples also exhibited good magnetic properties comparable to that of other magnetic glass-ceramics. The bioactivity of the BF glass-ceramics improved with increasing BF content as was evident by the formation of bone-like apatite layers on the surface of all of the glass-ceramics after soaking in SBF for 14 days. The results support the use of these bioactive glass-ceramics for hyperthermia treatment within the human body. - Highlights: Black-Right-Pointing-Pointer BF addition improves the magnetic property and bioactivity of 45S5 bioglasses. Black-Right-Pointing-Pointer Bioglass-ceramics exhibited soft magnetic properties with Mr=14.850 emu/g. Black-Right-Pointing-Pointer Magnetic property can be enhanced by crystallization of BF in 45S5 bioglasses.

  9. Popcorn balls-like ZnFe{sub 2}O{sub 4}-ZrO{sub 2} microsphere for photocatalytic degradation of 2,4-dinitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xi [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Liu, Yutang [Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Xia, Xinnian, E-mail: xnxia@hnu.edu.cn [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Wang, Longlu [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

    2017-06-15

    Highlights: • Popcorn balls-like microsphere photocatalyst. • High photocatalytic activity toward 2,4-DNP degradation. • Degradation kinetics, mechanism, active species were analyzed. • Excellent stable recycling performance. - Abstract: In this paper, novel popcorn balls-like ZnFe{sub 2}O{sub 4}-ZrO{sub 2} composite microspheres were successfully fabricated by a simple hydrothermal method. The morphology, structure and optical property of the microspheres were characterized. The microspheres were used as the photocatalysts to degrade 2,4-dinitrophenol, and exhibited superior photocatalytic performance. Under simulated solar visible light irradiation, the degradation rate of ZnFe{sub 2}O{sub 4}-ZrO{sub 2} photocatalyst (mass ratio of ZnFe{sub 2}O{sub 4}/ZrO{sub 2} = 2:1) was almost 7.4 and 2.4 times higher than those of pure ZnFe{sub 2}O{sub 4} and ZrO{sub 2}. The enhancement could attribute to stronger light absorption, lower carrier recombination and multi-porous structure of the microspheres. Moreover, the popcorn balls-like photocatalysts can be easily separated, because of the magnetism of the samples. After five times runs, the photocatalyst still showed 90% of its photocatalytic degradation efficiency. This work demonstrated a good prospect for removing organic pollutants in water.

  10. Raman Spectroscopy of SiO{sub 2}–Na{sub 2}O–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} glass doped with Nd{sup 3+} and CdS nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Serqueira, E.O.; Dantas, N.O. [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, Uberlândia, MG 38400-902 (Brazil); Anjos, V. [Grupo de Espectroscopia de Materiais, Departamento de Física, ICE – UFJF, Campus Universitário, Juiz de Fora, MG 36036-330 (Brazil); Bell, M.J.V., E-mail: mjvbell@yahoo.com.br [Grupo de Espectroscopia de Materiais, Departamento de Física, ICE – UFJF, Campus Universitário, Juiz de Fora, MG 36036-330 (Brazil)

    2014-01-05

    Highlights: • The formation of CdS nanocrystals in the glassy host is shown by Raman measurements. • Nd{sub 2}O{sub 3} modifies the growth of CdS nanocrystals in the SNAB glass. • Nd{sup 3+} ions are not incorporated inside the semiconductor nanocrystals. -- Abstract: We report the Raman spectroscopic characterization of a SNAB glass system doped with neodymium and CdS nanocrystals and fabricated by the fusion process. Raman spectra revealed CdS nanocrystals in the glass host and bands associated with Si–O vibrational modes with five structural configurations, boroxol modes of B{sub 2}O{sub 3}, Al–O and Cd–S vibrational modes. Additionally, Nd{sub 2}O{sub 3} modifies the growth of CdS nanocrystals in the SNAB glass and Nd{sup 3+} ions are not incorporated inside the semiconductor nanocrystals.

  11. Influence of TiO{sub 2} incorporation in HfO{sub 2} and Al{sub 2}O{sub 3} based capacitor dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Kukli, Kaupo [University of Helsinki, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki (Finland)]. E-mail: Kaupo.Kukli@helsinki.fi; Ritala, Mikko [University of Helsinki, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki (Finland); Leskelae, Markku [University of Helsinki, Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki (Finland); Sundqvist, Jonas [Qimonda Dresden GmbH and Co. OHG, Koenigsbruecker Strasse 180, 01099 Dresden (Germany); Oberbeck, Lars [Qimonda Dresden GmbH and Co. OHG, Koenigsbruecker Strasse 180, 01099 Dresden (Germany); Heitmann, Johannes [Qimonda Dresden GmbH and Co. OHG, Koenigsbruecker Strasse 180, 01099 Dresden (Germany); Schroeder, Uwe [Qimonda Dresden GmbH and Co. OHG, Koenigsbruecker Strasse 180, 01099 Dresden (Germany); Aarik, Jaan [University of Tartu, Institute of Physics, Taehe 4, 51010 Tartu (Estonia); Aidla, Aleks [University of Tartu, Institute of Physics, Taehe 4, 51010 Tartu (Estonia)

    2007-06-04

    Atomic layer deposition was applied to fabricate metal oxide films on planar substrates and also in deep trenches with appreciable step coverage. Atomic layer deposition of Ru electrodes was realized on planar substrates. Electrical and structural behaviour of HfO{sub 2}-TiO{sub 2} and Al{sub 2}O{sub 3}-TiO{sub 2} nanolaminates and mixtures as well as Al{sub 2}O{sub 3} films were evaluated. The lowest leakage current densities with the lowest equivalent oxide thickness were achieved in mixed Al{sub 2}O{sub 3}-TiO{sub 2} films annealed at 700 deg. C, compared to all other films in as-deposited state as well as annealed at 900 deg. C. The highest permittivities in this study were measured on HfO{sub 2}-TiO{sub 2} nanolaminates.

  12. Photocatalytic performances and activities of Ag-doped CuFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhengru, E-mail: zhengruzhu@gmail.com [Research Center of Hydrology and Water Source, School of Urban and Environment, Liaoning Normal University, Dalian, 116029 (China); State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024 (China); Li, Xinyong; Zhao, Qidong [State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024 (China); Li, Yonghua; Sun, Caizhi; Cao, Yongqiang [Research Center of Hydrology and Water Source, School of Urban and Environment, Liaoning Normal University, Dalian, 116029 (China)

    2013-08-01

    Graphical abstract: - Highlights: • CuFe{sub 2}O{sub 4} nanocrystals were synthesized by a co-precipitation method. • Ag/CuFe{sub 2}O{sub 4} catalyst was prepared by the wetness impregnation strategy. • The structural properties of Ag/CuFe{sub 2}O{sub 4} were investigated by XRD, TEM, DRS, and XPS techniques. • Ag/CuFe{sub 2}O{sub 4} has higher photocatalytic activity. - Abstract: In this work, CuFe{sub 2}O{sub 4} nanoparticles were synthesized by a chemical co-precipitation route. The Ag/CuFe{sub 2}O{sub 4} catalyst was prepared based on the CuFe{sub 2}O{sub 4} nanoparticles by the incipient wetness impregnation strategy, which showed excellent photoelectric property and catalytic activity. The structural properties of these samples were systematically investigated by X-ray powder diffraction (XRD), transmission electronic microscopy (TEM), UV–vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) techniques. The photo-induced charge separation in the samples was demonstrated by surface photovoltage (SPV) measurement. The photocatalytic degradation of 4-CP by the Ag/CuFe{sub 2}O{sub 4} and CuFe{sub 2}O{sub 4} samples were comparatively studied under xenon lamp irradiation. The results indicate that the Ag/CuFe{sub 2}O{sub 4} sample exhibited the higher efficiency for the degradation of 4-CP.

  13. Fabrication, characterization, and photocatalytic property of {alpha}-Fe{sub 2}O{sub 3}/graphene oxide composite

    Energy Technology Data Exchange (ETDEWEB)

    Li Hong; Zhao Qidong; Li Xinyong, E-mail: xinyongli@hotmail.com [School of Environmental Science and Technology, Dalian University of Technology, State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering (MOE) (China); Zhu Zhengru [Research Center of Hydrology and Engineering, Academy of City and Environment, Liaoning Normal University (China); Tade, Moses; Liu Shaomin, E-mail: shaomin.liu@curtin.edu.au [Curtin University, Department of Chemical Engineering (Australia)

    2013-06-15

    Spindle-shaped microstructure of {alpha}-Fe{sub 2}O{sub 3} was successfully synthesized by a simple hydrothermal method. The {alpha}-Fe{sub 2}O{sub 3}/graphene oxide (GO) composites was prepared using a modified Hummers' strategy. The properties of the samples were systematically investigated by X-ray powder diffraction (XRD), UV-Vis diffuse reflectance spectrophotometer, transmission electron microscope, atomic force microscope, X-ray photoelectron spectroscopy, and Raman spectroscopy (Raman) techniques. GO nanosheets act as supporting materials for anchoring the {alpha}-Fe{sub 2}O{sub 3} particles. The average crystallite sizes of the {alpha}-Fe{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3}/GO samples are ca. 27 and 24 nm, respectively. The possible growth of {alpha}-Fe{sub 2}O{sub 3} onto GO layers led to a higher absorbance capacity for visible light by {alpha}-Fe{sub 2}O{sub 3}/GO than {alpha}-Fe{sub 2}O{sub 3} composite. The photocatalytic degradation of toluene over the {alpha}-Fe{sub 2}O{sub 3} and {alpha}-Fe{sub 2}O{sub 3}/GO samples under xenon-lamp irradiation was comparatively studied by in situ FTIR technique. The results indicate that the {alpha}-Fe{sub 2}O{sub 3}/GO sample synthesized exhibited a higher capacity for the degradation of toluene. The composite of {alpha}-Fe{sub 2}O{sub 3}/GO could be promisingly applied in photo-driven air purification.

  14. Luminescence of Cr{sup 3+} ions in ZnAl{sub 2}O{sub 4} and MgAl{sub 2}O{sub 4} spinels: correlation between experimental spectroscopic studies and crystal field calculations

    Energy Technology Data Exchange (ETDEWEB)

    Brik, M.G., E-mail: mikhail.brik@ut.ee [College of Sciences, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, W. Ostwald Str. 1, Tartu 50411 (Estonia); Institute of Physics, Jan Dlugosz University, Al. Armii Krajowej 13/15, Czestochowa PL-42200 (Poland); Papan, J.; Jovanović, D.J. [University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, Belgrade 11001 (Serbia); Dramićanin, M.D., E-mail: dramican@vinca.rs [University of Belgrade, Vinča Institute of Nuclear Sciences, P.O. Box 522, Belgrade 11001 (Serbia)

    2016-09-15

    Details of preparation, spectroscopic and structural studies along with crystal field calculations for two Cr{sup 3+} doped spinels MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} are given in the present paper. Both compounds show efficient red emission at about 685 nm, which is due to the {sup 2}E{sub g} → {sup 4}A{sub 2g} spin-forbidden transition of Cr{sup 3+} ions located at the sites with D{sub 3d} local symmetry. Analysis of structure of the CrO{sub 6} clusters was performed; comparison of the crystal field effects in both compounds revealed that the low-symmetry splitting of the orbital triplet states is more pronounced in ZnAl{sub 2}O{sub 4}. Both compounds show potential for applications as red-emitting phosphors. - Highlights: • Cr{sup 3+}-doped MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} spinels were synthesized. • Excitation/emission spectra were recorded and analyzed. • Symmetry properties of the Cr-sites were analyzed. • Cr{sup 3+} energy levels in trigonal crystal field were calculated. • Cr{sup 3+}-doped MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} spinels can be used as red phosphors.

  15. Performance assessment of the catalyst ZnAl{sub 2}O{sub 4} and Cu/ZnAl{sub 2}O{sub 4} esterification reaction fatty acid in biodiesel; Avaliacao do desempenho do catalisador ZnAl{sub 2}O{sub 4} e Cu/ZnAl{sub 2}O{sub 4} na reacao de estereficacao de acidos graxos em biodiesel

    Energy Technology Data Exchange (ETDEWEB)

    Feitosa, A.C.; Dantas, J.; Costa, A.C.M.F., E-mail: alexcaval2@hotmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais; Barbosa, D.C.; Meneghetti, S.M.P. [Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil). Dept. de Quimica

    2012-07-01

    This study aims to evaluate the performance of the Cu/ZnAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} methyl esterification of fatty acids of soybean oil into biodiesel. The ZnAl{sub 2}O{sub 4} was synthesized by combustion reaction and then the sample was wet impregnated with a copper source. The samples were characterized by XRD, SEM, textural analysis and catalytic tests bench. The characterization results showed that the samples showed characteristic diffraction peaks spinel, with the characteristic of mesoporous material (10-250 Å), particles in the form of blocks and slabs of hard point. The results showed that the conversion impregnation of copper has increased by 17% conversion to biodiesel. (author)

  16. Simulated-sunlight-activated photocatalysis of Methyl Orange using carbon and lanthanum co-doped Bi{sub 2}O{sub 3}–TiO{sub 2} composite

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Hao [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Song, Mianxin, E-mail: songmianxin@swust.edu.cn [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Yi, Facheng [Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Bian, Liang [The Xinjiang Technical Institute of Physics & Chemistry, Urumqi 830011 (China); Liu, Pan [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Zhang, Shuai [Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China)

    2016-09-25

    The C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite was prepared by sol-gel method. The physicochemical properties of as-synthesized samples were characterized by the TG-DSC, FESEM, EDS, XRD, XPS, TEM, HRTEM and UV–vis DRS. Besides, their photoactivities were valuated by degrading Methyl Orange. The experimental results showed that the C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite has anatase crystal structure and exhibits a remarkable optical absorption in UV–visible light region. In addition, carbon and lanthanum are deposited in the Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of amorphous carbon and oxide, respectively. When the concentration of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} loading was 2.5 g/L, the decomposition rate of 25 mg/L Methyl Orange reached 94.3% under the irradiation of the 500 W xenon lamp after 60 min. The corresponding degradation rate constant of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} was 2.1, 9.2, 1.3 and 6.8 times higher than that of P25, Bi{sub 2}O{sub 3}–TiO{sub 2}, C/Bi{sub 2}O{sub 3}–TiO{sub 2} and La/Bi{sub 2}O{sub 3}–TiO{sub 2}, respectively. The reuse evaluation of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} indicated that its photocatalytic activity has good stability. - Highlights: • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite was prepared by sol-gel method. • Carbon is deposited in Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of amorphous carbon. • Lanthanum is deposited in Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of oxide. • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} exhibited superior photocatalytic activity than Bi{sub 2}O{sub 3}–TiO{sub 2}, C/Bi{sub 2}O{sub 3}–TiO{sub 2} and La/Bi{sub 2}O{sub 3}–TiO{sub 2}. • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} has good stability.

  17. Magnetism and thermal induced characteristics of Fe{sub 2}O{sub 3} content bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Chun-Shiang; Hsi, Chi-Shiung [Department of Materials Science and Engineering, National United University, Miaoli 36003, Taiwan (China); Hsu, Fang-Chi, E-mail: fangchi@nuu.edu.tw [Department of Materials Science and Engineering, National United University, Miaoli 36003, Taiwan (China); Wang, Moo-Chin [Department of Fragrance and Cosmetics, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Chen, Yung-Sheng [Department of Materials Science and Engineering, I-Shou University, Kaohsiung 803, Taiwan (China)

    2012-11-15

    Magnetic properties of Li{sub 2}O-MnO{sub 2}-CaO-P{sub 2}O{sub 5}-SiO{sub 2} (LMCPS) glasses doped with various amounts of Fe{sub 2}O{sub 3} were investigated. There is a dramatic change in the magnetic property of pristine LMCPS after the addition of Fe{sub 2}O{sub 3} and crystallized at 850 Degree-Sign C for 4 h. Both the electron paramagnetic resonance and magnetic susceptibility measurements showed that the glass ceramic with 4 at% Fe{sub 2}O{sub 3} exhibited the coexistence of superparamagnetism and ferromagnetism at room temperature. When the Fe{sub 2}O{sub 3} content was higher than 8 at%, the LMCPS glasses showed ferromagnetism behavior. The complex magnetic behavior is due to the distribution of (Li, Mn)ferrite particle sizes driven by the Fe{sub 2}O{sub 3} content. The thermal induced hysteresis loss of the crystallized LMCPS glass ceramics was characterized under an alternating magnetic field. The energy dissipations of the crystallized LMCPS glass ceramics were determined by the concentration and Mn/Fe ratios of Li(Mn, Fe)ferrite phase formed in the glass ceramics. - Highlights: Black-Right-Pointing-Pointer Presence of Fe{sub 2}O{sub 3} in LMCPS glass ceramic promotes the growth of (Li, Mn)ferrite. Black-Right-Pointing-Pointer The amount of Fe{sub 2}O{sub 3} determines the size of (Li,Mn)ferrite particles. Black-Right-Pointing-Pointer Room temperature superparamagnetism was obtained at 4 at% of Fe{sub 2}O{sub 3} addition. Black-Right-Pointing-Pointer In addition, Li(Mn, Fe)ferrite phase contributes to the magnetic energy loss. Black-Right-Pointing-Pointer The largest energy loss is the trade-off between the ferrite content and Mn/Fe ratio.

  18. A comparative study of charge trapping in HfO{sub 2}/Al{sub 2}O{sub 3} and ZrO{sub 2}/Al{sub 2}O{sub 3} based multilayered metal/high-k/oxide/Si structures

    Energy Technology Data Exchange (ETDEWEB)

    Spassov, D., E-mail: d_spassov@abv.bg [Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Skeparovski, A. [Institute of Physics, Faculty of Natural Sciences and Mathematics, University “Ss. Cyril and Methodius”, Arhimedova 3, 1000 Skopje (Macedonia, The Former Yugoslav Republic of); Paskaleva, A. [Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia 1784 (Bulgaria); Novkovski, N. [Institute of Physics, Faculty of Natural Sciences and Mathematics, University “Ss. Cyril and Methodius”, Arhimedova 3, 1000 Skopje (Macedonia, The Former Yugoslav Republic of)

    2016-09-01

    The electrical properties of multilayered HfO{sub 2}/Al{sub 2}O{sub 3}/HfO{sub 2}/SiO{sub 2} and ZrO{sub 2}/Al{sub 2}O{sub 3}/ZrO{sub 2}/SiO{sub 2} metal-oxide semiconductor capacitors were investigated in order to evaluate the possibility of their application in charge-trapping non-volatile memory devices. The stacks were deposited by reactive radiofrequency magnetron sputtering on Si substrates with thermal SiO{sub 2} with a thickness ranging from 2 to 5 nm. Both types of stacks show negative initial oxide charge and its density is higher for HfO{sub 2}-based structures. Memory window up to 6V at sweeping voltage range of ± 16V was obtained for HfO{sub 2}-based stacks. The hysteresis in these structures is mainly due to a trapping of electrons injected from the Si substrate. The charge-trapping properties of ZrO{sub 2}-based samples are compromised by the high leakage currents and the dielectric breakdown. The conduction through the capacitors at low applied voltages results from hopping of thermally excited electrons from one isolated state to another. The energy depth of the traps participating in the hopping conduction was determined as ~ 0.7 eV for the HfO{sub 2}-based layers and ~ 0.6 eV for ZrO{sub 2}-based ones, originating from negatively charged oxygen vacancies. At high electric fields, the current voltage characteristics were interpreted in terms of space charge limited currents, Fowler–Nordheim tunneling, Schottky emission, and Poole–Frenkel mechanism. The charge retention characteristics do not depend on the thickness of the tunnel SiO{sub 2}. - Highlights: • Sputtered HfO{sub 2}/Al{sub 2}O{sub 3}/HfO{sub 2} and ZrO{sub 2}/Al{sub 2}O{sub 3}/ZrO{sub 2} charge-trapping layers were studied. • HfO{sub 2}/Al{sub 2}O{sub 3}/HfO{sub 2} stacks show memory window up to 6 V and good retention times. • Negatively charged oxygen vacancies were identified as main defects in the stacks. • Electrical breakdown compromise the charge-trapping properties

  19. Chemical synthesis of Fe{sub 2}O{sub 3} thin films for supercapacitor application

    Energy Technology Data Exchange (ETDEWEB)

    Kulal, P.M.; Dubal, D.P.; Lokhande, C.D. [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India); Fulari, V.J., E-mail: vijayfulari@gmail.com [Holography and Material Research Laboratory, Department of Physics, Shivaji University, Kolhapur 416004, M.S. (India)

    2011-02-03

    Research highlights: > Simple chemical synthesis of Fe{sub 2}O{sub 3}. > Formation of amorphous and hydrous Fe{sub 2}O{sub 3}. > Potential candidate for supercapacitors. - Abstract: Fe{sub 2}O{sub 3} thin films have been prepared by novel chemical successive ionic layer adsorption and reaction (SILAR) method. Further these films were characterized for their structural, morphological and optical properties by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, scanning electron microscopy (SEM), wettability test and optical absorption studies. The XRD pattern showed that the Fe{sub 2}O{sub 3} films exhibit amorphous in nature. Formation of iron oxide compound was confirmed from FTIR studies. The optical absorption showed existence of direct optical band gap of energy 2.2 eV. Fe{sub 2}O{sub 3} film surface showed superhydrophilic nature with water contact angle less than 10{sup o}. The supercapacitive properties of Fe{sub 2}O{sub 3} thin film investigated in 1 M NaOH electrolyte showed supercapacitance of 178 F g{sup -1} at scan rate 5 mV/s.

  20. Degradation and mineralization of organic UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) using UV-254 nm/H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Abdelraheem, Wael H.M. [Chemistry Department, Faculty of Science, Sohag University, Sohag 82524 (Egypt); Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); He, Xuexiang; Duan, Xiaodi [Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); NIREAS-International Water Research Center, University of Cyprus, Nicosia 1678 (Cyprus); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); NIREAS-International Water Research Center, University of Cyprus, Nicosia 1678 (Cyprus)

    2015-01-23

    Graphical abstract: - Highlights: • UV-254 nm/H{sub 2}O{sub 2} AOP was utilized for the degradation and mineralization of PBSA and BSA. • Promotion of k{sub obs} with [H{sub 2}O{sub 2}]{sub 0} ≤ 4 mM and inhibition at higher [H{sub 2}O{sub 2}]{sub 0} were observed. • The S and N were released and monitored as SO{sub 4}{sup 2−} and NH{sub 4}{sup +}, respectively. • Br{sup −} inhibited both the degradation and mineralization much more significantly than Cl{sup −}. • There was an increase in [NH{sub 4}{sup +}] at higher [H{sub 2}O{sub 2}]{sub 0} and its further destruction at higher UV fluence. - Abstract: Various studies have revealed the non-biodegradable and endocrine disrupting properties of sulfonated organic UV absorbers, directing people's attention toward their risks on ecological and human health and hence their removal from water. In this study, UV-254 nm/H{sub 2}O{sub 2} advanced oxidation process (AOP) was investigated for degrading a model UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and a structurally similar compound 1H-benzimidazole-2-sulfonic acid (BSA), with a specific focus on their mineralization. At 4.0 mM [H{sub 2}O{sub 2}]{sub 0}, a complete removal of 40.0 μM parent PBSA and 25% decrease in TOC were achieved with 190 min of UV irradiation; SO{sub 4}{sup 2−} was formed and reached its maximum level while the release of nitrogen as NH{sub 4}{sup +} was much lower (around 50%) at 190 min. Sulfate removal was strongly enhanced by increasing [H{sub 2}O{sub 2}]{sub 0} in the range of 0–4.0 mM, with slight inhibition in 4.0–12.0 mM. Faster and earlier ammonia formation was observed at higher [H{sub 2}O{sub 2}]{sub 0}. The presence of Br{sup −} slowed down the degradation and mineralization of both compounds while a negligible effect on the degradation was observed in the presence of Cl{sup −}. Our study provides important technical and fundamental results on the HO{sup ·} based degradation and

  1. Compatibility of yttria (Y{sub 2}O{sub 3}) with liquid lithium

    Energy Technology Data Exchange (ETDEWEB)

    Mitsuyama, Takaaki; Yoneoka, Toshiaki; Terai, Takayuki; Tanaka, Satoru [Tokyo Univ. (Japan). Faculty of Engineering

    1996-10-01

    Compatibility of Y{sub 2}O{sub 3} sintered specimens with liquid lithium was tested at 773K. No configuration change was observed with a slight increase of thickness for 1419 hr. Lithium-yttrium complex oxide (LiYO{sub 2}) was formed on the surface, and the inner part changed to gray or black nonstoichiometric Y{sub 2}O{sub 3-X} with lower electrical resistibility. It is concluded that Y{sub 2}O{sub 3} has a possibility as a ceramic coating material for liquid blankets if it can be made into a dense coating on the surface of piping materials. (author)

  2. Neutron scattering study on cathode LiMn{sub 2}O{sub 4} and solid electrolyte 5(Li{sub 2}O)(P{sub 2}O{sub 5})

    Energy Technology Data Exchange (ETDEWEB)

    Kartini, E., E-mail: kartini@batan.go.id; Putra, Teguh P., E-mail: kartini@batan.go.id; Jahya, A. K., E-mail: kartini@batan.go.id; Insani, A., E-mail: kartini@batan.go.id [Technology Center for Nuclear Industry Materials, National Nuclear Energy Agency, Serpong 15314 (Indonesia); Adams, S. [Department of Materials Science and Engineering, National University of Singapore, Singapore-117576 (Singapore)

    2014-09-30

    Neutron scattering is very important technique in order to investigate the energy storage materials such as lithium-ion battery. The unique advantages, neutron can see the light atoms such as Hydrogen, Lithium, and Oxygen, where those elements are negligible by other corresponding X-ray method. On the other hand, the energy storage materials, such as lithium ion battery is very important for the application in the electric vehicles, electronic devices or home appliances. The battery contains electrodes (anode and cathode), and the electrolyte materials. There are many challenging to improve the existing lithium ion battery materials, in order to increase their life time, cyclic ability and also its stability. One of the most scientific challenging is to investigate the crystal structure of both electrode and electrolyte, such as cathodes LiCoO{sub 2}, LiMn{sub 2}O{sub 4} and LiFePO{sub 4}, and solid electrolyte Li{sub 3}PO{sub 4}. Since all those battery materials contain Lithium ions and Oxygen, the used of neutron scattering techniques to study their structure and related properties are very important and indispensable. This article will review some works of investigating electrodes and electrolytes, LiMn{sub 2}O{sub 4} and 5(Li{sub 2}O)(P{sub 2}O{sub 5}), by using a high resolution powder diffraction (HRPD) at the multipurpose research reactor, RSG-Sywabessy of the National Nuclear Energy Agency (BATAN), Indonesia.

  3. Facile synthesis and electrical switching properties of V{sub 2}O{sub 3} powders

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Haining; Liu, Dongqing, E-mail: dongqingliu@ymail.com; Cheng, Haifeng; Yang, Lixiang; Zhang, Chaoyang; Zheng, Wenwei

    2017-03-15

    Highlights: • Single crystal uniform V{sub 2}O{sub 3} powders have been synthesized without additional surfactant. • Powders were obtained in only 6 h. • Powders exhibit reversible phase transition properties. • Powders have excellent electrical switching properties with resistance changes as large as 10{sup 4}. - Abstract: V{sub 2}O{sub 3} powders were synthesized with mercaptoacetic acid (C{sub 2}H{sub 4}O{sub 2}S) as reducing agent and stabilizer via a facile hydrothermal approach. The crystalline structure, surface morphology, valence state of the derived V{sub 2}O{sub 3} powders were characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy. It was found that the ratio and reaction time played a duel role in the formation and morphology of the V{sub 2}O{sub 3} powders. The metal-insulator transition properties of V{sub 2}O{sub 3} powders were studied by the differential scanning calorimetry curve and variable temperature Raman spectra. The change in electrical resistance due to the metal-insulator transition was measured from 80 to 240 K using physical property measurement system. The results showed V{sub 2}O{sub 3} samples had excellent electrical switching properties with resistance changes as large as 10{sup 4}. This simple and fast synthesis approach makes the V{sub 2}O{sub 3} powders easily accessible for exploring their fundamental properties and potential applications in novel electronic devices.

  4. A practical pathway for the preparation of Fe{sub 2}O{sub 3} decorated TiO{sub 2} photocatalyst with enhanced visible-light photoactivity

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Li; Qiu, Shoufei [Institute of Polymer Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen, Juanrong, E-mail: Juanrongchen@ujs.edu.cn [School of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013 (China); Shao, Jian [Institute of Polymer Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Cao, Shunsheng, E-mail: sscaochem@hotmail.com [Institute of Polymer Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2017-04-01

    Shifting the ultra-violet of titania to visible light driven photocatalysis can be realized by coupling with metallic or non-metallic elements. However, time-consuming multi-step process and significant loss of UV photocatalytic activity of such TiO{sub 2}-based photocatalysts severely hinder their practical applications. In this work, we explore the idea of creating a practical method for the preparation of Fe{sub 2}O{sub 3} decorated TiO{sub 2} (TiO{sub 2}/Fe{sub 2}O{sub 3}) photocatalyst with controlled visible-light photoactivity. This method only involves the calcination of the mixture (commercial P25 powders and magnetic Fe{sub 3}O{sub 4} nanoparticles) prepared by a mechanical process. The morphology and properties of TiO{sub 2}/Fe{sub 2}O{sub 3} composites were characterized by Transmission electron microscope, X-ray diffraction, UV–vis spectroscopy, and X-ray photoelectron spectroscopy. Results confirm the fusion of TiO{sub 2} and Fe{sub 2}O{sub 3}, which promotes photo-generated electrons/holes migration and separation. Because of the strong synergistic effect, the as-synthesized TiO{sub 2}/Fe{sub 2}O{sub 3} composites manifest an enhanced visible-light photocatalytic activity. Especially, the TiO{sub 2}/Fe{sub 2}O{sub 3} photocatalyst is very easy to be constructed via an one-step protocol that efficiently overcomes the time-consuming multi-step processes used in existed strategies for the preparation of Fe{sub 2}O{sub 3}/TiO{sub 2} photocatalysts, providing a new insight into the practical application of TiO{sub 2}/Fe{sub 2}O{sub 3} visible light photocatalyst. - Highlights: • We introduced a practical preparation of Fe{sub 2}O{sub 3} decorated TiO{sub 2} photocatalyst. • TiO{sub 2}/Fe{sub 2}O{sub 3} was developed using commercial precursors in a high efficient manner. • Visible-light activity of TiO{sub 2}/Fe{sub 2}O{sub 3} could be tuned by changing amount of Fe{sub 3}O{sub 4} precursor. • TiO{sub 2}/Fe{sub 2}O{sub 3} exhibited a higher

  5. Synthesis, characterization and adsorptive performance of MgFe{sub 2}O{sub 4} nanospheres for SO{sub 2} removal

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Ling [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian 116024 (China); Li Xinyong, E-mail: xyli@dlut.edu.cn [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian 116024 (China); Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Zhao Qidong; Qu Zhenping; Yuan Deling [Key Laboratory of Industrial Ecology and Environmental Engineering and State Key Laboratory of Fine Chemical, School of Environmental Sciences and Technology, Dalian University of Technology, Dalian 116024 (China); Liu Shaomin [Department of Chemical Engineering, Curtin University of Technology, Perth, WA 6845 (Australia); Hu Xijun; Chen Guohua [Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2010-12-15

    A type of uniform Mg ferrite nanospheres with excellent SO{sub 2} adsorption capacity could be selectively synthesized via a facile solvothermal method. The size of the MgFe{sub 2}O{sub 4} nanospheres was controlled to be 300-400 nm in diameter. The structural, textural, and surface properties of the adsorbent have been fully characterized by a variety of techniques (Brunauer-Emmett-Teller, BET; X-ray diffraction analysis, XRD; scanning electron microscopy, SEM; and energy-dispersive X-ray spectroscopy, EDS). The valence states and the surface chemical compositions of MgFe{sub 2}O{sub 4} nanospheres were further identified by X-ray photoelectron spectroscopy (XPS). The behaviors of SO{sub 2} oxidative adsorption on MgFe{sub 2}O{sub 4} nanospheres were studied using Fourier transform infrared spectroscopy (FTIR). Both the sulfite and sulfate species could be formed on the surface of MgFe{sub 2}O{sub 4}. The adsorption equilibrium isotherm of SO{sub 2} was analyzed using a volumetric method at 298 K and 473 K. The results indicate that MgFe{sub 2}O{sub 4} nanospheres possess a good potential as the solid-state SO{sub 2} adsorbent for applications in hot fuel gas desulfurization.

  6. Photoelectric characteristics of metal-Ga{sub 2}O{sub 3}-GaAs structures

    Energy Technology Data Exchange (ETDEWEB)

    Kalygina, V. M., E-mail: Kalygina@ngs.ru; Vishnikina, V. V.; Petrova, Yu. S.; Prudaev, I. A.; Yaskevich, T. M. [National Research Tomsk State University (Russian Federation)

    2015-03-15

    We investigate the effect of thermal annealing in argon and of oxygen plasma processing on the photoelectric properties of GaAs-Ga{sub 2}O{sub 3}-Me structures. Gallium-oxide films are fabricated by photostimulated electrochemical oxidation of epitaxial gallium-arsenide layers with n-type conductivity. The as-deposited films were amorphous, but their processing in oxygen plasma led to the nucleation of β-Ga{sub 2}O{sub 3} crystallites. The unannealed films are nontransparent in the visible and ultraviolet (UV) ranges and there is no photocurrent in structures based on them. After annealing at 900°C for 30 min, the gallium-oxide films contain only β-Ga{sub 2}O{sub 3} crystallites and become transparent. Under illumination of the Ga{sub 2}O{sub 3}-GaAs structures with visible light, the photocurrent appears. This effect can be attributed to radiation absorption in GaAs. The photocurrent and its voltage dependence are determined by the time of exposure to the oxygen plasma. In the UV range, the sensitivity of the structures increases with decreasing radiation wavelength, starting at λ ≤ 230 nm. This is due to absorption in the Ga{sub 2}O{sub 3} film. Reduction in the structure sensitivity with an increase in the time of exposure to oxygen plasma can be caused by the incorporation of defects both at the Ga{sub 2}O{sub 3}-GaAs interface and in the Ga{sub 2}O{sub 3} film.

  7. The effects of de-humidification and O{sub 2} direct injection in oxy-PC combustion

    Energy Technology Data Exchange (ETDEWEB)

    Choi, C.G.; Na, I.H.; Lee, J.W.; Chae, T.Y.; Yang, W. [Korea Insitute of Industrial Technology, Seoul (Korea, Republic of). Energy System R and D Dept.

    2013-07-01

    This study is aimed to derive effects of de-humidification and O{sub 2} direct injection in oxy-PC combustion system. Temperature distribution and flue gas composition were observed for various air and oxy-fuel conditions such as effect of various O{sub 2} concentration of total oxidant, O{sub 2} concentration of primary stream and O{sub 2} direct injection through 0-D heat and mass balance calculation and experiments in the oxy-PC combustion system of 0.3 MW scale in KITECH (Korea Institute of Industrial Technology). Flame attachment characteristic related to O{sub 2} direct injection was also observed experimentally. We found that FEGT (furnace exit gas temperature) of 100% de-humidification to oxidizer is lower than humidification condition; difference between two conditions is lower than 20 C in all cases. The efficiency changing of combustion was negligible in O{sub 2} direct injection. But O{sub 2} direct injection should be carefully designed to produce a stable flame.

  8. Preparation and photocatalytic activity of ZnO/Fe{sub 2}O{sub 3} nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yanjun; Sun, Li; Wu, Jiagen; Fang, Ting; Cai, Ran; Wei, Ang, E-mail: wei1177@126.com

    2015-04-15

    Highlights: • ZnO/Fe{sub 2}O{sub 3} tubular structure was prepared via photochemical deposition at RT. • The composites show a great improvement in photocatalytic characteristics. • The possible reasons of photocatalytic performance of composites were researched. • The formation mechanism of ZnO/Fe{sub 2}O{sub 3} tubular structure was discussed. - Abstract: Fe{sub 2}O{sub 3} nanoparticles were grown on ZnO nanorods (NRs) to form ZnO/Fe{sub 2}O{sub 3} nanotube (NT) composites via photochemical deposition under ultraviolet light irradiation at a room temperature. Fe{sup 3+} ions in the solution preferentially adhere to the metastable Zn-rich (0 0 0 1) polar surfaces in ZnO NRs, which leading to the formation of ZnO/Fe{sub 2}O{sub 3} NTs. ZnO/Fe{sub 2}O{sub 3} NT nanocomposites show a great improvement in photocatalytic characteristics compared with the bare ZnO NRs. It can be inferred that the enhanced photocatalytic performance of ZnO/Fe{sub 2}O{sub 3} is benefit from the synergistic effect of ZnO and Fe{sub 2}O{sub 3} semiconductors.

  9. Thermal and fragility studies on microwave synthesized K{sub 2}O-B{sub 2}O{sub 3}-V{sub 2}O{sub 5} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Harikamalasree [R& D Center, Bharatiar University, Coimbatore, Tamil Nadu (India); Department of Physics, M LR Institute of Technology Hyderabad-043 (India); Reddy, M. Sudhakara [Department of Physics, School of Graduate Studies, Jain University, Bangalore56002 (India); Viswanatha, R. [Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012 (India); Reddy, C. Narayana, E-mail: nivetejareddy@gmail.com [Department of Physics, Sree Siddaganga College of Arts, Science and Commerce, Tumkur 572102 (India)

    2016-05-06

    Glasses with composition xK{sub 2}O–60B{sub 2}O{sub 3}–(40-x) V{sub 2}O{sub 5} (15 ≤ x ≤ 39 mol %) was prepared by an energy efficient microwave method. The heat capacity change (ΔC{sub p}) at glass transition (T{sub g}), width of glass transition (ΔT{sub g}), heat capacities in the glassy (C{sub pg}) and liquid (C{sub pl}) state for the investigated glasses were extracted from Modulated Differential Scanning Calorimetry (MDSC) thermograms. The width of glass transition is less than 30°C, indicating that these glasses belongs to fragile category. Fragility functions [NBO]/(V{sub m}{sup 3}T{sub g}) and (ΔC{sub p}/C{sub pl})increases with increasing modifier oxide concentration. Increase in fragility is attributed to the increasing coordination of boron. Further, addition of K{sub 2}O creates NBOs and the flow mechanism involves bond switching between BOs and NBOs. Physical properties exhibit compositional dependence and these properties increase with increasing K{sub 2}O concentration. The observed variations are qualitatively analyzed.

  10. Improving photoelectrochemical performance by building Fe{sub 2}O{sub 3} heterostructure on TiO{sub 2} nanorod arrays

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Chunlan [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Key Laboratory of Special Power Supply, Chongqing Communication Institute, Chongqing 400035 (China); Hu, Chenguo, E-mail: hucg@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Shen, Weidong [Key Laboratory of Special Power Supply, Chongqing Communication Institute, Chongqing 400035 (China); Wang, Shuxia, E-mail: wangshuxia@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Song, Sihong [Key Laboratory of Special Power Supply, Chongqing Communication Institute, Chongqing 400035 (China); Wang, Mingjun [Department of Applied Physics, Chongqing University, Chongqing 400044 (China)

    2015-10-15

    Highlights: • Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure was fabricated by two-step method. • The photoelectrochemical properties were studied upon visible light irradiation. • Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure shows superior photoelectrochemical property. • A possible mechanism for enhanced photoelectrochemical property was put forward. - Abstract: Fe{sub 2}O{sub 3}@TiO{sub 2} heterostructure nanorod arrays were synthesized on a fluorine-doped tin oxide conductive (FTO) glass substrate via two-step method for improving photoelectrochemical activity of TiO{sub 2}. The TiO{sub 2} nanorod arrays on FTO substrate were first prepared by hydrothermal method and then Fe{sub 2}O{sub 3} nanoparticles were coated onto the surface of TiO{sub 2} nanorod arrays through chemical bath deposition. The heterojunction yielded a photocurrent density of 39.75 μA cm{sup −2} at a bias potential of 0 V (vs. Ag/AgCl) under visible light irradiation, which is 2.2 times as much as that produced by the pure TiO{sub 2} nanorod arrays. The enhanced photoelectrochemical activity is attributed to the extension of the light response range and efficient separation of photogenerated carriers. Our results have demonstrated the advantage of the novel Fe{sub 2}O{sub 3}@TiO{sub 2} heterojunction and will provide a new path to the fabrication of heterostructural materials.

  11. Structure of Na/sub 2/As/sub 4/O/sub 11/

    Energy Technology Data Exchange (ETDEWEB)

    Driss, A.; Jouini, T.; Omezzine, M.

    1988-05-15

    Disodium tetraarsenate, M/sub r/=521.66, monoclinic, C2/c, a=9.049(3), b=8.287(3), c=11.508(5) A, ..beta..=102.74(4)/sup 0/, V=842(2) A/sup 3/, Z=4, D/sub m/=4.06 (by flotation), D/sub x/=4.11 Mg m/sup -3/, lambda(AgK anti ..cap alpha..)=0.5608 A, ..mu..=8.6 mm/sup -1/, F(000)=968, room temperature, final R=0.046 and ..omega..R=0.048 for 1153 independent reflections. The main feature of this structure is the existence of the first three-dimensional anion (As/sub 4/O/sub 11/)/sub n//sup 2n-/ in the chemistry of the condensed arsenates. It has the lowest O/As ratio (2.75) of the known arsenates showing marked condensation: all the O atoms are shared except one per AsO/sub 4/ tetrahedron. The structural unit is the As/sub 4/O/sub 15/ ring with point symmetry 2, built up from alternate AsO/sub 4/ tetrahedra and AsO/sub 6/ octahedra sharing corners. In addition, the two octahedra share one O atom located on the 2 axis. The As/sub 4/O/sub 15/ ring derives from the known centrosymmetric As/sub 4/O/sub 14/ ring by the cleavage of one As-O-As linkage between the two octahedra of the ring to form two new As-O-As linkages with AsO/sub 4/ tetrahedra connecting two rings, leading to a decrease of the O/As ratio. The As/sub 4/O/sub 15/ rings are further linked by sharing edges of AsO/sub 6/ octahedra to form a three-dimensional framework. This completes the set of the already known arrangements of the As/sub 4/O/sub 14/ ring (isolated units, infinite chains, layers).

  12. Thermoluminescence and optically stimulated luminescence properties of Dy{sup 3+}-doped CaO–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3}-based glasses

    Energy Technology Data Exchange (ETDEWEB)

    Yahaba, T., E-mail: takuma.yahaba.s1@dc.tohoku.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Fujimoto, Y. [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Yanagida, T. [Nara Institute of Science and Technology (NAIST), 8916-5 Takayama, Ikoma 630-0192 (Japan); Koshimizu, M.; Tanaka, H.; Saeki, K.; Asai, K. [Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-07 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan)

    2017-02-01

    We developed Dy{sup 3+}-doped CaO–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} based glasses with Dy concentrations of 0.5, 1.0, and 2.0 mol% using a melt-quenching technique. The as-synthesized glasses were applicable as materials exhibiting thermoluminescence (TL) and optically stimulated luminescence (OSL). The optical and radiation response properties of the glasses were characterized. In the photoluminescence (PL) spectra, two emission bands due to the {sup 4}F{sub 9/2} → {sup 6}H{sub 15/2} and {sup 4}F{sub 9/2} → {sup 6}H{sub 13/2} transitions of Dy{sup 3+} were observed at 480 and 580 nm. In the OSL spectra, the emission band due to the {sup 4}F{sub 9/2} → {sup 6}H{sub 15/2} transition of Dy{sup 3+} was observed. Excellent TL and OSL responses were observed for dose ranges of 0.1–90 Gy. In addition, TL fading behavior was better than that of OSL in term of the long-time storage. These results indicate that the Dy{sup 3+}-doped CaO–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3}-based glasses are applicable as TL materials.

  13. From Ba{sub 3}Ta{sub 5}O{sub 14}N to LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2}: Decreasing the optical band gap of a photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Anke, B. [Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany); Bredow, T. [Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie, Universität Bonn, Beringstr. 4, 53115 Bonn (Germany); Pilarski, M.; Wark, M. [Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany); Lerch, M., E-mail: martin.lerch@tu-berlin.de [Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin (Germany)

    2017-02-15

    Yellow LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} was successfully synthesized as phase-pure material crystallizing isostructurally to previously reported Ba{sub 3}Ta{sub 5}O{sub 14}N and mixed-valence Ba{sub 3}Ta{sup V}{sub 4}Ta{sup IV}O{sub 15}. The electronic structure of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} was studied theoretically with the range-separated hybrid method HSE06. The most stable structure was obtained when lanthanum was placed on 2a and nitrogen on 4h sites confirming Pauling's second rule. By incorporating nitrogen, the measured band gap decreases from ∼3.8 eV for the oxide via 2.74 eV for Ba{sub 3}Ta{sub 5}O{sub 14}N to 2.63 eV for the new oxide nitride, giving rise to an absorption band well in the visible-light region. Calculated fundamental band gaps confirm the experimental trend. The atom-projected density of states has large contributions from N2p orbitals close to the valence band edge. These are responsible for the observed band gap reduction. Photocatalytic hydrogen formation was investigated and compared with that of Ba{sub 3}Ta{sub 5}O{sub 14}N revealing significantly higher activity for LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} under UV-light. - Graphical abstract: X-ray powder diffraction pattern of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} with the results of the Rietveld refinements. Inset: Unit cell of LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2} and polyhedral representation of the crystal structure. - Highlights: • Synthesis of a new oxide nitride LaBa{sub 2}Ta{sub 5}O{sub 13}N{sub 2}. • Refinement of the crystal structure. • Quantum chemical calculations provided band gap close to the measured value. • New phase shows a higher photocatalytic H{sub 2} evolution rate compared to prior tested Ba{sub 3}Ta{sub 5}O{sub 14}N.

  14. Raman and FTIR spectra of CeO{sub 2} and Gd{sub 2}O{sub 3} in iron phosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Yuanming, E-mail: laiyuanming@ipm.com.cn [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106 (China); State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Liang, Xiaofeng; Yang, Shiyuan [State Key Laboratory Cultivation Base for Nonmetal Composite and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Liu, Pei; Zeng, Yiming; Hu, Changyi [State Key Laboratory of Advanced Technologies for Comprehensive Utilization of Platinum Metals, Kunming Institute of Precious Metals, Kunming 650106 (China)

    2014-12-25

    Highlights: • The structure of the studied samples has been investigated by Raman and FTIR spectroscopy. • The structure for the all samples has similar features. • The structure consists of predominantly Q{sup 1} with a fraction of Q{sup 0} and Q{sup 2} units. • The Ce and Gd enters in the structure of studied glasses as a network modifier. - Abstract: In the present work, multicomponent oxide samples of composition x(CeO{sub 2} + Gd{sub 2}O{sub 3})–(40 − x)Fe{sub 2}O{sub 3}–60P{sub 2}O{sub 5} (0 ⩽ x ⩽ 8 mol%) were produced by conventional melting method. The samples were investigated to examine the effect of the CeO{sub 2} and Gd{sub 2}O{sub 3} composition on the structure of the iron phosphate glasses system. The X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) for the x ⩽ 6 mol% samples show all the samples formed homogeneous glass, but for the x = 8 mol% samples show the presence of randomly distributed crystalline phase embedded in an amorphous matrix. The x(CeO{sub 2} + Gd{sub 2}O{sub 3})–(40 − x)Fe{sub 2}O{sub 3}–60P{sub 2}O{sub 5} glass containing 8 mol% CeO{sub 2} and Gd{sub 2}O{sub 3} partially crystallized during annealing and Ce/Gd-rich were identified by EDS in the crystalline phase. The structure of the studied samples has been investigated using Raman and Fourier transform infrared spectroscopy (FTIR). The Raman and FTIR spectra for the samples have analogous spectral features. The Raman and FTIR spectra suggest that the structure is mainly constituted by the pyrophosphate glass based structure, with a part proportion of metaphosphate and orthophosphate structure. Raman and FTIR spectra allowed us to identify the structural units which appear in the structural network of these phosphate glasses and also the network modifier role of cerium and gadolinium ions.

  15. Method for fluorination of actinide fluorides and oxyfluorides using O/sub 2/F/sub 2/

    Science.gov (United States)

    Eller, P.G.; Malm, J.G.; Penneman, R.A.

    1984-08-01

    The present invention relates generally to methods of fluorination and more particularly to the use of O/sub 2/F/sub 2/ for the preparation of actinide hexafluorides, and for the extraction of deposited actinides and fluorides and oxyfluorides thereof from reaction vessels. The experiments set forth hereinabove demonstrate that the room temperature or below use of O/sub 2/F/sub 2/ will be highly beneficial for the preparation of pure actinide hexafluorides from their respective tetrafluorides without traces of HF being present as occurs using other fluorinating agents: and decontamination of equipment previously exposed to actinides: e.g., walls, feed lines, etc.

  16. Sintering densification of CaO–UO{sub 2}–Gd{sub 2}O{sub 3} nuclear fuel pellets

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yun [Fundamental Science on Radioactive Geology and Exploration Technology Laboratory, East China Institute of Technology, Nanchang, 330013, Jiangxi (China); Sun, Huidong [China Nucle Power Engineering Co., Ltd (China); Wang, Hui, E-mail: yinchanggeng5525@163.com [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chengdu, 610041 (China); Pan, Xiaoqiang; Li, Tongye; Liu, Jinhong; Zhang, Yong; Wang, Xinjie [National Key Laboratory for Nuclear Fuel and Materials, Nuclear Power Institute of China, Chengdu, 610041 (China)

    2015-10-15

    CaO-doped UO{sub 2}-10 wt% Gd{sub 2}O{sub 3} burnable poison fuel was prepared by co-precipitation reaction method. It was found that 0.3 wt% CaO-doping significantly improved the sintered density, grain sizes and crushing strength of UO{sub 2}–Gd{sub 2}O{sub 3} fuel pellets at the sintering temperature of 1650 °C in the sintering atmosphere of hydrogen for 3.5 h. In addition, homogeneous solid solution without precipitation of free phases of CaO and Gd{sub 2}O{sub 3} was successfully achieved. CaO doping in UO{sub 2}–Gd{sub 2}O{sub 3} fuel pellet system accelerated the thermally activated material transport, so the onset temperature of densification as well as the temperature of the maximum densification rate shifted to a lower temperature region. - Highlights: • A small amount of 0.3% doped CaO{sub 2} can significantly improve the sintered density. • Homogeneous solid solution forms without precipitation of free phases. • The pellet has good density, high strength and increasing grain sizes with homogeneity. • The pellet accelerates a thermally activated material transport.

  17. Lambda based control O{sub 2} set point optimisation and evaluation; Lambdabaserad reglering. Boervaerdesoptimering av O{sub 2} och utvaerdering

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Mikael; Brodin, Peter [Vattenfall Utveckling, Aelvkarleby (Sweden)

    2004-10-01

    During winter and spring 2003, the project 'Lambda based control' was carried out at Vattenfall Utveckling AB in Aelvkarleby, Sweden. The main purpose of the project was to explore if conventional lambda sensors could be used to control the fuel/air-ratio in small boilers. The conclusion was that this is possible. To be able to make use of the result, the question of what the numerical set value for O{sub 2} should be, has to be answered. Several parameters have impact on the oxygen level in combustion gas. The main purpose of this project is to explore if there is a cost efficient way of controlling fuel/air-ratio by using lambda sensors. The scope of the project is achieve the following, by using the experience from project P4-209: find out which parameters that correlate most strongly with lambda; develop a method to decide which and how many parameters to use, in order to optimize cost efficiency; calculate optimal set value for O{sub 2} in one of the boilers used for experiments in the project; and evaluate the method and compare important parameters of operation, such as efficiency and emissions. The method developed in the project uses initial measurements to find out the relation between O{sub 2} and emissions at different power levels. Then a set point curve is calculated where set point for O{sub 2} is expressed as a function of power level in the current boiler. The method has been implemented and evaluated at a 400 kW boiler in Aelvkarleby, Sweden. The results are improvements in efficiency (6 %) and emissions, CO decreased 40 %, NO decreased by 20 %. The conclusion is that lambda based control according to this method could be a profitable investment under the right circumstances, where stability in characteristics is the most important property. What makes the method uncertain is its inability to handle changes in characteristics of a boiler.

  18. Influence of O{sub 2} on the dielectric properties of CO{sub 2} at the elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Rong, Mingzhe; Sun, Hao; Yang, Fei, E-mail: yfei2007@mail.xjtu.edu.cn; Wu, Yi, E-mail: wuyic51@mail.xjtu.edu.cn; Chen, Zhexin; Wang, Xiaohua; Wu, Mingliang [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an Shaanxi 710049 (China)

    2014-11-15

    SF{sub 6} gas is widely used in the high voltage circuit breakers but considering its high global warming potential other substitutes are being sought. Among them CO{sub 2} was investigated and even has been used in some practical products. However, at room temperature, the dielectric properties of CO{sub 2} are relatively lower than SF{sub 6} and air. The goal of this work is to investigate a CO{sub 2}-based gas to improve the performance of the pure CO{sub 2}. In this paper, the dielectric properties of hot CO{sub 2}/O{sub 2} mixtures related to the dielectric recovery phase of the circuit breaker were investigated in the temperature range from 300 K to 4000 K and in the pressure range from 0.01 MPa to 1.0 MPa. The species compositions of hot CO{sub 2}/O{sub 2} were obtained based on Gibbs free energy minimization under the assumptions of local thermodynamic equilibrium and local chemical equilibrium. The reduced critical electric field strength of CO{sub 2}/O{sub 2} was determined by balancing electron generation and loss. These were calculated using the electron energy distribution function by solving the Boltzmann transport equation. The validity of the calculation method and the cross sections data was confirmed by comparing the measurements and calculations of the electron swarm data in previous work. The results indicate that in pure CO{sub 2} the critical electric field strength is higher only in higher temperature range. By adding the O{sub 2} into the CO{sub 2}, the critical electric field strength at lower temperature is effectively enhanced. CO{sub 2}/O{sub 2} mixtures have a much better dielectric strength than both the pure CO{sub 2} and air and thus have the potential to improve the CO{sub 2}-based gas circuit breakers. Similar conclusions can also be found in others’ work, which further confirm the validity of these results.

  19. Combined effects of radiation damage and He accumulation on bubble nucleation in Gd{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Caitlin A., E-mail: ctayl105@vols.utk.edu [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Patel, Maulik K. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Aguiar, Jeffery A. [Fuel Performance and Design Department, Idaho National Laboratory, Idaho Falls, ID 83415-6188 (United States); Material Science Center, National Renewable Energy Laboratory, Golden, CO 80220 (United States); Zhang, Yanwen [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Crespillo, Miguel L. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Wen, Juan [School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu 730000 (China); Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Xue, Haizhou [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Wang, Yongqiang [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Weber, William J. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2016-10-15

    Pyrochlores have long been considered as host phases for long-term immobilization of radioactive waste nuclides that would undergo α-decay for hundreds of thousands of years. This work utilizes ion-beam irradiations to examine the combined effects of radiation damage and He accumulation on bubble formation in Gd{sub 2}Ti{sub 2}O{sub 7} over relevant waste-form timescales. Helium bubbles are not observed in pre-damaged Gd{sub 2}Ti{sub 2}O{sub 7} implanted with 2 × 10{sup 16} He/cm{sup 2}, even after post-implantation irradiations with 7 MeV Au{sup 3+} at 300, 500, and 700 K. However, He bubbles with average diameters of 1.5 nm and 2.1 nm are observed in pre-damaged (amorphous) Gd{sub 2}Ti{sub 2}O{sub 7} and pristine Gd{sub 2}Ti{sub 2}O{sub 7}, respectively, after implantation of 2 × 10{sup 17} He/cm{sup 2}. The critical He concentration for bubble nucleation in Gd{sub 2}Ti{sub 2}O{sub 7} is estimated to be 6 at.% He. - Highlights: • He bubbles not formed in amorphous Gd{sub 2}Ti{sub 2}O{sub 7} implanted with 2 × 10{sup 16} He/cm{sup 2}, even after additional irradiation at 300 to 700 K. • He bubbles, 1.5 and 2.1 nm diameter, respectively, observed in amorphous and pristine Gd{sub 2}Ti{sub 2}O{sub 7} implanted to 2 × 10{sup 17} He/cm{sup 2}. • The critical He dose for bubble nucleation is estimated to be 6 at.% He.

  20. Domain matching epitaxy of cubic In{sub 2}O{sub 3} on r-plane sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, Patrick; Trampert, Achim; Ramsteiner, Manfred; Bierwagen, Oliver [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117, Berlin (Germany)

    2015-07-15

    Undoped, Sn-doped, and Mg-doped In{sub 2}O{sub 3} layers were grown on rhombohedral r-plane sapphire (α-Al{sub 2}O{sub 3} (10.2)) by plasma-assisted molecular beam epitaxy. X-ray diffraction and Raman scattering experiments demonstrated the formation of phase-pure, cubic (110)-oriented In{sub 2}O{sub 3} for Sn- and Mg-concentrations up to 2 x 10{sup 20} and 6 x 10{sup 20} cm{sup -3}, respectively. Scanning electron microscopy images showed facetted domains without any surface-parallel (110) facets. High Mg- or Sn-doping influenced surface morphology and the facet formation. X-ray diffraction Φ-scans indicated the formation of two rotational domains separated by an angle Φ = 86.6 due to the substrate mirror-symmetry around the in-plane-projected Al{sub 2}O{sub 3} c-axis. The in-plane epitaxial relationships to the substrate were determined for both domains. For the first domain it is Al{sub 2}O{sub 3}[01.0] parallel In{sub 2}O{sub 3}[3 anti 3 anti 4]. For the second domain the inplane epitaxial relation is Al{sub 2}O{sub 3}[01.0] parallel In{sub 2}O{sub 3}[3 anti 34]. A low-mismatch coincidence lattice of indium atoms from the film and oxygen atoms from the substrate rationalizes this epitaxial relation by domain-matched epitaxy. Cross-sectional transmission-electron microscopy showed a columnar domain-structure, indicating the vertical growth of the rotational domains after their nucleation. Coincidence structure of In{sub 2}O{sub 3} (110) (In atoms in red) grown on Al{sub 2}O{sub 3} (10.2) (O atoms in blue) showing two rotational domians. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Three series of quaternary rare-earth transition-metal pnictides with CaAl{sub 2}Si{sub 2}-type structures: RECuZnAs{sub 2}, REAgZnP{sub 2}, and REAgZnAs{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Stoyko, Stanislav S.; Ramachandran, Krishna K.; Blanchard, Peter E.R. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Rosmus, Kimberly A.; Aitken, Jennifer A. [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282 (United States); Mar, Arthur, E-mail: arthur.mar@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)

    2014-05-01

    Three series of quaternary rare-earth transition-metal pnictides REMM′Pn{sub 2} (M=Cu, Ag; M′=Zn; Pn=P, As) have been prepared by reaction of the elements at 800 °C, with crystal growth promoted through the addition of iodine. The extent of RE substitution is broad in these series: RECuZnAs{sub 2} (RE=Y, La-Nd, Sm, Gd–Lu), REAgZnP{sub 2} (RE=La–Nd, Sm, Gd–Dy), and REAgZnAs{sub 2} (RE=La-Nd, Sm, Gd-Dy). Powder and single-crystal X-ray diffraction analysis revealed that they adopt the trigonal CaAl{sub 2}Si{sub 2}-type structure (space group P3{sup ¯}m1, Z=1), in which Cu or Ag atoms are disordered with Zn atoms over the unique tetrahedrally coordinated transition-metal site. Magnetic measurements indicated Curie–Weiss behavior for several members of the RECuZnAs{sub 2} and REAgZnP{sub 2} series. Core-line X-ray photoelectron spectra (XPS) collected on some RECuZnAs{sub 2} members corroborate the charge assignment deduced by the Zintl concept for these compounds, (RE{sup 3+})(M{sup 1+})(Zn{sup 2+})(Pn{sup 3−}){sub 2}. Optical diffuse reflectance spectra and valence band XPS spectra established that these compounds are small band-gap semiconductors (up to ∼0.8 eV in REAgZnP{sub 2}) or semimetals (RECuZnAs{sub 2}). Band structure calculations also support this electronic structure and indicate that the band gap can be narrowed through appropriate chemical substitution (RE=smaller atoms, M=Cu, and Pn=As). - Graphical abstract: Cu or Ag atoms are disordered with Zn atoms over the tetrahedral site within relatively rigid [M{sub 2}Pn{sub 2}] slabs in three series of quaternary pnictides adopting the CaAl{sub 2}Si{sub 2}-type structure. - Highlights: • Three series (comprising 25 compounds) of pnictides REMM'Pn{sub 2} were prepared. • Cu or Ag atoms are disordered with Zn atoms within relatively rigid [M{sub 2}Pn{sub 2}] slabs. • They are semimetals or small band-gap semiconductors. • RECuZnAs{sub 2} and REAgZnP{sub 2} are generally

  2. Study of irradiation damages in MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} spinels in the framework of nuclear waste transmutation; Dommages d'irradiation dans des ceramiques de structure spinelle MgAl{sub 2}O{sub 4} et ZnAl{sub 2}O{sub 4} application a la transmutation des dechets nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Thiriet-Dodane, C

    2002-07-01

    The transmutation of minor actinides in-reactor is one solution currently being studied for the long time management of nuclear waste. In the heterogeneous concept the radionuclides are incorporating in an inert ceramic matrix. The support material must be insensitive to radiation damage. Fission product damage is the main radiation damage source during the transmutation process and therefore it is of the utmost importance to study their effects. We irradiated spinels MgAl{sub 2}O{sub 4} (matrix of reference) and ZnAl{sub 2}O{sub 4} by fast ions (by example: {sup 86}Kr of approximately 400 MeV) simulating the fission products. Under these conditions, the damage is primarily due to the electronic energy losses (S{sub e}). One of the structural features of spinel AB{sub 2}O{sub 4} is that the two cations (A{sup 2+} and B{sup 3+}) can exchange their site. This phenomenon is quantified by the inversion parameter. We highlight by XRD in grazing incidence that the structural changes observed in MgAl{sub 2}O{sub 4} correspond to an order-disorder transition from the cation sub-networks and not to a phase shift as described in the literature. Using other techniques characterizing the space group (Raman spectroscopy) as well as the local order (NMR 27Al, spectroscopy of absorption X with the thresholds K of Al and Zn), we confirm this interpretation. Moreover, for a fluence of 10{sup 14} ions/cm{sup 2}, the loss of the order at long distance is observed thus meaning a beginning of amorphization of material. The ZnAl{sub 2}O{sub 4} spinel presents the same behaviour. For this last spinel, an evolution of the inversion parameter according to the stopping power 2 was highlighted after irradiation by ions {sup 86}Kr from approximately 20 MeV. We illustrate our study by the analysis of the results obtained in XRD of an irradiation out of composite fuel (MgAl{sub 2}O{sub 4} + UO{sub 2}) called THERMHET. (authors)

  3. Post-irradiation examination of prototype Al-64 wt% U{sub 3}Si{sub 2} fuel rods from NRU

    Energy Technology Data Exchange (ETDEWEB)

    Sears, D.F.; Primeau, M.F.; Buchanan, C.; Rose, D. [Chalk River Labs., Ontario (Canada)

    1997-08-01

    Three prototype fuel rods containing Al-64 wt% U{sub 3}Si{sub 2} (3.15 gU/cm{sup 3}) have been irradiated to their design burnup in the NRU reactor without incident. The fuel was fabricated using production-scale equipment and processes previously developed for Al-U{sub 3}Si fuel fabrication at Chalk River Laboratories, and special equipment developed for U{sub 3}Si{sub 2} powder production and handling. The rods were irradiated in NRU up to 87 at% U-235 burnup under typical driver fuel conditions; i.e., nominal coolant inlet temperature 37{degrees}C, inlet pressure 654 kPa, mass flow 12.4 L/s, and element linear power ratings up to 73 kW/m. Post-irradiation examinations showed that the fuel elements survived the irradiation without defects. Fuel core diametral increases and volumetric swelling were significantly lower than that of Al-61 wt% U{sub 3}Si fuel irradiated under similar conditions. This irradiation demonstrated that the fabrication techniques are adequate for full-scale fuel manufacture, and qualified the fuel for use in AECL`s research reactors.

  4. Single-step synthesis of In{sub 2}O{sub 3} nanowires decorated with TeO{sub 2} nanobeads and their acetone-sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sunghoon; Kheel, Hyejoon; Sun, Gun-Joo; Lee, Chongmu [Inha University, Department of Materials Science and Engineering, Incheon (Korea, Republic of); Park, Sang Eon [Inha University, Department of Chemistry, Incheon (Korea, Republic of)

    2016-04-15

    In{sub 2}O{sub 3} nanowires decorated with TeO{sub 2} nanobeads were synthesized by a facile single-step thermal evaporation process, and their acetone-gas-sensing properties were examined. The diameters and lengths of the In{sub 2}O{sub 3} nanowires ranged from 10 to 20 nm and up to 100 μm, respectively, whereas the diameters of the TeO{sub 2} beads ranged from 50 to 200 nm. The TeO{sub 2}-decorated In{sub 2}O{sub 3} nanowire sensor showed stronger response to acetone gas than the pristine In{sub 2}O{sub 3} nanowire sensor. The pristine and TeO{sub 2}-decorated In{sub 2}O{sub 3} nanowires exhibited sensitivity of ∝10.13 and ∝24.87, respectively, to 200 ppm acetone at 300 C. The decorated nanowire sensor also showed much more rapid response and recovery than the latter. Both sensors showed the strongest response to acetone gas at 300 C, respectively. The mechanism and origin of the enhanced acetone-gas-sensing performance of the TeO{sub 2}-decorated In{sub 2}O{sub 3} nanowire sensor compared to the pristine In{sub 2}O{sub 3} nanowire sensor were discussed in detail. The enhanced sensing performance of the TeO{sub 2}-decorated In{sub 2}O{sub 3} nanowire is mainly due to the modulation of the potential barrier height at the TeO{sub 2}-In{sub 2}O{sub 3} interface, high catalytic activity of TeO{sub 2,} and creation of active adsorption sites by incorporation of TeO{sub 2}. (orig.)

  5. Gamma radiation/H{sub 2}O{sub 2} treatment of a nonylphenol ethoxylates: Degradation, cytotoxicity, and mutagenicity evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Munawar, E-mail: bosalvee@yahoo.com [National Center of Excellence in Physical Chemistry, University of Peshawar, Peshawar-25120 (Pakistan); Bhatti, Ijaz Ahmad [Department of Chemistry, University of Agriculture, Faisalabad-38040 (Pakistan)

    2015-12-15

    Highlights: • Nonylphenol ethoxylates undergone gamma ray/H{sub 2}O{sub 2} treatment. • Treatment efficiency was evaluated on the basis of degradation and toxicity reduction. • A significant reductions in COD and TOC were achieved. • Radiolytic by-products were low carbon carboxylic acids. • AOP reduced the cytotoxicity and mutagenicity considerably. - Abstract: Gamma radiation/H{sub 2}O{sub 2} treatment of nonylphenol polyethoxylates (NPEO) was performed and treatment effect was evaluated on the basis of degradation, chemical oxygen demand (COD) and total organic carbon (TOC), and toxicity reduction efficiencies. The radiolytic by-products were determined by Fourier Transform Infrared Spectroscopy (FTIR), High-Performance Liquid Chromatography (HPLC), and Gas Chromatography–Mass Spectrometry (GC–MS) techniques. Low mass carboxylic acids, aldehyde, ketone, and acetic acid were identified as the by-products of the NPEO degradation. NPEO sample irradiated to the absorbed dose of 15 kGy/4.58% H{sub 2}O{sub 2} showed more than 90% degradation. Allium cepa (A. cepa), brine shrimp, heamolytic tests were used for cytotoxicity study, while mutagenicity was evaluated through Ames test (TA98 and TA100 strains) of treated and un-treated NPEO. The reductions in COD and TOC were greater than 70% and 50%, respectively. Gamma radiation/H{sub 2}O{sub 2} treatment revealed a considerable reduction in cytotoxicity and mutagenicity. A. cepa, heamolytic and shrimp assays showed cytotoxicity reduction up to 68.65%, 77%, and 94%, respectively. The mutagenicity reduced up to 62%, 74%, and 79% (TA98) and 68%, 78%, and 82% (TA100), respectively of NPEO-6, NPEO-9, and NPEO-30 irradiated to the absorbed dose of 15 kGy/4.58% H{sub 2}O{sub 2}. NPEO-6 detoxified more efficiently versus NPEO-9 and NPEO-30 and results showed that Gamma radiation/H{sub 2}O{sub 2} treatment has the potential to mineralize and detoxify NPEO.

  6. Interaction of Ce{sub 1−x}Er{sub x}O{sub 2−y} nanoparticles with Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Krajczyk, L.; Kraszkiewicz, P.; Kepinski, L., E-mail: L.Kepinski@int.pan.wroc.pl

    2015-02-01

    The interaction of nanocrystalline Ce{sub 0.5}Er{sub 0.5}O{sub 1.75} mixed oxide with an amorphous Al{sub 2}O{sub 3} in oxidizing and reducing atmosphere up to 1100 °C was studied by XRD, TEM, SEM-EDS and BET. Uniform, chemically homogeneous Ce{sub 0.5}Er{sub 0.5}O{sub 1.75} nanoparticles (2 nm in size) were prepared by microemulsion method and deposited on a high surface γ-alumina support. The nanoparticles were structurally and chemically stable in the oxidizing atmosphere up to 1100 °C, exhibiting only an increase of the mean crystallite size to 9 nm after 3 h treatment. Prolonged heating (24 h) at 1100 °C caused partial decomposition of the mixed oxide and reaction of the extracted erbium with the support with formation of hexagonal (P6{sub 3}/mmc) ErAlO{sub 3} aluminate. The same hexagonal ErAlO{sub 3} occurred also in Er/Al{sub 2}O{sub 3} sample prepared by impregnation of Al{sub 2}O{sub 3} support with an aqueous solution of Er nitrate and subjected to heating in air or hydrogen at 1100 °C. In the reducing atmosphere the Ce{sub 0.5}Er{sub 0.5}O{sub 1.75} reacted with Al{sub 2}O{sub 3} already at 800 °C, to form an amorphous surface phase. At 900 °C monoclinic (P2{sub 1}/c) (Er,Ce){sub 4}Al{sub 2}O{sub 9} mixed aluminate was formed with the unit cell volume 4.5% bigger than that of pure Er{sub 4}Al{sub 2}O{sub 9} phase. After 3 h treatment at 1000 °C more than half of the (Er,Ce){sub 4}Al{sub 2}O{sub 9} aluminate decomposed into two nanocrystalline mixed monoaluminates: tetragonal (I4/mcm) (Ce,Er)AlO{sub 3} and hexagonal (P6{sub 3}/mmc) (Er,Ce)AlO{sub 3}. Nanocrystalline mixed aluminate particles with Er{sup 3+} ions placed in well-defined lattice sites and supported at the surface of Al{sub 2}O{sub 3} support, may be interesting as highly efficient active components of optical waveguides amplifiers. - Graphical abstract: Structure evolution of Ce{sub 0.5}Er{sub 0.5}O{sub 1.75} on Al{sub 2}O{sub 3} in air and in H{sub 2}. - Highlights:

  7. Synthesis, crystal and electronic structures, and magnetic properties of LiLn{sub 9}Mo{sub 16}O{sub 35} (Ln=La, Ce, Pr, and Nd) compounds containing the original cluster Mo{sub 16}O{sub 36}

    Energy Technology Data Exchange (ETDEWEB)

    Gougeon, Patrick; Gall, Philippe [UMR CNRS 6226 - ' ' Sciences Chimiques de Rennes' ' , Universite de Rennes 1 - INSA (France); Cuny, Jerome; Gautier, Regis; Le Polles, Laurent [UMR CNRS 6226 - ' ' Sciences Chimiques de Rennes' ' , Ecole Nationale Superieure de Chimie de Rennes (France); Delevoye, Laurent; Trebosc, Julien [UMR CNRS 8181 - UCCS, ENSCL, Universite Lille Nord de France, Villeneuve d' Ascq (France)

    2011-12-02

    The new compounds LiLn{sub 9}Mo{sub 16}O{sub 35} (Ln=La, Ce, Pr, and Nd) were synthesized from stoichiometric mixtures of Li{sub 2}MoO{sub 4}, Ln{sub 2}O{sub 3}, Pr{sub 6}O{sub 11} or CeO{sub 2}, MoO{sub 3}, and Mo heated at 1600 C for 48 h in a molybdenum crucible sealed under a low argon pressure. The crystal structure, determined from a single crystal of the Nd member, showed that the main building block is the Mo{sub 16}O{sub 36} unit, the Mo{sub 16} core of which is totally new and results from the fusion of two bioctahedral Mo{sub 10} clusters. It can also be viewed as a fragment of an infinite twin chain of edge-sharing Mo{sub 6} octahedra. The Mo{sub 16}O{sub 36} cluster units share some oxygen atoms to form infinite chains running parallel to the b axis, which are separated by the rare-earth and lithium cations. {sup 7}Li-NMR experiments, carried out at high field on the nonmagnetic LiLa{sub 9}Mo{sub 16}O{sub 35}, provided insights into the local environment of the lithium ions. Magnetic susceptibility measurements confirmed the trivalent oxidation state of the magnetic rare-earth cations and indicated the absence of localized moments on the Mo{sub 16} clusters. The electronic structure of the LiLn{sub 9}Mo{sub 16}O{sub 35} compounds was analyzed using molecular and periodic quantum calculations. The study of the molecular orbital diagrams of isolated Mo{sub 16}O{sub 36} models allowed the understanding of this unique metallic architecture. Periodic density functional theory calculations demonstrated that few interactions occur between the Mo{sub 16} clusters, and predicted semiconducting properties for LiLn{sub 9}Mo{sub 16}O{sub 35} as a band gap of 0.57 eV was computed for the lanthanum phase. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Stability of defects in monolayer MoS{sub 2} and their interaction with O{sub 2} molecule: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, B. [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan, 430072 (China); Shang, C. [Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074 (China); Qi, N. [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan, 430072 (China); Chen, Z.Y. [School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning, 437100 (China); Chen, Z.Q., E-mail: chenzq@whu.edu.cn [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan, 430072 (China)

    2017-08-01

    Highlights: • Defects can exist steadily in monolayer MoS{sub 2} and break surface chemical inertness. • Activated surfaces are beneficial to the adsorption of O{sub 2} through the introduction of defect levels. • Adsorbed O{sub 2} on defective surface can dissociate with low activation energy barrier. • Defective system may be a potential substrate to design MoS{sub 2}-based gas sensor or catalysts. - Abstract: The stability of various defects in monolayer MoS{sub 2}, as well as their interactions with free O{sub 2} molecules were investigated by density functional theory (DFT) calculations coupled with the nudged elastic band (NEB) method. The defects including S vacancy (monosulfur and disulfue vacancies), antisite defect (Mo{sub S}) and external Mo atom can exist steadily in monolayer MoS{sub 2}, and introduce defect levels in these defective systems, which breaks the surface chemical inertness and significantly enhances the adsorption capacity for free O{sub 2}. The adsorption energy calculations and electronic properties analysis suggest that there is a strong interaction between O{sub 2} molecule and defective system. The adsorbed O{sub 2} on the defective surface can dissociate with a lower activation energy barrier, which produce two active oxygen atoms. Especially, two Mo atoms can occupy one Mo lattice site, and adsorbed O{sub 2} on the top of the Mo atom can then dissociate directly with the lowest activation energy barrier. Hence, our work may provide useful information to design MoS{sub 2}-based gas sensor or catalysts.

  9. Hot corrosion of the ceramic composite coating Ni{sub 3}Al-Al{sub 2}O{sub 3}-Al{sub 2}O{sub 3}/MgO plasma sprayed on 316L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Shirazi, Amir Khodaparast; Kiahosseini, Seyed Rahim [Islamic Azad Univ., Damghan (Iran, Islamic Republic of). Dept. of Engineering

    2017-08-15

    Ni{sub 3}Al-Al{sub 2}O{sub 3}-Al{sub 2}O{sub 3}/MgO three-layered coatings with thicknesses of 50, 100, and 150 μm for Al{sub 2}O{sub 3}/MgO and 100 μm for the other layers were deposited on 316L stainless steel using plasma spraying. X-ray diffraction, atomic force microscopy, furnace hot corrosion testing in the presence of a mixture of Na{sub 2}SO{sub 4} and V{sub 2}O{sub 5} corrosive salts and scanning electron microscopy were used to determine the structural, morphological and hot corrosion resistance of samples. Results revealed that the crystalline grains of MgO and Al{sub 2}O{sub 3} coating were very small. Weight loss due to hot corrosion decreased from approximately 4.267 g for 316L stainless steel without coating to 2.058 g. The samples with 150 μm outer coating showed improved resistance with the increase in outer layer thickness. Scanning electron microscopy of the coated surface revealed that the coating's resistance to hot corrosion is related to the thickness and the grain size of Al{sub 2}O{sub 3}/MgO coatings.

  10. Degradation characteristic of monoazo, diazo and anthraquinone dye by UV/H{sub 2}O{sub 2} process

    Energy Technology Data Exchange (ETDEWEB)

    Abidin, Che Zulzikrami Azner, E-mail: zulzikrami@unimap.edu.my, E-mail: drfahmi@unimap.edu.my, E-mail: umifazara@unimap.edu.my, E-mail: fatinnadhirah89@gmail.com; Fahmi, Muhammad Ridwan, E-mail: zulzikrami@unimap.edu.my, E-mail: drfahmi@unimap.edu.my, E-mail: umifazara@unimap.edu.my, E-mail: fatinnadhirah89@gmail.com; Fazara, Md Ali Umi, E-mail: zulzikrami@unimap.edu.my, E-mail: drfahmi@unimap.edu.my, E-mail: umifazara@unimap.edu.my, E-mail: fatinnadhirah89@gmail.com; Nadhirah, Siti Nurfatin, E-mail: zulzikrami@unimap.edu.my, E-mail: drfahmi@unimap.edu.my, E-mail: umifazara@unimap.edu.my, E-mail: fatinnadhirah89@gmail.com [School of Environmental Engineering, University Malaysia Perlis (UniMAP), Kompleks Pusat Pengajian Jejawi 3, 02600 Arau, Perlis (Malaysia)

    2014-10-24

    In this study, the degradation characteristic of monoazo, diazo and anthraquinone dye by UV/H{sub 2}O{sub 2} process was evaluated based on the trend of color, chemical oxygen demand (COD) and total organic carbon (TOC) removal. Three types of dyes consist of monoazo, diazo and anthraquinone dyes were used to compare the degradation mechanism of the dyes. The UV/H{sub 2}O{sub 2} experiments were conducted in a laboratory scale cylindrical glass reactor operated in semi-batch mode. The UV/Vis characterization of monoazo, diazo and anthraquinone dye indicated that the rapid degradation of the dyes by UV/H{sub 2}O{sub 2} process is meaningful with respect to decolourization, as a result of the azo bonds and substitute antraquinone chromophore degradation. However, this process is not efficient for aromatic amines removal. The monoazo MO was difficult to be decolorized than diazo RR120 dye, which imply that number of sulphonic groups in the dye molecules determines the reactivity with hydroxyl radical. The increased in COD removal is the evidence for oxidation and decreased in carbon content of dye molecules. TOC removal analysis shows that low TOC removal of monoazo MO and diazo RR120, as compared to anthraquinone RB19 may indicate an accumulation of by-products that are resistant to the H{sub 2}O{sub 2} photolysis.

  11. Amorphous and crystalline In{sub 2}O{sub 3}-based transparent conducting films for photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Koida, Takashi [Research Center for Photovoltaics, National Institute of Advanced Industrial Science and Technology, Tsukuba (Japan)

    2017-02-15

    We reported solar cells with reduced electrical and optical losses using hydrogen-doped In{sub 2}O{sub 3} (In{sub 2}O{sub 3}:H) transparent conducting layers with low sheet resistance and high transparence characteristics. The transparent conducting oxide (TCO) films were prepared by solid-phase crystallization of amorphous (a-) In{sub 2}O{sub 3}:H films grown by magnetron sputtering. The polycrystalline (poly-) In{sub 2}O{sub 3}:H films exhibited electron mobilities (over 100 cm{sup 2}V{sup -1} s{sup -1}) 2 and 3 times greater than those of conventional TCO films. This paper describes (i) the current status of the electrical properties of In{sub 2}O{sub 3}-based TCO; (ii) the structural and optoelectrical properties of the a-In{sub 2}O{sub 3}:H and poly-In{sub 2}O{sub 3}:H films, focusing on the inhomogeneity and stability characteristics of the films; and (iii) the electrical properties of bilayer TCO. The potential of these high mobility TCO films for solar cells was also described. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. A feasibility study on SnO{sub 2}/NiFe{sub 2}O{sub 4} nanocomposites as anodes for Li ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Balaji, S., E-mail: sbalaji@tce.edu [Department of Chemistry, Thiagarajar College of Engineering, Madurai 625 015 (India); Vasuki, R. [Department of Physics, Thiagarajar College of Engineering, Madurai (India); Mutharasu, D. [School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2013-03-25

    Highlights: ► The morphological analysis performed has shown the existence of nanocomposite. ► Sp. capacity after 50 cycles of pure NiFe{sub 2}O{sub 4}, 5 and 10 wt.% SnO{sub 2} are 450, 750 and 780 mA h/g. ► The results are higher than the theoretical capacity of graphite (374 mA h/g). ► The capacity retention is also found to increase with SnO{sub 2} addition in the NiFe{sub 2}O{sub 4}. ► Charge and discharge capacities of LiMn{sub 2}O{sub 4} vs. 10 wt.% SnO{sub 2}/NiFe{sub 2}O{sub 4} are 232 and 138 mA h/g. -- Abstract: The SnO{sub 2}/NiFe{sub 2}O{sub 4} nanocomposite samples with varying concentration of SnO{sub 2} such as 5 wt.% and 10 wt.% were synthesized via urea assisted combustion synthesis. The kinetics of the combustion reactions were studied using thermo gravimetry analysis and from which the compound formation temperature of all the samples were observed to be below 400 °C. From the morphological analysis the grain size of NiFe{sub 2}O{sub 4}, 5 wt.% SnO{sub 2}/NiFe{sub 2}O{sub 4} and 10 wt.% SnO{sub 2}/NiFe{sub 2}O{sub 4} samples were observed to be around 1.7, 2.3 and 3.5 μm. The chrono potentiometry analyses of the samples were performed against lithium metal electrode. The capacity retention was found to be higher for composite with 10 wt.% SnO{sub 2}. The discharge capacity of 10 wt.% SnO{sub 2} sample with respect to Li metal and LiMn{sub 2}O{sub 4} electrode was observed to be around 980 mA h/g and 138 mA h/g respectively.

  13. Positron annihilation studies in the high-temperature superconductors YBa2Cu3Osub(7-x) and HoBa2Cu3Osub(7-x)

    International Nuclear Information System (INIS)

    Mandal, P.; Poddar, A.; Nambissan, P.M.G.; Choudhury, P.; Ghosh, B.; Sen, P.; Majumdar, C.K.

    1988-01-01

    In the high-Tsub(c) superconductors YBa 2 Cu 3 Osub(7-x) and HoBa 2 Cu 3 Osub(7-x) the Doppler-broadened positron annihilation lineshape parameter is studied as a function of temperature. Anomalies are detected around the transition temperature found by resistance measurements, giving indirect support for an electronic mechanism for superconductivity. The positron lifetimes in these compounds are measured at room temperature and are found to be similar. The origins of the several lifetimes found and their intensities are discussed. (author)

  14. Microstructural characterization of Al{sub 2}O{sub 3}: Eu with dosimetric purposes; Cracterizacion microestructural de Al{sub 2}O{sub 3}: Eu con fines dosimetricos

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza A, D.; Espinosa P, M.E.; Gonzalez M, P.R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Rubio, E. [BUAP, Facultad de Ingenieria Quimica, 72570 Puebla (Mexico)

    2004-07-01

    In this work a microstructural analysis is presented, through Sem, EDS and XRD, of the alumina with Europium (Al{sub 2}O{sub 3}: Eu) synthesized by the sol gel method. According to those obtained results, a previous thermal treatment to 1000 C to the samples, induces the formation of the {gamma}-alumina phase for the samples that does not contain Eu; however when there is presence of this element, the {theta} alumina phase is obtained. Likewise, it was observed that the particle size is increased with the presence of Eu. When analyzing the thermoluminescent response (TL) induced by the gamma radiation, it was observed that the pure Al{sub 2}O{sub 3} presents an intense TL sign; while the Al{sub 2}O{sub 3}: Eu, the sign suffers a marked decrement. (Author)

  15. Trial synthesis of Li{sub 2}Be{sub 2}O{sub 3} for high-functional tritium breeders

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Tsuyoshi, E-mail: hoshino.tsuyoshi@jaea.go.jp [Breeding Functional Materials Development Group, Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-166, Obuchi, Omotedate, Rokkasho-mura, Kamikita-gun, Aomori 039-3212 (Japan); Oikawa, Fumiaki [Breeding Functional Materials Development Group, Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-166, Obuchi, Omotedate, Rokkasho-mura, Kamikita-gun, Aomori 039-3212 (Japan); Natori, Yuri; Kato, Kenichi; Sakka, Tomoko; Nakamura, Mutsumi; Tatenuma, Katsuyoshi [Kaken, Co. Ltd., 1044, Hori, Mito-city, Ibaraki 310-0903 (Japan)

    2013-10-15

    Highlights: • Mixtures of tritium breeder and neutron multiplier (Be or Be{sub 12}Ti) pebbles are being considered for increasing the tritium breeding ratio in DEMO blankets. • A high-functional tritium breeder such as lithium beryllium oxide (Li{sub 2}Be{sub 2}O{sub 3}) needs to be developed to compensate for this reaction under high-temperatures. • Solid-state reaction of LiOH·H{sub 2}O and BeO is well-suited for synthesizing Li{sub 2}Be{sub 2}O{sub 3}. • The optimum sintering temperature was selected from 1000 K to 1273 K by TG–DTA. -- Abstract: Mixtures of tritium breeder (lithium) and neutron multiplier (beryllium) are being considered for use in increasing the tritium breeding ratio in breeding blankets. However, lithium and beryllium react under normal operating conditions, and therefore, a high-functional tritium breeder such as lithium beryllium oxide (Li{sub 2}Be{sub 2}O{sub 3}) needs to be developed to compensate for this reaction under high-temperatures. LiOH·H{sub 2}O and BeO powders were mixed in stoichiometric proportions at a Li/Be molecular ratio of 1.0. The sintering temperature was established as 1073 K by thermogravimetric/differential thermal analysis (TG–DTA). The Li/Be molar ratio of the reaction products measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES) after the reaction agreed with the nominal molar ratio obtained by mixing LiOH·H{sub 2}O and BeO. Crystal structure analysis of this powder was performed by the XRD technique. The XRD patterns of products were the same as those of Li{sub 2}Be{sub 2}O{sub 3} as listed in the JC-PDF-Card, and no impurities were indicated. The results indicate that the solid-state reaction of LiOH·H{sub 2}O and BeO is suitable for synthesizing lithium beryllium oxide (Li{sub 2}Be{sub 2}O{sub 3})

  16. Thermal stability of the grain structure in the W-2V and W-2V-0.5Y{sub 2}O{sub 3} alloys produced by hot isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Martínez, J.; Savoini, B.; Monge, M.A. [Departamento de Física, Universidad Carlos III de Madrid, 28911-Leganés Madrid (Spain); Muñoz, A., E-mail: angel.munoz@uc3m.es [Departamento de Física, Universidad Carlos III de Madrid, 28911-Leganés Madrid (Spain); Armstrong, D.E.J. [Department of Materials, University of Oxford, Park Road, Oxford OX1 3PH (United Kingdom); Pareja, R. [Departamento de Física, Universidad Carlos III de Madrid, 28911-Leganés Madrid (Spain)

    2013-10-15

    Highlights: • W-2V and ODS W-2V-0.5Y{sub 2}O{sub 3} alloys have been produced following a powder metallurgy route. • Grain microstructure and microhardness have been studied after isothermal treatments in vacuum. • Both alloys exhibit a duplex grain size population: a submicron-sized grain and a coarse grained one. • The Y{sub 2}O{sub 3} addition inhibits growth of the coarse grains for T < 1973 K. • The Y{sub 2}O{sub 3} nanoparticles enhance the microhardness of W-2V-0.5Y{sub 2}O{sub 3}. -- Abstract: W-2V and ODS W-2V-0.5Y{sub 2}O{sub 3} alloys have been produced following a powder metallurgy route consisting of mechanical alloying and a subsequent high isostatic pressing HIP at 1573 K. The grain microstructure and microhardness recovery of the alloys have been studied in samples subjected to isothermal treatments in vacuum in temperature range 1073–1973 K. Both alloys exhibit a duplex grain size distribution consisting of a submicron-sized grain and a coarse-grained population. It has been found that the Y{sub 2}O{sub 3} addition inhibits growth of the coarse grains at T < 1973 K. Submicron grain growth, with activation enthalpy of 1.9 and 2.49 eV for W-2V and W-2V-0.5Y{sub 2}O{sub 3}, respectively, was observed at T ≥ 1573 K. It resulted that the rate constant for grain growth is 30 times higher in W-2V-0.5Y{sub 2}O{sub 3} than in W-2V. The considerable enhancement of the microhardness in the W-2V-0.5Y{sub 2}O{sub 3} appears to be associated to dispersion strengthening.

  17. Microstructure and temperature dependence of the microhardness of W–4V–1La{sub 2}O{sub 3} and W–4Ti–1La{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Savoini, B., E-mail: begona.savoini@uc3m.es; Martínez, J.; Muñoz, A.; Monge, M.A.; Pareja, R.

    2013-11-15

    W–4V–1La{sub 2}O{sub 3} and W–4Ti–1La{sub 2}O{sub 3} (wt.%) alloys have been produced by mechanical alloying and subsequent hot isostatic pressing. Electron microscopy observations revealed that these alloys exhibit a submicron grain structure with a dispersion of La oxide nanoparticles. Large V or Ti pools with martensitic characteristics are found segregated in the interstices between the W particles of the respective alloys. Microhardness tests were carried out over the temperature range 300–1073 K in vacuum. The microhardness–temperature curve for W–4V–1La{sub 2}O{sub 3} exhibited the expected decreasing trend with increasing temperature although the microhardness stayed constant between ∼473 and 773 K. The W–4Ti–1La{sub 2}O{sub 3} presented quite different temperature dependence with an anomalous microhardness increase for temperatures above ∼473 K.

  18. Comparison of the growth kinetics of In{sub 2}O{sub 3} and Ga{sub 2}O{sub 3} and their suboxide desorption during plasma-assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Vogt, Patrick, E-mail: vogt@pdi-berlin.de; Bierwagen, Oliver, E-mail: bierwagen@pdi-berlin.de [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, D-10117 Berlin (Germany)

    2016-08-08

    We present a comprehensive study of the In{sub 2}O{sub 3} growth kinetics during plasma-assisted molecular beam epitaxy and compare it to that of the related oxide Ga{sub 2}O{sub 3} [P. Vogt and O. Bierwagen, Appl. Phys. Lett. 108, 072101 (2016)]. The growth rate and desorbing fluxes were measured during growth in-situ by a laser reflectometry set-up and line-of-sight quadrupole mass spectrometer, respectively. We extracted the In incorporation as a function of the provided In flux, different growth temperatures T{sub G}, and In-to-O flux ratios r. The data are discussed in terms of the competing formation of In{sub 2}O{sub 3} and desorption of the suboxide In{sub 2}O and O. The same three growth regimes as in the case of Ga{sub 2}O{sub 3} can be distinguished: (i) In-transport limited, O-rich (ii) In{sub 2}O-desorption limited, O-rich, and (iii) O-transport limited, In-rich. In regime (iii), In droplets are formed on the growth surface at low T{sub G}. The growth kinetics follows qualitatively that of Ga{sub 2}O{sub 3} in agreement with their common oxide and suboxide stoichiometry. The quantitative differences are mainly rationalized by the difference in In{sub 2}O and Ga{sub 2}O desorption rates and vapor pressures. For the In{sub 2}O, Ga{sub 2}O, and O desorption, we extracted the activation energies and frequency factors by means of Arrhenius-plots.

  19. Synthesis and characterization of novel PPy/Bi{sub 2}O{sub 2}CO{sub 3} composite with improved photocatalytic activity for degradation of Rhodamine-B

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qizhao, E-mail: wangqizhao@163.com [College of Chemistry and Chemical Engineering, Northwest Normal University, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Gansu Polymer Materials, Lanzhou 730070 (China); Zheng, Longhui; Chen, Yutao; Fan, Jiafeng [College of Chemistry and Chemical Engineering, Northwest Normal University, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Gansu Polymer Materials, Lanzhou 730070 (China); Huang, Haohao, E-mail: scuthhh@hotmail.com [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Su, Bitao [College of Chemistry and Chemical Engineering, Northwest Normal University, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of Gansu Polymer Materials, Lanzhou 730070 (China)

    2015-07-15

    Highlights: • A new photocatalyst PPy/Bi{sub 2}O{sub 2}CO{sub 3} was synthesized by a simple hydrothermal method. • The PPy/Bi{sub 2}O{sub 2}CO{sub 3} photocatalyst shows enhanced degradation activity of RhB under UV light irradiation. • A photocatalytic mechanism is proposed based on the synergistic effect of PPy and Bi{sub 2}O{sub 2}CO{sub 3}. - Abstract: Photocatalyst Bi{sub 2}O{sub 2}CO{sub 3} modified by polypyrrole (PPy) was synthesized via a facile hydrothermal method. As-prepared PPy/Bi{sub 2}O{sub 2}CO{sub 3} composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and UV–vis diffuse reflectance spectroscopy (DRS). Presence of PPy did not affect the crystal structure, but exerted great influence on the photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3} and enhanced absorption band of pure Bi{sub 2}O{sub 2}CO{sub 3}. The photocatalytic activities of the PPy/Bi{sub 2}O{sub 2}CO{sub 3} samples were determined by photocatalytic degradation of Rhodamine-B (RhB) under ultra violet (UV) irradiation and 0.75 wt.% PPy/Bi{sub 2}O{sub 2}CO{sub 3} composite showed the highest photocatalytic activity. The enhanced photocatalytic performance could be attributed to the synergistic effect of PPy and Bi{sub 2}O{sub 2}CO{sub 3}. A possible photocatalytic mechanism of the PPy/Bi{sub 2}O{sub 2}CO{sub 3} photocatalysts was proposed in order to guide the further improvement of its photocatalytic performance.

  20. Enhancement of the secondary ion emission from Si by O/sub 2 and H/sub 2/O adsorption

    International Nuclear Information System (INIS)

    Huan, C.H.; Wee, A.T.S.; Tan, K.L.

    1992-01-01

    The positive and negative secondary ion emission of Si are examined as a function of O/sub 2 and H/sub 2/O surface coverage under conditions of simultaneous adsorption and Ar/sup+ ion bombardment. It is found that the ion-molecule mechanism accounts for the adsorbate-induced signals and that yield enhancement by H/sub 2/O adsorption is less effective than O/sub 2 adsorption. (authors)

  1. Synthesis and characterization of new fluoride-containing manganese vanadates A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} (A=Rb, Cs) and Mn{sub 2}VO{sub 4}F

    Energy Technology Data Exchange (ETDEWEB)

    Sanjeewa, Liurukara D. [Department of Chemistry and Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University, Clemson, SC 29634-0973 (United States); McGuire, Michael A. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Smith Pellizzeri, Tiffany M.; McMillen, Colin D. [Department of Chemistry and Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University, Clemson, SC 29634-0973 (United States); Ovidiu Garlea, V. [Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Willett, Daniel; Chumanov, George [Department of Chemistry and Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University, Clemson, SC 29634-0973 (United States); Kolis, Joseph W., E-mail: kjoseph@clemson.edu [Department of Chemistry and Center for Optical Materials Science and Engineering Technologies (COMSET), Clemson University, Clemson, SC 29634-0973 (United States)

    2016-09-15

    Large single crystals of A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} (A=Rb, Cs) and Mn{sub 2}VO{sub 4}F were grown using a high-temperature (~600 °C) hydrothermal technique. Single crystal X-ray diffraction and powder X-ray diffraction were utilized to characterize the structures, which both possess MnO{sub 4}F{sub 2} building blocks. The A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} series crystallizes as a new structure type in space group Pbcn (No. 60), Z=4 (Rb{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2}: a=7.4389(17) Å, b=11.574(3) Å, c=10.914(2) Å; Cs{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2}: a=7.5615(15) Å, b=11.745(2) Å, c=11.127(2) Å). The structure is composed of zigzag chains of edge-sharing MnO{sub 4}F{sub 2} units running along the a-axis, and interconnected through V{sub 2}O{sub 7} pyrovanadate groups. Temperature dependent magnetic susceptibility measurements on this interesting one-dimensional structural feature based on Mn{sup 2+} indicated that Cs{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} is antiferromagnetic with a Neél temperature, T{sub N}=~3 K and a Weiss constant, θ, of −11.7(1) K. Raman and infrared spectra were also analyzed to identify the fundamental V–O vibrational modes in Cs{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2}. Mn{sub 2}(VO{sub 4})F crystalizes in the monoclinic space group of C2/c (no. 15), Z=8 with unit cell parameters of a=13.559(2) Å, b=6.8036(7) Å, c=10.1408(13) Å and β=116.16(3)°. The structure is associated with those of triplite and wagnerite. Dynamic fluorine disorder gives rise to complex alternating chains of five-and six-coordinate Mn{sup 2+}. These interpenetrating chains are additionally connected through isolated VO{sub 4} tetrahedra to form the condensed structure. - Graphical abstract: New vanadate fluorides A{sub 2}Mn{sub 2}V{sub 2}O{sub 7}F{sub 2} (A=Rb, Cs) and Mn{sub 2}(VO{sub 4})F have been synthesized hydrothermally. Upon cooling, the one-dimensional Mn(II) substructure results in antiferromagnetic

  2. Effects of NO{sub x}, {alpha}-Fe{sub 2}O{sub 3}, {gamma}-Fe{sub 2}O{sub 3}, and HCl on mercury transformations in a 7-kW coal combustion system

    Energy Technology Data Exchange (ETDEWEB)

    Galbreath, Kevin C.; Zygarlicke, Christopher J.; Tibbetts, James E.; Schulz, Richard L.; Dunham, Grant E. [University of North Dakota Energy and Environmental Research Center, 15 North 23rd Street, P.O. Box 9018, Grand Forks, ND 58202-9018 (United States)

    2005-01-25

    Bench-scale investigations indicate that NO, NO{sub 2}, hematite ({alpha}-Fe{sub 2}O{sub 3}), maghemite ({gamma}-Fe{sub 2}O{sub 3}), and HCl promote the conversion of gaseous elemental mercury (Hg{sup 0}) to gaseous oxidized mercury (Hg{sup 2+}) and/or particle-associated mercury (Hg[p]) in simulated coal combustion flue gases. In this investigation, the effects of NO{sub x}, {alpha}-Fe{sub 2}O{sub 3}, {gamma}-Fe{sub 2}O{sub 3}, and HCl on Hg transformations were evaluated by injecting them into actual coal combustion flue gases produced from burning subbituminous Absaloka and lignitic Falkirk coals in a 7-kW down-fired cylindrical furnace. A bituminous Blacksville coal known to produce an Hg{sup 2+}-rich combustion flue gas was also burned in the system. The American Society for Testing and Materials Method D6784-02 (Ontario Hydro method) or an online Hg analyzer equipped to measure Hg{sup 0} and total gaseous mercury (Hg[tot]) was used to monitor Hg speciation at the baghouse inlet (160-195 {sup o}C) and outlet (110-140 {sup o}C) locations of the system. As expected, the baseline Blacksville flue gas was composed predominantly of Hg{sup 2+} (Hg{sup 2+}/Hg[tot]=0.77), whereas Absaloka and Falkirk flue gases contained primarily Hg{sup 0} (Hg{sup 0}/Hg[tot]=0.84 and 0.78, respectively). Injections of NO{sub 2} (80-190 ppmv) at 440-880 {sup o}C and {alpha}-Fe{sub 2}O{sub 3} (15 and 6 wt.%) at 450 {sup o}C into Absaloka and Falkirk coal combustion flue gases did not significantly affect Hg speciation. The lack of Hg{sup 0} to Hg{sup 2+} conversion suggests that components of Absaloka and Falkirk combustion flue gases and/or fly ashes inhibit heterogeneous Hg{sup 0}-NO{sub x}-{alpha}-Fe{sub 2}O{sub 3} reactions or that the flue gas quench rate in the 7-kW system is much different in relation to bench-scale flue gas simulators.An abundance of Hg{sup 2+}, HCl, and {gamma}-Fe{sub 2}O{sub 3} in Blacksville flue gas and the inertness of injected {alpha}-Fe{sub 2}O{sub 3

  3. PEG/CaFe{sub 2}O{sub 4} nanocomposite: Structural, morphological, magnetic and thermal analyses

    Energy Technology Data Exchange (ETDEWEB)

    Khanna, Lavanya, E-mail: lavanshya@yahoo.co.in; Verma, Narendra K., E-mail: nkverma@thapar.edu

    2013-10-15

    The coating of Polyethylene Glycol (PEG) on calcium ferrite (CaFe{sub 2}O{sub 4}) nanoparticles has been reported in the present study. The X-ray diffraction pattern revealed the formation of orthorhombic structure of bare CaFe{sub 2}O{sub 4} nanoparticles, which was also retained after the PEG coating, along with additional characteristic peaks of PEG at 19° and 23°. The rings of CaFe{sub 2}O{sub 4} nanoparticles were identified by the selected area electron diffraction pattern. The characteristic bands of PEG as observed in its Fourier transform infrared spectrum were also present in PEG coated CaFe{sub 2}O{sub 4} nanoparticles, hence confirming its presence. In the thermal gravimetric studies, the complete thermal decomposition of PEG occurred in a one step process, but in case of PEG coated CaFe{sub 2}O{sub 4} nanoparticles, the decomposition took place at a higher temperature owing to the formation of covalent bonds of PEG with CaFe{sub 2}O{sub 4} nanoparticles. The presence of PEG on CaFe{sub 2}O{sub 4} nanoparticles, spherical formation of PEG coated CaFe{sub 2}O{sub 4} nanoparticles and reduced agglomeration in the CaFe{sub 2}O{sub 4} nanoparticles were revealed by high resolution transmission electron microscope, transmission electron microscope and scanning electron microscope studies, respectively. In vibrating sample magnetometer analysis, both bare as well as coated CaFe{sub 2}O{sub 4} nanoparticles exhibited superparamagnetic behavior. However, a drop in the magnetic saturation value was observed from 36.76 emu/g for CaFe{sub 2}O{sub 4} nanoparticles to 6.74 emu/g for PEG coated CaFe{sub 2}O{sub 4} nanoparticles, due to the formation of magnetically dead layer of PEG. In ZFC and FC analyses, superparamagnetic behavior with blocking temperature for bare and coated nanoparticles has been observed at ∼40 K and ∼60 K, respectively. The increase in the blocking temperature is attributed to the increase in the particle size after PEG coating.

  4. A novel material Li{sub 2}NiFe{sub 2}O{sub 4}: Preparation and performance as anode of lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Keqiang, E-mail: dkeqiang@263.net [College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang, Hebei, 050024 (China); Zhao, Jing [College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang, Hebei, 050024 (China); Zhou, Jinming, E-mail: zhoujm@iccas.ac.cn [College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang, Hebei, 050024 (China); Zhao, Yongbo; Chen, Yuying; Liu, Likun [College of Chemistry and Materials Science, Hebei Normal University, Shijiazhuang, Hebei, 050024 (China); Wang, Li [Institute of Nuclear & New Energy Technology, Beijing Key Lab of Fine Ceramics, Tsinghua University, Beijing, 100084 (China); He, Xiangming, E-mail: hexm@tsinghua.edu.cn [Institute of Nuclear & New Energy Technology, Beijing Key Lab of Fine Ceramics, Tsinghua University, Beijing, 100084 (China); Guo, Zhanhu, E-mail: zguo10@utk.edu [Integrated Composites Laboratory (ICL), Chemical and Biomolecular Engineering Department, University of Tennessee Knoxville, Knoxville, NT, 37996 (United States)

    2016-07-01

    For the first time, the preparation and characterization of a novel anode material Li{sub 2}NiFe{sub 2}O{sub 4} are reported in this work. The preparation of Li{sub 2}NiFe{sub 2}O{sub 4} is conducted under the air conditions by using a subsection calcination method. The influence of annealing periods on the properties of the resultant materials is thoroughly explored. The characteristics of the materials are mainly examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), cyclic voltammetry (CV), galvanostatic charge-discharge tests and electrochemical impedance spectroscopy (EIS). The results of the XRD patterns effectively demonstrate the formation of crystalline Li{sub 2}NiFe{sub 2}O{sub 4}, and the SEM images indicate that particles with octahedron crystal morphology are prepared and the 9 h-annealed sample has the smallest particle size among all the prepared samples. The results of electrochemical measurements reveal that 9 h-calcined sample delivers a high specific capacity of 203 mAh g{sup −1} after 20 cycles at a current density of 100 mA g{sup −1}. The successful preparation of Li{sub 2}NiFe{sub 2}O{sub 4} is believed to be able to trigger the research work concerning the novel group of Li{sub 2}MFe{sub 2}O{sub 4} materials. - Highlights: • A novel anode material Li{sub 2}NiFe{sub 2}O{sub 4} was prepared under the air conditions. • Li{sub 2}NiFe{sub 2}O{sub 4} showed well-defined octahedron crystal morphology. • 9 h-annealed Li{sub 2}NiFe{sub 2}O{sub 4} delivered a capacity of 203 mAh g{sup −1}.

  5. Luminescence characteristics of Sr{sub 1-x}Ba{sub x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphors for white light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Anoop, G.; Cho, I.H.; Suh, D.W.; Yoo, J.S. [Display Materials Laboratory, School of Chemical Engineering and Materials Science, Chung-Ang University, Heukseok-Dong 221, Dongjak-gu, Seoul 156-756 (Korea, Republic of)

    2012-12-15

    Sr{sub 1-x}Ba{sub x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphors were synthesized using high temperature solid state reaction. The effect of Ba incorporation on the structural and luminescence characteristics of SrSi{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphors were studied. The phosphors were crystallized in triclinic crystal structure and the cell volume increases monotonically with Ba addition. The PL emission peak wavelength red shifts with Ba up to x = 0.50 beyond which no red shift is observed. The XPS analysis shows that nitrogen is being incorporated into the host lattice along with Ba addition up to x = 0.50. The as synthesized phosphors show high thermal stability. Phosphor converted light emitting diodes were realized using Sr{sub 1-x}Ba{sub x}Si{sub 2}O{sub 2}N{sub 2}:Eu{sup 2+} phosphors (x = 0 and x = 0.40) showing luminance efficacies of 108 and 101 lm W{sup -1}. The CIE chromaticity coordinates of Sr{sub 1-x}Ba{sub x}Si{sub 2}O{sub 2}N{sub 2}:Eu (x = 0 and x = 0.40) phosphors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. New α-Zn{sub 2}V{sub 2}O{sub 7}/carbon nanotube nanocomposite for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Venugopal, Nulu; Kim, Woo-Sik [Kyung Hee University, Yongin (Korea, Republic of)

    2015-09-15

    This study synthesized α-Zn{sub 2}V{sub 2}O{sub 7} nanopowders using a hydrothermal approach followed by annealing treatment. The resulting powders were then mixed with multi-walled carbon nanotubes and electrochemically characterized as new nanocomposite electrodes for supercapacitors. The structure and surface morphology of the powders were characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Plus, the capacitive behavior of the composite electrodes was evaluated by cyclic voltammetry and galvanostatic charge-discharge cycles in different molar aqueous KCl solutions. The α-Zn{sub 2}V{sub 2}O{sub 7}/multi-walled carbon nanotube composite electrodes were prepared using three different ratios and screened for their use in supercapacitors. As a result, the α-Zn{sub 2}V{sub 2}O{sub 7}/ multi-walled carbon nanotube composite electrode with a 1 : 2 ratio was identified as the best electrode with a specific capacitance value of 44.8 F g{sup -1} in 0.5M KCl. Notwithstanding, all the tested composite electrodes demonstrated an excellent cycle stability and showed a less than 4% change in their specific capacitance values when compared to the initial values.

  7. Luminescence dosemeter of the Al{sub 2}O{sub 3}:Er,Yb

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Katia A.; Ventieri, Alexandre; Bitencourt, Jose F.S. [Universidade de Sao Paulo (EP/USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Eletrica; Mittani, Juan C.R.; Tatumi, Sonia H. [Faculdade de Tecnologia de Sao Paulo (CEETEPS), SP (Brazil)

    2011-07-01

    The present work deals with the thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) properties of {alpha}-Al{sub 2}O{sub 3}: Er,Yb obtained by sol gel process. Nanocrystals formations composed by Er{sub 2}O{sub 3}, Yb{sub 2}O{sub 3} and Yb{sub 3}Al{sub 5}O{sub 12} were observed by TEM images, EDS, electron beam diffraction and RXD, located at the surface of the alumina grains. The sample codoped with 1mol% of Er and 2 mol% of Yb supplied the best results for TL and OSL responses. The growth of the intensity of dosimetric TL peak at 205 deg C was linear with gamma radiation doses and the same behavior was observed in OSL growth curve. The luminescence fading of the sample after a dose of 5 Gy was found initially for a period of 30 days and minimum detectable dose measured for TL was 60.78 mGy and for OSL was 13.09 mGy. (author)

  8. Effect of Cr{sub 2}O{sub 3} on the microstructure and non-ohmic properties of (Co, Sb)-doped SnO{sub 2} varistors

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar M, J. A. [Centro de Investigac ion en Materiales Avanzados, S. C., Alianza Norte No. 202, Parque de Investigacion e Innovacion Tecnologica, Nueva Carretera Aeropuerto Km. 10 Apodaca 66600, Nuevo Leon (Mexico); Pech C, M. I. [IPN, Centro de Investigacion y de Estudios Avanzados, Unidad Saltillo, Carretera Saltillo-Monterrey Km. 13, Saltillo 25900, Coahuila (Mexico); Hernandez, M. B.; Rodriguez, E.; Garcia O, L. [Universidad Autonoma de Nuevo Leon, Facultad de Ingenieria Mecanica y Electrica, San Nicolas de los Garza, Nuevo Leon (Mexico); Glot, A. B., E-mail: josue.aguilar@cimav.edu.mx [Universidad Tecnologica de la Mixteca, Division de Estudios de Posgrado, Carretera Acatlima Km. 2.5, Huajuapan de Leon 69000, Oaxaca (Mexico)

    2013-10-01

    The effect of Cr{sub 2}O{sub 3} addition on the physical characteristics, microstructure, and current-voltage properties of (Co-Sb)-doped SnO{sub 2} varistors was investigated. SnO{sub 2}-Co{sub 3}O{sub 4}-Sb{sub 2}O{sub 5} ceramics with additions of 0.0, 0.03, 0.05 and 0.07 mol % Cr{sub 2}O{sub 3} were sintered at 1350 C under ambient atmosphere and characterized micro structurally and electrically. The characterization by X-ray diffraction and scanning electron microscopy show that the microstructure remains as a single phase material with multimodal size distribution of SnO{sub 2} grains. The greatest effect of Cr{sub 2}O{sub 3} additions is manifested in the electric breakdown field. Additions of high levels (0.07 and 0.05 %) of this oxide promote and increase of approximately 55% in this parameter compared to the Cr{sub 2}O{sub 3}-free sample. Another physical property is affected: the measured density values decreases as the Cr{sub 2}O{sub 3} content increases. A change in the nonlinearity coefficient value is produced only at the highest Cr{sub 2}O{sub 3} content while at intermediate levels there is not change at all. Consequently, when seeking high nonlinearity coefficients, intermediate levels of Cr{sub 2}O{sub 3} are not recommended. (Author)

  9. Electrocatalytic reduction of H{sub 2}O{sub 2} by Pt nanoparticles covalently bonded to thiolated carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    You, Jung-Min; Kim, Daekun [Department of Chemistry and Institute of Basic Science, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Jeon, Seungwon [Department of Chemistry and Institute of Basic Science, Chonnam National University, Gwangju 500-757 (Korea, Republic of)

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer Novel thiolated carbon nanostructures - platinum nanoparticles [t-GO-C(O)-pt and t-MWCNT-C(O)-S-pt] have been synthesized, and [t-GO-C(O)-pt and t-MWCNT-C(O)-S-pt] denotes as t-GO-pt and t-MWCNT-Pt in manuscript, respectively. Black-Right-Pointing-Pointer The modified electrode denoted as PDDA/t-GO-pt/GCE was used for the electrochemical determination of H{sub 2}O{sub 2} for the first time. Black-Right-Pointing-Pointer The results show that PDDA/t-GO-pt nanoparticles have the promising potential as the basic unit of the electrochemical biosensors for the detection of H{sub 2}O{sub 2}. Black-Right-Pointing-Pointer The proposed H{sub 2}O{sub 2} biosensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s. - Abstract: Glassy carbon electrodes were coated with thiolated carbon nanostructures - multi-walled carbon nanotubes and graphene oxide. The subsequent covalent addition of platinum nanoparticles and coating with poly(diallydimethylammonium chloride) resulted in biosensors that detected hydrogen peroxide through its electrocatalytic reduction. The sensors were easily and quickly prepared and showed improved sensitivity to the electrocatalytic reduction of H{sub 2}O{sub 2}. The Pt nanoparticles covalently bonded to the thiolated carbon nanostructures were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and energy dispersive X-ray spectroscopy. Cyclic voltammetry and amperometry were used to characterize the biosensors' performances. The sensors exhibited wide linear ranges and low detection limits, giving fast responses within 10 s, thus demonstrating their potential for use in H{sub 2}O{sub 2} analysis.

  10. Emission of NO and SO{sub 2} in a 300 kW pilot scale O{sub 2}/RFG Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Tai; Liu, Zhaohui; Huang, Xiaohong; Liu, Jingzhang; Wang, Dingbang; Zheng, Chuguang [Huazhong Univ. of Science and Technology, Wuhan (China). State Key Lab. of Coal Combustion

    2013-07-01

    The present work was addressed toward the NO and SO{sub 2} emission results on a 300 kW pilot scale facility, and discussed the impact of the different flue gas recycle ratios on the O{sub 2}/RFG coal combustion. In this study, a Chinese lean coal was burned with air and three kinds of O{sub 2}/RFG conditions in the pilot scale oxy-fuel coal combustion facility. The composition of the flue gas was sampled and analyzed by the FT/IR gas analyzer. The ashes were sampled in different place and analyzed to study the burnout rate and the mineral transformation. And in-furnace limestone injection under the air and oxy-fuel condition was used to study the desulfurization efficiency. The comparison was made between the air combustion and O{sub 2}/RFG combustion. It can be seen that NOx emissions decrease significantly (296 mg/MJ for air-firing, 80-145 mg/MJ for oxy-firing), compared with the air condition and three kind of oxy-fuel condition. It can be seen that the low NO{sub x} characteristic of the Oxy-fuel combustion causes lower emission of NO compared with the air combustion. For the emission of SO{sub 2}, Fuel-S to SO{sub 2} conversion rate dropped from 77% in air to 50% under O{sub 2}/RFG condition. And the desulfurization efficiencies of the air combustion and O{sub 2}/RFG combustion were 28.4 and 59.1%, respectively. The contribution of SO{sub 2} enriched in the flue gas to the desulfurization efficiency was more than the contribution of increased reactivity of the limestone. By the analyzing of the ash, it was the similar between the air combustion and O{sub 2}/RFG combustion.

  11. On a two-layer Si{sub 3}N{sub 4}/SiO{sub 2} dielectric mask for low-resistance ohmic contacts to AlGaN/GaN HEMTs

    Energy Technology Data Exchange (ETDEWEB)

    Arutyunyan, S. S., E-mail: spartakmain@gmail.com; Pavlov, A. Yu.; Pavlov, B. Yu.; Tomosh, K. N.; Fedorov, Yu. V. [Russian Academy of Sciences, Institute of Ultrahigh Frequency Semiconductor Electronics (Russian Federation)

    2016-08-15

    The fabrication of a two-layer Si{sub 3}N{sub 4}/SiO{sub 2} dielectric mask and features of its application in the technology of non-fired epitaxially grown ohmic contacts for high-power HEMTs on AlGaN/GaN heterostructures are described. The proposed Si{sub 3}N{sub 4}/SiO{sub 2} mask allows the selective epitaxial growth of heavily doped ohmic contacts by nitride molecular-beam epitaxy and the fabrication of non-fired ohmic contacts with a resistance of 0.15–0.2 Ω mm and a smooth surface and edge morphology.

  12. Reactivity feedback coefficients of a material test research reactor fueled with high-density U{sub 3}Si{sub 2} dispersion fuels

    Energy Technology Data Exchange (ETDEWEB)

    Muhammad, Farhan [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)], E-mail: farhan73@hotmail.com; Majid, Asad [Department of Nuclear Engineering, Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650 (Pakistan)

    2008-10-15

    The reactivity feedback coefficients of a material test research reactor fueled with high-density U{sub 3}Si{sub 2} dispersion fuels were calculated. For this purpose, the low-density LEU fuel of an MTR was replaced with high-density U{sub 3}Si{sub 2} LEU fuels currently being developed under the RERTR program. Calculations were carried out to find the fuel temperature reactivity coefficient, moderator temperature reactivity coefficient and moderator density reactivity coefficient. Nuclear reactor analysis codes including WIMS-D4 and CITATION were employed to carry out these calculations. It is observed that the average values of fuel temperature reactivity feedback coefficient, moderator temperature reactivity coefficient and moderator density reactivity coefficient from 20 deg. C to 100 deg. C, at the beginning of life, followed the relationships (in units of {delta}k/k x 10{sup -5} K{sup -1}) -2.116 - 0.118 {rho}{sub U}, 0.713 - 37.309/{rho}{sub U} and -12.765 - 34.309/{rho}{sub U}, respectively for 4.0 {<=} {rho}{sub U} (g/cm{sup 3}) {<=} 6.0.

  13. Improved electrochemical performance of LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} cathode material by double-layer coating with graphene oxide and V{sub 2}O{sub 5} for lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Wenbin, E-mail: wenbin.luo@hotmail.com; Zheng, Baolin

    2017-05-15

    Highlights: • Citric acid assisted sol-gel method was used for synthesizing LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2}. • The pristine LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} was surface-modified by double-layer coating. • The double coating layer consists of graphene oxide and V{sub 2}O{sub 5}. • Electrochemical performance was improved by double-layer coating. - Abstract: LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} cathode material synthesized by a sol-gel method was surface-modified by double-layer coating. The results of X-ray diffraction (XRD) confirm that the intrinsic structure was no change after surface modification. A double-layer structure consisting of an inner V{sub 2}O{sub 5} (VO) layer and an outer conductive graphene oxide (GO) layer was coated on the surface of active material, as confirmed by transmission electron microscopy (TEM). The results of field emission scanning electron microscope (FE-SEM) equipped with an energy dispersive spectroscope (EDS) show that both graphene oxide and V{sub 2}O{sub 5} uniformly covered LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} cathode material. The double-layer-coated LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} cathode material shows improved electrochemical performance with a capacity retention of 74.2% after 50 cycles in a range of 2.5–4.5 V at 55 °C, compared with only 67.8% capacity retention for the pristine material. In addition, the double-layer-coated LiNi{sub 0.5}Co{sub 0.2}Mn{sub 0.3}O{sub 2} releases 116.6 mAh g{sup −1} under a high current rate, while the pristine material only remains at 105.7 mAh g{sup −1}. The results can be ascribed to the double coating layer not only avoids the side reaction between electrolyte and active material but also promotes Li{sup +} and electronic conductivity. Differential capacity (dQ/dV) and electrochemical impedance spectroscopy (EIS) measurements reveal that the double coating layer effectively suppresses the increase of the electrode

  14. Electrodeposition of Fe{sub 2}O{sub 3} nanoparticles and its supercapacitive properties

    Energy Technology Data Exchange (ETDEWEB)

    Kadam, S. L., E-mail: snehal.kadam54@gmail.com; Padwal, P. M., E-mail: pal-soni279@yahoo.com; Mane, S. M., E-mail: manesagar99@gmail.com; Kulkarni, S. B., E-mail: sbk-physics@yahoo.com [Department of Physics, The Institute of Science, Madam Cama Road, Mumbai-400032 (India)

    2016-04-13

    Fe{sub 2}O{sub 3} metal oxide nanoparticles are synthesized by electrodeposition method on stainless steel substrate. The crystal structure and surface morphological studies of the obtained metal oxide thin film are carried out by using X-ray diffraction (XRD) technique and Scanning Electron Microscopy (SEM) respectively. The electrochemical properties of Fe{sub 2}O{sub 3} thin film like Cyclic Voltammetry (CV), Galvonostatic Charge-Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS) are studied in a bath of 0.5 M Na{sub 2}SO{sub 4} as electrolyte. The observed specific capacitance shows improved values 135 Fg{sup −1} at 5 mVs{sup −1} scan rate. The electrochemical stability of Fe{sub 2}O{sub 3} electrode is investigated using cyclic voltammetry for 1000 cycles at a scan rate 50 mVs{sup −1}. The Fe{sub 2}O{sub 3} electrode exhibits superior cycling stability with only 4-5% capacitance loss after one thousand cycles. The values of specific power and specific energy of Fe{sub 2}O{sub 3} electrode obtained from Galvonostatic charge discharge studies are 2250 W.kg{sup −1} and 63.15 Wh.kg{sup −1} respectively at current density 1 A/g. From all the electrochemical properties of Fe{sub 2}O{sub 3} electrode, it indicates that it will be promising electrode material for supercapacitor application.

  15. X-ray diffraction analysis of LiCu{sub 2}O{sub 2} crystals with additives of silver atoms

    Energy Technology Data Exchange (ETDEWEB)

    Sirotinkin, V. P., E-mail: irotinkin.vladimir@mail.ru; Bush, A. A.; Kamentsev, K. E. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation); Dau, H. S. [People’s Friendship University of Russia (Russian Federation); Yakovlev, K. A. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation); Tishchenko, E. A. [People’s Friendship University of Russia (Russian Federation)

    2015-09-15

    Silver-containing LiCu{sub 2}O{sub 2} crystals up to 4 × 8 × 8 mm in size were grown by the crystallization of 80(1-x)CuO · 20{sub x}AgNO{sub 3} · 20Li{sub 2}CO{sub 3} (0 ≤ x ≤ 0.5) mixture melt. According to the X-ray spectral and Rietveld X-ray diffraction data, the maximum amount of silver incorporated in the LiCu{sub 2}O{sub 2} structure is about 4 at % relative to the copper content. It was established that silver atoms occupy statistically crystallographic positions of lithium atoms. The incorporation of silver atoms is accompanied by a noticeable increase in parameter c of the LiCu{sub 2}O{sub 2} rhombic unit cell, a slight increase in parameter a, and a slight decrease in parameter b.

  16. Effect of exposure to O/sub 3/, SO/sub 2/, and NO/sub 2/ upon the lung histamine content of guinea pigs

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, T

    1969-01-01

    Male guinea pigs were exposed to 1 or 4 to 8 ppM O/sub 3/, 10 or 50 ppM SO/sub 2/, or 10 or 80 ppM NO/sub 2/ for 3 hr. Histamine and water content of lungs were measured. Animals exposed to higher concentrations of O/sub 3/ or NO/sub 2/ had edematous lungs. Lungs of those exposed to lower concentrations of O/sub 3/ or NO/sub 2/ also had slightly higher water contents. Lung histamine content and concentration decreased by O/sub 3/ exposure but not by any other treatment. In vitro exposure of lung to O/sub 3/ showed released histamine occurring in the perfusion outflow. Endogenous, cellular, inert histamine evidently was released by O/sub 3/ stimulant. However, the mechanism for NO/sub 2/-caused edema was not revealed, but could be direct action on lung vessels rather than through histamine mediation.

  17. Effect of symbiotic compound Fe{sub 2}P{sub 2}O{sub 7} on electrochemical performance of LiFePO{sub 4}/C cathode materials

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuxin, E-mail: liushuxin88@126.com [School of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang, Sichuan 621000 (China); Gu, Chunlei [School of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018 (China); Wang, Haibin [School of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang, Sichuan 621000 (China); Liu, Ruijiang [School of Pharmacy, Jiangsu University, Zhenjiang, Jiangsu 212013 (China); Wang, Hong; He, Jichuan [School of Chemistry and Chemical Engineering, Mianyang Normal University, Mianyang, Sichuan 621000 (China)

    2015-10-15

    In order to study the effect of symbiotic compound Fe{sub 2}P{sub 2}O{sub 7} on electrochemical performance of LiFePO{sub 4}/C cathode materials, the LiFePO{sub 4}/Fe{sub 2}P{sub 2}O{sub 7}/C cathode materials were synthesized by in-situ synthesis method. The phase compositions and microstructures of the products were characterized by X-ray powder diffraction (XRD) and field emission scanning electron microscope (FESEM). Results indicate that the existence of Fe{sub 2}P{sub 2}O{sub 7} does not alter LiFePO{sub 4} crystal structure and the existence of Fe{sub 2}P{sub 2}O{sub 7} decreases the particles size of LiFePO{sub 4}. The electrochemical behavior of cathode materials was analyzed using galvanostatic measurement and cyclic voltammetry (CV). The results show that the existence of Fe{sub 2}P{sub 2}O{sub 7} improves electrochemical performance of LiFePO{sub 4} cathode materials in specific capability and lithium ion diffusion rate. The charge–discharge specific capacity and apparent lithium ion diffusion coefficient increase with Fe{sub 2}P{sub 2}O{sub 7} content and maximizes around the Fe{sub 2}P{sub 2}O{sub 7} content is 5 wt%. It has been had further proved that the Fe{sub 2}P{sub 2}O{sub 7} adding enhances the lithium ion transport to improve the electrochemical performance of LiFePO{sub 4} cathode materials. However, excessive Fe{sub 2}P{sub 2}O{sub 7} will block the electron transfer pathway and affect the electrochemical performances of LiFePO{sub 4} directly. - Graphical abstract: The LiFePO{sub 4}/Fe{sub 2}P{sub 2}O{sub 7}/C cathode materials were synthesized by in-situ synthesis method. The existence of Fe{sub 2}P{sub 2}O{sub 7} does not alter LiFePO{sub 4} crystal structure and the existence of Fe{sub 2}P{sub 2}O{sub 7} decreases the particles size of LiFePO{sub 4}. The charge–discharge specific capacity and apparent lithium ion diffusion coefficient increase with Fe{sub 2}P{sub 2}O{sub 7} content. However, excessive Fe{sub 2}P{sub 2}O{sub 7} will

  18. Synthesis of Bi{sub 2}O{sub 3} architectures in DMF–H{sub 2}O solution by precipitation method and their photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Li-Li; Han, Qiao-Feng, E-mail: hanqiaofeng@njust.edu.cn; Zhao, Jin; Zhu, Jun-Wu; Wang, Xin, E-mail: wangx@njust.edu.cn; Ma, Wei-Hua

    2014-11-25

    Graphical abstract: Flowerlike α-Bi{sub 2}O{sub 3} architectures assembled by nanobrick-based petals with pineapple surface were firstly synthesized by precipitation method at room temperature in DMF–H{sub 2}O solution. - Highlights: • Nanobrick-based flowerlike Bi{sub 2}O{sub 3} crystals with pineapple surface were synthesized by precipitation method. • Good solubility of Bi(NO{sub 3}){sub 3} in DMF played a crucial role in the growth of flowerlike Bi{sub 2}O{sub 3}. • The growth mechanism of Bi{sub 2}O{sub 3} microcrystallites has been explained in detail. - Abstract: Well-crystalline flowerlike α-Bi{sub 2}O{sub 3} hierarchical architectures with pineapple-shaped petals have been synthesized by precipitation method at a volume ratio of DMF/H{sub 2}O of 5, where DMF and H{sub 2}O were used to dissolve Bi(NO{sub 3}){sub 3} and KOH, respectively. If the DMF/H{sub 2}O ratio was decreased to 2:1, 1:1 and 0:30, flower-, bundle- and dendrite-shaped α-Bi{sub 2}O{sub 3} microcrystallites aggregated by nanorods were formed, respectively. The simple synthetic route and thus obtained Bi{sub 2}O{sub 3} architectures of various morphologies provide a basis insight for their formation mechanism. The photocatalytic activity of the as-prepared Bi{sub 2}O{sub 3} particles for degradation of Rhodamine B (RhB) under visible-light irradiation was obviously influenced by their morphologies. Bi{sub 2}O{sub 3} of nanorod-based microstructures exhibited higher photodegradation activity than nanobrick-based ones, owing to higher light absorption and carrier separation efficiency in one-dimensional (1D) nanostructured materials.

  19. [O{sub 2}Pb{sub 3}]{sub 2}(BO{sub 3})Br. An oxidoborate oxide bromide with the {sub ∞}{sup 1}[O{sub 2}Pb{sub 3}] double chains based on edge-sharing OPb{sub 4} tetrahedra

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Lingyun [College of Chemistry and Environmental Science, Hebei University, Baoding (China); Biology and Chemistry Department, Baoding University (China); Yang, Jiao; Shen, Shigang; Liu, Zhenzhen; Sun, Sufang [College of Chemistry and Environmental Science, Hebei University, Baoding (China); Chen, Xiaojing [Biology and Chemistry Department, Baoding University (China)

    2017-04-04

    Through extensive research on the PbO / PbBr{sub 2} / B{sub 2}O{sub 3} system, a new single crystal of yellow lead-containing oxyborate bromine, [O{sub 2}Pb{sub 3}]{sub 2}(BO{sub 3})Br, was grown from the melt. It crystallizes in the centrosymmetric space group Cmcm (no. 63) of the orthorhombic system with the following unit cell dimensions: a = 9.5748(8) Aa, b = 20.841(2) Aa, c = 5.7696(5) Aa, and Z = 4. The whole structure is characterized by an infinite one-dimensional (1D) {sub ∞}{sup 1}[O{sub 2}Pb{sub 3}] double chain, which is based on the OPb{sub 4} oxocentered tetrahedra and considered as the derivative of the continuous sheet of OPb{sub 4} tetrahedra from the tetragonal modification of α-PbO. The 1D {sub ∞}{sup 1}[O{sub 2}Pb{sub 3}] double chains are further bridged by the BO{sub 3} units through common oxygen atoms to form two-dimensional (2D) {sub ∞}{sup 1}[(O{sub 2}Pb{sub 3})(BO{sub 3})] layers, with Br atoms situated between the layers. IR spectroscopy, UV/Vis/NIR diffuse reflectance spectroscopy, and thermal analysis were also performed on the reported material. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Evaluation of Gd{sub 2}O{sub 2}S:Pr granular phosphor properties for X-ray mammography imaging

    Energy Technology Data Exchange (ETDEWEB)

    David, S.; Michail, C. [Department of Biomedical Engineering, Technological Educational Institute (TEI) of Athens, Ag. Spyridonos Street, 122 10 Egaleo (Greece); Seferis, I. [Department of Biomedical Engineering, Technological Educational Institute (TEI) of Athens, Ag. Spyridonos Street, 122 10 Egaleo (Greece); Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Valais, I.; Fountos, G.; Liaparinos, P.; Kandarakis, I. [Department of Biomedical Engineering, Technological Educational Institute (TEI) of Athens, Ag. Spyridonos Street, 122 10 Egaleo (Greece); Kalyvas, N., E-mail: nkalyvas@teiath.gr [Department of Biomedical Engineering, Technological Educational Institute (TEI) of Athens, Ag. Spyridonos Street, 122 10 Egaleo (Greece)

    2016-01-15

    Phosphor materials are widely used in X-ray medical imaging detector applications, coupled with suitable photoreceptors. Upon the most demanding imaging modality is X-ray mammography, since the best defense against breast cancer is its early detection. A material suitable as a mammographic detector should efficiently absorb X-ray photons and transform them to optical photons, so as to minimize breast dose. The aim of the present study was to investigate the X-ray absorption efficiency and the absolute efficiency (AE), defined as the output optical photon power divided by the incident exposure, of Gd{sub 2}O{sub 2}S:Pr powder scintillator. For the purposes of this study, three scintillating screens with coating thicknesses, 34.1, 46.0 and 81.5 mg/cm{sup 2} respectively, were prepared in our laboratory from Gd{sub 2}O{sub 2}S:Pr powder (Phosphor Technology, Ltd.) by sedimentation on silica substrates. The quantum detection efficiency (QDE), the energy absorption efficiency (EAE), the spectral matching factor and the absolute efficiency (AE) were evaluated for X-ray mammographic conditions. Furthermore theoretical models were utilized to investigate the optical photon transmission properties through the phosphor mass. Gd{sub 2}O{sub 2}S:Pr presented high X-ray absorption properties and good spectral compatibility with several photoreceptors. It may be utilized for X-ray mammographic imaging if it is put in conjunction with a sensitive photoreceptor, so as to enhance Gd{sub 2}O{sub 2}S:Pr light emission properties. - Highlights: • Gd{sub 2}O{sub 2}S:Pr phosphor evaluated for mammography detectors. • The X-ray absorption efficiency was found high. • Spectral matching compatibility found for several photoreceptors. • X-ray absolute efficiency measured smaller than other phosphors. • Optical diffusion length and the light transmission per layer was theoretically calculated.

  1. Fabrication of low thermal expansion SiC/ZrW{sub 2}O{sub 8} porous ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Poowancum, A; Matsumaru, K; Juarez-Ramirez, I; Ishizaki, K [Department of Mechanical Engineering, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Torres-Martinez, L M [Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, San Nicolas de los Garza, NL, C.P. 66451 (Mexico); Fu, Z Y [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, Hubei, 430070 (China); Lee, S W, E-mail: anurat@ishizaki.nagaokaut.ac.jp [Department of Environment Engineering, Sun Moon University, 100, Kalsan-ri, Tangjeong-myeon, Asan, Chungnam 336-708 (Korea, Republic of)

    2011-03-15

    Low or zero thermal expansion porous ceramics are required for several applications. In this work near zero thermal expansion porous ceramics were fabricated by using SiC and ZrW{sub 2}O{sub 8} as positive and negative thermal expansion materials, respectively, bonded by soda lime glass. The mixture of SiC, ZrW{sub 2}O{sub 8} and soda lime glass was sintered by Pulsed Electric Current Sintering (PECS, or sometimes called Spark Plasma Sintering, SPS) at 700 deg. C. Sintered samples with ZrW{sub 2}O{sub 8} particle size smaller than 25 {mu}m have high thermal expansion coefficient, because ZrW{sub 2}O{sub 8} has the reaction with soda lime glass to form Na{sub 2}ZrW{sub 3}O{sub 12} during sintering process. The reaction between soda lime glass and ZrW{sub 2}O{sub 8} is reduced by increasing particle size of ZrW{sub 2}O{sub 8}. Sintered sample with ZrW{sub 2}O{sub 8} particle size 45-90 {mu}m shows near zero thermal expansion.

  2. Characterization of Pt catalysts supported in TiO{sub 2} and ZrO{sub 2} stabilized with La{sub 2}O{sub 3} for the nitric oxide elimination; Caracterizacion de catalizadores de Pt soportado en TiO{sub 2} y ZrO{sub 2} estabilizados con La{sub 2}O{sub 3} para la eliminacion de oxido nitrico

    Energy Technology Data Exchange (ETDEWEB)

    Perez H, R.; Arenas, J.; Rodriguez, V.; Aguilar, A.; Gomez C, A.; Diaz, G. [ININ, Carretera Mexico-Toluca, Km. 36.5 Salazar, Estado de Mexico, C.P. 52045 (Mexico)

    2000-07-01

    Simple oxides TiO{sub 2}, ZrO{sub 2}, La{sub 2}O{sub 3} and mixed TiO{sub 2}-La{sub 2}O{sub 3}, ZrO{sub 2}-La{sub 2}O{sub 3} at 10% mol of lanthane were prepared by the precipitation technique. The incorporation of Pt to the supports was by the classical impregnation method. It was characterized the catalytic materials by diverse techniques for determining the lost weight by thermogravimetric analysis (TGA), superficial area (BET), crystallinity of catalytic supports (DR-X) total acidity and for the catalytic activity was realized in the reaction model NO + CH{sub 4}. (Author)

  3. Thermoluminescence studies of γ-irradiated Al{sub 2}O{sub 3}:Ce{sup 3+} phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, S. Satyanarayana [Physics R & D Center, PES Institute of Technology, BSK 3rd Stage, Bangalore 560085 (India); Nagabhushana, K.R., E-mail: bhushankr@gmail.com [Physics R & D Center, PES Institute of Technology, BSK 3rd Stage, Bangalore 560085 (India); Department of Physics, PES University, BSK 3rd Stage, Bangalore 560085 (India); Singh, Fouran [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

    2016-07-15

    Pure and Ce{sup 3+} doped Al{sub 2}O{sub 3} phosphors were synthesized by solution combustion method. The synthesized samples were characterized by X-ray diffraction (XRD) and its shows α-phase of Al{sub 2}O{sub 3}. Crystallite size was estimated by Williamson–Hall (W–H) method and found to be 49, 59 and 84 nm for pure, 0.1 mol% and 1 mol% Ce{sup 3+} doped Al{sub 2}O{sub 3} respectively. Trace elemental analysis of undoped Al{sub 2}O{sub 3} shows impurities viz. Fe, Cr, Mn, Mg, Ti, etc. Photoluminescence (PL) spectra of Al{sub 2}O{sub 3}:Ce{sup 3+} shows emission at 367 nm and excitation peak at 273 nm, which are corresponding to {sup 5}D → {sup 4}F and {sup 4}F → {sup 5}D transitions respectively. PL intensity decreases with concentration up to 0.4 mol%, beyond this mol% PL intensity increases with doping concentration up to 2 mol%. Thermoluminescence (TL) studies of γ-rayed pure and Ce{sup 3+} doped Al{sub 2}O{sub 3} have been studied. Two well resolved TL glow peaks at 457.5 K and 622 K were observed in pure Al{sub 2}O{sub 3}. Additional glow peak at 566 K was observed in Al{sub 2}O{sub 3}:Ce{sup 3+}. Maximum TL intensity was observed for Al{sub 2}O{sub 3}:Ce{sup 3+} (0.1 mol%) beyond this TL intensity decreases with increasing Ce{sup 3+} concentration. Computerized glow curve deconvolution (CGCD) method was used to resolve the multiple peaks and to calculate TL kinetic parameters. Thermoluminescence emission (TLE) spectra of pure Al{sub 2}O{sub 3} glow peaks (457.5 K and 622 K) shows sharp emission at 694 nm and two small humps at 672 nm and 709 nm. The sharp peak at 696 nm corresponds to Cr{sup 3+} impurity of {sup 2}E{sub g} → {sup 4}A{sub 2g} transition of R lines and 713 nm hump is undoubtedly belongs to Cr{sup 3+} emission of near neighbor pairs. The emission at 672 nm is characteristic of Mn{sup 4+} impurity ions of {sup 2}E → {sup 4}A{sub 2} transition. TLE of Al{sub 2}O{sub 3}:Ce{sup 3+} (0.1 mol%) shows additional broad emission at 412 nm

  4. A novel organic–inorganic hybrid with Anderson type polyanions as building blocks: (C{sub 6}H{sub 10}N{sub 3}O{sub 2}){sub 2}Na(H{sub 2}O){sub 2}[Al(OH){sub 6}Mo{sub 6}O{sub 18}]·6H{sub 2}O

    Energy Technology Data Exchange (ETDEWEB)

    Thabet, Safa, E-mail: safathabet@hotmail.fr [Laboratoire de matériaux et cristallochimie, Département de chimie, Institut Supérieur des Sciences Appliquées et Technologier, Avenue El Mourouj, 5111 Mahdia (Tunisia); Ayed, Brahim, E-mail: brahimayed@yahoo.fr [Laboratoire de matériaux et cristallochimie, Département de chimie, Institut Supérieur des Sciences Appliquées et Technologier, Avenue El Mourouj, 5111 Mahdia (Tunisia); Haddad, Amor [Laboratoire de matériaux et cristallochimie, Département de chimie, Institut Supérieur des Sciences Appliquées et Technologier, Avenue El Mourouj, 5111 Mahdia (Tunisia)

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ► Synthesis of a novel inorganic–organic hybrid compound based on Anderson polyoxomolybdates. ► Characterization by X-ray diffraction, IR and UV–Vis spectroscopies of the new compound. ► Potential applications in catalysis, biochemical analysis and electrical conductivity of the organic–inorganic compound. -- Abstract: A new organic–inorganic hybrid compound based on Anderson polyoxomolybdates, (C{sub 6}H{sub 10}N{sub 3}O{sub 2}){sub 2}Na(H{sub 2}O){sub 2}[Al(OH){sub 6}Mo{sub 6}O{sub 18}]·6H{sub 2}O (1) have been isolated by the conventional solution method and characterized by single-crystal X-ray diffraction, infrared, ultraviolet spectroscopy and Thermogravimetric Analysis (TGA). This compound crystallized in the triclinic system, space group P−1, with a = 94.635(1) Å, b = 10.958(1) Å, c = 11.602(1) Å, α = 67.525(1)°, β = 71.049(1)°, γ = 70.124(1)° and Z = 1. The crystal structures of the compounds exhibit three-dimensional supramolecular assembly based on the extensive hydrogen bonding interactions between organic cations, sodium cations, water molecules and Anderson polyoxoanions. The infrared spectrum fully confirms the X-ray crystal structure and the UV spectrum of the title compound exhibits an absorption peak at 210 nm.

  5. Homogeneous samples of Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}

    Energy Technology Data Exchange (ETDEWEB)

    Hoogenboom, B.W.; Kadowaki, K.; Revaz, B.; Fischer, O

    2003-09-15

    Recently, much attention has been paid to inhomogeneity in samples of the high-temperature superconductor Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}}. In this work it is shown that homogeneous samples can indeed be obtained in the slightly overdoped range. However, the homogeneity critically depends on sample preparation.

  6. Cobalt surface modification during γ-Fe{sub 2}O{sub 3} nanoparticle synthesis by chemical-induced transition

    Energy Technology Data Exchange (ETDEWEB)

    Li, Junming [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Li, Jian, E-mail: aizhong@swu.edu.cn [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Chen, Longlong; Lin, Yueqiang; Liu, Xiaodong; Gong, Xiaomin [School of Physical Science and Technology, Southwest University, Chongqing 400715 (China); Li, Decai [School of Mechanical and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China)

    2015-02-01

    In the chemical-induced transition of FeCl{sub 2} solution, the FeOOH/Mg(OH){sub 2} precursor was transformed into spinel structured γ-Fe{sub 2}O{sub 3} crystallites, coated with a FeCl{sub 3}·6H{sub 2}O layer. CoCl{sub 2} surface modified γ-Fe{sub 2}O{sub 3} nanoparticles were prepared by adding Co(NO{sub 3}){sub 2} during the synthesis. CoFe{sub 2}O{sub 4} modified γ-Fe{sub 2}O{sub 3} nanoparticles were prepared by adding NaOH during the surface modification with Co(NO{sub 3}){sub 2}. The CoFe{sub 2}O{sub 4} layer grew epitaxially on the γ-Fe{sub 2}O{sub 3} crystallite to form a composite crystallite, which was coated by CoCl{sub 2}·6H{sub 2}O. The composite could not be distinguished using X-ray diffraction or transmission electron microscopy, since CoFe{sub 2}O{sub 4} and γ-Fe{sub 2}O{sub 3} possess similar spinel structures and lattice constants. X-ray photoelectron spectroscopy was used to distinguish them. The saturation magnetization and coercivity of the spinel structured γ-Fe{sub 2}O{sub 3}-based nanoparticles were related to the grain size. - Highlights: • γ-Fe{sub 2}O{sub 3} nanoparticles were synthesized by chemical induced transition. • CoCl{sub 2} modified nanoparticles were prepared by additional Co(NO{sub 3}){sub 2} during synthesization. • CoFe{sub 2}O{sub 4} modified nanoparticles were prepared by additional Co(NO{sub 3}){sub 2} and NaOH. • The magnetism of the nanoparticles is related to the grain size.

  7. Crystallization behavior of (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Moo-Chin [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 807, Taiwan (China); Cheng, Chih-Wei; Chang, Kuo-Ming [Department of Mechanical Engineering, National Kaohsiung University of Applied Sciences, 415 Chien-Kung Road, Kaohsiung 80782, Taiwan (China); Hsi, Chi-Shiung, E-mail: chsi@nuu.edu.t [Department of Materials Science and Engineering, National United University, 1 Lien-Da, Kung-Ching Li, Miao-Li 36003, Taiwan (China)

    2010-07-02

    The crystallization behavior of the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses has been investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and energy dispersive spectroscopy (EDS). The crystalline phase was composed of {beta}-spodumene. The isothermal crystallization kinetics of {beta}-spodumene from the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses has also been studied by a quantitative X-ray diffraction method. The activation energy of {beta}-spodumene formation decreases from 359.2 to 317.8 kJ/mol when the Na{sub 2}O content increases from 0 to 0.4 mol and it increases from 317.8 to 376.9 kJ/mol when the Na{sub 2}O content increases from 0.4 to 0.6 mol. The surface nucleation and plate-like growth were dominant in the crystallization of the (1 - x)Li{sub 2}O.xNa{sub 2}O.Al{sub 2}O{sub 3}.4SiO{sub 2} glasses.

  8. Gas-sensing properties of In{sub 2}O{sub 3} films modified with gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Korotcenkov, G., E-mail: ghkoro@yahoo.com [School of Material Science and Engineering, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Brinzari, V. [Department of Theoretical Physics, State University of Moldova, Chisinau, Republic of Moldova (Moldova, Republic of); Han, S.H. [Division of Maritime Transportation System, Mokpo National Maritime University, Mokpo (Korea, Republic of); Cho, B.K., E-mail: chobk@gist.ac.kr [School of Material Science and Engineering, Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of)

    2016-06-01

    A study of the surface and gas–sensitive properties of In{sub 2}O{sub 3} films modified with gold nanoparticles and synthesized by the successive ionic layer deposition (SILD) method was conducted. In{sub 2}O{sub 3} films were prepared using the spray pyrolysis method. The gas-sensing characteristics were tested using CO, H{sub 2}, and O{sub 3} as target gases. It has been shown that the surface modification with gold nanoparticles gives the opportunity to optimize the response of In{sub 2}O{sub 3}-based gas sensors to both reducing (CO, H{sub 2}) and oxidizing (O{sub 3}) gases. It has been found that the sensitizing effect during ozone detection was significantly higher than the effect during CO and H{sub 2} detection. It has been demonstrated that the sensitizing effect depended on the number of SILD cycles used for gold nanoparticle deposition and was maximal for the In{sub 2}O{sub 3} surface decorated with gold nanoparticles with the smallest size. The mechanism of the gold nanoparticles' influence on the gas-sensing properties of the In{sub 2}O{sub 3} films is also discussed. It is suggested that to explain the observed effects, we have to consider both the “electronic” and “chemical” mechanisms of sensitization. Suggestions for studies to be carried out to further improve both the understanding of the nature of the gas-sensitive effects and the parameters of In{sub 2}O{sub 3}:Au-based gas sensors are also formulated. - Highlights: • In{sub 2}O{sub 3} gas sensors modified with gold nanoparticles using SILD method are studied. • AuNPs exhibit activity during interaction with either reducing or oxidizing gases. • Maximal effect of optimization is observed during ozone detection. • Sensitizing effect depends on the number of SILD cycles. • Proposed mechanisms explain effects observed in the In{sub 2}O{sub 3}:Au based gas sensors.

  9. Interaction of low-expansion NZP ceramics with Na{sub 2}SO{sub 4} at 1000{degrees}C

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.Y.; Cooley, K.M.; Stinton, D.P.; Joslin, D.L. [Oak Ridge National Lab., TN (United States)

    1996-08-01

    The interaction between several low-expansion NZP materials and Na{sub 2}SO{sub 4} at 1000{degrees}C in pure O{sub 2} was studied. Ba{sub 1.25}Zr{sub 4}P{sub 5.5}Si{sub 0.5}O{sub 24} experienced extensive cracking and delamination upon reaction with Na{sub 2}SO{sub 4}. On the other hand, Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}P{sub 6}O{sub 24} remained intact in terms of visual appearance, and had no significant weight loss or gain. However, the ion exchange between Na{sup +} ions and Ca{sup +2} ions was observed to be sufficiently rapid to allow the penetration of the Na{sup +} ions into the test specimens in 100h. The segregation of Ca to the specimen surface was observed due to the ion exchange. Ca{sub 0.6}Mg{sub 0.4}Zr{sub 4}P{sub 6}O{sub 24} was also tested, but its stability could not properly be assessed because the as-received specimens contained a significant amount of MgZr{sub 4}P{sub 6}O{sub 24} as an impurity phase.

  10. De-chlorination and solidification of radioactive LiCl waste salt by using SiO{sub 2}-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5} (SAP) inorganic composite including B{sub 2}O{sub 3} component

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ki Rak; Park, Hwan-Seo; Cho, In-Hak; Choi, Jung-Hoon; Eun, Hee-Chul; Lee, Tae-Kyo; Han, Seung Youb; Ahn, Do-Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2017-09-15

    SAP (SiO{sub 2}-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5}) composite has been recently studied in KAERI to deal with the immobilization of radioactive salt waste, one of the most problematic wastes in the pyro-chemical process. Highly unstable salt waste was successfully converted into stable compounds by the dechlorination process with SAPs, and then a durable waste form with a high waste loading was produced when adding glassy materials to dechlorination product. In the present study, U-SAP composite which is SAP bearing glassy component (Boron) was synthesized to remove the adding and mixing steps of glassy materials for a monolithic wasteform. With U-SAPs prepared by a sol-gel process, a series of wasteforms were fabricated to identify a proper reaction condition. Physical and chemical properties of dechlorination products and U-SAP wasteforms were characterized by XRD, DSC, SEM, TGA and PCT-A. A U-SAP wasteform showed suitable properties as a radioactive wasteform such as dense surface morphology, high waste loading, and high durability at the optimized U-SAP/salt ratio 2.

  11. Synthesis, optical, and photocatalytic properties of a new visible-light-active ZnFe{sub 2}O{sub 4}-TiO{sub 2} nanocomposite material

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, E. [University of Lisbon, Department of Chemistry and Biochemistry, Faculty of Sciences (Portugal); Fraga, L. A. [Universidade da Coruna, Facultade de Ciencias (Spain); Mendonca, M. H.; Monteiro, O. C., E-mail: ocmonteiro@fc.ul.pt [University of Lisbon, Department of Chemistry and Biochemistry, Faculty of Sciences (Portugal)

    2012-06-15

    The synthesis of new ZnFe{sub 2}O{sub 4}-TiO{sub 2} crystalline nanocomposites with enhanced visible-light catalytic performance is reported. Zinc ferrite powders were prepared by a wet method through oxalate precursor at 400 Masculine-Ordinal-Indicator C during 12 h and the nanocomposite materials were obtained through TiO{sub 2} incorporation before (ZnFe{sub 2}O{sub 4}/TiO{sub 2}) and after (TiO{sub 2}/ZnFe{sub 2}O{sub 4}) the ZnFe{sub 2}O{sub 4} synthesis. The influence of the nanocomposite design in the structural, morphological, and optical properties of the composite oxide materials was studied, by XRD, SEM/TEM, BET measurements, and DRS. New and improved optical features were observed in the ZnFe{sub 2}O{sub 4}-TiO{sub 2} absorption spectra comparatively with the TiO{sub 2} and ZnFe{sub 2}O{sub 4} ones. These results are discussed based on the interface effect and a proposal for the photogenerated electron transitions in the ZnFe{sub 2}O{sub 4}-TiO{sub 2} is presented. The photocatalytic performance of the prepared samples was evaluated for the methyl orange (MO) degradation process. From all the tested materials, the TiO{sub 2}/ZnFe{sub 2}O{sub 4} was the one with the best photocatalytic activity, even superior to the nanocrystalline TiO{sub 2} one. 100 % reduction of the MO concentration was achieved after 10 min of UV-Vis irradiation on a 10 ppm dye aqueous solution with 0.43 g L{sup -1} of TiO{sub 2}/ZnFe{sub 2}O{sub 4} catalyst. By performing visible-light experiments, it was possible to discuss the influence of the visible-light absorption, charge separation, and photogenerated charge-carrier recombination in the TiO{sub 2}/ZnFe{sub 2}O{sub 4} photocatalytic performance.

  12. Magnetic and luminescent properties of Fe/Fe{sub 3}O{sub 4}-Y{sub 2}O{sub 3}:Eu nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Wang Qin [College of Chemistry, Jilin University, Changchun 130012 (China); College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot (China); Yang Xuwei; Yu Lianxiang [College of Chemistry, Jilin University, Changchun 130012 (China); Yang Hua, E-mail: huayang86@sina.com [College of Chemistry, Jilin University, Changchun 130012 (China)

    2011-09-15

    Highlights: > We synthesize multifunctional Fe/Fe{sub 3}O{sub 4}-Y{sub 2}O{sub 3}:Eu nanocomposites. > The luminescent and magnetic properties of the nanocomposites are researched. > The nanocomposites showed both ferrimagnetic behavior and unique europium fluorescence properties with high emission intensity. > The spectra changes induced by the UV light irradiation and the magnetic field have been systematically studied and compared in detail. > And the hysteresis curve changes induced by the UV light irradiation have been discussed. - Abstract: Multifunctional nanocomposites with Fe/Fe{sub 3}O{sub 4} nanoparticles as the core and europium-doped yttrium oxide (Y{sub 2}O{sub 3}:Eu) as the shell (Fe/Fe{sub 3}O{sub 4}-Y{sub 2}O{sub 3}:Eu) have been obtained successfully employing a solvothermal method. The nanocomposites showed both ferrimagnetic behavior and unique europium fluorescence properties with high emission intensity. The spectra changes induced by the UV light irradiation and the magnetic field have been systematically studied and compared in detail. The relationship between fluorescence and magnetic properties of the multifunctional nanocomposites has been investigated in our manuscript. These multifunctional nanocomposites could be used in a number of biomedical applications, such as drug targeting, cell separation and bioimaging.

  13. Remarkable catalytic activity of Bi{sub 2}O{sub 3}/TiO{sub 2} nanocomposites prepared by hydrothermal method for the degradation of methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Malligavathy, M. [Manonmaniam Sundaranar University, Department of Physics (India); Iyyapushpam, S. [Thanthai Hans Roever Arts and Science College, PG and Research Department of Physics (India); Nishanthi, S. T. [Central Electro Chemical Research Institute, Electrochemical Materials Division (India); Pathinettam Padiyan, D., E-mail: dppadiyan@msuniv.ac.in [Manonmaniam Sundaranar University, Department of Physics (India)

    2017-04-15

    Visible light Bi{sub 2}O{sub 3}/TiO{sub 2} nanocomposites are successfully prepared with different dosages of Bi{sub 2}O{sub 3} by hydrothermal process. All the as-prepared samples are characterized by X-ray diffraction (XRD), scanning and transmission electron microscopes (SEM and TEM), Brunauer-Emmett-Teller analysis (BET), N{sub 2} adsorption-desorption measurement, and UV-Vis diffuse reflectance spectra (DRS). XRD and Raman spectra reveal the anatase phase of both TiO{sub 2} and Bi{sub 2}O{sub 3}/TiO{sub 2} nanocomposites. X-ray diffraction patterns demonstrate that the bismuth ions did not enter into the lattice of TiO{sub 2}, and Bi{sub 2}O{sub 3} is extremely dispersive on the surface of TiO{sub 2} nanoparticles. The incorporation of Bi{sub 2}O{sub 3} in TiO{sub 2} leads to the spectral response of TiO{sub 2} in the visible light region and efficient separation of charge carriers. The enhanced visible light activity is tested by the photocatalytic degradation of methyl orange under light illumination, and the performance of Bi{sub 2}O{sub 3}/TiO{sub 2} nanocomposites are superior than that of pure TiO{sub 2} which is ascribed to the efficient charge separation and transfer across the Bi{sub 2}O{sub 3}/TiO{sub 2} junction. Bi{sub 2}O{sub 3}/TiO{sub 2} nanocomposite (20 mg) loaded with 0.25 of Bi{sub 2}O{sub 3} dispersed in 50 ml of 5 ppm methyl orange solution exhibited the highest photocatalytic activity of 98.86% within 240 min of irradiation, which is attributed to the low band gap, high surface area, and the strong interaction between Bi{sub 2}O{sub 3} and TiO{sub 2}.

  14. Evaluation of H{sub 2}O{sub 2}-generation during oxygen reduction at electrodeposited Pt particles on mask scratched electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Kishi, Akira; Inoue, Mitsuhiro; Umeda, Minoru, E-mail: mumeda@vos.nagaokaut.ac.jp

    2013-08-15

    In this study, the Pt particle deposition was systematically performed by our proposed mask scratch and subsequent Pt electrodeposition in order to investigate the H{sub 2}O{sub 2}-byproduct generation efficiency during O{sub 2} reduction. By peeling a part of polymer layer coated on a glassy carbon substrate using an atomic force microscope cantilever, scratched areas are regularly made. The Pt particles are deposited only on the above-mentioned scratched areas, indicating that the controlled Pt deposition has been achieved. The background cyclic voltammetry of the prepared electrodes showed that the deposited nanoparticles are certainly composed of Pt. Moreover, the electrochemical surface area of the deposited Pt (Pt-ESA) linearly increases with the increasing scratched area, revealing that the Pt-ESAs can be controlled by the mask scratch-based Pt electrodeposition method. It should be noted that an increase in the Pt-ESA not only increases the O{sub 2} reduction currents, but also enhances the H{sub 2}O{sub 2} generation efficiency.

  15. Investigation of fluorine adsorption on nitrogen doped MgAl{sub 2}O{sub 4} surface by first-principles

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Xiaojun; Xu, Zhenming [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Li, Jie, E-mail: 15216105346@163.com [School of Metallurgy and Environment, Central South University, Changsha 410083 (China); Chen, Jiangan [Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China); Liu, Qingsheng [Faculty of Metallurgical and Chemical Engineering, Jiangxi University of Science and Technology, Ganzhou 341000 (China)

    2016-07-15

    Graphical abstract: First-principles calculations indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, but hydrophobic. N doped MgAl{sub 2}O{sub 4} (100) surface structure shows the highest fluorine adsorption performance and fluorine atom is more preferentially adsorbed on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). N doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Highlights: • MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. • Fluorine preferentially adsorbs on the Mg-Al bridge site. • Adsorption intensity follow this order: N doped MgAl{sub 2}O{sub 4} > Al{sub 2}O{sub 3} > MgAl{sub 2}O{sub 4} > MgO. • Excellent adsorption performance attributes to electron compensation of N atom. • Nitrogen doped MgAl{sub 2}O{sub 4} is a promising candidate for fluorine removal. - Abstract: The nature of fluorine adsorption on pure and N doped MgAl{sub 2}O{sub 4} surface has been investigated by first-principles calculations based on the density functional theory. Calculated results indicate that MgAl{sub 2}O{sub 4} surface is fluorine-loving, not hydrophilic. Nitrogen doped MgAl{sub 2}O{sub 4} (100) surface shows the highest fluorine adsorption performance and fluorine atom preferentially adsorbs on the Mg-Al bridge site. The fluorine adsorption intensity follow this order: Nitrogen doped MgAl{sub 2}O{sub 4} (100) > Al{sub 2}O{sub 3} (0001) > MgAl{sub 2}O{sub 4} (100) > MgO (100). In-depth PDOS analysis suggested that 2p orbitals of F atom strongly hybridized with 3s- and 3p-orbitals of Al atom contribute to its high adsorption intensity. According to the analysis of Hirshfeld charge, the excellent fluorine adsorption performance of nitrogen doped MgAl{sub 2}O{sub 4} attributes to the electron compensation effect of nitrogen atom and strong electrostatic interactions. All these

  16. Structural and optical properties of Ta{sub 2}O{sub 5}:Eu{sup 3+}: Mg{sup 2+} or Ca{sup 2+} phosphor prepared by molten salt method

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Naveen, E-mail: vermanaveen17@gmail.com; Singh, Krishan Chander; Jindal, Jitender [Department of chemistry, Maharshi Dayanand University, Rohtak-124001 – India (India); Mari, Bernabe; Mollar, Miguel; Manjón, F. J. [Institut de Disseny per la Fabricació Automatitzada - Departament de Física Aplicada, Universitat Politècnica de València, Camí de Vera s/n, 46022 València (Spain); Rana, Ravi [Department of Chemistry, SGT University, Gurgaon (India); Pereira, A. L. J. [Universitat Politècnica de València, 46022 València (Spain)

    2016-04-13

    Ta{sub 2}O{sub 5}:Eu{sup 3+}: Mg{sup 2+} or Ca{sup 2+} phosphor materials were prepared by molten salt method using KCl as flux. The X-ray diffraction (XRD) patterns illustrated that the well crystallized Ta{sub 2}O{sub 5}:Eu{sup 3+}: Mg{sup 2+} or Ca{sup 2+} were formed in the presence of flux under reduced temperature (800 °C) in contrast to conventional solid state method (1200-1500 °C). Scanning electron microscope (SEM) images indicate the achievement of well dispersed particles (hexagonal tablet and rod-like structures). Meanwhile, the photo-luminescent studies demonstrated that Ta{sub 2}O{sub 5} is an efficient host to sensitize europium red emissions. The addition of Mg{sup 2+} or Ca{sup 2+} as co-dopant enhanced the luminescent intensity of Ta{sub 2}O{sub 5}: Eu{sup 3+} compound.

  17. Nickel catalyst supported on magnesium and zinc aluminates (MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4}) spinels for dry reforming of methane

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, L.C.B. de; Melo, D.M. de A.; Melo, M.A. de F.; Barros, J.M. de F.; Braga, R.M.; Costa, C. de C.; Rodrigues, G., E-mail: ieda.garcia@pq.cnpq.br [Universidade Federal da Paraiba (LACOM/UFPB), Joao Pessoa, PB (Brazil). Dept. de Quimica

    2017-01-15

    Materials such as MgAl{sub 2}O{sub 4} and ZnAl{sub 2}O{sub 4} assessed in the reaction of dry reforming of methane to produce syngas were synthesized by microwave-assisted combustion method using urea as fuel. Samples of synthesized oxides were calcined at 800 °C for 2 h and impregnated with 5% nickel. The impregnated samples were calcined at 850 °C for 4 h to obtain the desired phases. The results of the catalytic tests showed that the catalysts are active for the reaction of dry reforming of methane, and the catalyst that showed the best performance for methane conversion was 5% Ni/MgAl{sub 2}O{sub 4} calcined at 850 °C/4 h. (author)

  18. Characterization of Ni-P-SiO{sub 2}-Al{sub 2}O{sub 3} nanocomposite coatings on aluminum substrate

    Energy Technology Data Exchange (ETDEWEB)

    Rahemi Ardakani, S., E-mail: saeed.rahemi69@gmail.com [Department of Materials Science and Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Afshar, A. [Department of Materials Science and Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Sadreddini, S., E-mail: sina.sadreddini1986@gmail.com [Young Researchers and Elites Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Ghanbari, A.A. [Department of Materials Science and Engineering, Sharif University of Technology, International Campus, Kish Island (Iran, Islamic Republic of)

    2017-03-01

    In the present work, nano-composites of Ni-P-SiO{sub 2}-Al{sub 2}O{sub 3} were coated on a 6061 aluminum substrate. The surface morphology of the nano-composite coating was studied by field emission scanning electron microscopy (FESEM). The amount of SiO{sub 2} in the coating was determined by Energy Dispersive Analysis of X-Ray (EDX) and the crystalline structure of the coating was examined by X-ray diffractometer (XRD). All the experiments concerning the corrosion behavior of the coating carried out in 3.5%wt NaCl solution and evaluated by electrochemical impedance spectroscopy (EIS) and polarization technique. The results showed that an incorporation of SiO{sub 2} and Al{sub 2}O{sub 3} in Ni-P coating at the SiO{sub 2} concentration of 10 g/L and 14 g/L Al{sub 2}O{sub 3} led to the lowest corrosion rate (i{sub corr} = 0.88 μA/cm{sup 2}), the most positive E{sub corr} and maximum microhardness (537 μHV). Furthermore, increasing the amount of nanoparticles in the coating was found to decrease CPE{sub dl} and improve porosity. - Highlights: • The maximum content of Al{sub 2}O{sub 3} and SiO{sub 2} in the coating was increased to 14.02%wt and 4.54%wt, respectively. • By enhancing the amount of nanoparticles in the coating, there was higher corrosion resistance. • Increasing the nanoparticles content in the coating improved microhardness of coating. • The maximum of microhardness of Ni-P-SiO{sub 2}-Al{sub 2}O{sub 3} was measured to be 537 μHV.

  19. Structure and properties of ZnO-B{sub 2}O{sub 3}-P{sub 2}O{sub 5}-TeO{sub 2} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Mosner, Petr, E-mail: petr.mosner@upce.cz [Department of General and Inorganic Chemistry, University of Pardubice, Faculty of Chemical Technology, 53210 Pardubice (Czech Republic); Vosejpkova, Katerina; Koudelka, Ladislav [Department of General and Inorganic Chemistry, University of Pardubice, Faculty of Chemical Technology, 53210 Pardubice (Czech Republic); Montagne, Lionel; Revel, Bertrand [Unite de Catalyse et de Chimie du Solide - UCCS, Univ Lille Nord de France, F-59000, CNRS UMR 8181, USTL F-59655, ENSCL F-59652, Villeneuve d' Ascq (France)

    2010-11-01

    Zinc borophosphate glasses doped with TeO{sub 2} were studied in the compositional series (100 - x)[0.5ZnO-0.1B{sub 2}O{sub 3}-0.4P{sub 2}O{sub 5}]-xTeO{sub 2} in a broad concentration range of x = 0-80 mol% TeO{sub 2}. The structure of the glasses was studied by Raman and IR spectroscopy and by {sup 31}P and {sup 11}B MAS NMR spectroscopy. According to the Raman and IR spectra, TeO{sub 2} is incorporated in the structural network in the form of TeO{sub 3}, TeO{sub 3+1} and TeO{sub 4} structural units. The ratio of TeO{sub 4}/TeO{sub 3} increases with increasing TeO{sub 2} content in the glasses. The incorporation of TeO{sub x} units into the glass network is associated with the depolymerisation of phosphate chains, as revealed by Raman spectroscopy. The incorporation of TeO{sub 2} modifies also the coordination of boron atoms, where B(OP){sub 4} structural units are gradually replaced by B(OP){sub 4-n}(OTe){sub n} units. The addition of TeO{sub 2} to the parent zinc borophosphate glass results in a decrease of glass transition temperature associated with the replacement of stronger P-O and B-O bonds by weaker Te-O bonds. Chemical durability of glasses reveals a minimum at the glass containing 10 mol% TeO{sub 2}, but with further additions of TeO{sub 2} it improves and the glasses with a high TeO{sub 2} content reveal better durability than the parent zinc borophosphate glass.

  20. Rotationally resolved pulsed-field ionization photoelectron bands for O{sub 2}{sup +}(A {sup 2}{pi}{sub u},v{sup +}=0-12) in the energy range of 17.0-18.2 eV

    Energy Technology Data Exchange (ETDEWEB)

    Song, Y. [Ames Laboratory, U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States); Evans, M. [Ames Laboratory, U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States); Ng, C. Y. [Ames Laboratory, U.S. Department of Energy and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States); Hsu, C.-W. [Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Jarvis, G. K. [Chemical Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2000-01-15

    We have obtained rotationally resolved pulsed-field ionization photoelectron (PFI-PE) spectra for O{sub 2} in the energy range of 17.05-18.13 eV, covering the ionization transitions O{sub 2}{sup +}(A {sup 2}{pi}{sub u},v{sup +}=0-12,N{sup +})(<-)O{sub 2}(X {sup 3}{sigma}{sub g}{sup -},v{sup ''}=0,N{sup ''}). Although these O{sub 2}{sup +}(A {sup 2}{pi}{sub u},v{sup +}) PFI-PE bands have significant overlaps with vibrational bands for O{sub 2}{sup +}(a {sup 4}{pi}{sub u}) and O{sub 2}{sup +}(X {sup 2}{pi}{sub g}), we have identified all the O{sub 2}{sup +}(A {sup 2}{pi}{sub u},v{sup +}=0-12) bands by simulation of spectra obtained using supersonically cooled O{sub 2} samples with rotational temperatures {approx_equal}20 and 220 K. While these v{sup +}=0-12 PFI-PE bands represent the first rotationally resolved photoelectron data for O{sub 2}{sup +}(A {sup 2}{pi}{sub u}), the PFI-PE bands for O{sub 2}{sup +}(A {sup 2}{pi}{sub u},v{sup +}=9 and 10) are the first rotationally resolved spectroscopic data for these levels. The simulation also allows the determination of accurate ionization energies, vibrational constants, and rotational constants for O{sub 2}{sup +}(A {sup 2}{pi}{sub u},v{sup +}=0-12). The analysis of the PFI-PE spectra supports the conclusion of the previous emission study that the O{sub 2}{sup +}(A {sup 2}{pi}{sub u},v{sup +}=9 and 10) states are strongly perturbed by a nearby electronic state. (c) 2000 American Institute of Physics.

  1. Effects of substrate pretreatments on diamond synthesis for Si{sub 3}N{sub 4} based ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Shibuya, Y. [Prefectural Industrial Research Inst., Shizuoka (Japan); Takaya, M. [Chiba Institute of Technology, Tsudanuma 2-chome, Narashino-shi, 275 (Japan)

    1998-07-08

    Diamond synthesis for Si{sub 3}N{sub 4} ceramics after various substrate pretreatments has been carried out by the microwave-plasma enhanced chemical vapor deposition (CVD) method using a mixture of methane and hydrogen gases. Four types of pretreatments for various substrates were performed as follows: scratching with diamond powder (I), applying O{sub 2}-C{sub 2}H{sub 2} combustion flames (II), polishing with alumina (III), and platinum vapor deposition (IV). The products deposited on the substrate were examined with micro-Raman spectroscopy, scanning electron microscopy (SEM) and an X-ray diffractometer (XRD). It was found that the application of O{sub 2}-C{sub 2}H{sub 2} flames as a pretreatment of the substrate in diamond synthesis was suitable, because a higher density of diamond nucleation could be obtained, and a film-like diamond could be formed on the surface in a shorter time than without applying them. The diamond could be synthesized on the surface for all four types of substrate pretreatments performed in the present study. The effects of the substrate pretreatments on the surface morphology of grown diamond were that a film-like diamond for (I) or (II), a particle-like diamond for (III) and a particle and/or a film-like diamond for (IV) were formed on the surface. The surface morphology of grown diamond depended very much on the substrate temperature under deposition. (orig.) 18 refs.

  2. Analysis of (Ba,Ca,Sr){sub 3}MgSi{sub 2}O{sub 8}:Eu{sup 2+}, Mn{sup 2+} phosphors for application in solid state lighting

    Energy Technology Data Exchange (ETDEWEB)

    Han, J.K. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); Piqutte, A.; Hannah, M.E. [OSRAM SYLVANIA Central Research, 71 Cherry Hill Drive Beverly, MA 01915 (United States); Hirata, G.A. [Centro de Nanociencias y Nanotecnolgía, Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada Apdo, Ensenada MX CP 22860 (Mexico); Talbot, J.B. [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); University of California, San Diego, Department of Nanoengineering, La Jolla, CA 92093 (United States); Mishra, K.C. [OSRAM SYLVANIA Central Research, 71 Cherry Hill Drive Beverly, MA 01915 (United States); McKittrick, J., E-mail: jmckittrick@ucsd.edu [University of California, San Diego, Materials Science and Engineering Program, La Jolla, CA 92093 (United States); University of California, San Diego, Department of Mechanical and Aerospace Engineering, La Jolla, CA 92093 (United States)

    2014-04-15

    The luminescence properties of Eu{sup 2+} and Mn{sup 2+} co-activated (Ba,Ca,Sr){sub 3}MgSi{sub 2}O{sub 8} phosphors prepared by combustion synthesis were studied. Eu{sup 2+}-activated (Ba,Ca,Sr){sub 3}MgSi{sub 2}O{sub 8} has a broad blue emission band centered at 450–485 nm and Eu{sup 2+}–Mn{sup 2+}-activated (Ba,Ca,Sr){sub 3}MgSi{sub 2}O{sub 8} exhibits a red emission around 620–703 nm, depending on the relative concentrations of Ba, Ca and Sr. The particle size of Eu{sup 2+} and Mn{sup 2+} co-activated (Ba,Ca){sub 3}MgSi{sub 2}O{sub 8} ranges from 300 nm to 1 μm depending on the metal ion and are agglomerated due to post-synthesis, high temperature annealing. The green emission of Ba{sub 3}MgSi{sub 2}O{sub 8} originates from secondary phases (Ba{sub 2}SiO{sub 4} and BaMgSiO{sub 4}) confirmed by emission spectra and X-ray diffraction patterns. The secondary phases of Ba{sub 3}MgSi{sub 2}O{sub 8} are removed by the addition of Sr. The quantum efficiencies range from 45% to 70% under 400 nm excitation and the lifetime of red emission of Ba{sub 3}MgSi{sub 2}O{sub 8} decreases significantly with increasing temperature, which is 54% at 400 K of that at 80 K compared to that of blue emission (90% at 400 K of that at 80 K). -- highlights: • (Ba,Ca,Sr){sub 3}MgSi{sub 2}O{sub 8}:Eu{sup 2+}, Mn{sup 2+} phosphors were prepared by a combustion synthesis method. • The emission spectra consist of broad blue-emission band and red-emission band. • The quantum efficiencies range between 45% and 70%, depending on the relative concentrations of Ba, Ca and Sr. • The secondary phases were eliminated by additions of Sr. • Lifetime of the red-emission decreases with increasing temperature, suggesting that these phosphors are not useful for solid state lighting applications.

  3. Thermally induced structural modifications and O{sub 2} trapping in highly porous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Alessi, A., E-mail: antonino.alessi@unipa.it; Agnello, S.; Iovino, G.; Buscarino, G.; Melodia, E.G.; Cannas, M.; Gelardi, F.M.

    2014-12-15

    In this work we investigate by Raman spectroscopy the effect of isochronal (2 h) thermal treatments in air in the temperature range 200–1000 °C of amorphous silicon dioxide porous nanoparticles with diameters ranging from 5 up to 15 nm and specific surface 590–690 m{sup 2}/g. Our results indicate that the amorphous structure changes similarly to other porous systems previously investigated, in fact superficial SiOH groups are removed, Si–O–Si linkages are created and the ring statistic is modified, furthermore these data evidence that the three membered rings do not contribute significantly to the Raman signal detected at about 495 cm{sup −1}. In addition, after annealing at 900 and 1000 °C we noted the appearance of the O{sub 2} emission at 1272 nm, absent in the not treated samples. The measure of the O{sub 2} emission has been combined with electron paramagnetic resonance measurements of the γ irradiation induced HO{sup ·}{sub 2} radicals to investigate the O{sub 2} content per mass unit of thin layers of silica. Our data reveal that the porous nanoparticles have a much lower ability to trap O{sub 2} molecules per mass units than nonporous silica supporting a model by which O{sub 2} trapping inside a surface layer of about 1 nm of silica is always limited. - Highlights: • O{sub 2} emission and HO{sup ·}{sub 2} electron paramagnetic resonance signals are investigated. • Silica surface ability to trap O{sub 2} molecules is explored by thermal treatments. • Raman study of thermally induced structural changes in porous silica nanoparticles. • Raman signal attributable to the three membered rings in silica.

  4. Electrical properties of reactive-ion-sputtered Al{sub 2}O{sub 3} on 4H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Shukla, Madhup, E-mail: madhup.iit@gmail.com [Microelectronics and MEMS Laboratory, Electrical Engineering Department, Indian Institute of Technology Madras, Chennai 600036 (India); Dutta, Gourab [Microelectronics and MEMS Laboratory, Electrical Engineering Department, Indian Institute of Technology Madras, Chennai 600036 (India); Mannam, Ramanjaneyulu [Department of Physics and Nano Functional Materials Technology Centre, Indian Institute of Technology Madras, Chennai 600036 (India); DasGupta, Nandita [Microelectronics and MEMS Laboratory, Electrical Engineering Department, Indian Institute of Technology Madras, Chennai 600036 (India)

    2016-05-31

    Al{sub 2}O{sub 3} was deposited on n-type 4H-SiC by reactive-ion-sputtering (RIS) at room temperature using aluminum target and oxygen as a reactant gas. Post deposition oxygen annealing was carried out at a temperature of 1100 °C. Metal-oxide-semiconductor (MOS) test structures were fabricated on 4H-SiC using RIS-Al{sub 2}O{sub 3} as gate dielectric. The C-V characteristics reveal a significant reduction in flat band voltage for oxygen annealed RIS-Al{sub 2}O{sub 3} samples (V{sub fb} = 1.95 V) compared to as-deposited Al{sub 2}O{sub 3} samples (V{sub fb} > 10 V), suggesting a reduction in negative oxide charge after oxygen annealing. Oxygen annealed RIS-Al{sub 2}O{sub 3} samples also showed significant improvement in I-V characteristics compared to as-deposited RIS-Al{sub 2}O{sub 3} samples. A systematic analysis was carried out to investigate the leakage current mechanisms present in oxygen annealed RIS-Al{sub 2}O{sub 3} on 4H-SiC at higher gate electric field and at different operating temperature. For measurement temperature (T) < 303 K, Fowler–Nordheim (FN) tunneling was found to be the dominant leakage mechanism and for higher temperature (T ≥ 303 K), a combination of FN tunneling and Poole-Frenkel (PF) emission was confirmed. The improvement in I-V characteristics of oxygen annealed RIS-Al{sub 2}O{sub 3}/4H-SiC MOS devices is attributed to large effective barrier height (Φ{sub B} = 2.53 eV) at Al{sub 2}O{sub 3}/SiC interface, due to the formation of an interfacial SiO{sub 2} layer during oxygen annealing, as confirmed from X-ray Photoelectron Spectroscopy results. Further improvement in C-V characteristics for oxygen annealed RIS-Al{sub 2}O{sub 3}/4H-SiC MOS devices was observed after forming gas annealing at 400 °C. - Highlights: • O{sub 2} annealed RIS-Al{sub 2}O{sub 3} on 4H-SiC showed better performance than other reported result. • FN, FN + PF tunneling was found in O{sub 2} annealed RIS-Al{sub 2}O{sub 3} for different temp. ranges. • Al

  5. Electronic structure of layered ferroelectric high-k titanate Pr{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Gavrilova, T.A. [Laboratory of Nanodiagnostics and Nanolithography, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Grivel, J.-C. [Materials Research Division, National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde (Denmark); Kesler, V.G. [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Troitskaia, I.B. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2012-11-15

    The spectroscopic parameters and electronic structure of binary titanate Pr{sub 2}Ti{sub 2}O{sub 7} have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr{sub 2}Ti{sub 2}O{sub 7} have been determined as {alpha}{sub Ti}=872.8 and {alpha}{sub O}=1042.3 eV. Variations of cation-anion bond ionicity have been discussed using binding energy differences {Delta}{sub Ti}=(BE O 1s-BE Ti 2p{sub 3/2})=71.6 eV and {Delta}{sub Pr}=BE(Pr 3d{sub 5/2})-BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides. Highlights: Black-Right-Pointing-Pointer Solid state synthesis of polar titanate Pr{sub 2}Ti{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Structural and spectroscopic properties and electronic structure determination. Black-Right-Pointing-Pointer Ti-O and Pr-O bonding analysis using Ti 2p{sub 3/2}, Pr 3d{sub 5/2} and O 1s core levels.

  6. Effects of Al{sub 2}O{sub 3} phase and Cl component on dehydrogenation of propane

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie; Liu, Changcheng; Ma, Aizeng; Rong, Junfeng; Da, Zhijian, E-mail: dazhijianripp@163.com; Zheng, Aiguo; Qin, Ling

    2016-04-15

    Graphical abstract: - Highlights: • Comparative study of Al{sub 2}O{sub 3} phase on dehydrogenation of propane was implemented. • Pore structures and acid properties of Pt-Al{sub 2}O{sub 3} are correlated to the activities. • Pt-θ-Al{sub 2}O{sub 3} with abundant Cl content shows the highest activity and stability. - Abstract: The effects of two Al{sub 2}O{sub 3} phases, γ- and θ-Al{sub 2}O{sub 3}, and Cl component on the performances of Pt-Al{sub 2}O{sub 3} catalysts in the dehydrogenation of propane were investigated in this work. The catalysts were systematically characterized by various techniques, such as scanning transmission electron microscopy (STEM), temperature-programmed desorption with ammonia as probe molecules (NH{sub 3}-TPD) and temperature-programmed oxidation (TPO). The characterizations and catalytic results show that: (i) the pore structures and acid properties of the two Al{sub 2}O{sub 3} phases can change the quantity, location and property of the carbon deposition, (ii) the existence of Cl plays a significant role on the agglomeration of Pt particles and carbon deposition, which further influence the catalytic performances of Pt-Al{sub 2}O{sub 3} catalysts with different support phases for propane dehydrogenation.

  7. Structural, optical, and magnetic properties of Fe doped In{sub 2}O{sub 3} powders

    Energy Technology Data Exchange (ETDEWEB)

    Krishna, N. Sai [Thin Films Laboratory, School of Advanced Sciences, VIT University, Vellore 632 014, Tamilnadu (India); Kaleemulla, S., E-mail: skaleemulla@gmail.com [Thin Films Laboratory, School of Advanced Sciences, VIT University, Vellore 632 014, Tamilnadu (India); Amarendra, G. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamilnadu (India); UGC-DAE-CSR, Kalpakkam Node, Kokilamedu 603 104, Tamilnadu (India); Rao, N. Madhusudhana; Krishnamoorthi, C.; Kuppan, M.; Begam, M. Rigana [Thin Films Laboratory, School of Advanced Sciences, VIT University, Vellore 632 014, Tamilnadu (India); Reddy, D. Sreekantha [Department of Physics and Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Omkaram, I. [Department of Electronics and Radio Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

    2015-01-15

    Highlights: • Synthesis of Fe doped In{sub 2}O{sub 3} powders using a solid state reaction. • Characterization of the samples using XRD, UV–vis-NIR, FT-IR, and VSM. • All Fe doped In{sub 2}O{sub 3} powders exhibited the cubic structure of In{sub 2}O{sub 3}. • All the Fe doped In{sub 2}O{sub 3} samples exhibited room temperature ferromagnetism. - Abstract: Iron doped indium oxide dilute magnetic semiconductor (In{sub 1−x}Fe{sub x}){sub 2}O{sub 3} (x = 0.00, 0.03, 0.05, and 0.07) powders were synthesized by standard solid state reaction method followed by vacuum annealing. The effect of Fe concentration on structural, optical, and magnetic properties of the (In{sub 1−x}Fe{sub x}){sub 2}O{sub 3} powders have been systematically studied. X-ray diffraction patterns confirmed the polycrystalline cubic structure of all the samples. An optical band gap increases from 3.12 eV to 3.16 eV while Fe concentration varying from 0.03 to 0.07. Magnetic studies reveal that virgin/undoped In{sub 2}O{sub 3} is diamagnetic. However, all the Fe-doped In{sub 2}O{sub 3} samples are ferromagnetic. The saturation magnetization (M{sub s}) of ferromagnetic (In{sub 1−x}Fe{sub x}){sub 2}O{sub 3} (x = 0.03, 0.05, and 0.07) samples increases from 11.56 memu/g to 148.64 memu/g with x = 0.03–0.07. The observed ferromagnetism in these samples was attributed to magnetic nature of the dopant (Fe) as well as defects created in the samples during vacuum annealing.

  8. H{sub 2} assisted NH{sub 3}-SCR over Ag/Al{sub 2}O{sub 3} for automotive applications

    Energy Technology Data Exchange (ETDEWEB)

    Fogel, S.

    2013-05-15

    The up-coming strict emission legislation demands new and improved catalysts for diesel vehicle deNO{sub x}. The demand for low-temperature activity is especially challenging. H{sub 2}-assisted NH{sub 3}-SCR over Ag/Al{sub 2}O{sub 3} has shown a very promising low-temperature activity and a combination of Ag/Al{sub 2}O{sub 3} and Fe-BEA can give a high NO{sub x} conversion in a broad temperature window without the need to dose H{sub 2} at higher temperatures. The aim of this study has been to investigate the combined Ag/Al{sub 2}O{sub 3} and Fe-BEA catalyst system both at laboratory-scale and in full-scale engine bench testing. The catalysts were combined both in a sequential dual-bed layout and a dual-layer layout where the catalysts were coated on top of each other. The Ag/Al{sub 2}O{sub 3} catalyst was also investigated with the aim of improving the sulphur tolerance and low-temperature activity by testing different alumina-supports. A large focus of this study has been the preparation of monolithic catalyst bricks for the catalyst testing. A high SBET and higher Ag loading gave a high sulphur tolerance and activity. It was believed that the high S{sub BET} is needed to give a higher NH{sub 3} adsorption capacity, necessary for the SCR reaction. A higher Ag loading gives more Ag sites and probably a favourable Ag dispersion. Testing with sulphur gave an increased activity of the catalysts. Testing of monolithic catalysts showed a similar activity enhancement after a few standard test cycles. A change in the dispersion or state of Ag can be possible reasons for the activation seen and the activation was believed to be related to Ag and not the alumina. Small-scale laboratory testing showed that it was preferred to have Ag/Al{sub 2}O{sub 3} either upstream or as the outer layer of Fe-BEA. This was attributed to complete NH{sub 3} oxidation over Fe-BEA giving a deficit of NH{sub 3} over the Ag/Al{sub 2}O{sub 3} if it was placed downstream or as the inner layer

  9. Preparation and catalytic activities for H{sub 2}O{sub 2} decomposition of Rh/Au bimetallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haijun, E-mail: zhanghaijun@wust.edu.cn [Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); The State Key Laboratory of Refractory and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China); Deng, Xiangong; Jiao, Chengpeng; Lu, Lilin; Zhang, Shaowei [The State Key Laboratory of Refractory and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081 (China)

    2016-07-15

    Graphical abstract: PVP-protected Rh/Au bimetallic nanoparticles (BNPs) were prepared by using hydrogen sacrificial reduction method, the activity of Rh80Au20 BNPs were about 3.6 times higher than that of Rh NPs. - Highlights: • Rh/Au bimetallic nanoparticles (BNPs) of 3∼5 nm in diameter were prepared. • Activity for H{sub 2}O{sub 2} decomposition of BNPs is 3.6 times higher than that of Rh NPs. • The high activity of BNPs was caused by the existence of charged Rh atoms. • The apparent activation energy for H{sub 2}O{sub 2} decomposition over the BNPs was calculated. - Abstract: PVP-protected Rh/Au bimetallic nanoparticles (BNPs) were prepared by using hydrogen sacrificial reduction method and characterized by UV–vis, XRD, FT-IR, XPS, TEM, HR-TEM and DF-STEM, the effects of composition on their particle sizes and catalytic activities for H{sub 2}O{sub 2} decomposition were also studied. The as-prepared Rh/Au BNPs possessed a high catalytic activity for the H{sub 2}O{sub 2} decomposition, and the activity of the Rh{sub 80}Au{sub 20} BNPs with average size of 2.7 nm were about 3.6 times higher than that of Rh monometallic nanoparticles (MNPs) even the Rh MNPs possess a smaller particle size of 1.7 nm. In contrast, Au MNPs with size of 2.7 nm show no any activity. Density functional theory (DFT) calculation as well as XPS results showed that charged Rh and Au atoms formed via electronic charge transfer effects could be responsible for the high catalytic activity of the BNPs.

  10. Facile synthesis of Ca{sub 0.68}Si{sub 9}Al{sub 3}(ON){sub 16}:Eu{sup 2+} microbelts mat with the enhanced fluorescence and mechanical performance

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Hailei; Cui, Bo [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Wang, Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Zhang, Qinghong [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China); Li, Yaogang, E-mail: yaogang_li@dhu.edu.cn [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, College of Materials Science and Engineering, Donghua University, Shanghai 201620 (China)

    2016-01-15

    Yellow-emitting phosphor mat consisting of Ca{sub 0.68}Si{sub 9}Al{sub 3}(ON){sub 16}:Eu{sup 2+} microbelts was prepared by electrospinning and subsequent nitridation. The as-prepared fiber precursor is smooth and uniform with diameter of 800 to 900 nm. After removing organic templates and nitridation, the morphology of the fiber is well retained and thus a smooth microbelts phosphor mat was obtained. X-ray diffraction and the photoluminescence (PL) spectra reveals that a relatively pure Ca{sub 0.68}Si{sub 9}Al{sub 3}(ON){sub 16} phase and the highest spectral intensity could be obtained at a relatively low temperature of 1500 °C and Eu{sup 2+} doping molar concentration of 0.1. The excitation spectra exhibits a broad band, ranging from 300 to 550 nm, which could be excited by blue LED chip at room temperature. The emission spectra of all exhibits a single broad band in the 400 to 700 nm region, with the maximum intensity always being at 580 nm. The Ca{sub 0.68}Si{sub 9}Al{sub 3}(ON){sub 16}:Eu{sup 2+} microbelts phosphor mat has the bending strength about 4.5 MPa with a photoluminescence quantum yield as high as 65%. By employing it as yellow phosphor, a high-performance warm white LED could be fabricated with low correlated color temperature (2985 K), high-color-rendering index (Ra=86) and luminous efficacy of 129.5 lm W{sup −1}. Different color temperatures also could be tuned by employing microbelts phosphor mats with different thicknesses. - Graphical abstract: Yellow-emitting phosphor mat consisting of Ca{sub 0.68}Si{sub 9}Al{sub 3}(ON){sub 16}:Eu{sup 2+} microbelts fibers were prepared by electrospinning the fiber precursor and subsequent nitridation. Because the good mechanical strength it could be utilized to realize LEDs remote packaging. By employing it as yellow phosphor, a high-performance warm white LED could be fabricated. Different color temperatures also could be tuned by employing microbelts phosphor mats with different thicknesses

  11. SrBeB{sub 2}O{sub 5}: Growth, crystal structure and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Wenjiao; Wang, Xiaoshan [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Huang, Hongwei [National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Xu, Tao; Jiang, Xingxing [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Wang, Xiaoyang [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Lin, Zheshuai, E-mail: zslin@mail.ipc.ac.cn [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Chuangtian [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-04-01

    Graphical abstract: The crystal displays a layered configuration along c axis with the wrinkled infinite (BeB{sub 2}O{sub 5}){sub ∞} layers. Display Omitted - Highlights: • A new beryllium borate SrBeB{sub 2}O{sub 5} was synthesized. • A layered structure (BeB{sub 2}O{sub 5}){sub ∞} was formed by BO{sub 3} triangles and B/BeO{sub 4} tetrahedrons. • SrBeB{sub 2}O{sub 5} has a very wide transparency range of wavelengths from 200 nm to 1800 nm. • A-site ions impact greatly on the structures of beryllium borates. - Abstract: A novel beryllium borate SrBeB{sub 2}O{sub 5} is discovered for the first time through traditional solid state reaction and high temperature solution method. The framework of the structure is composed by two-dimensional [BeB{sub 2}O{sub 5}] layers determined from single-crystal X-ray diffraction data. The further structural analysis of beryllium borates reveals that the arrangement of anionic groups attributes to the structural stability. Moreover, the influences of the A-site cations on the structural features of fundamental building blocks in the alkaline or alkaline earth beryllium borates are discussed. The UV–Vis–NIR diffuse-reflectance pattern reveals that this compound has a very wide transparency range of wavelengths down to 200 nm. In addition, the properties of SrBeB{sub 2}O{sub 5} were also characterized by powder X-ray diffraction, differential scanning calorimetry, and IR spectroscopy.

  12. Radiation induced synthesis of In{sub 2}O{sub 3} nanoparticles - Part II: Synthesis of In{sub 2}O{sub 3} nanoparticles by thermal decomposition of un-irradiated and γ-irradiated indium acetylacetonate

    Energy Technology Data Exchange (ETDEWEB)

    Al-Resheedi, Ajayb Saud; Alhokbany, Norah Saad [Department of Chemistry, College of Science, King Saud University, KSU, (Saudi Arabia); Mahfouz, Refaat Mohammed, E-mail: rmhfouz@science.au.edu.eg [Chemistry Department, Faculty of Science, Assiut University, AUN, (Egypt)

    2015-09-15

    Pure cubic phase, In{sub 2}O{sub 3} nanoparticles with porous structure were synthesized by solid state thermal oxidation of un-irradiated and γ-irradiated indium acetyl acetonate in presence and absence of sodium dodecyl sulphate as surfactant. The as- synthesized In{sub 2}O{sub 3} nanoparticles were characterized by X-ray diffraction (XRD), fourier transformation infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transition electron microscopy (TEM) and thermogravimetry (TG). The shapes and morphologies of as- synthesized In{sub 2}O{sub 3} nanoparticles were highly affected by γ-irradiation of indium acetyl acetonate precursor and by addition of sodium dodecyl sulphate as surfactant. Calcination of un-irradiated indium acetyl acetonate precursor to 4 hours of 600 °C leads to the formation of spherical- shaped accumulative and merged In{sub 2}O{sub 3} nanoparticles with porous structure, whereas irregular porous architectures composed of pure In{sub 2}O{sub 3} nanoparticles were obtained by using γ-irradiated indium acetylacetonate precursor. The as- prepared In{sub 2}O{sub 3} nano products exhibit photoluminescence emission (PL) property and display thermal stability in a wide range of temperature (25-800 °C) which suggest possible applications in nanoscale optoelectronic devices. (author)

  13. Removal of aqueous Pb(II) by adsorption on Al{sub 2}O{sub 3}-pillared layered MnO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haipeng; Gu, Liqin; Zhang, Ling; Zheng, Shourong; Wan, Haiqin; Sun, Jingya [State Key Laboratory of Pollution Control and Resource Reuse, Jiangsu Key Laboratory of Vehicle Emissions Control, School of the Environment, Nanjing University, Nanjing 210023 (China); Zhu, Dongqiang [School of Urban and Environmental Sciences, Peking University, Beijing 100871 (China); Xu, Zhaoyi, E-mail: zhaoyixu@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, Jiangsu Key Laboratory of Vehicle Emissions Control, School of the Environment, Nanjing University, Nanjing 210023 (China)

    2017-06-01

    Highlights: • Al{sub 2}O{sub 3}-pillared layered MnO{sub 2} (p-MnO{sub 2}) was prepared from δ-MnO{sub 2} precursor. • p-MnO{sub 2} showed markedly higher Pb(II) adsorption capacity than pristine δ-MnO{sub 2.}. • Pillaring of Al{sub 2}O{sub 3} into the layer of δ-MnO{sub 2} enhanced the Pb(II) adsorption. - Abstract: In the present study, Al{sub 2}O{sub 3}-pillared layered MnO{sub 2} (p-MnO{sub 2}) was synthesized using δ-MnO{sub 2} as precursor and Pb(II) adsorption on p-MnO{sub 2} and δ-MnO{sub 2} was investigated. To clarify the adsorption mechanism, Al{sub 2}O{sub 3} was also prepared as an additional sorbent. The adsorbents were characterized by X-ray fluorescence analysis, powder X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and N{sub 2} adsorption-desorption. Results showed that in comparison with pristine δ-MnO{sub 2}, Al{sub 2}O{sub 3} pillaring led to increased BET surface area of 166.3 m{sup 2} g{sup −1} and enlarged basal spacing of 0.85 nm. Accordingly, p-MnO{sub 2} exhibited a higher adsorption capacity of Pb(II) than δ-MnO{sub 2}. The adsorption isotherms of Pb(II) on δ-MnO{sub 2} and Al{sub 2}O{sub 3} pillar fitted well to the Freundlich model, while the adsorption isotherm of Pb(II) on p-MnO{sub 2} could be well described using a dual-adsorption model, attributed to Pb(II) adsorption on both δ-MnO{sub 2} and Al{sub 2}O{sub 3}. Additionally, Pb(II) adsorption on δ-MnO{sub 2} and p-MnO{sub 2} followed the pseudo second-order kinetics, and a lower adsorption rate was observed on p-MnO{sub 2} than δ-MnO{sub 2}. The Pb(II) adsorption capacity of p-MnO{sub 2} increased with solution pH and co-existing cation concentration, and the presence of dissolved humic acid (10.2 mg L{sup −1}) did not markedly impact Pb(II) adsorption. p-MnO{sub 2} also displayed good adsorption capacities for aqueous Cu(II) and Cd(II). Findings in this study indicate that p-MnO{sub 2} could be used as a highly effective

  14. Photoluminescence properties of a novel red phosphor Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhonghua; Hu, Yihua; Zhang, Shaoan; Lin, Jun [Guangdong University of Technology, School of Physics and Optoelectronic Engineering, Guangzhou (China)

    2016-02-15

    Eu{sup 3+}-doped Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2} phosphors were synthesized successfully via a two-step solid-state reaction method. Phase purity and morphology of the phosphor were confirmed by XRD and SEM techniques. In the excitation spectra of Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+} phosphor, the broad excitation band centering at 310 nm is due to the combination of charge transfer from Eu{sup 3+}→O{sup 2-} and host absorption. And it matches well the emission wavelength from UV LEDs. Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+} phosphors show a bright orange-red luminescence under excitation with 301 nm. However, concentration quenching of Eu{sup 3+} in Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+} occurs at a low content of 0.07 in this work. The quenching mechanism of Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+} was discussed in detail on the basis of the experimental results. (orig.)

  15. Synthesis of stoichiometric Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles by high-energy ball milling and thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, B.F.; Morales, M.A.; Bohn, F.; Carriço, A.S. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Medeiros, S.N. de, E-mail: sndemedeiros@gmail.com [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Dantas, A.L. [Departamento de Física, Universidade do Estado do Rio Grande do Norte, 59610-210 Mossoró, RN (Brazil)

    2016-05-01

    We report the synthesis of Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles by high-energy ball milling and thermal annealing from α-Fe{sub 2}O{sub 3} and CaCO{sub 3}. Magnetization measurements, Mössbauer and X-ray spectra reveal that annealing at high temperatures leads to better quality samples. Our results indicate nanoparticles produced by 10 h high-energy ball milling and thermal annealing for 2 h at 1100 °C achieve improved stoichiometry and the full weak ferromagnetic signal of Ca{sub 2}Fe{sub 2}O{sub 5}. Samples annealed at lower temperatures show departure from stoichiometry, with a higher occupancy of Fe{sup 3+} in octahedral sites, and a reduced magnetization. Thermal relaxation for temperatures in the 700–1100 °C range is well represented by a Néel model, assuming a random orientation of the weak ferromagnetic moment of the Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles.

  16. Crystallization and magnetic properties of a 10Li{sub 2}O–9MnO{sub 2}–16Fe{sub 2}O{sub 3}–25CaO–5P{sub 2}O{sub 5}–35SiO{sub 2} glass

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Moo-Chin, E-mail: mcwang@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, 100 Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan (China); Cheng, Huy-Zu [Department of Materials Science and Engineering, I-Shou University, 1 123456789Hsueh-Cheng Road, Section 1, Ta-Hsu, Kaohsiung 84001, Taiwan (China); Lin, Huey-Jiuan [Department of Materials Science and Engineering, National United University, 1 Lien-Da Road, Kung-Ching Li, Miao-Li 36003, Taiwan (China); Wang, Chien-Fu [Department of Materials Science and Engineering, I-Shou University, 1 123456789Hsueh-Cheng Road, Section 1, Ta-Hsu, Kaohsiung 84001, Taiwan (China); Hsi, Chi-Shiung, E-mail: chsi@nuu.edu.tw [Department of Materials Science and Engineering, National United University, 1 Lien-Da Road, Kung-Ching Li, Miao-Li 36003, Taiwan (China)

    2013-06-15

    The crystallization behavior and magnetic properties of 10Li{sub 2}O–9MnO{sub 2}–16Fe{sub 2}O{sub 3}–25CaO–5P{sub 2}O{sub 5}–35SiO{sub 2} (10LFS) glass have been studied using differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) to observe the crystallization behavior and a superconducting quantum interference device (SQUID) for measurements of the magnetic properties. The DTA shows that the 10LFS glass has one broad exothermic peak at approximately 674 °C and one sharp (the highest) exothermic peak at 764 °C. When the 10LFS glass crystallized at 850 °C for 4 h, the crystalline phases identified by XRD were lithium silicate (Li{sub 2}SiO{sub 3}), β-wollastonite (β-CaSiO{sub 3}), lithium orthophosphate (Li{sub 3}PO{sub 4}), magnetite (FeFe{sub 2}O{sub 4}) and triphylite (Li(Mn{sub 0.5}Fe{sub 0.5})PO{sub 4}). The SEM surface analysis revealed that the β-wollastonite and lithium silicate have a lath morphology. The TEM microstructure examination showed that the largest FeFe{sub 2}O{sub 3} particles have a size of approximately 0.3 μm. When the 10LFS glass was heat treated at 850 °C for 16 h and a magnetic field of 1000 Oe was applied, a very small remnant magnetic induction of 0.01 emu g{sup −1} and a coercive force of 50 Oe were obtained, which revealed an inverse spinel structure. - Highlights: ► The phases formed at 850 °C in the 10LFS glass-ceramics are LiSiO{sub 3}, β-CaSiO{sub 3}, Li{sub 3}PO{sub 4}, FeFe{sub 2}O{sub 4} and Li(Mn{sub 0.5}Fe{sub 0.5})PO{sub 4}. ► The β-wollastonite and lithium silicate have a lath morphology. ► When 10LFS glass-ceramics applied magnetic field showing the ferromagnetic behavior of an inverse spinel structure.

  17. Photocatalytic degradation of methylene blue dye using Fe{sub 2}O{sub 3}/TiO{sub 2} nanoparticles prepared by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.A., E-mail: abdelhay71@hotmail.com [Chemistry Department, Faculty of Science, Ain-Shams University (Egypt); El-Katori, Emad E.; Gharni, Zarha H. [Chemistry Department, Faculty of Science, King Khaled University (Saudi Arabia)

    2013-03-15

    Graphical abstract: Photocatalytic degradation of methylene blue dye was successfully carried over Fe{sub 2}O{sub 3}/TiO{sub 2} nanorods embedded various proportion of Fe{sub 2}O{sub 3} (0–20) wt.%. Highlights: ► Fe{sub 2}O{sub 3}/TiO{sub 2} nano mixed oxide samples were successfully synthesized by sol–gel method. ► Manipulation of particle size and structure were achieved by micelle template approach. ► Both adsorption and photocatalytic reactivity are the main reasons for exceptional decolorization of methylene blue dye. ► A new mechanism for electronic transition between TiO{sub 2} and Fe{sub 2}O{sub 3} was proposed. -- Abstract: The photocatalytic degradation of methylene blue dye was successfully carried under UV irradiation over Fe{sub 2}O{sub 3}/TiO{sub 2} nanoparticles embedded various composition of Fe{sub 2}O{sub 3} (0–20) wt.% synthesized by sol–gel process. Structural and textural features of the mixed oxide samples were investigated by X-ray diffraction [XRD], Fourier transformer infra-red [FTIR], Energy dispersive X-ray [EDX], Field emission electron microscope [FESEM] and transmission electron microscope [TEM]. However, the optical features were estimated using UV–Vis spectrophotometer. The results reveal that the incorporation of various Fe{sub 2}O{sub 3} up to 7% is associated by remarkable increase in surface area, reduction of particle size, stabilization of anatase phase, shifting the photoexcitation response of the sample to visible region and exceptional degradation of methylene blue dye. On the other hand, increasing Fe{sub 2}O{sub 3} contents up to 20 wt.% is associated by anatase–rutile transformation, increasing in particle size and remarkable decrease in surface area which are prime factors in reducing the degradation process. The experimental results indicate that Fe{sub 2}O{sub 3}/TiO{sub 2} nanoparticles having both the advantages of photodegradation–adsorption process which considered a promising new

  18. Rose-like I-doped Bi{sub 2}O{sub 2}CO{sub 3} microspheres with enhanced visible light response: DFT calculation, synthesis and photocatalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Zai, Jiantao; Cao, Fenglei; Liang, Na; Yu, Ke; Tian, Yuan; Sun, Huai; Qian, Xuefeng, E-mail: xfqian@sjtu.edu.cn

    2017-01-05

    Highlights: • DFT reveals I{sup −} can partially substitute CO{sub 3}{sup 2−}to narrow the bandgap of Bi{sub 2}O{sub 2}CO{sub 3}. • Sodium citrate play a key role on the formation of rose-like I-doped Bi{sub 2}O{sub 2}CO{sub 3}. • Rose-like I-doped Bi{sub 2}O{sub 2}CO{sub 3} show enhanced visible light response. • The catalyst has enhanced photocatalytic activity to organic and Cr(VI) pollutes. - Abstract: Based on the crystal structure and the DFT calculation of Bi{sub 2}O{sub 2}CO{sub 3}, I{sup −} can partly replace the CO{sub 3}{sup 2−}in Bi{sub 2}O{sub 2}CO{sub 3} to narrow its bandgap and to enhance its visible light absorption. With this in mind, rose-like I-doped Bi{sub 2}O{sub 2}CO{sub 3} microspheres were prepared via a hydrothermal process. This method can also be extended to synthesize rose-like Cl- or Br-doped Bi{sub 2}O{sub 2}CO{sub 3} microspheres. Photoelectrochemical test supports the DFT calculation result that I- doping narrows the bandgap of Bi{sub 2}O{sub 2}CO{sub 3} by forming two intermediate levels in its forbidden band. Further study reveals that I-doped Bi{sub 2}O{sub 2}CO{sub 3} microspheres with optimized composition exhibit the best photocatalytic activity. Rhodamine B can be completely degraded within 6 min and about 90% of Cr(VI) can be reduced after 25 min under the irradiation of visible light (λ > 400 nm).

  19. Controlled synthesis, formation mechanism, and carbon oxidation properties of Ho{sub 2}Cu{sub 2}O{sub 5} nanoplates prepared with a coordination-complex method

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Rui [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); School of Metallurgy, Northeastern University, Shenyang 110004 (China); You, Junhua [School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870 (China); Han, Fei; Li, Chaoyang; Zheng, Guiyuan; Xiao, Weicheng [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); Liu, Xuanwen, E-mail: lxw@mail.neuq.edu.cn [School of Resources and Materials, Northeastern University at Qinhuangdao 066004 (China); School of Metallurgy, Northeastern University, Shenyang 110004 (China)

    2017-02-28

    Highlights: • The crystallization mechanism relies on Ho{sup 3+} and Cu{sup 2+} diffusion. • The Ho{sub 2}Cu{sub 2}O{sub 5} particles are refined by the coordination complex method under N{sub 2} environment. • The catalytic oxidation activity of Ho{sub 2}Cu{sub 2}O{sub 5} samples for carbon is enhanced. - Abstract: Ho{sub 2}Cu{sub 2}O{sub 5} nanoplates with perovskite structures were synthesized via a simple solution method (SSM) and a coordination-complex method (CCM) using [HoCu(3,4-pdc){sub 2}(OAc)(H{sub 2}O){sub 3}]·8H{sub 2}O (L = 3,4-pyridinedicarboxylic acid) as a precursor. The CCM was also performed in an N{sub 2} environment (CCMN) under various calcination conditions. The crystallization processes were characterized using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Ho{sub 2}Cu{sub 2}O{sub 5} formed through the diffusion of CuO into Ho{sub 2}O{sub 3} particles. Cu{sup 2+} diffused faster than Ho{sup 3+} during this process. The initial products of CCMN (along with the thermal decomposition products) were initially laminarized in the N{sub 2} atmosphere, which prevented the growth of CuO particles and decreased the size of the Ho{sub 2}Cu{sub 2}O{sub 5} particles. The final Ho{sub 2}Cu{sub 2}O{sub 5} particles from CCMN had a nanoplate morphology with an average thickness of 75 nm. The decomposition of organic molecules and protection from N{sub 2} played important roles in determining the morphology of the resulting Ho{sub 2}Cu{sub 2}O{sub 5}. The catalytic oxidation activity of Ho{sub 2}Cu{sub 2}O{sub 5} samples for carbon was characterized using a specific surface area measurement and thermogravimetric analysis, which revealed that the samples produced by CCMN had the highest catalytic activity.

  20. Co{sup 2+} adsorption in porous oxides Mg O, Al{sub 2}O{sub 3} and Zn O;Adsorcion de Co{sup 2+} en oxidos porosos MgO, Al{sub 2}O{sub 3} y ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Moreno M, J. E.; Granados C, F. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Bulbulian, S., E-mail: francisco.granados@inin.gob.m [UNAM, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

    2009-07-01

    The porous oxides Mg O, Al{sub 2}O{sub 3} and Zn O were synthesized by the chemical combustion in solution method and characterized be means of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The adsorption behavior of Co{sup 2+} ions present in aqueous solution were studied on the synthesized materials by means of experiments lots type to ambient temperature. It was found that the cobalt ions removal was of 90% in Mg O, 65% in Zn O and 72% in Al{sub 2}O{sub 3} respectively, indicating that the magnesium oxide is the best material to remove Co{sup 2+} presents in aqueous solution. (Author)

  1. Structure and crystallization behavior of La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} metaborate glasses doped with Nd{sup 3+} or Eu{sup 3+} ions

    Energy Technology Data Exchange (ETDEWEB)

    Pytalev, D.S., E-mail: pytalev@isan.troitsk.ru [Institute of Spectroscopy, Russian Academy of Sciences, 5 Fizicheskaya St., 142190 Troitsk, Moscow (Russian Federation); Caurant, D.; Majérus, O.; Trégouët, H. [Institut de Recherche de Chimie Paris, CNRS – Chimie ParisTech, 11 Rue Pierre et Marie Curie, 75005 Paris (France); Charpentier, T. [CEA, IRAMIS, NIMBE, CEA-CNRS UMR 3299, Laboratoire de Structure et Dynamique par Résonance Magnétique, 91191 Gif-sur-Yvette (France); Mavrin, B.N. [Institute of Spectroscopy, Russian Academy of Sciences, 5 Fizicheskaya St., 142190 Troitsk, Moscow (Russian Federation)

    2015-08-25

    Highlights: • The structure and crystallization behavior of the La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} glass are studied. • LaB{sub 3}O{sub 6} crystallizes congruently without intermediate but only from glass surface. • The structure of the amorphous and the crystalline phases differ significantly. • The activation energy of LaB{sub 3}O{sub 6} crystal growth is determined. - Abstract: The local structure and crystallization behavior of the stoichiometric La{sub 2}O{sub 3}⋅3B{sub 2}O{sub 3} (LaMB) metaborate glass doped with Nd{sup 3+} or Eu{sup 3+} ions are studied using differential thermal analysis (DTA), X-ray diffraction (XRD), Raman scattering and {sup 11}B magic-angle spinning nuclear magnetic resonance (MAS NMR), optical absorbance and luminescence techniques. In the crystallized samples, XRD, NMR and Raman spectroscopy have detected the formation of only one crystalline phase (congruent crystallization of LaB{sub 3}O{sub 6}). No intermediate metastable crystalline phase has been detected before LaB{sub 3}O{sub 6} crystals formation (single stage crystallization process). The observation of heat treated glass samples by scanning electron microscopy (SEM) and optical microscopy coupled with the study of the effect of varying the glass particle size on the DTA curves have both revealed that LaB{sub 3}O{sub 6} crystallization only occurs by a heterogeneous nucleation mechanism (needle-shape crystals) from glass surface. The activation energy E{sub c} of crystal growth has been determined by performing DTA experiments at different heating rates with the Kissinger (784 kJ/mol) and Ozawa (801 kJ/mol) equations than can be used for surface crystallization processes. The heterogeneous crystallization behavior and the spectroscopic results obtained in this work by comparing the LaMB glass with the LaB{sub 3}O{sub 6} crystalline phase suggest the existence of significant structural differences between the amorphous and the crystalline phases contrary to what

  2. Magnetic and catalytic properties of inverse spinel CuFe{sub 2}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Anandan, S., E-mail: sanand@nitt.edu [Nanomaterials and Solar Energy Conversion Lab, Department of Chemistry, National Institute of Technology, Trichy 620 015 (India); Department of Environmental Engineering and Science, Feng Chia University, Taichung 407, Taiwan (China); Selvamani, T.; Prasad, G. Guru [Nanomaterials and Solar Energy Conversion Lab, Department of Chemistry, National Institute of Technology, Trichy 620 015 (India); Asiri, A.M. [The Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21413 (Saudi Arabia); Wu, J.J., E-mail: jjwu@fcu.edu.tw [Department of Environmental Engineering and Science, Feng Chia University, Taichung 407, Taiwan (China)

    2017-06-15

    Highlights: • Copper ferrite (CuFe{sub 2}O{sub 4}) nanoparticles were synthesized via citrate-nitrate combustion method. • Spectroscopic information’s have found that CuFe{sub 2}O{sub 4} nanoparticles as an inverse spinel structure. • Magnetic study exhibits CuFe{sub 2}O{sub 4} nanoparticles have ferromagnetic behavior. • CuFe{sub 2}O{sub 4} nanoparticles employed for photocatalytic decolourisation of methylene blue under visible light irradiation. - Abstract: In this research, inverse spinel copper ferrite nanoparticles (CuFe{sub 2}O{sub 4} NPs) were synthesized via citrate-nitrate combustion method. The crystal structure, particle size, morphology and magnetic studies were investigated using various instrumental tools to illustrate the formation of the inverse spinel structure. Mossbauer spectrometry identified Fe is located both in the tetrahedral and octahedral site in the ratio (40:60) and the observed magnetic parameters values such as saturation magnetization (M{sub s} = 20.62 emu g{sup −1}), remnant magnetization (M{sub r} = 11.66 emu g{sup −1}) and coercivity (H{sub c} = 63.1 mTesla) revealed that the synthesized CuFe{sub 2}O{sub 4} NPs have a typical ferromagnetic behaviour. Also tested CuFe{sub 2}O{sub 4} nanoparticles as a photocatalyst for the decolourisation of methylene blue (MB) in the presence of peroxydisulphate as the oxidant.

  3. X-ray-induced dissociation of H.sub.2O and formation of an O.sub.2-H.sub.2 alloy at high pressure

    Science.gov (United States)

    Mao, Ho-kwang [Washington, DC; Mao, Wendy L [Washington, DC

    2011-11-29

    A novel molecular alloy of O.sub.2 and H.sub.2 and a method of producing such a molecular alloy are provided. When subjected to high pressure and extensive x-radiation, H.sub.2O molecules cleaved, forming O--O and H--H bonds. In the method of the present invention, the O and H framework in ice VII was converted into a molecular alloy of O.sub.2 and H.sub.2. X-ray diffraction, x-ray Raman scattering, and optical Raman spectroscopy demonstrate that this crystalline solid differs from previously known phases.

  4. Comparison in the electronic structure of YBa{sub 2}Fe{sub 3}O{sub 8} insulator with YBa{sub 2}Cu{sub 3}O{sub 7} and SmFeAsO{sub 0.8}F{sub 0.2} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Guan, X.Y. [Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Superconductivity R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Cheng, C.H. [School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Pan, M. [Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Superconductivity R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); Zhang, H. [Department of Physics, Peking University, Beijing 100871 (China); Zhao, Y., E-mail: yzhao@home.swjtu.edu.cn [Key Laboratory of Magnetic Suspension Technology and Maglev Vehicle, Ministry of Education, Superconductivity R and D Center, Southwest Jiaotong University, Chengdu 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)

    2013-10-15

    Highlights: • The electronic structure of YBa{sub 2}Fe{sub 3}O{sub 8}, YBa{sub 2}Cu{sub 3}O{sub 7} and SmFeAsO{sub 0.8}F{sub 0.2} were investigated by XPS. • The core-level and valence-band structures of these systems are different. • The density of states at Fermi level is related to the superconductivity. -- Abstract: The electronic structure and chemical states of relevant elements of YBa{sub 2}Fe{sub 3}O{sub 8} are investigated using X-ray photoemission spectroscopy (XPS), compared with those of YBa{sub 2}Cu{sub 3}O{sub 7} and SmFeAsO{sub 0.8}F{sub 0.2} superconductors. The typical differences and similarities in core-level and valence-band structures of these systems have been detected, strongly suggesting that the superconductivity have the finite density of states around Fermi level. Several features of O1s, Y3d, Ba3d, and Fe2p core lines in XPS spectra are also carefully compared and analyzed.

  5. Effect of atomic layer deposition temperature on current conduction in Al{sub 2}O{sub 3} films formed using H{sub 2}O oxidant

    Energy Technology Data Exchange (ETDEWEB)

    Hiraiwa, Atsushi, E-mail: hiraiwa@aoni.waseda.jp, E-mail: qs4a-hriw@asahi-net.or.jp [Research Organization for Nano and Life Innovation, Waseda University, 513 Waseda-Tsurumaki, Shinjuku, Tokyo 162-0041 (Japan); Matsumura, Daisuke [Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kawarada, Hiroshi, E-mail: kawarada@waseda.jp [Research Organization for Nano and Life Innovation, Waseda University, 513 Waseda-Tsurumaki, Shinjuku, Tokyo 162-0041 (Japan); Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); The Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-26 Nishiwaseda, Shinjuku, Tokyo 169-0051 (Japan)

    2016-08-28

    To develop high-performance, high-reliability gate insulation and surface passivation technologies for wide-bandgap semiconductor devices, the effect of atomic layer deposition (ALD) temperature on current conduction in Al{sub 2}O{sub 3} films is investigated based on the recently proposed space-charge-controlled field emission model. Leakage current measurement shows that Al{sub 2}O{sub 3} metal-insulator-semiconductor capacitors formed on the Si substrates underperform thermally grown SiO{sub 2} capacitors at the same average field. However, using equivalent oxide field as a more practical measure, the Al{sub 2}O{sub 3} capacitors are found to outperform the SiO{sub 2} capacitors in the cases where the capacitors are negatively biased and the gate material is adequately selected to reduce virtual dipoles at the gate/Al{sub 2}O{sub 3} interface. The Al{sub 2}O{sub 3} electron affinity increases with the increasing ALD temperature, but the gate-side virtual dipoles are not affected. Therefore, the leakage current of negatively biased Al{sub 2}O{sub 3} capacitors is approximately independent of the ALD temperature because of the compensation of the opposite effects of increased electron affinity and permittivity in Al{sub 2}O{sub 3}. By contrast, the substrate-side sheet of charge increases with increasing ALD temperature above 210 °C and hence enhances the current of positively biased Al{sub 2}O{sub 3} capacitors more significantly at high temperatures. Additionally, an anomalous oscillatory shift of the current-voltage characteristics with ALD temperature was observed in positively biased capacitors formed by low-temperature (≤210 °C) ALD. This shift is caused by dipoles at the Al{sub 2}O{sub 3}/underlying SiO{sub 2} interface. Although they have a minimal positive-bias leakage current, the low-temperature-grown Al{sub 2}O{sub 3} films cause the so-called blisters problem when heated above 400 °C. Therefore, because of the absence of blistering, a 450

  6. Preparation of high laser-induced damage threshold Ta{sub 2}O{sub 5} films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Cheng, E-mail: xucheng@cumt.edu.cn [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Yi, Peng; Fan, Heliang; Qi, Jianwei; Yang, Shuai; Qiang, Yinghuai; Liu, Jiongtian [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Li, Dawei [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2014-08-01

    High laser-induced damage threshold (LIDT) Ta{sub 2}O{sub 5} films were prepared by the sol–gel method using TaCl{sub 5} as a new precursor. The optical properties, surface morphologies, chemical composition, absorption and LIDT of the films were investigated. The results showed that the transparent and homogenous Ta{sub 2}O{sub 5} films had small surface roughness, low absorption and high LIDT even with large number of layers. The maximum LIDT at 1064 nm and 12 ns of the films was 24.8 J/cm{sup 2}. The ion chromatograph and Fourier transform infrared spectrum were used to reveal the functions of the addition of H{sub 2}O{sub 2} in the sol formation. It was shown that H{sub 2}O{sub 2} had two important functions, which were the decrease of Cl element content and the rapid generation of tantalum oxide. The high LIDT achieved was mainly due to the nearly free of defects in the films.

  7. Plasmonic Ag-pillared rectorite as catalyst for degradation of 2,4-DCP in the H{sub 2}O{sub 2}-containing system under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yunfang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Jianzhang, E-mail: fangjzh@scnu.edu.cn [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China); Lu, Shaoyou [Shenzhen Center for Disease Control and Prevention, Shenzhen 518055 (China); Wu, Yan; Chen, Dazhi; Huang, Liyan [Institute of Engineering Technology of Guangdong Province, Key Laboratory of Water Environmental Pollution Control of Guangdong Province, Guangzhou 510440 (China); Cheng, Cong; Ren, Lu; Zhu, Ximiao [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Fang, Zhanqiang [School of Chemistry and Environment, South China Normal University, Guangzhou 510006, Guangdong (China); Guangdong Technology Research Center for Ecological Management and Remediation of Urban Water System, Guangzhou 510006 (China)

    2015-10-30

    Highlights: • The Ag-R catalyst was synthesized via a novel thermal decomposition method. • Ag-R catalyst possessed the synergistic effects of SPR and adsorption capacity. • The degradation of 2,4-DCP was evaluated in Ag-R/H{sub 2}O{sub 2}/visible light system. - Abstract: This study aims at photocatalytic degradation of 2,4-DCP with the assistance of H{sub 2}O{sub 2} in aqueous solution by a composite catalyst of Ag-rectorite. The catalysts were prepared via a novel thermal decomposition method followed after the cation-exchange process. The synthesized nano-materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) surface analyzer, Ultraviolet–visible light (UV–vis) absorption spectra, field-emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM). The different mechanisms of degradation process with or without visible light irradiation were discussed, respectively. Moreover, the degradation efficiency of 2,4-DCP wastewater under Ag-rectorite/H{sub 2}O{sub 2}/visible light system was investigated by series of experiments, concerning on effects of major operation factors, such as H{sub 2}O{sub 2} dosage and the initial pH value. The highest degradation rate was observed when adding 0.18 mL H{sub 2}O{sub 2} into 50 mL 2,4-DCP solution, and the optimal pH value was 4 for the reaction. Afterwards, total organic carbon (TOC) experiments were carried out to evaluate the mineralization ratio of 2,4-DCP.

  8. La{sub 2}O{sub 3}-reinforced W and W-V alloys produced by hot isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, A., E-mail: angel.munoz@uc3m.es [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Monge, M.A., E-mail: mmonge@fis.uc3m.es [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Savoini, B., E-mail: bsavoi@fis.uc3m.es [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Rabanal, M.E., E-mail: eugenia@ing.uc3m.es [Departamento de Ciencia e Ingenieria de Materiales e Ingenieria Quimica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Garces, G., E-mail: ggarces@cenim.csic.es [Centro Nacional de Investigaciones Melaturgicas, CENIM, 28040 Madrid (Spain); Pareja, R., E-mail: rpp@fis.uc3m.es [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

    2011-10-01

    W and W-V alloys reinforced with La{sub 2}O{sub 3} particles have been produced by MA and subsequent HIP at 1573 K and 195 MPa. The microstructure of the consolidated alloys has been characterized by scanning electron microscopy, energy dispersive spectroscopy analyses and X-ray diffraction. The mechanical properties were studied by nanoindentation measurements. The results show that practically full dense billets of W-V, W-V-La{sub 2}O{sub 3} and W-La{sub 2}O{sub 3} alloys can be produced. The microstructure analysis has shown that islands of V are present in W-V and W-V-1La{sub 2}O{sub 3} alloys. In W-1La{sub 2}O{sub 3} islands of La{sub 2}O{sub 3} are also present. The nanohardness of the W matrix increases with the addition of V, while decreases with the addition of La{sub 2}O{sub 3}.

  9. Electronic Structure of TIBa(sub 2)CaCu(sub 2)O(sub 7-delta)

    Science.gov (United States)

    Vasquez, R. P.; Novikov, D. L.; Freeman, A. J.; Siegal, M. P.

    1996-01-01

    The core levels of TIBa(sub 2)CaCu(sub 2)O(sub 7-delta) epitaxial films have been measured with x-ray photoelectron spectroscopy (XPS). The valence electronic structure has been determined using the full-potential linear muffin tin orbital band structure method and measured with XPS.

  10. Czochralski growth and characterization of {beta}-Ga{sub 2}O{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Galazka, Z.; Uecker, R.; Irmscher, K.; Albrecht, M.; Klimm, D.; Pietsch, M.; Bruetzam, M.; Bertram, R.; Ganschow, S.; Fornari, R. [Leibniz Institute for Crystal Growth, Max-Born-Str. 2, 12489 Berlin (Germany)

    2010-12-15

    Transparent semiconducting {beta}-Ga{sub 2}O{sub 3} single crystals were grown by the Czochralski method from an iridium crucible under a dynamic protective atmosphere to control partial pressures of volatile species of Ga{sub 2}O{sub 3}. Thermodynamic calculations on different atmospheres containing CO{sub 2}, Ar and O{sub 2} reveal that CO{sub 2} growth atmosphere combined with overpressure significantly decreases evaporation of volatile Ga{sub 2}O{sub 3} species without any harm to iridium crucible. It has been found that CO{sub 2}, besides providing high oxygen concentration at high temperatures, is also acting as a minor reducing agent for Ga{sub 2}O{sub 3}. Different coloration of obtained crystals as well as optical and electrical properties are directly correlated with growth conditions (atmosphere, pressure and temperature gradients), but not with residual impurities. Typical electrical properties of the n-type {beta}-Ga{sub 2}O{sub 3} crystals at room temperature are: {rho} = 0.1 - 0.3 {omega}cm, {mu}{sub n,Hall} = 110 - 150 cm{sup 2}V{sup -1}s{sup -1}, n{sub Hall} = 2 - 6 x 10{sup 17} cm{sup -3} and E{sub Ionisation} = 30 - 40 meV. A decrease of transmission in the IR-region is directly correlated with the free carrier concentration and can be effectively modulated by the dynamic growth atmosphere. Electron paramagnetic resonance (EPR) spectra exhibit an isotropic shallow donor level and anisotropic defect level. According to differential thermal analysis (DTA) measurements, there is substantially no mass change of {beta}-Ga{sub 2}O{sub 3} crystals below 1200 C (i.e. no decomposition) under oxidizing or neutral atmosphere, while the mass gradually decreases with temperature above 1200 C. High resolution transmission electron microscopy (HRTEM) images at atomic resolution show the presence of vacancies, which can be attributed to Ga or O sites, and interstitials, which can likely be attributed to Ga atoms. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGa

  11. Fabrication of FeSi and Fe{sub 3}Si compounds by electron beam induced mixing of [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers grown by focused electron beam induced deposition

    Energy Technology Data Exchange (ETDEWEB)

    Porrati, F.; Sachser, R.; Huth, M. [Physikalisches Institut, Goethe-Universität, Max-von-Laue-Str. 1, D-60438 Frankfurt am Main (Germany); Gazzadi, G. C. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); Frabboni, S. [S3 Center, Nanoscience Institute-CNR, Via Campi 213/a, 41125 Modena (Italy); FIM Department, University of Modena and Reggio Emilia, Via G. Campi 213/a, 41125 Modena (Italy)

    2016-06-21

    Fe-Si binary compounds have been fabricated by focused electron beam induced deposition by the alternating use of iron pentacarbonyl, Fe(CO){sub 5}, and neopentasilane, Si{sub 5}H{sub 12} as precursor gases. The fabrication procedure consisted in preparing multilayer structures which were treated by low-energy electron irradiation and annealing to induce atomic species intermixing. In this way, we are able to fabricate FeSi and Fe{sub 3}Si binary compounds from [Fe/Si]{sub 2} and [Fe{sub 3}/Si]{sub 2} multilayers, as shown by transmission electron microscopy investigations. This fabrication procedure is useful to obtain nanostructured binary alloys from precursors which compete for adsorption sites during growth and, therefore, cannot be used simultaneously.

  12. A novel high color purity blue-emitting phosphor: CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiangong, E-mail: lijiangong01@gmail.com [Department of Electronic Science and Engineering, Huanghuai University, Zhumadian 463000 (China); Yan, Huifang [Department of Foreign Languages and Literature, Huanghuai University, Zhumadian 463000 (China); Yan, Fengmei [Department of Chemistry and Chemical Engineering, Huanghuai University, Zhumadian 463000 (China)

    2016-07-15

    Graphical abstract: - Highlights: • A series of Tm{sup 3+}-doped CaBi{sub 2}B{sub 2}O{sub 7} blue-emitting phosphors were prepared. • The optimum doping content of Tm{sup 3+} ions was found. • The critical distance and concentration quenching mechanism was discussed. • The color purity of as prepared sample was analyzed and compared. - Abstract: A series of Tm{sup 3+}-doped CaBi{sub 2−x}B{sub 2}O{sub 7}:xTm{sup 3+} (0.02 ≤ x ≤ 0.12) blue-emitting phosphors with high color purity were prepared by solid-state reaction method. The crystal structure and luminescence properties of the as-prepared phosphors were studied. This phosphor shows a satisfactory blue performance (peak at 453 nm) due to the {sup 1}D{sub 2} → {sup 3}F{sub 4} transition of Tm{sup 3+} excited by 357 nm light. Investigation of Tm{sup 3+} content dependent emission spectra indicates that x = 0.04 is the optimum doping content of Tm{sup 3+} ions in the CaBi{sub 2}B{sub 2}O{sub 7} host. The critical distance and the concentration quenching mechanism were also investigated. In particular, the color purity of as prepared sample was analyzed and the result shows that the color purity of CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+} is higher than the commercial blue phosphor BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} (BAM:Eu{sup 2+}) and the latest reported Tm{sup 3+} doped blue phosphors. The present work suggests that the CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+} phosphor is a potential blue-emitting candidate for the application in the near-UV WLEDs.

  13. Magnetic transitions in the system YBa2Cu/sub 2.8/Co/sub 0.2/O/sub 6+y/

    International Nuclear Information System (INIS)

    Miceli, P.F.; Tarascon, J.M.; Barboux, P.; Greene, L.H.; Bagley, B.G.; Hull, G.W.; Giroud, M.; Rhyne, J.J.; Neumann, D.A.; National Institute of Standards and Technology, Gaithersburg, Maryland 20899)

    1989-01-01

    We have studied the oxygen dependence of the two magnetic transitions (antiferromagnetic ordering of chains and planes) in YBa 2 Cu/sub 2.8/Co/sub 0.2/O/sub 6+y/ using neutron scattering. It is found that both transition temperatures increase with decreasing oxygen concentration. At y approx. 0.37 ( equivalent to y 0 ) the two transition temperatures are equal, so that chains and planes order at a single transition temperature for y less than or equal to y/sub 0/. For y=1 the compound is superconducting at 60 K. Therefore, this system qualitatively exhibits the magnetic and superconducting properties of pure YBa 2 Cu 3 O/sub 6+y/ while providing important insight on the oxygen dependence of chain site magnetic ordering. A discussion is presented which also includes results on Ni and Al substitutions

  14. Photochemical Degradation of Dimethyl Phthalate by Fe(III)/tartrate/H{sub 2}O{sub 2} System

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xianghua; Ding, Shimin; Xie, Faping [Yangtze Normal Univ., Fuling (China)

    2012-11-15

    Photochemical degradation of dimethyl phthalate (DMP) in Fe(III)/tartrate/H{sub 2}O{sub 2} system was investigated utilizing fluorescent lamps as the primary light source. Effects of initial pH, light source, and initial concentration of each reactant on DMP photodegradation was examined. The results show that the system was able to effectively photodegrade DMP utilizing visible light. Fluorescent lamp, halide lamp, UV lamp and sunlight could all be used as the light sources. The optimal pH ranged among 3.0-4.0 for the system. Increases of the initial concentrations of Fe(III) and H{sub 2}O{sub 2} accelerated the photodegradation of DMP, whereas excessively high initial tartrate concentration resulted in the decrease of photodegradation efficiency and rate of DMP.

  15. New quaternary oxides with both families of second-order Jahn–Teller (SOJT) distortive cations: Solid-state synthesis, structure determination, and characterization of YNbTe{sub 2}O{sub 8} and YNbSe{sub 2}O{sub 8}

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeong Hun [Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756 (Korea, Republic of); Jeon, Beom-Yong; You, Tae-Soo [Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Ok, Kang Min, E-mail: kmok@cau.ac.kr [Department of Chemistry, Chung-Ang University, 84 Heukseok-ro, Dongjak-gu, Seoul 156-756 (Korea, Republic of)

    2015-07-15

    Graphical abstract: Ball-and-stick representation of YNbTe{sub 2}O{sub 8} composed of polyhedra of SOJT distortive cations, i.e., NbO{sub 6} and TeO{sub 3}, in the ac-plane. - Highlights: • Two novel tellurite and selenite (YNbQ{sub 2}O{sub 8}; Q = Te and Se) are synthesized. • YNbQ{sub 2}O{sub 8} possess both families of second-order Jahn–Teller distortive cations. • The distortive environments and bonding nature are supported by electronic structure calculations. - Abstract: Two novel quaternary mixed metal tellurite and selenite, YNbTe{sub 2}O{sub 8} and YNbSe{sub 2}O{sub 8}, respectively, have been synthesized through standard solid-state reactions using Y{sub 2}O{sub 3}, Nb{sub 2}O{sub 5}, TeO{sub 2} or SeO{sub 2} as reagents. Single crystal X-ray and powder neutron diffraction analyses have been utilized to determine the structures of the reported materials. YNbTe{sub 2}O{sub 8} and YNbSe{sub 2}O{sub 8} are isostructural to each other and crystallize in the monoclinic centrosymmetric space group, C2/m (No. 12). Due to the two families of constituent second-order Jahn–Teller (SOJT) distortive cations, i.e., Nb{sup 5+} and Te{sup 4+}/Se{sup 4+}, local asymmetric environments occur from the three-dimensional frameworks. Intra-octahedral distortions along the local C{sub 4} direction and asymmetric trigonal pyramidal coordination moieties generated by stereoactive lone pairs are observed from the NbO{sub 6} octahedra and TeO{sub 3} (or SeO{sub 3}) polyhedra, respectively. Thermogravimetric analysis, infrared and UV–vis diffuse reflectance spectroscopies, elemental analysis, out-of-center distortions, dipole moment calculations, and electronic structure calculations for the reported materials are presented.

  16. The orthorhombic fluorite related compounds Ln/sub 3/RuO/sub 7/, Ln=Nd, Sm and Eu

    International Nuclear Information System (INIS)

    Van Berkel, F.P.F.; Ijdo, D.J.W.

    1986-01-01

    Fluorite-related Ru(V) compound with composition Ln/sub 3/RuO/sub 7/ have been found. These compounds with space group Cmcm adopt a superstructure of the cubic fluorite structure with a/sub orth/=2a/sub c/, b/sub orth/=c/sub orth/=a/sub c/√2. These compounds have the same structure as La/sub 3/NbO/sub 7/

  17. Structural, photoluminescence and radioluminescence properties of Eu{sup 3+} doped La{sub 2}Hf{sub 2}O{sub 7} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wahid, Kareem; Pokhrel, Madhab; Mao, Yuanbing, E-mail: yuanbing.mao@utrgv.edu

    2017-01-15

    This study presents the structural, optical, and radioluminescent characterization of newly synthesized europium-doped lanthanum hafnate (La{sub 2}Hf{sub 2}O{sub 7}:xmol%Eu{sup 3+}, x=0 to 35) nanoparticles (NPs) for use as phosphors and scintillation materials. Samples prepared through a combined co-precipitation and molten salt synthetic process were found to crystalize in the pyrochlore phase, a radiation tolerant structure related to the fluorite structure. These samples exhibit red luminescence under ultraviolet and X-ray excitation. Under these excitations, the optical intensity and quantum yield of the La{sub 2}Hf{sub 2}O{sub 7}:xmol%Eu{sup 3+} NPs depend on the Eu{sup 3+} concentration and are maximized at 5%. It is proposed that there is a trade-off between the quenching due to defect states/cross-relaxation and dopant concentration. An optimal dopant concentration allows the La{sub 2}Hf{sub 2}O{sub 7}:5 mol%Eu{sup 3+} NPs to show the best luminescent properties of all the samples. - Graphical abstract: Incident X-ray and UV photons interact with La{sub 2}Hf{sub 2}O{sub 7}: xmol%Eu{sup 3+}(x=1–35) nanoparticles (NPs) to yield strong red luminescence centered at 612 nm. Colored spheres inside NP diagram represent pyrochlore coordination environment of La{sub 2}Hf{sub 2}O{sub 7}:xmol%Eu{sup 3+}. Blue, red, yellow, green and black spheres represent hafnium(IV) atoms, lanthanum(III)/europium(III) atoms, oxygen atoms at 48f site, oxygen atoms at 8b site and oxygen vacancies, respectively. - Highlights: • La{sub 2}Hf{sub 2}O{sub 7}:xmol%Eu{sup 3+} (x=0–35) nanoparticles with weakly-ordered pyrochlore structures were synthesized. • Optically and X-ray excited emission spectra showed strong luminescence centered at 612 nm. • Photoluminescence quantum yield increases with doping concentration up to 5% and decreases at higher concentrations.

  18. Characteristic of Ti-based PbO{sub 2} anodes with SnO{sub 2}+Sb{sub 2}O{sub 3} intermediate layers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Tong, H.; Xu, W. [Yangzhou Univ., College of Chemistry and Chemical Engineering, Yangzhou (China)

    2006-07-01

    Ceramic coatings are used in many electrochemical applications, such as organic synthetic applications, wastewater treatment and oxygen production. These processes typically occur in aqueous sulphuric acid. Desirable features for electrode materials include electro-catalytic activity, high stability, low cost, good overall performance under mild conditions and commercial availability. Lead dioxide exhibits excellent chemical stability, high conductivity, high overpotential for oxygen evolution and lower cost in an acid medium. Studies have shown that the stability of active coating prepared by depositing lead dioxide on titanium substrate is poor. In order to solve this problems, methods of doping expensive noble metals or adding an intermediate layer have been examined. Electrode coatings are very sensitive to preparation procedures, in which precursors play an important role in the surface morphology, microstructure, final composition and stability of anodes. However, appreciable inorganic salt loss has been reported using traditional precursors. A polymeric precursor (PP) method commonly used in the preparation of nano-particles has certain advantages, such as easy manipulation and insensitivity to the presence of water. This study characterized the surface morphology and electrochemical behaviour of titanium (Ti)/tin oxide (SnO{sub 2}) plus antimony oxide ((Sb{sub 2}O{sub 3})/lead dioxide (PbO{sub 2}) anode with SnO{sub 2} plus Sb{sub 2}O{sub 3} intermediate coatings. The electrochemical performance of Ti/SnO{sub 2}+Sb{sub 2}O{sub 3}/PbO{sub 2} anode preparing intermediate layer by the PP method was compared with alcohol precursors. It was concluded that adding SnO{sub 2}+Sb2O{sub 3} intermediate layer to Ti/PbO{sub 2} anodes could enhance the lifetime and stability of the anodes, thus its performance. 10 refs., 2 tabs.

  19. Mn{sub 2}O{sub 3}/carbon aerogel microbead composites synthesized by in situ coating method for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xingyan, E-mail: wxianyou@yahoo.com [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China); Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Key Laboratory of Materials Design and Preparation Technology of Hunan, Xiangtan 411105 (China); Liu Li [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China); Wang Xianyou, E-mail: wqinyan801@yahoo.com.cn [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China); Key Laboratory of Materials Design and Preparation Technology of Hunan, Xiangtan 411105 (China); Yi Lanhua [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China); Hu Chuanyue [Hunan Institute of Humanities Science and Technology, Loudi 417000 (China); Zhang Xiaoyan [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, Chemistry School, Xiangtan University, Hunan, Xiangtan 411105 (China)

    2011-09-15

    Highlights: > Mn{sub 2}O{sub 3}/CAMB composite materials for supercapacitor were prepared by in situ coating method. > The optimum amount of Mn{sub 2}O{sub 3} in Mn{sub 2}O{sub 3}/CAMB composite is 10 wt%. > Coating nano-sized Mn{sub 2}O{sub 3} on the CAMB could improve the supercapacitive behaviors of composites. - Abstract: A series of Mn{sub 2}O{sub 3}/carbon aerogel microbead (Mn{sub 2}O{sub 3}/CAMB) composites for supercapacitor electrodes have been synthesized by in situ encapsulation method. The structure and morphology of Mn{sub 2}O{sub 3}/CAMB are characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrum and scanning electron microscopy (SEM). Electrochemical performances of the synthesized composites are evaluated by cyclic voltammetry and galvanostatic charge/discharge measurement. All the composites with different Mn{sub 2}O{sub 3} contents show higher specific capacitance than pure CAMB due to the pseudo-capacitance of the Mn{sub 2}O{sub 3} particles dispersed on the surface of CAMB. The highest specific capacitance is up to 368.01 F g{sup -1} when 10 wt% Mn{sub 2}O{sub 3} is coated on the surface of CAMB. Besides, 10%-Mn{sub 2}O{sub 3}/CAMB supercapacitor exhibits excellent cyclic stability, the specific capacitance still retains 90% of initial capacitance over 5000 cycles.

  20. Highly active sulfided CoMo catalysts supported on (ZrO{sub 2}–TiO{sub 2})/Al{sub 2}O{sub 3} ternary oxides

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, José, E-mail: jeaguila@imp.mx [Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, Gustavo A. Madero, México, D.F. 07730 (Mexico); De Los Reyes, José A., E-mail: jarh@xanum.uam.mx [Area de Ing. Química, UAM – Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, México, D.F. 09340 (Mexico); Ulín, Carlos A. [Area de Ing. Química, UAM – Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, México, D.F. 09340 (Mexico); Barrera, María C., E-mail: mcbdgavilan@gmail.com [Facultad de Ciencias Químicas, Universidad Veracruzana, Av. Universidad km. 7.5, Col. Santa Isabel, Coatzacoalcos, Veracruz, México, D.F. 96538 (Mexico)

    2013-12-16

    (ZrO{sub 2}–TiO{sub 2})/Al{sub 2}O{sub 3} ternary oxide at 20 mol% Al{sub 2}O{sub 3} (80% ZrO{sub 2}–TiO{sub 2}, in turn at 40–60 mol ratio) prepared by controlled co-precipitation (by urea thermal decomposition) of zirconium (ZrOCl{sub 2}·8H{sub 2}O) and titanium (TiCl{sub 4}) chlorides over a ground alumina substrate constitutes a promising material to be used as carrier of sulfided hydrodesulfurization (HDS) catalysts. After calcining (at 500 °C), the ternary oxide presented textural properties (S{sub g} = 387 m{sup 2} g{sup −1}, V{sub p} = 0.74 ml g{sup −1}, mean pore diameter = 7.6 nm) suitable to its utilization as carrier of catalysts applied in the oil-derived middle distillates HDS. As determined by temperature programmed-reduction and Raman and UV–vis spectroscopies ZrO{sub 2}–TiO{sub 2} deposition over alumina substrate resulted in decreased proportion of Mo{sup 6+} species in tetrahedral coordination on the oxidic impregnated material. As those species constitute hardly reducible precursors, their diminished concentration could be reflected in enhanced amount of Mo species susceptible of activation by sulfiding (H{sub 2}S/H{sub 2} at 400 °C) over our ternary carrier. Limiting the concentration of zirconia-titania (at 40–60 mol ratio) to 20 mol% in the mixed oxides support allowed the preparation of highly active promoted (by cobalt, at Co/(Co + Mo) = 0.3) MoS{sub 2} phase (at 2.8 atoms/nm{sup 2}), that formulation showing excellent properties in hydrodesulfurization (HDS) of both dibenzothiophene and highly-refractory 4,6-dimethyl-dibenzothiophene. Due to alike yields to various HDS products over CoMo/(ZrO{sub 2}–TiO{sub 2})/Al{sub 2}O{sub 3} and the corresponding Al{sub 2}O{sub 3}-supported formulation, presence of similar actives sites over those catalysts was strongly suggested. It seemed that enhanced concentration of octahedral Mo{sup 6+} over the oxidic impregnated precursor with (ZrO{sub 2}–TiO{sub 2})/Al{sub 2}O{sub 3

  1. Behavior of the antiferromagnetic phase transition near the fermion condensation quantum phase transition in YbRh{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Shaginyan, V.R., E-mail: vrshag@thd.pnpi.spb.r [Petersburg Nuclear Physics Institute, RAS, Gatchina 188300 (Russian Federation); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Popov, K.G. [Komi Science Center, Ural Division, RAS, Syktyvkar 167982 (Russian Federation)

    2010-01-11

    Low-temperature specific-heat measurements on YbRh{sub 2}Si{sub 2} at the second order antiferromagnetic (AF) phase transition reveal a sharp peak at T{sub N}=72 mK. The corresponding critical exponent alpha turns out to be alpha=0.38, which differs significantly from that obtained within the framework of the fluctuation theory of second order phase transitions based on the scale invariance, where alphaapprox =0.1. We show that under the application of magnetic field the curve of the second order AF phase transitions passes into a curve of the first order ones at the tricritical point leading to a violation of the critical universality of the fluctuation theory. This change of the phase transition is generated by the fermion condensation quantum phase transition. Near the tricritical point the Landau theory of second order phase transitions is applicable and gives alphaapprox =1/2. We demonstrate that this value of alpha is in good agreement with the specific-heat measurements.

  2. Specific heat of heavy-fermion CePd{sub 2}Si{sub 2} in high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Sheikin, I. [University of Geneva, DPMC, Geneva (Switzerland)]. E-mail: Ilya.Sheikin@physics.unige.ch; Wang, Y.; Bouquet, F.; Junod, A. [University of Geneva, DPMC, Geneva (Switzerland); Lejay, P. [CRTBT, CNRS, Grenoble (France)

    2002-07-22

    We report specific heat measurements on the heavy-fermion compound CePd{sub 2}Si{sub 2} in magnetic fields up to 16 T and in the temperature range 1.4-16 K. A sharp peak in the specific heat signals the antiferromagnetic transition at T{sub N} {approx} 9.3 K in zero field. The transition is found to shift to lower temperatures when a magnetic field is applied along the crystallographic a-axis, while a field applied parallel to the tetragonal c-axis does not affect the transition. The magnetic contribution to the specific heat below T{sub N} is well described by a sum of a linear electronic term and an antiferromagnetic spin-wave contribution. Just below T{sub N}, an additional positive curvature, especially at high fields, arises most probably due to thermal fluctuations. The field dependence of the coefficient of the low-temperature linear term, {gamma}{sub 0}, extracted from the fits shows a maximum at about 6 T, at the point where an anomaly was detected in susceptibility measurements. The relative field dependences of both T{sub N} and the magnetic entropy at T{sub N} scale as [1-(B/B{sub 0}){sup 2}] for B parallel a, suggesting the disappearance of antiferromagnetism at B{sub 0}{approx}42 T. The expected suppression of the antiferromagnetic transition temperature to zero makes the existence of a magnetic quantum critical point possible. (author). Letter-to-the-editor.

  3. Cubic-tetragonal transformation and magnetic properties in copper ferrites with excess Fe/sub 2/O/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Sugimoto, M [Saitama Univ., Urawa (Japan)

    1977-01-01

    Measurements have been performed of cubic-tetragonal transition temperatures and magnetic properties on a set of those samples of the binary system CuO-Fe/sub 2/O/sub 3/ which contain Fe/sub 2/O/sub 3/ more than stoichiometric CuFe/sub 2/O/sub 4/. A marked magnetic hardening was observed on a sample of 40CuO.60Fe/sub 2/O/sub 3/ which has been verified, through the X-ray analyses and measurements of Moessbauer spectra, to result from the precipitation of ..cap alpha..-Fe/sub 2/O/sub 3/ taking place during annealing.

  4. Stabilization/Solidification of radioactive molten salt waste by using xSiO{sub 2}-yAl{sub 2}O{sub 3}-zP{sub 2}O{sub 5} material

    Energy Technology Data Exchange (ETDEWEB)

    Hwan-Seo Park; In-Tae Kim; Yong-Zun Cho; Seong-Won Park; Eung-Ho Kim [Korea Atomic Energy Research Institute: 150 Deokjin-dong, Yuseong, Daejeon, 305-353 (Korea, Republic of)

    2008-07-01

    Molten salt waste generated from the electro metallurgical process to recover uranium and transuranic elements is considered as one of problematic wastes to be difficult to immobilize into a durable for final disposal. As an alternative, this study suggested a new method performed at molten state, where dechlorination was achieved with a new inorganic material containing SiO{sub 2}, Al{sub 2}O{sub 3} and P{sub 2}O{sub 5} (SAP). The SAP as a reactive material to molten salt was prepared by a conventional sol-gel process. The prepared SAPs were reacted with each metal chloride, LiCl, CsCl, SrCl{sub 2} and CeCl{sub 3} at 650 deg. C for 6 hours and also were reacted with simulated salt waste consisting of 90 wt% LiCl, 6.8 wt% CsCl and 3.2 wt% SrCl{sub 2} at different waste loading. All the reactions were carried out in oxidative atmosphere and metal chlorides were effectively converted into stable products under a reasonable reaction ratio.

  5. MnO - induced crystallization and optical characteristics of PbO-Sb{sub 2}O{sub 3}-B{sub 2}O{sub 3} glass system

    Energy Technology Data Exchange (ETDEWEB)

    Satyanarayana, T; Nagarjuna, G; Veeraiah, N [Department of Physics, Acharya Nagarjuna University-Nuzvid Campus, Nuzvid - 521 201, A.P (India); Raghavaiah, B V [St. Ann' s College of Engineering and Technology, Chirala-523 187, A.P (India); Mohan, N Krishna, E-mail: nvr8@rediffmail.com [Department of Physics, Akkineni Nageswara Rao College, Gudivada-521 301, A.P (India)

    2009-07-15

    PbO-Sb{sub 2}O{sub 3}-B{sub 2}O{sub 3} glasses mixed with different concentrations of MnO (ranging from 0 to 3.0 mol %) were crystallized. The samples were characterized by X-ray diffraction, scanning electron microscopy and EDS techniques. A number of studies viz., optical absorption, ESR, IR, magnetic susceptibility and luminescence of these glass ceramics have been carried out. The X-ray diffraction spectra revealed the presence of lead antimony oxide and manganese antimony oxide crystalline phases in these samples. The variations observed as the function of the crystallizing agent in all the properties have been analyzed in the light of different oxidation states (Mn{sup 2+} and Mn{sup 3+}) and environment of manganese ions in the glass ceramic network.

  6. Effect of phase interaction on catalytic CO oxidation over the SnO{sub 2}/Al{sub 2}O{sub 3} model catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Chai, Shujing [Collaborative Innovation Center of Chemical Science & Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science & Technology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300354 (China); The Institute of Seawater Desalination and Miltipurpose Utilization, State Oceanic Administration, Tianjin 300192 (China); Bai, Xueqin; Li, Jing; Liu, Cheng; Ding, Tong; Tian, Ye; Liu, Chang [Collaborative Innovation Center of Chemical Science & Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science & Technology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300354 (China); Xian, Hui [Tianjin Polytechnic University, School of Computer Science & Software Engineering, Tianjin 300387 (China); Mi, Wenbo [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparation Technology, Faculty of Science, Tianjin University, Tianjin 300354 (China); Li, Xingang, E-mail: xingang_li@tju.edu.cn [Collaborative Innovation Center of Chemical Science & Engineering (Tianjin), Tianjin Key Laboratory of Applied Catalysis Science & Technology, School of Chemical Engineering & Technology, Tianjin University, Tianjin 300354 (China)

    2017-04-30

    Highlights: • Activity for CO oxidation is greatly enhanced by interaction between SnO{sub 2} and Al{sub 2}O{sub 3}. • Interaction between SnO{sub 2} and Al{sub 2}O{sub 3} phases can generate oxygen vacancies. • Oxygen vacancies play an import role for catalytic CO oxidation. • Sn{sup 4+} cations are the effective sites for catalytic CO oxidation. • Langmuir-Hinshelwood model is preferred for catalytic CO oxidation. - Abstract: We investigated the catalytic CO oxidation over the SnO{sub 2}/Al{sub 2}O{sub 3} model catalysts. Our results show that interaction between the Al{sub 2}O{sub 3} and SnO{sub 2} phases results in the significantly improved catalytic activity because of the formation of the oxygen vacancies. The oxygen storage capacity of the SnO{sub 2}/Al{sub 2}O{sub 3} catalyst prepared by the physically mixed method is nearly two times higher than that of the SnO{sub 2}, which probably results from the change of electron concentration on the interface of the SnO{sub 2} and Al{sub 2}O{sub 3} phases. Introducing water vapor to the feeding gas would a little decrease the activity of the catalysts, but the reaction rate could completely recover after removal of water vapor. The kinetics results suggest that the surface Sn{sup 4+} cations are effective CO adsorptive sites, and the surface adsorbed oxygen plays an important role upon CO oxidation. The reaction pathways upon the SnO{sub 2}-based catalysts for CO oxidation follow the Langmuir-Hinshelwood model.

  7. Investigating the electronic properties of Al{sub 2}O{sub 3}/Cu(In,Ga)Se{sub 2} interface

    Energy Technology Data Exchange (ETDEWEB)

    Kotipalli, R., E-mail: raja.kotipalli@uclouvain.be; Rajkumar, R.; Flandre, D. [ICTEAM, Université catholique de Louvain, Louvain-la-Neuve, 1348 (Belgium); Vermang, B., E-mail: bart.vermang@imec.be [Ångström Solar Center, University of Uppsala, Uppsala, 75121 (Sweden); ESAT-KU Leuven, University of Leuven, Leuven, 3001 (Belgium); IMEC, Kapeldreef 75, Leuven, 3001 (Belgium); Joel, J.; Edoff, M. [Ångström Solar Center, University of Uppsala, Uppsala, 75121 (Sweden)

    2015-10-15

    Atomic layer deposited (ALD) Al{sub 2}O{sub 3} films on Cu(In,Ga)Se{sub 2} (CIGS) surfaces have been demonstrated to exhibit excellent surface passivation properties, which is advantageous in reducing recombination losses at the rear metal contact of CIGS thin-film solar cells. Here, we report, for the first time, experimentally extracted electronic parameters, i.e. fixed charge density (Q{sub f}) and interface-trap charge density (D{sub it}), for as-deposited (AD) and post-deposition annealed (PDA) ALD Al{sub 2}O{sub 3} films on CIGS surfaces using capacitance–voltage (C-V) and conductance-frequency (G-f) measurements. These results indicate that the AD films exhibit positive fixed charges Q{sub f} (approximately 10{sup 12} cm{sup −2}), whereas the PDA films exhibit a very high density of negative fixed charges Q{sub f} (approximately 10{sup 13} cm{sup −2}). The extracted D{sub it} values, which reflect the extent of chemical passivation, were found to be in a similar range of order (approximately 10{sup 12} cm{sup −2} eV{sup −1}) for both AD and PDA samples. The high density of negative Q{sub f} in the bulk of the PDA Al{sub 2}O{sub 3} film exerts a strong Coulomb repulsive force on the underlying CIGS minority carriers (n{sub s}), preventing them to recombine at the CIGS/Al{sub 2}O{sub 3} interface. Using experimentally extracted Q{sub f} and D{sub it} values, SCAPS simulation results showed that the surface concentration of minority carriers (n{sub s}) in the PDA films was approximately eight-orders of magnitude lower than in the AD films. The electrical characterization and estimations presented in this letter construct a comprehensive picture of the interfacial physics involved at the Al{sub 2}O{sub 3}/CIGS interface.

  8. Rapid fabrication of Al{sub 2}O{sub 3} encapsulations for organic electronic devices

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Kamran; Ali, Junaid [Department of Mechatronics Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); Mehdi, Syed Murtuza [Department of Mechanical Engineering, NED University of Engineering and Technology, Karachi 75270 (Pakistan); Choi, Kyung-Hyun, E-mail: amm@jejunu.ac.kr [Department of Mechatronics Engineering, Jeju National University, Jeju 690-756 (Korea, Republic of); An, Young Jin [Jeonnam Science and Technology Promotion Center, Yeongam-gun, Jeollanam-do 526-897 (Korea, Republic of)

    2015-10-30

    Highlights: • Al{sub 2}O{sub 3} encapsulations are being developed through a unique R2R-AALD system. • The encapsulations have resulted in life time enhancement of PVP memristor devices. • The Al{sub 2}O{sub 3} encapsulated memristor performed with superior stability for four weeks. • Encapsulated devices performed efficiently even after bending test for 100 cycles. - Abstract: Organic electronics have earned great reputation in electronic industry yet they suffer technical challenges such as short lifetimes and low reliability because of their susceptibility to water vapor and oxygen which causes their fast degradation. This paper report on the rapid fabrication of Al{sub 2}O{sub 3} encapsulations through a unique roll-to-roll atmospheric atomic layer deposition technology (R2R-AALD) for the life time enhancement of organic poly (4-vinylphenol) (PVP) memristor devices. The devices were then categorized into two sets. One was processed with R2R-AALD Al{sub 2}O{sub 3} encapsulations at 50 °C and the other one was kept as un-encapsulated. The field-emission scanning electron microscopy (FESEM) results revealed that pin holes and other irregularities in PVP films with average arithmetic roughness (R{sub a}) of 9.66 nm have been effectively covered by Al{sub 2}O{sub 3} encapsulation having R{sub a} of 0.92 nm. The X-ray photoelectron spectroscopy XPS spectrum for PVP film showed peaks of C 1s and O 1s at the binding energies of 285 eV and 531 eV, respectively. The respective appearance of Al 2p, Al 2s, and O 1s peaks at the binding energies of 74 eV, 119 eV, and 531 eV, confirms the fabrication of Al{sub 2}O{sub 3} films. Electrical current–voltage (I–V) measurements confirmed that the Al{sub 2}O{sub 3} encapsulation has a huge influence on the performance, robustness and life time of memristor devices. The Al{sub 2}O{sub 3} encapsulated memristor performed with superior stability for four weeks whereas the un-encapsulated devices could only last for one

  9. Tuning of the acid–base properties of primary Me{sub 2}O{sub 3} (Me = Al, Ga, In) and binary (ZrO{sub 2}–Me{sub 2}O{sub 3}) (Me = B, Al, Ga, In) oxides by adding WO{sub 3}: A calorimetric study

    Energy Technology Data Exchange (ETDEWEB)

    Kourieh, Reem; Bennici, Simona; Auroux, Aline, E-mail: aline.auroux@ircelyon.univ-lyon1.fr

    2013-09-10

    Highlights: • Preparation of WO{sub 3}/Me{sub 2}O{sub 3} and WO{sub 3}/(ZrO{sub 2}–Me{sub 2}O{sub 3}) catalysts (Me{sub 2}O{sub 3} = group III oxides). • Acid–base properties were estimated by adsorption microcalorimetry of NH{sub 3} and SO{sub 2}. • The tuning of acid–base properties of amphoteric oxides was achieved by adding WO{sub 3}. • Pyridine adsorption showed that acidity is due to the presence of Lewis acid sites. - Abstract: In this work two series of samples were prepared by impregnation of Me (Me = Al, Ga, In) hydroxides and Zr–Me (Me = B, Al, Ga, In) mixed hydroxides with an ammonium metatungstate hydrate solution followed by calcination at 400 °C. The obtained WO{sub 3}/Me{sub 2}O{sub 3} and WO{sub 3}/(ZrO{sub 2}–Me{sub 2}O{sub 3}) samples have been characterized in terms of their structural, textural, and surface properties, including the acid features, by a variety of techniques (BET, XRD, TG) and microcalorimetry. The acid–base properties were estimated by the adsorption of NH{sub 3} and SO{sub 2} as probe molecules, respectively. The prepared mixed oxide samples showed very different properties in terms of surface area and X-ray diffractograms. All obtained samples showed a specific acidic–basic character influenced by the relative amounts of each oxide, the most acidic samples being WO{sub 3}/ZrO{sub 2} and WO{sub 3}/Al{sub 2}O{sub 3} and WO{sub 3}/(Al{sub 2}O{sub 3}–ZrO{sub 2})

  10. Tetragonal-cubic phase boundary in nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions synthesized by gel-combustion

    Energy Technology Data Exchange (ETDEWEB)

    Fabregas, Ismael O. [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Craievich, Aldo F.; Fantini, Marcia C.A. [Instituto de Fisica, Universidade de Sao Paulo, Travessa R da Rua do Matao, No. 187, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Millen, Ricardo P.; Temperini, Marcia L.A. [Instituto de Quimica, Universidade de Sao Paulo, Avenida Prof. Lineu Prestes 748, Cidade Universitaria, 05508-900 Sao Paulo (Brazil); Lamas, Diego G., E-mail: dlamas@uncoma.edu.ar [CINSO (Centro de Investigaciones en Solidos), CITEFA-CONICET, J.B. de La Salle 4397, 1603 Villa Martelli, Pcia. de Buenos Aires (Argentina); Laboratorio de Caracterizacion de Materiales, Facultad de Ingenieria, Universidad Nacional del Comahue, Buenos Aires 1400, (8300) Neuquen Capital, Prov. de Neuquen (Argentina)

    2011-04-21

    Research highlights: > Gel-combustion synthesis yields compositionally homogeneous, single-phased ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders, that exhibit the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms (t' and t'') and the cubic phase. > Phase identification can be achieved by synchrotron XPD (SXPD) and Raman spectroscopy since the tetragonal forms and the cubic phase can be distinguished by these techniques. > The crystallographic features of ZrO{sub 2}-Y{sub 2}O{sub 3} nanopowders were determined by SXPD. They are similar to those reported by Yashima and coworkers for compositionally homogeneous materials containing larger (micro)crystals. However, the lattice parameters are slightly different and the axial ratios c/a of our t' samples are smaller than those reported by these authors. > Compositional t'/t'' and t''/cubic phase boundaries are located at (9 {+-} 1) and (10.5 {+-} 0.5) mol% Y{sub 2}O{sub 3}, respectively. > For the whole series of nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions studied in the present work, no evidences of the presence of a mixture of phases - as reported by Yashima and coworkers for microcrystalline solid solutions - were detected. - Abstract: By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO{sub 2}-Y{sub 2}O{sub 3} solid solutions, the presence at room temperature of three different phases depending on Y{sub 2}O{sub 3} content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO{sub 2}-Y{sub 2}O{sub 3} solid

  11. Effect of Fe{sub 2}O{sub 3} addition in Yttria-stabilized zirconia properties; Efeito da adicao de Fe{sub 2}O{sub 3} nas propriedades da zirconia estabilizada com itria

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Pedro de Freitas Castro; Elias, Carlos Nelson; Santos, Heraldo Elias Salomao dos, E-mail: elias@ime.eb.br [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Engenharia Mecanica e de Materiais. Laboratorio de Biomateriais

    2017-04-15

    The zirconium oxide (ZrO{sub 2}) polycrystalline partially stabilized by yttrium oxide (Y{sub 2}O{sub 3}) at 3mol%, 3Y-TZP, has its use been increased as a biomaterial. However, as dental prosthetics, its indication is still limited because of its white color and high opacity. Seeking improvements regarding aesthetics without compromising its functional performance, oxides such as iron oxide (Fe{sub 2}O{sub 3}) has been added to the microstructure of zirconia in order to provide a yellow-brownish color similar to natural teeth. This study evaluated the effect of adding Fe{sub 2}O{sub 3} on the microstructure and mechanical and optical properties of 3Y-TZP. Five groups were investigated containing different concentrations of Fe{sub 2}O{sub 3}. Firstly, a chemical characterization of each group was carried out through X-ray fluorescence test (XRF). Microstructural characterization was performed by density and average grain size measurements. Mechanical properties were evaluated by performing hardness and four points flexural strength tests. Quantitative analysis of phase transformation was done using the Rietveld method, for each group submitted to the test of X-ray diffraction (XRD). Fractography by SEM analysis were also made on the fracture surface of the samples from tensile test. The results showed that the Fe{sub 2}O{sub 3} addition influenced the phase transformation process, and proportionally increased the samples hardness and flexural strength when their concentrations varied from 0.02% to 0.17% of the total weight. Above this range, the samples showed losses in their mechanical performance. The Fe{sub 2}O{sub 3} additions showed no significant changes in the density and average grain size of 3Y-TZP. (author)

  12. Photocatalytic characteristics for the nanocrystalline TiO{sub 2} on the Ag-doped CaAl{sub 2}O{sub 4}:(Eu,Nd) phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung-Sik, E-mail: jskim@uos.ac.kr; Sung, Hyun-Je; Kim, Bum-Joon

    2015-04-15

    Highlights: • The photocatalytic reactivity of the TiO{sub 2}-coated on the Ag-doped long-lasting phosphor (CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+}). • The photodecomposition of benzene gas under visible light irradiation. • The TiO{sub 2}-coated on the Ag-doped long-lasting phosphor showed much higher photocatalytic reactivity. • The light emitted from the long-lasting phosphors contributed to the photo generation of TiO{sub 2}. - Abstract: This study investigated the photocatalytic behavior of nanocrystalline TiO{sub 2} deposited on Ag-doped long-lasting phosphor (CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+}). The CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} phosphor powders were prepared via conventional sintering using CaCO{sub 3}, Al{sub 2}O{sub 3}, Eu{sub 2}O{sub 3}, and Nd{sub 2}O{sub 3} as raw materials according to the appropriate molar ratios. Silver nanoparticles were loaded on the phosphor by mixing with an aqueous Ag-dispersion solution. Nanocrystalline TiO{sub 2} was deposited on Ag-doped CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} powders via low-pressure chemical vapor deposition (LPCVD). The TiO{sub 2} coated on the phosphor was actively photo-reactive under irradiation with visible light and showed much faster benzene degradation than pure TiO{sub 2}, which is almost non-reactive. The coupling of TiO{sub 2} with phosphor may result in an energy band bending in the junction region, which then induces the TiO{sub 2} crystal at the interface to be photo-reactive under irradiation with visible light. In addition, the intermetallic compound of CaTiO{sub 3} that formed at the interface between TiO{sub 2} and the CaAl{sub 2}O{sub 4}:(Eu{sup 2+},Nd{sup 3+}) phosphor results in the formation of oxygen vacancies and additional electrons that promote the photodecomposition of benzene gas. The addition of Ag nanoparticles enhanced the photocatalytic reactivity of the TiO{sub 2}/CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} phosphor. TiO{sub 2} on the Ag

  13. Facile preparation of large-scale α-Fe{sub 2}O{sub 3} nanorod/SnO{sub 2} nanorod composites and their LPG-sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Vuong, Dang Duc [School of Engineering Physics, Hanoi University of Science and Technology, No. 1, Dai Co Viet Road, Hai Ba Trung District, Hanoi (Viet Nam); Trung, Khuc Quang [University of Fire Fighting and Protection, No. 243, Khuat Duy Tien Street, Thanh Xuan District, Hanoi (Viet Nam); Hung, Nguyen Hoang [School of Engineering Physics, Hanoi University of Science and Technology, No. 1, Dai Co Viet Road, Hai Ba Trung District, Hanoi (Viet Nam); Hieu, Nguyen Van [International Training Institute for Materials Science, Hanoi University of Science and Technology (Viet Nam); Chien, Nguyen Duc, E-mail: chien.nguyenduc@hust.edu.vn [School of Engineering Physics, Hanoi University of Science and Technology, No. 1, Dai Co Viet Road, Hai Ba Trung District, Hanoi (Viet Nam)

    2014-06-25

    Highlights: • A simple method was used for synthesis of α-Fe{sub 2}O{sub 3} nanorod/SnO{sub 2} nanorod composites. • LPG-sensing properties of the composites were studied and explained consistently. • The results demonstrate a potential method for the mass production of gas sensors. - Abstract: α-Fe{sub 2}O{sub 3} nanorods (NRs) with length and diameter of 300 and 50 nm, and SnO{sub 2} NRs with length and diameter of 30 and 10 nm, respectively, were prepared through hydrothermal treatment method. Morphologies of α-Fe{sub 2}O{sub 3} and SnO{sub 2} NRs and their composites with different weight ratios were studied by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The SEM and TEM images showed SnO{sub 2} NRs attached on (branch onto) the surface of the α-Fe{sub 2}O{sub 3} NRs. Liquefied petroleum gas (LPG)-sensing properties of films with bare α-Fe{sub 2}O{sub 3}, SnO{sub 2} NRs, and their composite NRs were investigated. The composite of 75 wt% α-Fe{sub 2}O{sub 3}/25 wt% SnO{sub 2} exhibits the highest response to LPG at optimum operating temperature of 370 °C. The improvement in the gas-sensing characteristics of the composite NRs compared with bare NRs is attributed to the formation of hetero-junctions in α-Fe{sub 2}O{sub 3} NRs/SnO{sub 2} NRs and to their porous structure.

  14. Electronic structure of layered ferroelectric high-k titanate La{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V V [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Gavrilova, T A [Laboratory of Electron Microscopy and Submicron Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Grivel, J-C [Materials Research Department, National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde (Denmark); Kesler, V G, E-mail: atuchin@thermo.isp.nsc.r [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2009-02-07

    The electronic structure of binary titanate La{sub 2}Ti{sub 2}O{sub 7} has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La{sub 2}Ti{sub 2}O{sub 7} are determined as alpha{sub Ti} = 872.4 and alpha{sub O} = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences DELTA{sub Ti} = (BE O 1s - BE Ti 2p{sub 3/2}) = 71.6 eV and DELTA{sub La} = (BE La 3d{sub 5/2} - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  15. A novel iron-containing polyoxometalate heterogeneous photocatalyst for efficient 4-chlorophennol degradation by H{sub 2}O{sub 2} at neutral pH

    Energy Technology Data Exchange (ETDEWEB)

    Zhai, Qian; Zhang, Lizhong [Department of Chemistry and Applied Chemistry, Changji University, Changji 831100 (China); Zhao, Xiufeng, E-mail: zhaoxiufeng19670@126.com [Department of Chemistry and Applied Chemistry, Changji University, Changji 831100 (China); Chen, Han; Yin, Dongju [Department of Chemistry and Applied Chemistry, Changji University, Changji 831100 (China); Li, Jianhui [Department of Chemistry and Applied Chemistry, Changji University, Changji 831100 (China); National Engineering Laboratory for Green Chemical Productions of Alcohols-Ethers-Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China)

    2016-07-30

    Graphical abstract: An iron-containing polyoxometalate (Fe{sup III}LysSiW) catalyst showes good performance in the degradation of 4-chlorophenol by H{sub 2}O{sub 2}, especially in irradiated system. The catalytic activity of Fe{sup III}LysSiW stems from synergetic effect of ferric iron for Fenton-like catalysis and SiW{sub 12}O{sub 40}{sup 4−} for photocatalysis, respectively. The chemisorption of H{sub 2}O{sub 2} on Fe{sup III}LysSiW surface by hydrogen bonding also promotes both the Fenton-like and photocatalytic processes. - Highlights: • An iron-containing POM was synthesized as heterogeneous Fenton-like catalyst. • The catalyst has both the Fenton-like and photocatalytic activity at neutral pH. • The activity stems from the co-existence of iron and heteropolyanion in the catalyst. • The hydrogen bonding of H{sub 2}O{sub 2} on the catalyst surface enhances the reaction rate. - Abstract: An iron-containing polyoxometalate (Fe{sup III}LysSiW) was synthesized from ferric chloride (Fe{sup III}), lysine (Lys) and silicotungstic acid (SiW), and characterized using ICP-AES, TG, FT-IR, UV–vis DRS, XRD and SEM. The chemical formula of Fe{sup III}LysSiW was determined as [Fe(H{sub 2}O){sub 5}(C{sub 6}H{sub 14}N{sub 2}O{sub 2})]HSiW{sub 12}O{sub 40}·8H{sub 2}O, with Keggin-structured SiW{sub 12}O{sub 40}{sup 4−} heteropolyanion and lysine moiety. As a heterogeneous catalyst, the as prepared Fe{sup III}LysSiW showed good performance in the degradation of 4-chlorophenol by H{sub 2}O{sub 2} in both the dark and irradiated systems. Under the conditions of 4-chlorophenol 100 mg/L, Fe{sup III}LysSiW 1.0 g/L, H{sub 2}O{sub 2} 20 mmol/L and pH 6.5, 4-chlorophenol could be completely degraded in ca. 40 min in the dark and ca. 15 min upon irradiation. Prolonging the reaction time to 3 h, the TOC removal reached to ca. 71.3% in the dark and ca. 98.8% under irradiation. The catalytic activity of Fe{sup III}LysSiW stems from synergetic effect of ferric iron and Si

  16. Synthesis of NiCo{sub 2}O{sub 4} nanostructures with different morphologies for the removal of methyl orange

    Energy Technology Data Exchange (ETDEWEB)

    Tian, Yaxi; Li, Haizhen; Ruan, Zhongyuan; Cui, Guijia; Yan, Shiqiang, E-mail: yansq@lzu.edu.cn

    2017-01-30

    Highlights: • Magnetic materials NiCo{sub 2}O{sub 4} with six different morphologies were successfully synthesized by a facile method. • Adsorption capacity strongly depends on the morphology. • It could be easily recovered from solution. - Abstract: Aiming to investigate the adsorption removal performance of NiCo{sub 2}O{sub 4} as water purification adsorbents, magnetic materials NiCo{sub 2}O{sub 4} with six different morphologies were successfully synthesized by a facile method. NiCo{sub 2}O{sub 4} with six different morphologies were characterized by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, N{sub 2} adsorption-desorption, vibrating sample magnetometry and X-ray energy dispersive spectrometry. In this study, we mainly explored the effect of specific surface area, pore volume and pore size on the performance for the removal of methyl orange, and the adsorption capacity followed an order of (b) NiCo{sub 2}O{sub 4} nanorods > (e) balsam-like NiCo{sub 2}O{sub 4} > (f) rose-like NiCo{sub 2}O{sub 4} > (d) NiCo{sub 2}O{sub 4} nanoribbons > (a) NiCo{sub 2}O{sub 4} flowerlike nanostructures > (c) dandelion-like NiCo{sub 2}O{sub 4} spheres. The results indicated that NiCo{sub 2}O{sub 4} nanorods exhibited better adsorption performance. The reasons for the excellent adsorption capacity of NiCo{sub 2}O{sub 4} nanorods were also discussed in depth by analyzing scale and surface characteristics. Besides, NiCo{sub 2}O{sub 4} could be easily recovered from solution, which may avoid potential secondary pollution. Moreover, adsorption kinetics, the influence of pH and adsorption mechanism were comprehensively investigated. This finding indicated that NiCo{sub 2}O{sub 4} were promising adsorbents for water purification.

  17. Fluorescence Quenching of Dendrimer-Encapsulated CdS Quantum Dots for the Detection of H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hyojung; Kim, Hai Dong; Kim, Joohoon [Kyung Hee Un iversity, Seoul (Korea, Republic of)

    2016-02-15

    Hydrogen peroxide (H{sub 2}O{sub 2}) exists in natural environments as a byproduct of various enzymatic and photochemical reactions. Various approaches have been reported for the synthesis of cadmium sulfide (CdS) QDs using dendrimers, which can be categorized mainly into two general approaches. The first approach utilizes dendrimers as capping agents, resulting in the formation of agglomerates of spatially segregated QDs stabilized by multiple dendrimers. We have described the synthesis and characterization of the CdS QDs using G6-NH{sub 2} dendrimers. By controlling the molar ratios (n = Cd2+/G6-NH{sub 2}) between the Cd{sup 2+} ions and G6-NH{sub 2} dendrimers, we synthesized a set of CdS QDs with different structural and optical properties. Importantly, the synthesized CdS QDs exhibited H{sub 2}O{sub 2}-sensitive fluorescence, which can be utilized for the detection of H{sub 2}O{sub 2}. Especially, the CdS QDs with n = 64 displayed a Stern–Volmer relationship between the fluorescence of the CdS QDs and the concentration of H{sub 2}O{sub 2}, as well as the strongest fluorescence among the set of the synthesized CdS QDs. Since core-shell structures of QDs often result in enhanced stability and quantum efficiency of the QDs, we are currently working on core-shell structured QDs prepared using dendrimers to improve their stability and quantum yield compared to the CdS QDs reported in the present study.

  18. Facile synthesis of surface N-doped Bi{sub 2}O{sub 2}CO{sub 3}: Origin of visible light photocatalytic activity and in situ DRIFTS studies

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ying, E-mail: yzhou@swpu.edu.cn [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Zhao, Ziyan [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Wang, Fang; Cao, Kun [The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Doronkin, Dmitry E. [Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Dong, Fan [College of Environmental and Biological Engineering, Chonqing Technology and Business University, Chongqing 400067 (China); Grunwaldt, Jan-Dierk, E-mail: grunwaldt@kit.edu [Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany)

    2016-04-15

    Graphical abstract: Surfactant (CTAB) can induce nitrogen interstitially doping in the Bi{sub 2}O{sub 2}CO{sub 3} surface, leading to the formation of localized states from N−O bond, which probably account for the origin of the visible light activity. Moreover, the photocatalytic NO oxidation processes over Bi{sub 2}O{sub 2}CO{sub 3} were successfully monitored for the first time by in situ DRIFTS. - Highlights: • Interstitially doping N in the Bi{sub 2}O{sub 2}CO{sub 3} surface was achieved at room temperature. • N-doped Bi{sub 2}O{sub 2}CO{sub 3} exhibited significantly enhanced visible light photocatalytic activity compared to the pristine Bi{sub 2}O{sub 2}CO{sub 3}. • The formation of localized states from N−O bond could account for the visible light activity of Bi{sub 2}O{sub 2}CO{sub 3}. • The photocatalytic NO oxidation process was monitored by in situ DRIFTS. - Abstract: Bi{sub 2}O{sub 2}CO{sub 3} nanosheets with exposed {001} facets were prepared by a facile room temperature chemical method. Due to the high oxygen atom density in {001} facets of Bi{sub 2}O{sub 2}CO{sub 3}, the addition of cetyltrimethylammonium bromide (CTAB) does not only influence the growth of crystalline Bi{sub 2}O{sub 2}CO{sub 3}, but also modifies the surface properties of Bi{sub 2}O{sub 2}CO{sub 3} through the interaction between CTAB and Bi{sub 2}O{sub 2}CO{sub 3}. Nitrogen from CTAB as dopant interstitially incorporates in the Bi{sub 2}O{sub 2}CO{sub 3} surface evidenced by both experimental and theoretical investigations. Hence, the formation of localized states from N−O bond improves the visible light absorption and charge separation efficiency, which leads to an enhancement of visible light photocatalytic activity toward to the degradation of Rhodamine B (RhB) and oxidation of NO. In addition, the photocatalytic NO oxidation over Bi{sub 2}O{sub 2}CO{sub 3} nanosheets was successfully monitored for the first time using in situ diffuse reflectance infrared Fourier

  19. Poly(o-phenylenediamine)/NiCoFe{sub 2}O{sub 4} nanocomposites: Synthesis, characterization, magnetic and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Kannapiran, Nagarajan [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Muthusamy, Athianna, E-mail: muthusrkv@gmail.com [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Chitra, Palanisamy; Anand, Siddeswaran [PG and Research Department of Chemistry, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Jayaprakash, Rajan [Nanotechnology Laboratory, Department of Physics, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India)

    2017-02-01

    In this study, poly(o-phenylenediamine) (PoPD)/NiCoFe{sub 2}O{sub 4} nanocomposites were synthesized by in-situ oxidative chemical polymerization method with different amount of NiCoFe{sub 2}O{sub 4} nanoparticles. The NiCoFe{sub 2}O{sub 4} nanoparticles were prepared by auto-combustion method. The structural, morphological, thermal properties of the synthesized PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were characterized by fourier transform infrared spectrum (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). Magnetic properties of NiCoFe{sub 2}O{sub 4} nanoparticles and PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were studied by vibrating sample magnetometer (VSM). The FTIR and XRD techniques were used to confirm the formation of PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites. The average crystalline size of NiCoFe{sub 2}O{sub 4} nanoparticles and PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites were calculated from XRD. From the SEM analysis, spherical morphology of the PoPD was confirmed. The TGA results showed that the NiCoFe{sub 2}O{sub 4} nanoparticles have improved the thermal stability of PoPD. Dielectric properties of PoPD/NiCoFe{sub 2}O{sub 4} nanocomposites at different temperatures have been carried in the frequency range 50 Hz to 5 MHz. - Highlights: • Auto-combustion method was support to achieve less particle size. • Green synthesis of PoPD and nanocomposites by in-situ oxidative chemical polymerization method. • For the first time, PoPD incorporated with NiCoFe{sub 2}O{sub 4} nanoparticles. • Ferrite content affects the magnetic and dielectric properties of the nanocomposites.

  20. Kinetics of the reaction of hydrated lime with SO{sub 2} at low temperatures: effects of the presence of CO{sub 2}, O{sub 2}, and NOx

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.F.; Shih, S.M. [National Taiwan University, Taipei (Taiwan). Dept. of Chemical Engineering

    2008-12-15

    The effects of the presence Of CO{sub 2}, O{sub 2}, and NOx in the flue gas on the kinetics of the sulfation of hydrated lime at low temperatures were studied using a differential fixed-bed reactor. When O{sub 2} and NOx were not present together the reaction kinetics was about the same as that under gas mixtures containing SO{sub 2}, H{sub 2}O, and N2 only. When both O{sub 2} and NOx were present, sulfation of hydrated lime was greatly enhanced, forming a large amount of calcium sulfate in addition to calcium sulfite. Sulfation of hydrated lime was well described by the surface coverage model, despite the gas-phase conditions being different. Relative humidity is the major factor affecting the reaction, and its effect was more marked when both O{sub 2} and NOx were present. The kinetic model equations obtained in this work can be used to describe the sulfation of hydrated lime in the low-temperature dry and semidry flue gas desulfurization processes with or without an upstream NOx removal unit.

  1. Dielectric measurements of magnetic monopoles on the spin-ice compounds (Ho/Dy){sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Pietsch, Manuel; Grams, Christoph P.; Welter, Jean-Francois; Cho, Victoria; Lorenz, Thomas; Hemberger, Joachim [II. Physikalisches Institut, Universitaet zu Koeln, Cologne (Germany)

    2015-07-01

    In so-called spin-ice compounds a frustrated ground-state with finite zero-point entropy is stabilized via competing interactions and emergent magnetic monopoles excitations. It was postulated that a magnetic monopole holds an electric dipole moment, which allows to investigate their dynamics via the dielectric function ε(ν). In Dy{sub 2}Ti{sub 2}O{sub 7} a critical speeding-up for frequencies up to 100 kHz was reported down to temperatures of 200 mK with a specific focus on the critical endpoint present for a [111] magnetic field. In Ho{sub 2}Ti{sub 2}O{sub 7} both faster relaxation dynamics compared to the sister-compound and an additional relaxation process are suspected. Here we report on broadband dielectric spectroscopy measurements of ε(ν) in Ho{sub 2}Ti{sub 2}O{sub 7}.

  2. Overall conductivity and NCL-type relaxation behavior in nanocrystalline sodium peroxide Na{sub 2}O{sub 2}—Consequences for Na-oxygen batteries

    Energy Technology Data Exchange (ETDEWEB)

    Dunst, Andreas; Sternad, Michael; Wilkening, Martin, E-mail: wilkening@tugraz.at

    2016-09-15

    Highlights: • Na{sub 2}O{sub 2} turned out to be a poor electrical conductor. • Total conductivity of nanocrystalline Na{sub 2}O{sub 2} measured slightly above room temperature is in the order of 10{sup −15} S cm{sup −1}. • Activation energies of micro- and nanocrystalline Na{sub 2}O{sub 2} are in the order of 1 eV. • At low temperatures nearly constant loss behavior showed up pointing to locally restricted electrical relaxation processes. - Abstract: Metal air batteries are considered as promising candidates for room-temperature batteries with high-energy densities. On discharge, atmospheric oxygen is reduced at the positive electrode which, in the ideal case, forms the discharge products in a reversible cell reaction. In Na-O{sub 2} batteries upon discharge either sodium peroxide (Na{sub 2}O{sub 2}) or sodium superoxide (NaO{sub 2}) is reported to be formed. So far, the charge carrier transport remains relatively unexplored but is expected to crucially determine the efficiency of such energy storage systems. Na{sub 2}O{sub 2} is predicted to be an electrical insulator wherein the transport presumably is determined by very slow hopping processes. Understanding the basic fundamental properties of the overall charge carrier transport, including also nanostructured forms of Na{sub 2}O{sub 2}, is key to developing high-energy metal oxygen batteries. The present study answers the question how overall, i.e., total, conductivity changes when going from microcrystalline to nanocrystalline, defect-rich Na{sub 2}O{sub 2}. Nanocrystalline Na{sub 2}O{sub 2} was prepared via a top-down approach, viz by high-energy ball milling. Milling does not only shrink the average crystallite diameter but also introduces a large amount of defects which are anticipated to influence total conductivity. It turned out that even after vigorous mechanical treatment the conductivity of the sample is only increased by ca. one order of magnitude. The activation energy remains almost

  3. Structural and optical characterization of In{sub 2}O{sub 3}/PANI nanocomposite prepared by in-situ polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Janeoo, Shashi; Sharma, Mamta, E-mail: mamta.phy85@gmail.com; Goswamy, J. [Department of Applied Sciences (Physics), UIET, Panjab University, Chandigarh-160 014 (India); Singh, Gurinder [Department of Applied Sciences (Physics), UIET, PUSSGSRC, Hoshiarpur (Punjab) (India)

    2016-05-23

    Polyaniline-indium oxide (In{sub 2}O{sub 3}/PANI) nanocomposite have been prepared by in-situ polymerization of aniline and as-synthesized In{sub 2}O{sub 3} nanoparticles. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Fourier transformation infrared (FTIR) and UV/Vis spectroscopy techniques are used to investigate the structural and optical properties of In{sub 2}O{sub 3}/PANI nanocomposite. TEM analysis shows In{sub 2}O{sub 3} nanoparticles are embedded in PANI nanofibers. FTIR spectra show the good interactions between PANI nanofibers and In{sub 2}O{sub 3} nanoparticles. The band gap and electronic transitions in In{sub 2}O{sub 3}/PANI nanocomposite is determined by using UV/Vis spectra.

  4. Photocatalytic activity of titanium dioxide modified by Fe{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wodka, Dawid [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland); Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4 (Switzerland); Socha, Robert P.; Bielańska, Elżbieta [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland); Elżbieciak-Wodka, Magdalena [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland); Department of Analytical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4 (Switzerland); Nowak, Paweł, E-mail: ncnowak@cyf-kr.edu.pl [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland); Warszyński, Piotr [J. Haber Institute of Catalysis and Surface Chemistry PAS, Niezapominajek 8, 30-239 Krakow (Poland)

    2014-11-15

    Highlights: • 1% Fe{sub 2}O{sub 3}/TiO{sub 2} composite showing high activity in the photocatalytic oxidation of organics was synthetized. • Electrochemical analysis indicated that surface modification of Degussa P25 by Fe{sub 2}O{sub 3} causes the appearance of surface states in such a material. • The enhanced activity of the prepared composite may be ascribed to the occurrence of the photo-Fenton process. - Abstract: Photocatalytic activity of Fe{sub 2}O{sub 3}/TiO{sub 2} composites obtained by precipitation was investigated. The composite material containing 1.0 wt% of iron(III) oxide nanoparticles was obtained by depositing Fe{sub 2}O{sub 3} on the Evonic-Degussa P25 titania surface. SEM, XPS, DRS, CV and EIS techniques were applied to examine synthetized pale orange photocatalyst. The XPS measurements revealed that iron is present mainly in the +3 oxidation state but iron in the +2 oxidation state can be also detected. Electrochemical analysis indicated that surface modification of Degussa P25 by Fe{sub 2}O{sub 3} causes the appearance of surface states in such a material. Nevertheless, based on the DRS measurement it was shown that iron(III) oxide nanoparticles modified the P25 spectral properties but they did not change the band gap width. The photocatalytic activity of Fe{sub 2}O{sub 3}/TiO{sub 2} composite was compared to photocatalytic activity of pristine P25 in photooxidation reaction of model compounds: oxalic acid (OxA) and formic acid (FA). Photodecomposition reaction was investigated in a batch reactor containing aqueous suspension of a photocatalyst illuminated by either UV or artificial sunlight (halogen lamp). The tests proved that nanoparticles deposited on titania surface triggers the increase in photocatalytic activity, this increase depends however on the decomposed substance.

  5. Enhanced dielectric properties of thin Ta{sub 2}O{sub 5} films grown on 65 nm SiO{sub 2}/Si

    Energy Technology Data Exchange (ETDEWEB)

    Kolkovsky, Vl.; Kurth, E.; Kunath, C. [IPMS Fraunhofer, Dresden, Maria-Reiche Str. 2, 01109 Dresden (Germany)

    2016-12-15

    The structural and electrical properties of Ta{sub 2}O{sub 5}/65 nm SiO{sub 2} structures with different thicknesses of Ta{sub 2}O{sub 5} varying in the range of 0-260 nm are investigated. We find that the stack structures grown by the magnetron sputtering technique and annealed at 1220 K in O and Ar atmosphere show one of the highest dielectric constant of Ta{sub 2}O{sub 5}(about 64) among those previously reported in the literature. The structure of the annealed polycrystalline Ta{sub 2}O{sub 5} films is orthorhombic, as obtained from X-ray diffraction measurements and we do not observe any preferential orientation of the annealed films. The Ta{sub 2}O{sub 5} films contain positively charged defects which become mobile at around 400 K and they are tentatively correlated with the oxygen vacancies. The leakage current in the stack structures is a factor of 20 higher compared to that in thin layers with 65 nm SiO{sub 2}. The conduction mechanism in the stack structures can be described by the Fowler-Nordheim model with a barrier height that decreases slightly (<10%) as a function of the thickness of the films. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Enhancing photocatalytic CO{sub 2} reduction by coating an ultrathin Al{sub 2}O{sub 3} layer on oxygen deficient TiO{sub 2} nanorods through atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Huilei; Chen, Jiatang; Rao, Guiying; Deng, Wei; Li, Ying, E-mail: yingli@tamu.edu

    2017-05-15

    Highlights: • Oxygen deficient TiO{sub 2} anatase nanorods are coated with an ultrathin Al{sub 2}O{sub 3} layer by ALD. • Exposed {100} facets and oxygen vacancies promote CO{sub 2} photoreduction to CO and CH{sub 4}. • Al{sub 2}O{sub 3} overlayer passivates surface states and mitigates surface charge recombination. • Two cycles of ALD coating lead to maximum photocatalytic CO{sub 2} reduction. • More than five cycles of ALD coating prohibits electron transfer to the surface. - Abstract: In this work, anatase nanorods (ANR) of TiO{sub 2} with active facet {100} as the major facet were successfully synthesized, and reducing the ANR by NaBH{sub 4} led to the formation of gray colored oxygen deficient TiO{sub 2-x} (ReANR). On the surface of ReANR, a thin layer of Al{sub 2}O{sub 3} was deposited using atomic layer deposition (ALD), and the thickness of Al{sub 2}O{sub 3} varied by the number of ALD cycles (1, 2, 5, 10, 50, 100, or 200). The growth rate of Al{sub 2}O{sub 3} was determined to be 0.25 Å per cycle based on high-resolution TEM analysis, and the XRD result showed the amorphous structure of Al{sub 2}O{sub 3}. All the synthesized photocatalysts (ANR, ReANR, and Al{sub 2}O{sub 3} coated ReANR) were tested for CO{sub 2} photocatalytic reduction in the presence of water vapor, with CO detected as the major reduction product and CH{sub 4} as the minor product. Compared with ANR, ReANR had more than 50% higher CO production and more than ten times higher CH{sub 4} production due to the oxygen vacancies that possibly enhanced CO{sub 2} adsorption and activation. By applying less than 5 cycles of ALD, the Al{sub 2}O{sub 3} coated ReANR had enhanced overall production of CO and CH{sub 4} than uncoated ReANR, with 2 cycles being the optimum, about 40% higher overall production than ReANR. Whereas, both CO and CH{sub 4} production decreased with increasing number of ALD cycles when more than 5 cycles were applied. Photoluminescence (PL) analysis showed an

  7. Facile synthesis, dielectric properties and electrocatalytic activities of PMMA-NiFe{sub 2}O{sub 4} nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Maji, Pranabi; Choudhary, Ram Bilash, E-mail: rbcism@gmail.com

    2017-06-01

    The paper deals with the dielectric and catalytic properties of poly (methyl methacrylate)-nikel ferrite (PMMA-NiFe{sub 2}O{sub 4}) nanocomposite. The nanocomposite was prepared by using a general and facile synthesis strategy. Fourier transform infrared (FTIR) and X-ray diffraction (XRD) spectra confirmed the formation of PMMA-NiFe{sub 2}O{sub 4} nanocomposite. Field effect scanning electron microscopic (FESEM) and transmission electron microscopic (TEM) images revealed that NiFe{sub 2}O{sub 4} nanoparticles were uniformly distributed and were tightly adhered with PMMA matrix owing to surface modification with 3-methacryloyloxy propyl trimethoxy silane (KH-570). Thermal stability was enhanced by incorporation of NiFe{sub 2}O{sub 4} nanofillers. The nanocomposite showed high dielectric constant and low dielectric loss. The achieved dielectric and thermal property inferred the potential application of this material in energy storage and embedded electronics devices. Further, the as prepared nanocomposite also offered a remarkable electrochemical performance towards hydrogen peroxide (H{sub 2}O{sub 2}) sensing. - Highlights: • PMMA-NiFe{sub 2}O{sub 4} nanocomposite was synthesized via free radical polymerization. • The nanocomposite exhibited high value of dielectric constant (51) and tanδ (0.3). • Thermal stability of the PMMA matrix was improved by the incorporation of NiFe{sub 2}O{sub 4.} • The H{sub 2}O{sub 2} detection limit was estimated 44 μM when signal to noise (S/N) ration was 3. • The electrochemical sensitivity of H{sub 2}O{sub 2} was calculated 0.6727 μA mM{sup -1}.

  8. Beryllium-free β-Rb{sub 2}Al{sub 2}B{sub 2}O{sub 7} as a possible deep-ultraviolet nonlinear optical material replacement for KBe{sub 2}BO{sub 3}F{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tran, T. Thao; Halasyamani, P. Shiv [Department of Chemistry, University of Houston, TX (United States); Koocher, Nathan Z.; Rondinelli, James M. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL (United States)

    2017-03-06

    A new beryllium-free deep-ultraviolet (DUV) nonlinear optical (NLO) material, β-Rb{sub 2}Al{sub 2}B{sub 2}O{sub 7} (β-RABO), has been synthesized and characterized. The chiral nonpolar acentric material shows second-harmonic generation (SHG) activity at both 1064 and 532 nm with efficiencies of 2 x KH{sub 2}PO{sub 4} and 0.4 x β-BaB{sub 2}O{sub 4}, respectively, and exhibits a short absorption edge below 200 nm. β-Rb{sub 2}Al{sub 2}B{sub 2}O{sub 7} has a three-dimensional structure of corner-shared Al(BO{sub 3}){sub 3}O polyhedra. The discovery of β-RABO shows that through careful synthesis and characterization, replacement of KBe{sub 2}BO{sub 3}F{sub 2} (KBBF) by a Be-free DUV NLO material is possible. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Preliminary study in development of glass-ceramic based on SiO{sub 2}-LiO{sub 2} system, starting of different SiO{sub 2} starting powders; Um estudo preliminar do desenvolvimento de materiais vitroceramicos do sistema SiO{sub 2}-LiO{sub 2} obtidos a partir de diferentes fontes de silica

    Energy Technology Data Exchange (ETDEWEB)

    Daguano, J.K.M.F.; Santos, F.A.; Santos, C.; Marton, L.F.M.; Conte, R.A.; Rodrigues Junior, D. [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Materiais; Melo, F.C.L. [Centro Tecnico Aeroespacial (AMR/CTA/IAE), Sao Jose dos Campos, SP (Brazil). Instituto de Aeronautica e Espaco. Div. de Materiais

    2009-07-01

    In this work, lithium disilicate glass-ceramics were developed starting of the rice ash- SiO{sub 2} and Li{sub 2}CO{sub 3} powders. The results were compared with glass ceramics based on the lithium disilicate obtained by commercial SiO{sub 2} powders. Glass were melted at 1580 deg C, and annealed at 850 deg C. X-Ray diffraction and scanning electron microscopy were used for characterization of the materials, and hardness and fracture toughness were evaluated using Vickers indentation method. Glasses with amorphous structure were obtained in both materials. After annealing, 'rice-ash' samples presented Li{sub 2}SiO{sub 3} and residual SiO{sub 2} as crystalline phases. On the other side, commercial SiO{sub 2}- Samples presented only Li{sub 2}Si{sub 2}O{sub 5} as crystalline phases and the better results of hardness and fracture toughness. (author)

  10. Simultaneous oxidative conversion and co/sub 2/ reforming of methane to syngas over modified Ni/Al/sub 2/O/sub 3/ catalysts

    International Nuclear Information System (INIS)

    Eli, W.

    2013-01-01

    A series of Ni/Al/sub 2/O/sub 3/ and modified Ni-M/Al/sub 2/O/sub 3/ (MLa, Na, K, Ca and Ba) catalysts have been prepared and characterized by XRD, BET, XPS, TGA, TEM and SEM. The performance of these catalysts for simultaneous oxidative conversion and CO/sub 2/ reforming of methane to syngas was evaluated using a fixed-bed reactor. The results indicated that the catalytic activity of Ni/Al/sub 2/O/sub 3/ increased with Ni loading, and reached maximum at 12% Ni loading. The La-modified Ni/Al/sub 2/O/sub 3/ exhibited an excellent catalytic activity and stability within 20 h as compared with unmodified and Na-modified ones. It was found that the addition of La decreased the particle size of nickel, thus increased the Ni dispersion accordingly as indicated by the characterization data. The catalytic activity of Na-modified Ni/Al/sub 2/O/sub 3/ decreased obviously only after 6 h of reaction due to aggregation of metallic Ni particles. Hence, it was suggested that the sintering of Ni particles dominated the catalyst deactivation during the catalytic reaction process. (author)

  11. Characterization of γ- Al{sub 2}O{sub 3} nanopowders synthesized by Co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Jbara, Ahmed S., E-mail: ahmedsbhe@yahoo.com [Center for Sustainable Nanomaterials, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Physics Department, Science College, Al-Muthanna University, Samawah - 66001 (Iraq); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Othaman, Zulkafli [Center for Sustainable Nanomaterials, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Ati, Ali A. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Saeed, M.A., E-mail: moalsd@gmail.com [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Division of Science and Technology, University of Education, Township, Lahore - 54770 (Pakistan)

    2017-02-15

    Co-precipitation technique has been used to synthesize gamma-Al{sub 2}O{sub 3} (γ-Al{sub 2}O{sub 3}) nanopowders under annealing temperature effect. The crystalline phase and purity for the prepared powder were characterized by different spectroscopy techniques. XRD analysis confirms the gamma phase of alumina nanopowders with particle diameter ranging from 6 to 24 nm, which confirms the quantum dots formation, which is also supported by the BET measurement. The surface area of the prepared nanopowders is in the range of 109–367 m{sup 2}/g. Morphology analysis indicates that γ-Al{sub 2}O{sub 3} nanopowders are consisted of grains almost spherical in shape. Some agglomeration of nanoparticles occurs, which become more regular hexagonal shaped with the increasing annealing temperature. The small nanoparticles size and the high surface area from a simple procedure for preparing γ-Al{sub 2}O{sub 3} may make it more suitable for use as an adsorbent for malachite green. - Highlights: • Co-precipitation technique is used to synthesize gamma- Al{sub 2}O{sub 3} nanopowders. • Pure gamma- Al{sub 2}O{sub 3} phase was obtained having maximum nanoparticle size is 24 nm. • The quantum dots were formed inside powder. • High surface area of nanopowders at the low annealing temperature. • Increasing annealing temperature causes the hexagonal agglomeration shape.

  12. Degradation of process water containing polymers UV/H{sub 2}O{sub 2} system; Degradacao de agua de processo contendo polimeros via sistema UV/H{sub 2}O{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Will, Isabela B.S.; Telemaco, Emmanuelle P.; Chiavone-Filho, Osvaldo; Guardani, Roberto; Nascimento, Claudio A.O. do

    2004-07-01

    The water rationalization has been one of the goals of the petrochemical industry. Such goals in such a way demand technological innovations for new productive processes how much for new techniques of treatment and reuse of water in the production chain. The high industrial water costs in Brazil, particularly in the regions metropolitans, have stimulated the national industries to evaluate the possibilities of reuse. The objective of this work is the application of the process water treatment containing polypropylene using ultraviolet radiation and hydrogen peroxide, that is system UV/H{sub 2}O{sub 2}, aiming at to adjust them for reuses in the proper process, reducing the water capitation daily pay-treated and improving the water exploitation. Photochemical annular reactor with medium pressure mercury vapor lamp was used and the following parameters of process had been evaluated: radiation, temperature of reaction and hydrogen peroxide concentration. The monitoring of the experiments was based on the measurement of contents of dissolved organic carbon, total carbon and inorganic carbon. Additionally, experiments using solar radiation had been evaluated. The experimental results had indicated the viability of application of system UV/H{sub 2}O{sub 2} having used artificial and solar light sources. The quality of the water obtained in the treatment was adequate to reuse it. (author)

  13. Thermal relaxation and heat transport in spin ice Dy{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Klemke, Bastian; Meissner, M.; Tennant, D.A. [Helmholtz-Zentrum Berlin (Germany); Technische Universitaet Berlin (Germany); Strehlow, P. [Technische Universitaet Berlin (Germany); Physikalisch Technische Bundesanstalt, Institut Berlin (Germany); Kiefer, K. [Helmholtz-Zentrum Berlin (Germany); Grigera, S.A. [School of Physics and Astronomy, St. Andrews (United Kingdom); Instituto de Fisica de Liquidos y Sistemas Biologicos, CONICET, UNLP, La Plata (Argentina)

    2011-07-01

    The thermal properties of single crystalline Dy{sub 2}Ti{sub 2}O{sub 7} have been studied at temperature below 30 K and magnetic fields applied along [110] direction up to 1.5 T. Based on a thermodynamic field theory (TFT) various heat relaxation and thermal transport measurements were analysed. So we were able to present not only the heat capacity of Dy{sub 2}Ti{sub 2}O{sub 7}, but also for the first time the different contributions of the magnetic excitations and their corresponding relaxation times in the spin ice phase. In addition, the thermal conductivity and the shortest relaxation time were determined by thermodynamic analysis of steady state heat transport measurements. Finally, we were able to reproduce the temperature profiles recorded in heat pulse experiments on the basis of TFT using the previously determined heat capacity and thermal conductivity data without additional parameters. Thus, TFT has been proved to be thermodynamically consistent in describing three thermal transport experiments on different time scales. The observed temperature and field dependencies of heat capacity contributions and relaxation times indicate the magnetic excitations in the spin ice Dy{sub 2}Ti{sub 2}O{sub 7} as thermally activated monopole-antimonopole defects.

  14. Giant T{sub c} shift in HgBa{sub 2}CaCu{sub 2}O{sub 6+{delta}} and TlBa{sub 2}CaCu{sub 2}O{sub 7{minus}{delta}} superconductors due to Hg-Tl exchange

    Energy Technology Data Exchange (ETDEWEB)

    Gapud, A.A.; Wu, J.Z.; Kang, B.W.; Yan, S.L.; Xie, Y.Y. [Department of Physics and Astronomy, University of Kansas, Lawrence, Kansas 66045-2151 (United States); Siegal, M.P. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)

    1999-01-01

    The irreversibility lines of epitaxial thin films of HgBa{sub 2}CaCu{sub 2}O{sub 6+{delta}} and TlBa{sub 2}CaCu{sub 2}O{sub 7{minus}{delta}}, whether deduced from field-induced magnetoresistive broadening or onset of nonhysteretic magnetization, were found to coincide when plotted against reduced temperature, showing the same exponential-decay temperature behavior for T/T{sub c}{lt}0.8 and power-law behavior for T/T{sub c}{gt}0.8 (where T{sub c} is zero-field, zero-resistivity critical temperature). These results indicate that replacing Tl with Hg has no noticeable effect on the anisotropy and suggests that T{sub c} is not determined by anisotropy. {copyright} {ital 1999} {ital The American Physical Society}

  15. Dependence of O{sub 2} diffusion dynamics on pressure and temperature in silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Iovino, G., E-mail: giuseppe.iovino@unipa.it; Agnello, S., E-mail: simonpietro.agnello@unipa.it; Gelardi, F. M., E-mail: franco.gelardi@unipa.it [University of Palermo, Department of Physics and Chemistry (Italy)

    2013-10-15

    An experimental study of the molecular O{sub 2} diffusion process in high purity non-porous silica nanoparticles having 50 m{sup 2}/g BET specific surface and 20 nm average radius was carried out in the temperature range from 127 to 177 Degree-Sign C at O{sub 2} pressure in the range from 0.2 to 66 bar. The study was performed by measuring the volume average interstitial O{sub 2} concentration by a Raman and photoluminescence technique using a 1,064 nm excitation laser to detect the singlet to triplet emission at 1,272 nm of the molecular oxygen in silica. A dependence of the diffusion kinetics on the O{sub 2} absolute pressure, in addition to temperature dependence, was found. The kinetics can be fit by the solution of Fick's diffusion equation using an effective diffusion coefficient related to temperature and O{sub 2} external pressure. The fit results have evidenced that the temperature and pressure dependencies can be disentangled and that the pressure effects are more pronounced at lower temperatures. An Arrhenius temperature law is determined for the effective diffusion coefficient and the activation energy and pre-exponential factor are found in the explored experimental range. The reported findings have not been evidenced previously in the studies in bulk silica and could probably be originated by the reduced spatial extension of the considered system.

  16. Zero photoelastic and water durable ZnO–SnO–P{sub 2}O{sub 5}–B{sub 2}O{sub 3} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Saitoh, Akira; Nakata, Kohei; Yamamoto, Naoki; Takebe, Hiromichi [Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama 790-8577 (Japan); Tricot, Grégory; Chen, Yuanyuan [LASIR UMR-CNRS 8516, Université de Lille 1, Villeneuve d’Ascq F-59655 (France)

    2015-04-01

    We report properties of zero birefringent xZnO–(67–x)SnO–(33–y)P{sub 2}O{sub 5}–y B{sub 2}O{sub 3} glasses, within 18.5 ≤ x ≤ 22 and y = 0, 3, and 10 mol. %. These compositions of boro-phosphate glasses provide both zero photoelastic constant (PEC) and improved water durability. x = 19 and y = 3 compositions show minimum PEC of −0.002 × 10{sup −12} Pa{sup −1}, which can contribute to candidate material for fiber current sensor devise without lead. The structures of zero photoelastic glasses were investigated by Raman scattering and nuclear magnetic resonance spectroscopies. Compositions of zero PEC glasses are explained by the empirical model proposed by Zwanziger et al. [Chem. Mater. 19, 286-290 (2007)].

  17. Magnetic properties of NiFe{sub 2}O{sub 4}/carbon nanofibers from Venezuelan petcoke

    Energy Technology Data Exchange (ETDEWEB)

    Briceño, Sarah, E-mail: sbriceno@ivic.gob.ve [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Silva, Pedro; Molina, Wilmer; Brämer-Escamilla, Werner; Alcalá, Olgi [Laboratorio de Física de la Materia Condensada, Centro de Física, Instituto Venezolano de Investigaciones Científicas IVIC, Apartado 20632, Caracas 1020-A (Venezuela, Bolivarian Republic of); Cañizales, Edgard [Área de Análisis Químico Inorgánico, PDVSA, INTEVEP, Los Teques 1070-A (Venezuela, Bolivarian Republic of)

    2015-05-01

    NiFe{sub 2}O{sub 4}/carbon nanofibers (NiFe{sub 2}O{sub 4}/CNFs) have been successfully synthesized by hydrotermal method using Venezuelan petroleum coke (petcoke) as carbon source and NiFe{sub 2}O{sub 4} as catalyst. The morphology, structural and magnetic properties of nanocomposite products were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), vibrating sample magnetometry (VSM) and electron paramagnetic resonance (EPR). XRD analysis revealed a cubic spinel structure and ferrite phase with high crystallinity. HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. At room temperature, NiFe{sub 2}O{sub 4}/CNFs show superparamagnetic behavior with a maximum magnetization of 15.35 emu/g. Our findings indicate that Venezuelan petroleum coke is suitable industrial carbon source for the growth of magnetic CNFs. - Highlights: • NiFe{sub 2}O{sub 4}/CNFs have been synthesized by hydrothermal method using petroleum coke. • Nickel ferrite nanoparticles were used as the catalyst. • HR-TEM reveals the presence of CNFs with diameters of 4±2 nm. • The size of the nanoparticles defines the diameter of the CNFs.

  18. Mechanical dispersion of Y{sub 2}O{sub 3} nanoparticles in steel EUROFER 97: process and optimisation

    Energy Technology Data Exchange (ETDEWEB)

    Castro, V. de E-mail: mvcastro@fis.uc3m.es; Leguey, T.; Monge, M.A.; Munoz, A.; Pareja, R.; Amador, D.R.; Torralba, J.M.; Victoria, M

    2003-11-01

    The procedures followed to produce Y{sub 2}O{sub 3}-dispersed EUROFER 97 powder ready to be compacted and hot isostatic pressing processed are reported. An attrition mill has been used under controlled conditions. The compositional and microstructural characterization of the Y{sub 2}O{sub 3}/EUROFER powder along the different steps of the milling process has allowed optimising the processing conditions to obtain a nanosized Y{sub 2}O{sub 3} dispersion. TEM observations performed on Y{sub 2}O{sub 3}/EUROFER powder milled under these specific conditions reveal the presence of monoclinic Y{sub 2}O{sub 3} dispersoids having sizes around 10 nm in the ferrite/martensite matrix.

  19. Preparation, structural characterization, and enhanced electrical conductivity of pyrochlore-type (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Xia, X.L. [Institute for Advanced Ceramics, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin (China); Institute of Oceanography Instruments, Shandong Academy of Science, Chinese National Engineering Research Center for Marine Monitoring Equipment, Qingdao (China); Liu, Z.G.; Ouyang, J.H. [Institute for Advanced Ceramics, School of Materials Science and Engineering, Harbin Institute of Technology, Harbin (China); Zheng, Y. [Institute of Oceanography Instruments, Shandong Academy of Science, Chinese National Engineering Research Center for Marine Monitoring Equipment, Qingdao (China)

    2012-08-15

    (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} (0 {<=} x {<=} 1.0) samples are prepared by solid state reaction method using Sm{sub 2}O{sub 3}, Eu{sub 2}O{sub 3}, and ZrO{sub 2} as starting materials. The phase composition and microstructure of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics are investigated by X-ray diffraction (XRD), scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM) coupled with selected area electron diffraction and Raman spectroscopy. XRD and TEM show that all the samples exhibit a single pyrochlore-type structure. HRTEM observation indicates that the whole grain interior of Sm{sub 2}Zr{sub 2}O{sub 7} ceramic is a perfect crystal free of any dislocation. Raman spectroscopy reveals that the degree of structural disorder of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics increases gradually with increasing Eu content. The electrical conductivity of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics is investigated by impedance spectroscopy in the air and hydrogen atmospheres, respectively. The electrical conductivity of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} ceramics increases with increasing Eu content at identical temperature levels. Both the activation energy E{sub g} and the pre-exponential factor {sigma}{sub 0g} for the grain conductivity gradually increase with increasing Eu content. As the ionic conductivity shows no obvious change in both air and hydrogen atmospheres, the conduction of (Sm{sub 1-x}Eu{sub x}){sub 2}Zr{sub 2}O{sub 7} is purely ionic with negligible electronic conduction. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Thermodynamic analysis of binary Fe{sub 85}B{sub 15} to quinary Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloys for primary crystallizations of α-Fe in nanocrystalline soft magnetic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, A., E-mail: takeuchi@imr.tohoku.ac.jp; Zhang, Y.; Takenaka, K.; Makino, A. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2015-05-07

    Fe-based Fe{sub 85}B{sub 15}, Fe{sub 84}B{sub 15}Cu{sub 1}, Fe{sub 82}Si{sub 2}B{sub 15}Cu{sub 1}, Fe{sub 85}Si{sub 2}B{sub 12}Cu{sub 1}, and Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} (NANOMET{sup ®}) alloys were experimental and computational analyzed to clarify the features of NANOMET that exhibits high saturation magnetic flux density (B{sub s}) nearly 1.9 T and low core loss than conventional nanocrystalline soft magnetic alloys. The X-ray diffraction analysis for ribbon specimens produced experimentally by melt spinning from melts revealed that the samples were almost formed into an amorphous single phase. Then, the as-quenched samples were analyzed with differential scanning calorimeter (DSC) experimentally for exothermic enthalpies of the primary and secondary crystallizations (ΔH{sub x1} and ΔH{sub x2}) and their crystallization temperatures (T{sub x1} and T{sub x2}), respectively. The ratio ΔH{sub x1}/ΔH{sub x2} measured by DSC experimentally tended to be extremely high for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy, and this tendency was reproduced by the analysis with commercial software, Thermo-Calc, with database for Fe-based alloys, TCFE7 for Gibbs free energy (G) assessments. The calculations exhibit that a volume fraction (V{sub f}) of α-Fe tends to increase from 0.56 for the Fe{sub 85}B{sub 15} to 0.75 for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy. The computational analysis of the alloys for G of α-Fe and amorphous phases (G{sub α-Fe} and G{sub amor}) shows that a relationship G{sub α-Fe} ∼ G{sub amor} holds for the Fe{sub 85}Si{sub 2}B{sub 12}Cu{sub 1}, whereas G{sub α-Fe} < G{sub amor} for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy at T{sub x1} and that an extremely high V{sub f} = 0.75 was achieved for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy by including 2.8 at. % Si and 4.5 at. % P into α-Fe. These computational results indicate that the Fe{sub 85}Si{sub 2}B