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Sample records for ba mg zr

  1. The depolarization performances of 0.97PbZrO3-0.03Ba(Mg1/3Nb2/3)O3 ceramics under hydrostatic pressure

    Science.gov (United States)

    Su, Rigu; Nie, Hengchang; Liu, Zhen; Peng, Ping; Cao, Fei; Dong, Xianlin; Wang, Genshui

    2018-02-01

    Several 0.97PbZrO3-0.03Ba(Mg1/3Nb2/3)O3 (0.97PZ-0.03BMN) ceramics were prepared via the columbite precursor method. Their microstructures and pressure-dependent ferroelectric and depolarization performances were then studied. The X-ray diffraction patterns of ground and fresh samples indicate that a main rhombohedral symmetry crystal structure is present in the bulk and that it sits alongside a trace quantity of an orthorhombic antiferroelectric phase that results from the effect of grinding on the surface. The remanent polarization (Pr) of the 0.97PZ-0.03BMN reached 32.4 μC/cm2 at 4.5 kV/mm and ambient pressure. In an in situ pressure-induced current measurement, more than 91% of the retained Pr of the pre-poled sample was released when the pressure was increased from 194 MPa to 238 MPa. That this pressure-driven depolarization should be attributed to the pressure-induced ferroelectric-antiferroelectric phase transition is supported by the emergence of double P-E loops at high hydrostatic pressures. Moreover, the 0.97PZ-0.03BMN ceramics exhibit no temperature-induced phase transitions and little related polarization loss up to 125 °C, which suggests that Pr has excellent thermal stability. The sharp depolarization behavior at low pressures and excellent temperature stability reveal that our 0.97PZ-0.03BMN ceramics exhibit superior performances in mechanical-electrical energy conversion applications.

  2. Uncertainty estimation of analysis of Fe, Ca, Zr, Ba, La, Ti and Ce in sediment sample using XRF method

    International Nuclear Information System (INIS)

    Sukirno; Agus Taftazani

    2010-01-01

    An uncertainty of analysis of Fe, Ca, Zr, Ba, La, Ti and Ce in river sediment of Panfuran Wariness sample by X RF method has been done. The result value of testing is meaningless if it isn't completed without uncertainty value. The calculation of Ba metal have been presented for example. The aim of the research is to get accreditation certificate of X-Ray Fluorescence method on laboratory of analytical PTAPB – BATAN as well as ISO guide 17025-2005. The result of calculation uncertainty of Fe, Zr, Ba, La, Ce, Ti and Ca analysis showed that the uncertainty components come from: preparation of sample and standard/comparator, purity of material, counting statistic (sample and standard ) and repeatability. The results showed that metals in river sediment of Pancuran Wonosari were Fe = 7.290%, Zr = 54.5 mg/kg, Ba = 1661.6 mg/kg, La = 22.9 mg/kg, Ce = 161.0 mg/kg, Ti = 3193.2 and Ca = 7.816%, and the result of uncertainty estimate of Fe, Zr, Ba, La, Ce, Ti and Ca were ± 0.60%, ± 4.5 mg/kg, ± 55 mg/kg, ± 1.4 mg/kg, 12.0 mg/kg, ± 208 mg/kg and ± 0.61%. (author)

  3. Phase equilibria in the BaUO3-BaZrO3-BaMoO3 system

    International Nuclear Information System (INIS)

    Kurosaki, Ken; Yamanaka, Shinsuke; Matsuda, Tetsushi; Uno, Masayoshi; Yamamoto, Kazuya; Namekawa, Takashi

    2002-01-01

    The phase equilibria in the pseudo-ternary BaUO 3 -BaZrO 3 -BaMoO 3 system were studied to understand the thermochemical properties of the perovskite type gray oxide phase in high burnup MOX fuel. Thermodynamic equilibrium calculation for the system was performed by using a Chem Sage program under the various oxygen potentials. Solid solutions existing in the system were treated by an ideal solution model. The present calculation results well agreed with the previous reported post irradiation examination results, showing that BaMoO 3 was scarcely included in the gray oxide phase. (author)

  4. Microstructural and magnetic studies on BaMg{sub x}Zn{sub x}X{sub 2x}Fe{sub 12−4x}O{sub 19} (X=Zr,Ce,Sn) prepared via mechanical activation method to act as a microwave absorber in X-band

    Energy Technology Data Exchange (ETDEWEB)

    Afghahi, Seyyed Salman Seyyed [Department of Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@iau-shahrood.ac.ir [Department of Material Engineering, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Atassi, Yomen [Department of Applied Physics, Higher Institute for Applied Sciences and Technology, Damascus (Syrian Arab Republic)

    2016-05-15

    In this study, doped barium hexaferrite with the composition of BaMg{sub x}Zn{sub x}X{sub 2x}Fe{sub 12−4x}O{sub 19} (where x= 0.3, 0.5, 0.7, 0.9 and X= Zr, Ce, Sn) was prepared via mechanical activation. X-ray diffractometer (XRD), FTIR spectrophotometer, Field emission scanning electron microscope (FE-SEM), vibrating sample magnetometer (VSM) and vector network analyzer (VNA) were used to analyze its phases, structure, electromagnetic and microwave absorption properties respectively. Based on the results, single phase barium hexaferrite was obtained in all cases after milling the mixed powders for 20 h plus calcination at 1000 °C for 5 h. Morphology of the particles in all of the doped samples was completely hexagonal shape and they had an appropriate distribution. It was found that the sample of BaMg{sub 0.9}Zn{sub 0.9}Zr{sub 1.8}Fe{sub 8.4}O{sub 19} with saturation magnetization and coercive force of 37.3 emu/g and 94 Oe respectively possessed the maximum reflection loss of −19.3 dB at 12.3 GHz with 1.7 GHz bandwidth. - Highlights: • The mechanical activation method was used to prepare: BaMg{sub x}Zn{sub x}X{sub 2x}Fe{sub 12−4x}O{sub 19}(X=Zr, Ce, and Sn) with values of xequal to 0.3, 0.5, 0.7, and 0.9. • Morphology of the particles in all of the doped samples was completely hexagonal shape and they had an appropriate distribution. • BaMg{sub 0.9}Zn{sub 0.9}Zr{sub 1.8}Fe{sub 8.4}O{sub 19} possesses the maximum reflection loss of −19.3 dB at 12.3 GHz with 1.7 GHz bandwidth.

  5. Epitaxial thin-film growth of Ruddlesden-Popper-type Ba3Zr2O7 from a BaZrO3 target by pulsed laser deposition

    International Nuclear Information System (INIS)

    Butt, Shariqa Hassan; Rafique, M.S.; Siraj, K.; Latif, A.; Afzal, Amina; Awan, M.S.; Bashir, Shazia; Iqbal, Nida

    2016-01-01

    Ruddlesden-Popper Ba 3 Zr 2 O 7 thin films have been synthesized via pulsed laser deposition (PLD) technique. The optimization of deposition parameters in PLD enables the formation of thin film of metastable Ba 3 Zr 2 O 7 phase from BaZrO 3 target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba 3 Zr 2 O 7 thin films were annealed at 500, 600 and 800 C. X-ray diffraction (XRD) reveals the formation of Ba 3 Zr 2 O 7 phase with tetragonal structure. The changes in the surface of the deposited films were analysed by FE-SEM and AFM. The thin film post-annealed at 500 C exhibited the best structural, optical and surface properties. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Zr and O exist mainly in the form of Ba 3 Zr 2 O 7 Ruddlesden-Popper-type perovskite structure. (orig.)

  6. Determination of the UO2-ZrO2-BaO equilibrium diagram

    International Nuclear Information System (INIS)

    Paschoal, J.O.A.; Kleykanp, H.; Thuemmler, F.

    1984-01-01

    It is determined the equilibrium diagram of UO 2 - ZrO 2 - BaO to interpret and predict changes in the chemical properties of ceramic (oxide) nuclear fuels during irradiation. The isothermal section of the system at 1700 0 C was determined experimentally, utilizing the techniques of ceramography, X-ray diffraction analysis, microprobe analysis and differential thermal analysis. The solid solubility limits at 1700 0 C between UO 2 and ZrO 2 , UO 2 and BaO, ZrO 2 and BaO, ZrO 2 and BaO and BaUO 3 and BaZrO 3 is presented. The influence of oxygen potential in relation to the different phases is discussed and the phase diagram of the system presented. (M.C.K.) [pt

  7. Ion conductivities of ZrF4-BaF2-CsF glasses

    International Nuclear Information System (INIS)

    Kawamoto, Yoji; Nohara, Ichiro

    1987-01-01

    The glass-forming region in the ZrF 4 -BaF 2 -CsF glass system has been determined and the ac conductivity and the transport number of fluoride ions have been measured. The conductivities of compounds β-Cs 2 ZrF 6 , α-SrZrF 6 , α-BaZrF 6 , β-BaZrF 6 and α-PbZrF 6 have also been measured. These results and a previous study of ZrF 4 -BaF 2 -MF n (M: the groups I-IV metals) glasses revealed the following: (1) the ZrF 4 -BaF 2 -CsF glasses are exclusively fluoride-ion conductors; (2) the ionic conductivities of ZrF 4 -based glasses are predominantly determined by the activation energies for conduction; (3) the activation energy for conduction decreases with an increase in the average polarizability of glass-constituting cations; (4) a decrease in average Zr-F bond length and a lowering of the average F coordination number of Zr are presumed to increase the activation energy for conduction. Principles of developing ZrF 4 -based glasses with higher conductivities have also been proposed. (Auth.)

  8. Thermodynamic evaluation of the Cu-Mg-Zr system

    International Nuclear Information System (INIS)

    Haemaelaeinen, M.; Zeng, K.

    1999-01-01

    The thermodynamic evaluation of the Cu-Mg-Zr system is presented in this paper. A literature survey was carried out first based on the most recent literature, which was scanned from the THERMET literature database. The evaluation of the thermodynamic parameters was carried out using Thermo-Calc (version H) software. The evaluation of the Cu-Mg-Zr system was carried out using the most recent experimental data from the literature and a set of DTA measurements. DTA measurements were done using alumina (Al 2 O 3 ) crucibles under helium atmosphere with the niobium (Nb) reference crucible. The evaluated Cu-Mg-Zr phase diagram fitted well with experimental data with the liquidus data in a limited range of composition. There were two miscibility gaps observe in the system. New τ phase was detected using the X-ray and microscopic analysis and the data was used in this evaluation. (orig.)

  9. Laser cladding of Zr on Mg for improved corrosion properties

    International Nuclear Information System (INIS)

    Subramanian, R.; Sircar, S.; Mazumder, J.

    1989-01-01

    This paper reports the results of laser cladding of Mg-2wt%Zr, and Mg-5wt%Zr powder mixture onto magnesium. The microstructure of the laser clad was studied. From the microstructural study, the epitaxial regrowth of the clad region on the underlying substrate was observed. Martensite plates of different size were observed in transmission electron microscope for MG-2wt%Zr and Mg-5wt%Zr laser clad. The corrosion properties of the laser clad were evaluated in sea water (3.5% NaCl). The position of the laser claddings in the galvanic series of metals in sea water, the anodic polarization characteristics of the laser claddings and the protective nature and the stability of the passivating film formed have been determined. The formation of pits on the surface of the laser clad subjected to corrosion is reported. The corrosion properties of the laser claddings are compared with that of the commercially used magnesium alloy AZ91B

  10. Structural phase transition of BaZrO3 under high pressure

    International Nuclear Information System (INIS)

    Yang, Xue; Li, Quanjun; Liu, Ran; Liu, Bo; Zhang, Huafang; Jiang, Shuqing; Zou, Bo; Cui, Tian; Liu, Bingbing; Liu, Jing

    2014-01-01

    We studied the phase transition behavior of cubic BaZrO 3 perovskite by in situ high pressure synchrotron X-ray diffraction experiments up to 46.4 GPa at room temperature. The phase transition from cubic phase to tetragonal phase was observed in BaZrO 3 for the first time, which takes place at 17.2 GPa. A bulk modulus 189 (26) GPa for cubic BaZrO 3 is derived from the pressure–volume data. Upon decompression, the high pressure phase transforms into the initial cubic phase. It is suggested that the unstable phonon mode caused by the rotation of oxygen octahedra plays a crucial role in the high pressure phase transition behavior of BaZrO 3

  11. Synthesis and characterization of nanostructured CaZrO{sub 3} and BaZrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Ibiapino, Amanda Laura; Figueiredo, Laysa Pires de [Departamento de Quimica, Instituto de Ciencias Exatas e da Terra, Universidade Federal do Mato Grosso, MT (Brazil); Lascalea, Gustavo E. [LISAMEN/CONICET, Ciudad de Mendoza (Argentina); Prado, Rogerio Junqueira, E-mail: rjprado@ufmt.br [Instituto de Fisica, Universidade Federal do Mato Grosso, Cuiaba - MT (Brazil)

    2013-09-01

    In this work, nanostructured samples of barium zirconate (BaZrO{sub 3}) and calcium zirconate (CaZrO{sub 3}) were synthesized by the gel-combustion method, using glycine as fuel. The ceramic powders were calcined at 550 Degree-Sign C for 2 h and subsequently heat treated at 1350 Degree-Sign C for 10 min (fast-firing). The X-ray diffraction technique was employed to identify and characterize the crystalline phases present in the synthesized powders, using the Rietveld method. Monophasic nanostructured samples of BaZrO{sub 3} and CaZrO{sub 3} presenting average crystallite sizes of around 8.5 and 10.3 nm, respectively, were found after fast-firing. (author)

  12. Growth and scintillation properties of BaMgF4

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Kawaguchi, Noriaki; Fujimoto, Yutaka; Sugiyama, Makoto; Furuya, Yuki; Kamada, Kei; Yokota, Yuui; Yoshikawa, Akira; Chani, Valery

    2010-01-01

    By using the micro-pulling down (μ-PD) method, the barium magnesium fluoride (BaMgF 4 ) single crystalline scintillator was produced. The crystal was cut and mirror polished to the physical dimensions of 1x2x10 mm 3 for examination of scintillation properties. BaMgF 4 demonstrated ∼70% transmittance in wavelength range above 170 nm, and strong emission peaking around 205 nm was observed under X-ray excitation. The absolute light yield of BaMgF 4 was 1300±100 ph/MeV, and the decay time profile showed two components as 0.57±0.01 (70%) and 2.2±0.31 (30%) ns at room temperature.

  13. Structural study, photoluminescence, and photocatalytic activity of semiconducting BaZrO{sub 3}:Bi nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Borja-Urby, R. [Grupo de Espectroscopia de Materiales Avanzados y Nanoestructurados (EMANA), Centro de Investigaciones en Optica A.C., Leon, Gto 37150 (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., Leon, Gto 37150 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro 76000 (Mexico); Moctezuma, E. [Facultad de Ciencias Quimicas, Universidad Autonoma de San Luis Potosi, Av. Manuel Nava 6, San Luis Potosi, S.L.P., Mexico 78290 (Mexico); Vega, M. [Centro de Geociencias-UNAM, A.P. 1-1010, Queretaro 76000 (Mexico); Angeles-Chavez, C. [Instituto Mexicano del Petroleo, Ciudad de Mexico, D.F. 07730 (Mexico)

    2011-10-25

    Wide band gap nanocrystalline bismuth doped barium zirconate is synthesized by a facile hydrothermal method at 100 deg. C. The obtained cubic perovskites are characterized by powder X-ray diffraction (XRD), UV-VIS diffuse reflectance spectroscopy, photoluminescence (PL) spectroscopy, and photocatalytic activity. The estimated band gap in the 2.4-4.9 eV range, depending on Bi concentration, suggests nanocrystalline BaZrO{sub 3}:Bi as a useful visible-light activated photocatalyst under excitation wavelengths <800 nm. Displacement of main XRD pattern peaks suggest that bismuth ion mostly substitutes into Zr{sup 4+} sites within the BaZrO{sub 3} host lattice. It is found that BaZrO{sub 3}:Bi decomposes methylene blue (MB) under both UV and visible light irradiation. The photocatalyst efficiency depends strongly on Bi content and induced defects.

  14. First-principles study of (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 solid solutions

    Science.gov (United States)

    Amoroso, Danila; Cano, Andrés; Ghosez, Philippe

    2018-05-01

    (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 solid solutions are the building blocks of lead-free piezoelectric materials that attract a renewed interest. We investigate the properties of these systems by means of first-principles calculations, with a focus on the lattice dynamics and the competition between different ferroelectric phases. We first analyze the four parent compounds in order to compare their properties and their different tendency towards ferroelectricity. The core of our study is systematic characterization of the binary systems (Ba ,Ca ) TiO3 and Ba (Ti ,Zr ) O3 within both the virtual crystal approximation and direct supercell calculations. In the case of Ca doping, we find a gradual transformation from B -site to A -site ferroelectricity due to steric effects that largely determines the behavior of the system. In the case of Zr doping, in contrast, the behavior is eventually dominated by cooperative Zr-Ti motions and the local electrostatics. In addition, our comparative study reveals that the specific microscopic physics of these solids sets severe limits to the applicability of the virtual crystal approximation for these systems.

  15. Enhanced Optical Performance of BaMgAl

    NARCIS (Netherlands)

    Yin, L.J.; Dong, Juntao; Wang, Yinping; Zhang, Bi; Zhou, Zheng Yang; Jian, Xian; Wu, Mengqiang; Xu, Xin; van Ommen, J.R.; Hintzen, H.T.J.M.

    2016-01-01

    Many strategies have been adopted to improve thermal degradation of phosphors. Because of the stability and high transmittance of graphene, here we report a novel method of carbon coating on BaMgAl10O17:Eu2+ (BAM) phosphor particles through chemical vapor

  16. Magnetoelectric effect of (1-x) Ba0.5Sr0.5Zr0.5Ti0.5O3+(x) Ni0.12Mg0.18Cu0.2Zn0.5Fe2O4 composites

    Science.gov (United States)

    Rahaman, Md. D.; Saha, S. K.; Ahmed, T. N.; Saha, D. K.; Hossain, A. K. M. Akther

    2014-12-01

    The magnetoelectric composites with chemical compositions (1-x) Ba0.5Sr0.5Zr0.5Ti0.5O3+(x) Ni0.12Mg0.18Cu0.2Zn0.5Fe2O4 (x=20, 40, 60 and 80 wt%) was prepared by the conventional solid state reaction method. The presence of a biphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric dispersion is observed at lower frequencies due to interfacial polarization arising from the interface of the two phases. At higher frequencies, the dielectric constant is almost constant due to the inability of electric dipoles to follow the first variation of the alternating applied electric field. The dielectric loss shows maxima which are attributed when the hopping frequency of electrons between different ionic sites becomes nearly equal to the frequency of the applied field. The linearity in the log(σAC) vs. log(ω2) plots confirmed the small polaron hopping type of conduction mechanism. The composite materials are found to exhibit an excellent frequency dependence of magnetic properties. In the high frequency range, with increasing ferrite concentration the initial permeability increases and cut-off frequency decreases. An optimal magnetoelectric coupling responding voltage of about 600 μV cm-1 Oe-1 is obtained for x=20 wt% at room temperature.

  17. Path Integral Treatment of Proton Transport Processes in BaZrO3

    DEFF Research Database (Denmark)

    Zhang, Qianfan; Wahnstrom, Goran; Björketun, Mårten

    2008-01-01

    Nuclear quantum effects on proton transfer and reorientation in BaZrO3 is investigated theoretically using the ab initio path-integral molecular-dynamics simulation technique. The result demonstrates that adding quantum fluctuations has a large effect on, in particular, the transfer barrier...

  18. The transfer factors of I, Ba, Sr, Y and Zr from soil to leafy vegetables

    International Nuclear Information System (INIS)

    Luo Daling; Li Mianfeng; Weng Senhan; Wen Guanghao; Liu Xiaowei; Zhang Cunxiang; Zhang Zeng; Yu Junyue

    1996-01-01

    The transfer factors of I, Ba, Sr, Y and Zr from soil to leafy vegetables have been determined using method of radioisotope tracers and element content analysis. The effects of growth period, size of the vegetables, contents of the isotopes in the soil and other climatic factors on the transfer factors have also been studied

  19. Ba/ZrO2 nanoparticles as efficient heterogeneous base catalyst for ...

    Indian Academy of Sciences (India)

    activity of the Ba/ZrO2 catalyst was evaluated for synthesis of β-nitro alcohols and ... for base catalyzed reactions.10–17 The Ca2+ ions sub- .... by gold sputtering for three minutes. ..... Jain S R, Adiga K C and Verneker V R 1981 Combust.

  20. Competitive Heterogeneous Nucleation Between Zr and MgO Particles in Commercial Purity Magnesium

    Science.gov (United States)

    Peng, G. S.; Wang, Y.; Fan, Z.

    2018-06-01

    Grain refining of commercial purity (CP) Mg by Zr addition with intensive melt shearing prior to solidification has been investigated. Experimental results showed that, when intensive melt shearing is imposed prior to solidification, the grain structure of CP Mg exhibits a complex changing pattern with increasing Zr addition. This complex behavior can be attributed to the change of nucleating particles in terms of their crystal structure, size, and number density with varied Zr additions. Naturally occurring MgO particles are found to be {100} faceted with a cubic morphology and 50 to 300 nm in size. Such MgO particles are usually populated densely in a liquid film (usually referred as oxide film) and can be effectively dispersed by intensive melt shearing. It has been confirmed that the dispersed MgO particles can act as nucleating substrates resulting in a significant grain refinement of CP Mg when no other more potent particles are present in the melt. However, Zr particles in the Mg-Zr alloys are more potent than MgO particles for nucleation of Mg due to their same crystal structure and similar lattice parameters with Mg. With the addition of Zr, Zr and the MgO particles co-exist in the melt. Grain refining efficiency is closely related to the competition for heterogeneous nucleation between Zr and the MgO particles. The final solidified microstructure is mainly determined by the interplay of three factors: nucleation potency (measured by lattice misfit), particle size, and particle number density.

  1. Competitive Heterogeneous Nucleation Between Zr and MgO Particles in Commercial Purity Magnesium

    Science.gov (United States)

    Peng, G. S.; Wang, Y.; Fan, Z.

    2018-04-01

    Grain refining of commercial purity (CP) Mg by Zr addition with intensive melt shearing prior to solidification has been investigated. Experimental results showed that, when intensive melt shearing is imposed prior to solidification, the grain structure of CP Mg exhibits a complex changing pattern with increasing Zr addition. This complex behavior can be attributed to the change of nucleating particles in terms of their crystal structure, size, and number density with varied Zr additions. Naturally occurring MgO particles are found to be {100} faceted with a cubic morphology and 50 to 300 nm in size. Such MgO particles are usually populated densely in a liquid film (usually referred as oxide film) and can be effectively dispersed by intensive melt shearing. It has been confirmed that the dispersed MgO particles can act as nucleating substrates resulting in a significant grain refinement of CP Mg when no other more potent particles are present in the melt. However, Zr particles in the Mg-Zr alloys are more potent than MgO particles for nucleation of Mg due to their same crystal structure and similar lattice parameters with Mg. With the addition of Zr, Zr and the MgO particles co-exist in the melt. Grain refining efficiency is closely related to the competition for heterogeneous nucleation between Zr and the MgO particles. The final solidified microstructure is mainly determined by the interplay of three factors: nucleation potency (measured by lattice misfit), particle size, and particle number density.

  2. Porous composite materials ZrO2(MgO)-MgO for osteoimplantology

    International Nuclear Information System (INIS)

    Buyakov, Ales; Litvinova, Larisa; Shupletsova, Valeria; Kulbakin, Denis; Kulkov, Sergey

    2016-01-01

    The pore structure and phase composition of ceramic composite material ZrO 2 (Mg)-MgO at different sintering temperatures were studied. The main mechanical characteristics of the material were determined and it was shown that they are close to the characteristics of natural bone tissues. It was shown that material structure has a positive effect on the pre-osteoblast cells proliferation. In-vitro studies of pre-osteoblast cells, cultivation on material surface showed a good cell adhesion, proliferation and differentiation of MMSC by osteogenic type.

  3. Porous composite materials ZrO{sub 2}(MgO)-MgO for osteoimplantology

    Energy Technology Data Exchange (ETDEWEB)

    Buyakov, Ales, E-mail: alesbuyakov@gmail.com [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Litvinova, Larisa, E-mail: larisalitvinova@yandex.ru; Shupletsova, Valeria, E-mail: vshupletsova@mail.ru [Immanuel Kant Baltic Federal University, Kaliningrad (Russian Federation); Kulbakin, Denis, E-mail: kulbakin2012@gmail.com [Tomsk Cancer Research Institute, Tomsk, 634050 (Russian Federation); Kulkov, Sergey, E-mail: kulkov@ispms.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2016-08-02

    The pore structure and phase composition of ceramic composite material ZrO{sub 2}(Mg)-MgO at different sintering temperatures were studied. The main mechanical characteristics of the material were determined and it was shown that they are close to the characteristics of natural bone tissues. It was shown that material structure has a positive effect on the pre-osteoblast cells proliferation. In-vitro studies of pre-osteoblast cells, cultivation on material surface showed a good cell adhesion, proliferation and differentiation of MMSC by osteogenic type.

  4. Epitaxial thin-film growth of Ruddlesden-Popper-type Ba{sub 3}Zr{sub 2}O{sub 7} from a BaZrO{sub 3} target by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Butt, Shariqa Hassan; Rafique, M.S.; Siraj, K.; Latif, A.; Afzal, Amina [University of Engineering and Technology, Laser and Optronics Centre, Department of Physics, Lahore (Pakistan); Awan, M.S. [Ibn-e-Sina Institute of Science and Technology (ISIT), Islamabad (Pakistan); Bashir, Shazia [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Iqbal, Nida [Universiti Teknologi Malaysia, Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Johor Bahru, Johor (Malaysia)

    2016-07-15

    Ruddlesden-Popper Ba{sub 3}Zr{sub 2}O{sub 7} thin films have been synthesized via pulsed laser deposition (PLD) technique. The optimization of deposition parameters in PLD enables the formation of thin film of metastable Ba{sub 3}Zr{sub 2}O{sub 7} phase from BaZrO{sub 3} target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba{sub 3}Zr{sub 2}O{sub 7} thin films were annealed at 500, 600 and 800 C. X-ray diffraction (XRD) reveals the formation of Ba{sub 3}Zr{sub 2}O{sub 7} phase with tetragonal structure. The changes in the surface of the deposited films were analysed by FE-SEM and AFM. The thin film post-annealed at 500 C exhibited the best structural, optical and surface properties. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Zr and O exist mainly in the form of Ba{sub 3}Zr{sub 2}O{sub 7} Ruddlesden-Popper-type perovskite structure. (orig.)

  5. Experimental investigation and thermodynamic calculation of the Mg-Sr-Zr system

    International Nuclear Information System (INIS)

    Zhou, Hua; Chen, Chong; Du, Yong; Central South Univ., Hunan; Gong, Haoran

    2016-01-01

    Both experimental investigation and thermodynamic calculation were performed for the Mg-Sr-Zr system. Four decisive alloys were firstly selected and prepared using a powder metallurgy method to measure the isothermal section at 400 C via a combination of X-ray diffraction and electron probe microanalysis. No ternary compound has been observed for this ternary system. Four three-phase regions, (Mg) + (αZr) + Mg 17 Sr 2 , Mg 17 Sr 2 + (αZr) + Mg 38 Sr 9 , Mg 38 Sr 9 + (αZr) + Mg 23 Sr 6 , and Mg 23 Sr 6 + (αZr) + Mg 2 Sr, have been identified at 400 C. No appreciable ternary solubility has been detected in the binary Mg-Sr compounds. Phase transition temperatures of the Mg-Sr-Zr alloys were measured by means of differential scanning calorimetry. The thermodynamic calculations match well with the experimental data in the present work, indicating that no ternary thermodynamic parameters are needed for the thermodynamic description of this ternary system. In order to verify the reliability of the current thermodynamic calculations of the Mg-Sr-Zr system, eight as-cast alloys in the Mg-rich corner were also prepared. The calculated liquidus projection is consistent with the observed primary phase regions. The present thermodynamic calculations are reliable and can be used in the development of Mg alloys.

  6. Growth and characterization of acentric BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Mączka, Mirosław, E-mail: m.maczka@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Szymborska-Małek, Katarzyna; Gągor, Anna [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2 (Poland); Majchrowski, Andrzej [Institute of Applied Physics, Military University of Technology, 2 Kaliskiego Str., 00-908 Warszawa (Poland)

    2015-05-15

    Growth, single crystal X-ray diffraction, polarized Raman and infrared (IR) studies of BaHf(BO{sub 3}){sub 2} are presented. Raman and IR spectra of polycrystalline BaZr(BO{sub 3}){sub 2} are also reported to facilitate assignment of modes. BaHf(BO{sub 3}){sub 2} borate crystallizes in trigonal system, space group R3c, with lattice parameters: a=5.1540(4) Å, c=33.901(3) Å. It accommodates dolomite-like structure doubled in the c direction, which is built of alternating layers of HfO{sub 6} octahedra and BaO{sub 6} distorted trigonal prisms that are connected through borate groups. The obtained structural as well as spectroscopic data show that BaHf(BO{sub 3}){sub 2} is isostructural with BaZr(BO{sub 3}){sub 2} and the deviations from centrosymmetry is small. - Graphical abstract: Arrangement of BO{sub 3} groups in BaHf(BO{sub 3}){sub 2} along the c direction in one unit cell. Dark and light blue denote different borate groups. - Highlights: • BaHf(BO{sub 3}){sub 2} single crystals were grown. • X-ray diffraction showed that this borate crystallizes in the acentric R3c structure. • Raman and IR spectra were measured for BaHf(BO{sub 3}){sub 2} and BaZr(BO{sub 3}){sub 2}, respectively. • Assignment of modes is proposed.

  7. Fracture toughness of MgCr2O4-ZrO2 composities

    International Nuclear Information System (INIS)

    Singh, J.P.

    1985-01-01

    The effect of unstabilized ZrO 2 inclusions on the fracture surface energy of MgCr 2 O 4 was studied as a function of ZrO 2 content. It was observed that fracture surface energy increases with increasing ZrO 2 content, and reaches the maximum value of 24.5 j/m 2 at 16.5 vol% ZrO 2 . This represents an approx. = fourhold increase in the fracture surface energy of Mg 2 O 4 as a result of ZrO 2 inclusions. It is proposed that this improvement results from the energy absorbed by the microcracks formed in the MgCr 2 O 4 matrix as a result of the tetragonal → monoclinic phase transormation of ZrO 2 and the associated volume expansion

  8. Fatigue and retention in ferroelectric Y-Ba-Cu-O/Pb-Zr-Ti-O/Y-Ba-Cu-O heterostructures

    Science.gov (United States)

    Ramesh, R.; Chan, W. K.; Wilkens, B.; Gilchrist, H.; Sands, T.; Tarascon, J. M.; Keramidas, V. G.; Fork, D. K.; Lee, J.; Safari, A.

    1992-09-01

    Fatigue and retention characteristics of ferroelectric lead zirconate titanate thin films grown with Y-Ba-Cu-O(YBCO) thin-film top and bottom electrodes are found to be far superior to those obtained with conventional Pt top electrodes. The heterostructures reported here have been grown in situ by pulsed laser deposition on yttria-stabilized ZrO2 buffer [100] Si and on [001] LaAlO3. Both the a- and c-axis orientations of the YBCO lattice have been used as electrodes. They were prepared using suitable changes in growth conditions.

  9. Effect of annealing time on morphological characteristics of Ba(Zr,Ti)O3 thin films

    International Nuclear Information System (INIS)

    Cavalcante, L.S.; Anicete-Santos, M.; Pontes, F.M.; Souza, I.A.; Santos, L.P.S.; Rosa, I.L.V.; Santos, M.R.M.C.; Santos-Junior, L.S.; Leite, E.R.; Longo, E.

    2007-01-01

    Ba(Zr 0.50 Ti 0.50 )O 3 thin films were prepared by the polymeric precursor method using the annealing low temperature of 300 o C for 8, 16, 24, 48, 96 and 192h in a furnace tube with oxygen atmosphere. The X-ray diffraction patterns revealed that the film annealed for 192 h presented some crystallographic planes (1bar 0bar 0) (1bar 1bar 0) and (2bar 0bar 0) in its crystalline lattice. Fourier transformed infrared presented the formation of metal-oxygen stretching at around 756cm -1 . The atomic force microscopy analysis presented the growth of granules in the Ba(Zr 0.50 Ti 0.50 )O 3 films annealed from 8 to 96h. The crystalline film annealed for 192h already presents grains in its perovskite structure. It evidenced a reduction in the thickness of the thin films with the increase of the annealing time

  10. Dielectric and modulus studies of polycrystalline BaZrO3 ceramic

    Science.gov (United States)

    Saini, Deepash S.; Singh, Sunder; Kumar, Anil; Bhattacharya, D.

    2018-05-01

    In the present work, dielectric and modulus studies of polycrystalline BaZrO3 ceramic, prepared by modified combustion method followed by conventional sintering, are investigated over the frequency range of 100 Hz to 106 Hz at different temperatures from 250 to 500 °C in air. The high value of dielectric constant (ɛ' ˜ 103) of BaZrO3 at high temperature and low frequency can be attributed to the Maxwell-Wagner polarization mechanism as well as to the thermally activated mechanism of charge carriers. Electric modulus reveal two type relaxations in the 250 °C to 800 °C temperature region as studied at different frequencies over 100 Hz to 106 Hz in air.

  11. Mechanical properties, corrosion, and biocompatibility of Mg-Zr-Sr-Dy alloys for biodegradable implant applications.

    Science.gov (United States)

    Ding, Yunfei; Lin, Jixing; Wen, Cuie; Zhang, Dongmei; Li, Yuncang

    2017-11-28

    This study investigates the microstructure, mechanical properties, corrosion behavior, and biocompatibility of magnesium (Mg)-based Mg1Zr2SrxDy (x = 0, 1, 1.63, 2.08 wt %) alloys for biodegradable implant applications. The corrosion behavior of the Mg-based alloys has been evaluated in simulated body fluid using an electrochemical technique and hydrogen evolution. The biocompatibility of the Mg-based alloys has been assessed using SaSO2 cells. Results indicate that the addition of Dy to Mg-Zr-Sr alloy showed a positive impact on the corrosion behavior and significantly decreased the degradation rates of the alloys. The degradation rate of Mg1Zr2Sr1.0Dy decreased from 17.61 to 12.50 mm year -1 of Mg1Zr2Sr2.08Dy based on the hydrogen evolution. The ultimate compressive strength decreased from 270.90 MPa for Mg1Zr2Sr1Dy to 236.71 MPa for Mg1Zr2Sr2.08Dy. An increase in the addition of Dy to the Mg-based alloys resulted in an increase in the volume fraction of the Mg 2 Dy phase, which mitigated the galvanic effect between the Mg 17 Sr 2 phase and the Mg matrix, and led to an increase in the corrosion resistance of the base alloy. The biocompatibility of the Mg-based alloys was enhanced with decreasing corrosion rates. Mg1Zr2Sr2.08Dy exhibited the lowest corrosion rate and the highest biocompatibility compared with the other Mg-based alloys. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  12. Steam Electrolysis by Proton-Conducting Solid Oxide Electrolysis Cells (SOECs) with Chemically Stable BaZrO3-Based Electrolytes

    KAUST Repository

    Bi, Lei; Traversa, Enrico

    2015-01-01

    BaZrO3-based material was applied as the electrolyte for proton-conducting solid oxide fuel cells (SOECs). Compared with the instability of BaCeO3-based proton-conductors, BaZrO3-based material could be a more promising candidate for proton

  13. Spectroscopic studies on (Ba,Ca)(Ti,Zr)O3 ferroelectric ceramics with high piezoelectric coefficients

    International Nuclear Information System (INIS)

    Archana Kumar; Sreenivas, K.

    2013-01-01

    In recent year non lead-based multi component ceramics consisting Ba(Ti 0.8 Zr 0.2 )O 3- (Ba 0.7 Ca 0.3 )TiO 3 have been found to exhibit high piezoelectric coefficients comparable to those of PZT, and there is a lot interest to understand nature of phase transition in these novel compositions. In the present study 0.5Ba(Ti 0.8 Zr 0.2 )O 3- 0.5(Ba 0.7 Ca 0.3 )TiO 3 ceramic composition calcinated and sintered at different temperatures has been investigated. The ceramics are prepared from the raw powders and reacted by a solid state reaction method. Spectroscopic methods including DTA/TGA, FTIR and Raman spectroscopy been used to understand the changes occurring in the chemical and structural properties during processing. The nature of polymorphic phase transition has been studied through the temperature dependent Raman spectroscopy. The de-poling characteristics with temperature have been studied to assess their usefulness for high temperature transducer applications, and their ferroelectric properties have been studied. This new composition exhibits high piezoelectric (d 33 ), and the transition temperature is low around 120℃. (author)

  14. Synthesizing (ZrAl3 + AlN)/Mg-Al composites by a 'matrix exchange' method

    Science.gov (United States)

    Gao, Tong; Li, Zengqiang; Hu, Kaiqi; Han, Mengxia; Liu, Xiangfa

    2018-06-01

    A method named 'matrix exchange' to synthesize ZrAl3 and AlN reinforced Mg-Al composite was developed in this paper. By inserting Al-10ZrN master alloy into Mg matrix and reheating the cooled ingot to 550 °C, Al and Mg atoms diffuse to the opposite side. As a result, liquid melt occurs once the interface areas reach to proper compositions. Then dissolved Al atoms react with ZrN, leading to the in-situ formation of ZrAl3 and AlN particles, while the Al matrix is finally replaced by Mg. This study provides a new insight for preparing Mg composites.

  15. Corrosion of clean Mg-Zr alloys in various basic media for waste encapsulation

    International Nuclear Information System (INIS)

    Lambertin, D.; Frizon, F.; Blachere, A.; Bart, F.

    2012-01-01

    The dismantling of UNGG nuclear reactor generates a large volume of fuel decladding. These materials are based on Mg-Zr alloy. The strategy could be to encapsulate these wastes into an ordinary Portland cement (OPC) or geo-polymer (aluminosilicate material) in a form suitable for storage. Studies have been performed on Mg or Mg-Al alloy in basic media but no data are available on Mg-Zr behaviour. The influence of representative pore solution of OPC and geo-polymer with Mg-Zr alloy has been studied on corrosion behaviour. Electrochemical methods have been used to determine the corrosion densities at room temperature. Results show that the corrosion densities of Mg-Zr alloy in OPC solution is one order of magnitude more important than in geo-polymer solution environment and effect of inhibiting agent has been undertaken with Mg-Zr alloy. The evaluation of encapsulation of Mg-Zr alloy in OPC and geo-polymer has been done in term of corrosion hydrogen production. (authors)

  16. Electromagnetic Properties of (Gd, Y)Ba2Cu3Ox Superconducting Tapes With High Levels of Zr Addition

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y; Yao, Y; Chen, Y; Khatri, ND; Liu, J; Galtsyan, E; Lei, C; Selvamanickam, V

    2013-06-01

    The dependence of the critical current density (J(c)) on the orientation of applied magnetic fields was studied in Zr-doped (Gd, Y)Ba2Cu3Ox tapes fabricated by metal organic chemical vapor deposition. The in-field performance of J(c) of (Gd, Y)Ba2Cu3Ox tapes with Zr-doping levels of 7.5-30 at.% was investigated up to 5 T over a temperature range of 40-77 K. The highest critical currents (I-c) at H parallel to c and the highest values of minimum Ic in angular dependence measurements were achieved in the tapes with 20% Zr doping over a broad range of temperature and magnetic field conditions measured. The electromagnetic properties have been related to the changes in BaZrO3 content and microstructure.

  17. Synthesis and mechanical properties of stabilized zirconia ceramics: MgO-ZrO_2 and Y_2O_3-MgO- ZrO_2

    International Nuclear Information System (INIS)

    Yamagata, C.; Mello-Castanho, S.R.H.; Paschoal, J.O.A.

    2014-01-01

    Precursor MgO-ZrO_2 and Y_2O_3-MgO-ZrO_2 ceramic powders were synthesized by the method of co-precipitation and characterized by techniques such as laser diffraction, QELS (Quasi Elastic Light Scattering), XRD, BET, and SEM. Nanoscale powders with specific surface area higher than 60 m"2. g"-"1 was achieved. Sintered ceramic obtained from the synthesized powders, were characterized to mechanical tests using Vickers indentation technique. The addition of Y_2O_3 promoted an increase in hardness of the ceramics and total cubic crystalline phase stabilization. (author)

  18. Co2FeAl based magnetic tunnel junctions with BaO and MgO/BaO barriers

    Directory of Open Access Journals (Sweden)

    J. Rogge

    2015-07-01

    Full Text Available We succeed to integrate BaO as a tunneling barrier into Co2FeAl based magnetic tunnel junctions (MTJs. By means of Auger electron spectroscopy it could be proven that the applied annealing temperatures during BaO deposition and afterwards do not cause any diffusion of Ba neither into the lower Heusler compound lead nor into the upper Fe counter electrode. Nevertheless, a negative tunnel magnetoresistance (TMR ratio of -10% is found for Co2FeAl (24 nm / BaO (5 nm / Fe (7 nm MTJs, which can be attributed to the preparation procedure and can be explained by the formation of Co- and Fe-oxides at the interfaces between the Heusler and the crystalline BaO barrier by comparing with theory. Although an amorphous structure of the BaO barrier seems to be confirmed by high-resolution transmission electron microscopy (TEM, it cannot entirely be ruled out that this is an artifact of TEM sample preparation due to the sensitivity of BaO to moisture. By replacing the BaO tunneling barrier with an MgO/BaO double layer barrier, the electric stability could effectively be increased by a factor of five. The resulting TMR effect is found to be about +20% at room temperature, although a fully antiparallel state has not been realized.

  19. Effect of heat treatment on the microstructures and damping properties of biomedical Mg-Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Ming-Hung [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Department of Dentistry, Chang Yin dental clinic, No.46-1, Yangming St., Banqiao City, Taipei County 220, Taiwan (China); Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Chen, May-Show [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); School of Oral Hygiene, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); Lin, Ling-Hung [Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Lin, Ming-Hong [Department of Mechanical Engineering and Graduate Institute of Mechanical and Precision Engineering, National Kaoshiung University of Applied Sciences, Kaoshiung 807, Taiwan (China); Wu, Ching-Zong, E-mail: chinaowu@tmu.edu.tw [Department of Dentistry, Taipei Medical University Hospital, Taipei 110, Taiwan (China); School of Dentistry, College of Oral Medicine, Taipei Medical University, Taipei 110, Taiwan (China); Ou, Keng-Liang, E-mail: klou@tmu.edu.tw [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Graduated Institute of Biomedical Materials and Engineering, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China); Yu, Chih-Hua [Research Center for Biomedical Devices, Taipei Medical University, Taipei 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei 110, Taiwan (China)

    2011-01-21

    Research highlights: > When the as-quenched Mg-1Zr alloy was aged at temperatures ranging from 200 deg. C to 500 deg. C, a microstructural transformation sequence was found to be {alpha}-Mg {yields} ({alpha}-Mg + twin{sub dense}) {yields} ({alpha}-Mg + twin{sub loose}) {yields} ({alpha}-Mg + {alpha}-Zr). > As the as-quenched Mg-1Zr alloy was subjected to aging treatment at 300 deg. C for 16 h, it exhibited the maximum damping properties. > The twin structure plays a crucial role in increasing the damping capacity of the Mg-1Zr alloy. - Abstract: In this study, we elucidated the effect of heat treatment on the microstructures and damping properties of the biomedical Mg-1 wt% Zr (K1) alloy by optical microscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, and experimental model analysis. The following microstructural transformation occurred when the as-quenched (AQ, i.e., solution heat treated and quenched) K1 alloy was subjected to aging treatment in the temperature range 200-500 deg. C: {alpha}-Mg {yields} ({alpha}-Mg + twin{sub dense}) {yields} ({alpha}-Mg + twin{sub loose}) {yields} ({alpha}-Mg + {alpha}-Zr). This microstructural transformation was accompanied by variations in the damping capacity. The damping properties of the AQ K1 alloy subjected to aging treatment at 300 deg. C for 16 h were the best among those of the alloys investigated in the present study. The presence of twin structures in the alloy matrix was thought to play a crucial role in increasing the damping capacity of the K1 alloy. Hence, we state that a combination of solution treatment and aging is an effective means of improving the damping capacity of biomedical K1 alloys.

  20. Effect of heat treatment on the microstructures and damping properties of biomedical Mg-Zr alloy

    International Nuclear Information System (INIS)

    Tsai, Ming-Hung; Chen, May-Show; Lin, Ling-Hung; Lin, Ming-Hong; Wu, Ching-Zong; Ou, Keng-Liang; Yu, Chih-Hua

    2011-01-01

    Research highlights: → When the as-quenched Mg-1Zr alloy was aged at temperatures ranging from 200 deg. C to 500 deg. C, a microstructural transformation sequence was found to be α-Mg → (α-Mg + twin dense ) → (α-Mg + twin loose ) → (α-Mg + α-Zr). → As the as-quenched Mg-1Zr alloy was subjected to aging treatment at 300 deg. C for 16 h, it exhibited the maximum damping properties. → The twin structure plays a crucial role in increasing the damping capacity of the Mg-1Zr alloy. - Abstract: In this study, we elucidated the effect of heat treatment on the microstructures and damping properties of the biomedical Mg-1 wt% Zr (K1) alloy by optical microscopy, transmission electron microscopy, energy-dispersive X-ray spectrometry, and experimental model analysis. The following microstructural transformation occurred when the as-quenched (AQ, i.e., solution heat treated and quenched) K1 alloy was subjected to aging treatment in the temperature range 200-500 deg. C: α-Mg → (α-Mg + twin dense ) → (α-Mg + twin loose ) → (α-Mg + α-Zr). This microstructural transformation was accompanied by variations in the damping capacity. The damping properties of the AQ K1 alloy subjected to aging treatment at 300 deg. C for 16 h were the best among those of the alloys investigated in the present study. The presence of twin structures in the alloy matrix was thought to play a crucial role in increasing the damping capacity of the K1 alloy. Hence, we state that a combination of solution treatment and aging is an effective means of improving the damping capacity of biomedical K1 alloys.

  1. Preparation and characterization of Mg-Zr mixed oxide aerogels and their application as aldol condensation catalysts.

    Science.gov (United States)

    Sádaba, Irantzu; Ojeda, Manuel; Mariscal, Rafael; Richards, Ryan; López Granados, Manuel

    2012-10-08

    A series of Mg-Zr mixed oxides with different nominal Mg/(Mg+Zr) atomic ratios, namely 0, 0.1, 0.2, 0.4, 0.85, and 1, is prepared by alcogel methodology and fundamental insights into the phases obtained and resulting active sites are studied. Characterization is performed by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N(2) adsorption-desorption isotherms, and thermal and chemical analysis. Cubic Mg(x)Zr(1-x)O(2-x) solid solution, which results from the dissolution of Mg(2+) cations within the cubic ZrO(2) structure, is the main phase detected for the solids with theoretical Mg/(Mg+Zr) atomic ratio ≤0.4. In contrast, the cubic periclase (c-MgO) phase derived from hydroxynitrates or hydroxy precursors predominates in the solid with Mg/(Mg+Zr)=0.85. c-MgO is also incipiently detected in samples with Mg/(Mg+Zr)=0.2 and 0.4, but in these solids the c-MgO phase mostly arises from the segregation of Mg atoms out of the alcogel-derived c-Mg(x)Zr(1-x)O(2-x) phase during the calcination process, and therefore the species c-MgO and c-Mg(x)Zr(1-x)O(2-x) are in close contact. Regarding the intrinsic activity in furfural-acetone aldol condensation in the aqueous phase, these Mg-O-Zr sites located at the interface between c-Mg(x)Zr(1-x)O(2-x) and segregated c-MgO display a much larger intrinsic activity than the other noninterface sites that are present in these catalysts: Mg-O-Mg sites on c-MgO and Mg-O-Zr sites on c-Mg(x)Zr(1-x)O(2-x). The very active Mg-O-Zr sites rapidly deactivate in the furfural-acetone condensation due to the leaching of active phases, deposition of heavy hydrocarbonaceous compounds, and hydration of the c-MgO phase. Nonetheless, these Mg-Zr materials with very high specific surface areas would be suitable solid catalysts for other relevant reactions catalyzed by strong basic sites in nonaqueous environments. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Flux pinning properties of ErBa2Cu3Oy thin films with BaZrO3 nanorods

    International Nuclear Information System (INIS)

    Haruta, M; Fujiyoshi, T; Sueyoshi, T; Dezaki, K; Ichigosaki, D; Miyahara, K; Miyagawa, R; Mukaida, M; Matsumoto, K; Yoshida, Y; Ichinose, A; Horii, S

    2006-01-01

    ErBa 2 Cu 3 O y (ErBCO) thin films with BaZrO 3 (BZO) nanorods were prepared by a PLD method for an enhancement of the critical current density J c . The values of J c for the ErBCO thin film containing 1.5 wt% BZO (Er15) in magnetic fields are higher than those for the ErBCO thin film containing 0.5 wt% BZO (Er05). The peaks of J c have been observed in the angular dependence of J c in both the films when the magnetic field is applied parallel to the c-axis. It has been found that the peak is attributed to the flux pinning by BZO nanorods oriented parallel to the c-axis. The vortex glass-liquid transition temperature T g and the pinning parameter m were derived by fitting observed electric transport properties to the theoretical expression based on the percolation transition model. The value of T g of Er15 is higher than that of Er05. This result indicates that the vortex glass phase extends to a higher temperature region on increasing the fraction of BZO. The peak of m has been found in the magnetic field dependence. This fact is probably due to matching the density of BZO nanorods with that of fluxoids, which was confirmed by TEM observations

  3. Encapsulation of Mg-Zr alloy in metakaolin-based geo-polymer

    International Nuclear Information System (INIS)

    Rooses, Adrien; Steins, Prune; Dannoux-Papin, Adeline; Lambertin, David; Poulesquen, Arnaud; Frizon, Fabien

    2013-01-01

    Investigations were carried out to propose a suitable material for the encapsulation of Mg-Zr alloy wastes issued from fuel cladding of the first generation nuclear reactors. Stability over time, good mechanical properties and low gas production are the main requirements that embedding matrices must comply with in order to be suitable for long run storage. One of the main issues encapsulating Mg-Zr alloy in mineral binder is the hydrogen production related to Mg-Zr alloys corrosion and water radiolysis process. In this context, metakaolin geo-polymers offer an interesting outlook: corrosion densities of Mg-Zr alloys are significantly lower than in Portland cement. This work firstly presents the hydrogen production of Mg-Zr alloy embedded in geo-polymers prepared from different the activation solution (NaOH or KOH). The effect of addition of fluorine on the magnesium corrosion in geo-polymer has been investigated too. The results point out that sodium geo-polymer is a suitable binder for Mg-Zr alloy encapsulation with respect to magnesium corrosion resistance. Furthermore the presence of fluorine reduces significantly the hydrogen release. Then, the impact of fluorine on the geo-polymer network formation was studied by rheological, calorimetric and 19 F NMR measurements. No direct effect resulting from the addition of fluorine has been shown on the geo-polymer binder. Secondly, the formulation of the encapsulation matrix has been adjusted to fulfil the expected physical and mechanical properties. Observations, dimensional evolutions and compressive strengths demonstrated that addition of sand to the geo-polymer binder is efficient to meet the storage criteria. Consequently, a matrix formulation compatible with Mg-Zr alloy encapsulation has been proposed. Finally, irradiation tests have been carried out to assess the hydrogen radiolytic yield of the matrix under exposure to γ radiation. (authors)

  4. Enhanced stability of Zr-doped Ba(CeTb)O(3-δ)-Ni cermet membrane for hydrogen separation.

    Science.gov (United States)

    Wei, Yanying; Xue, Jian; Fang, Wei; Chen, Yan; Wang, Haihui; Caro, Jürgen

    2015-07-25

    A mixed protonic and electronic conductor material BaCe(0.85)Tb(0.05)Zr(0.1)O(3-δ) (BCTZ) is prepared and a Ni-BCTZ cermet membrane is synthesized for hydrogen separation. Stable hydrogen permeation fluxes can be obtained for over 100 h through the Ni-BCTZ membrane in both dry and humid conditions, which exhibits an excellent stability compared with Ni-BaCe(0.95)Tb(0.05)O(3-δ) membrane due to the Zr doping.

  5. Reverse micellar synthesis, structural characterization and dielectric properties of Sr-doped BaZrO_3 nanoparticles

    International Nuclear Information System (INIS)

    Ahmad, Tokeer; Ubaidullah, Mohd; Shahazad, Mohd; Kumar, Dinesh; Al-Hartomy, Omar A.

    2017-01-01

    Sr-doped BaZrO_3 nanoparticles with strontium content varying from 5 to 20 mol % were successfully synthesized by reverse micellar method at 900 °C for the first time. Systematic studies have been carried out to establish the structural and electrical properties of the as prepared nanoparticles. These nanoparticles were characterized using powder X-ray diffraction, transmission electron microscopy, BET surface area and dielectric measurements. X-ray diffraction analysis showed the formation of monophasic and highly crystalline nanoparticles which could be indexed in cubic BaZrO_3 with contraction of lattice on strontium substitution. A monotonic shift of diffraction pattern towards higher angel confirms the formation of solid solutions of Ba_1_−_xSr_xZrO_3 (0.05 ≤ x ≤ 0.20) which was corroborating well with lattice parameter studies. Transmission electron microscopic studies showed the formation of cubic, spherical and hexagonal nanoparticles with an average grain size of 40–65 nm. Energy dispersive X-ray spectroscopic studies confirmed the presence of dopant (Sr"2"+) in the BaZrO_3 matrix and estimated chemical species corroborate well with the loaded composition. Specific surface area of the solid solution comes out to be in the range of 104–244 m"2 g"-"1. Smallest particle of size 40 nm shows highest surface area 244 m"2 g"-"1 for 20 mol% Sr-doped BaZrO_3. Dielectric and impedance studies were also carried out as a function of frequency and temperature to explore the electrical properties of Sr-doped BaZrO_3. The dielectric constant of Ba_1_−_xSr_xZrO_3 (0.05 ≤ x ≤ 0.20) was found to be in the range of 13–25 for x = 0.05 to x = 0.20 with nearly similar dielectric loss of the order of 0.02. The conductance increases linearly with increase in frequency at room temperature, however the impedance has an inverse effect. - Highlights: • Monophasic nanocrystalline Ba_1_−_xSr_xZrO_3 at low dopant concentration using reverse micelles for the first

  6. Reverse micellar synthesis, structural characterization and dielectric properties of Sr-doped BaZrO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Tokeer, E-mail: tahmad3@jmi.ac.in [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025 (India); Ubaidullah, Mohd [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025 (India); Department of Chemistry, Banasthali University, Tonk, Rajasthan, 304022 (India); School of Science and Technology, Glocal University, Mirzapur, Saharanpur, 247121, Uttar Pradesh (India); Shahazad, Mohd [Nanochemistry Laboratory, Department of Chemistry, Jamia Millia Islamia, New Delhi, 110025 (India); Kumar, Dinesh [Department of Chemistry, Banasthali University, Tonk, Rajasthan, 304022 (India); Al-Hartomy, Omar A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah, 21589 (Saudi Arabia)

    2017-01-01

    Sr-doped BaZrO{sub 3} nanoparticles with strontium content varying from 5 to 20 mol % were successfully synthesized by reverse micellar method at 900 °C for the first time. Systematic studies have been carried out to establish the structural and electrical properties of the as prepared nanoparticles. These nanoparticles were characterized using powder X-ray diffraction, transmission electron microscopy, BET surface area and dielectric measurements. X-ray diffraction analysis showed the formation of monophasic and highly crystalline nanoparticles which could be indexed in cubic BaZrO{sub 3} with contraction of lattice on strontium substitution. A monotonic shift of diffraction pattern towards higher angel confirms the formation of solid solutions of Ba{sub 1−x}Sr{sub x}ZrO{sub 3} (0.05 ≤ x ≤ 0.20) which was corroborating well with lattice parameter studies. Transmission electron microscopic studies showed the formation of cubic, spherical and hexagonal nanoparticles with an average grain size of 40–65 nm. Energy dispersive X-ray spectroscopic studies confirmed the presence of dopant (Sr{sup 2+}) in the BaZrO{sub 3} matrix and estimated chemical species corroborate well with the loaded composition. Specific surface area of the solid solution comes out to be in the range of 104–244 m{sup 2} g{sup -1}. Smallest particle of size 40 nm shows highest surface area 244 m{sup 2} g{sup -1} for 20 mol% Sr-doped BaZrO{sub 3}. Dielectric and impedance studies were also carried out as a function of frequency and temperature to explore the electrical properties of Sr-doped BaZrO{sub 3}. The dielectric constant of Ba{sub 1−x}Sr{sub x}ZrO{sub 3} (0.05 ≤ x ≤ 0.20) was found to be in the range of 13–25 for x = 0.05 to x = 0.20 with nearly similar dielectric loss of the order of 0.02. The conductance increases linearly with increase in frequency at room temperature, however the impedance has an inverse effect. - Highlights: • Monophasic nanocrystalline Ba{sub 1

  7. Biological activity evaluation of magnesium fluoride coated Mg-Zn-Zr alloy in vivo.

    Science.gov (United States)

    Jiang, Hongfeng; Wang, Jingbo; Chen, Minfang; Liu, Debao

    2017-06-01

    To explore the biodegradable characteristics and biological properties, which could promote new bone formation, of MgF 2 coated magnesium alloy (Mg-3wt%Zn-0.5wt%Zr) in rabbits. Magnesium alloy with MgF 2 coating was made and the MgF 2 /Mg-Zn-Zr was implanted in the femoral condyle of rabbits. Twelve healthy adult Japanese white rabbits in weight of 2.8-3.2kg were averagely divided into A(Mg-Zn-Zr) group and B(MgF 2 /MgZn-Zr) group. Indexes such as microstructural evolution, SEM scan, X-ray, Micro-CT and mechanical properties were observed and detected at 1th day, 2th, 4th, 8th, 12th, 24th week after implantation. Low-density regions occurred around the cancellous bone, and the regions gradually expanded during the 12weeks after implantation. The implant was gradually absorbed from 12 to 24weeks. The density of surrounding cancellous bone increased compared with the 12th week data. The degradation rate of B group was lower than that of A group (Pmagnesium ions. The biological properties of the coating itself presented good biocompatibility and bioactivity. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

    International Nuclear Information System (INIS)

    Wang, S.F.; Li, Q.; Zu, X.T.; Xiang, X.; Liu, W.; Li, S.

    2016-01-01

    (Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M"2"+ ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe_2O_4 magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe_2O_4 of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe_2O_4 nanoparticle synthesis, starting from EDTA-chelated M"2"+ (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

  9. Phase controlled synthesis of (Mg, Ca, Ba)-ferrite magnetic nanoparticles with high uniformity

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S.F., E-mail: wangshifa2006@yeah.net [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Science and technology on vacuum technology and physics laboratory, Lanzhou Institute of Physics, Lanzhou 730000, Gansu (China); Li, Q. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Zu, X.T., E-mail: xtzu@uestc.edu.cn [Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Xiang, X.; Liu, W. [School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054, Sichuan (China); Li, S., E-mail: sean.li@unsw.edu.au [School of Material Science and Engineering, University of New South Wales, Sydney 2052 (Australia)

    2016-12-01

    (Mg, Ca, Ba)-ferrite magnetic nanoparticles were successfully synthesized through modifying the atomic ratio of polysaccharide and chelating agent at an optimal sintering temperature. In the process, the polysaccharide plays an important role in drastically shrinking the precursor during the gel drying process. In the metal-complex structure, M{sup 2+} ion active sites were coordinated by −OH of the water molecules except for EDTA anions. The MFe{sub 2}O{sub 4} magnetic nanoparticles exhibited enhanced magnetic properties when compared with nano-MFe{sub 2}O{sub 4} of similar particle size synthesized by other synthesis route reported in the literature. In particular, the sintering temperature improves the crystallinity and increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles significantly. - Graphical abstract: Schematic representation of the proposed model for MFe{sub 2}O{sub 4} nanoparticle synthesis, starting from EDTA-chelated M{sup 2+} (M=Mg, Ca, or Ba) cations (left). High dispersion (Mg, Ca, Ba)-ferrite magnetic nanoparticles were prepared by a modified polyacrylamide gel route. Optimized utilization of polysaccharide, chelating agent, and sintering temperature allowed the formation of (Mg, Ca, Ba)-ferrite nanoparticles with a narrow diameter distribution. - Highlights: • We report a modified polyacrylamide gel route to synthesize (Mg, Ca, Ba)-ferrite magnetic nanoparticles. • Chelate mechanism of metal ions (Mg, Ca, Ba) and EDTA has been discussed. • Phase transformation process of (Mg, Ca, Ba)-ferrites has been discussed. • The preparation method increases the hysteresis loop squareness ratio of (Mg, Ca, Ba)-ferrite nanoparticles.

  10. Thermoluminescence of magnesium doped zirconium oxide (ZrO2:Mg) UV irradiated

    International Nuclear Information System (INIS)

    Rivera Montalvo, Teodoro; Furetta, Claudio

    2008-01-01

    Full text: The monitoring of ultraviolet radiation (UVR) different thermoluminescent (TL) materials have been used to measure UVR. UV dosimetry using thermoluminescence phenomena has been suggested in the past by several authors. This technique has an advantage over others methods due to the readout of the samples. Other advantages of these phosphors are their small size, portability, lack of any power requirements, linear response to increasing radiation dose and high sensitivity. Zirconium oxide, recently received full attention in view of their possible use as thermoluminescent dosimeter (TLD), if doped with suitable activators, in radiation dosimetry. In the present investigation thermoluminescent (TL) properties of magnesium doped zirconium oxide (ZrO 2 :Mg) under ultraviolet radiation (UVR) were studied. The ZrO 2 :Mg powder of size 30-40 nm, having mono clinical structure, exhibit a thermoluminescent glow curve with one peak centered at 180 C degrees. The TL response of ZrO 2 :Mg as a function ultraviolet radiation exhibits four maxima centered at 230, 260, 310 and 350 nmn. TL response of ZrO 2 :Mg as a function of spectral irradiance of UV Light was linear in a wide range. Fading and reusability of the phosphor were also studied. The results showed that ZrO 2 :Mg nano powder has the potential to be used as a UV dosemeter in UVR dosimetry. (author)

  11. Structure and Electrical-Transport Relations in Ba(Zr,Pr)O3-δ Perovskites.

    Science.gov (United States)

    Antunes, Isabel; Amador, Ulises; Alves, Adriana; Correia, Maria Rosário; Ritter, Clemens; Frade, Jorge Ribeiro; Pérez-Coll, Domingo; Mather, Glenn C; Fagg, Duncan Paul

    2017-08-07

    Members of the perovskite solid solution BaZr 1-x Pr x O 3-δ (0.2 ≤ x ≤ 0.8) with potential high-temperature electrochemical applications were synthesized via mechanical activation and high-temperature annealing at 1250 °C. Structural properties were examined by Rietveld analysis of neutron powder diffraction and Raman spectroscopy at room temperature, indicating rhombohedral symmetry (space group R3̅c) for members x = 0.2 and 0.4 and orthorhombic symmetry (Imma) for x = 0.6 and 0.8. The sequence of phase transitions for the complete solid solution from BaZrO 3 to BaPrO 3 is Pm3̅m → R3̅c → Imma → Pnma. The structural data indicate that Pr principally exists as Pr 4+ on the B site and that oxygen content increases with higher Pr content. Electrical-conductivity measurements in the temperature range of 250-900 °C in dry and humidified (pH 2 O ≈ 0.03 atm) N 2 and O 2 atmospheres revealed an increase of total conductivity by over 2 orders of magnitude in dry conditions from x = 0.2 to x = 0.8 (σ ≈ 0.08 S cm -1 at 920 °C in dry O 2 for x = 0.8). The conductivity for Pr contents x > 0.2 is attributable to positively charged electronic carriers, whereas for x = 0.2 transport in dry conditions is n-type. The change in conduction mechanism with composition is proposed to arise from the compensation regime for minor amounts of BaO loss changing from predominantly partitioning of Pr on the A site to vacancy formation with increasing Pr content. Conductivity is lower in wet conditions for x > 0.2 indicating that the positive defects are, to a large extent, charge compensated by less mobile protonic species. In contrast, the transport mechanism of the Zr-rich composition (x = 0.2), with much lower electronic conductivity, is essentially independent of moisture content.

  12. Analysis of Fe, Ca, Ti, Ba, Ce, Zr and La element in the Sea sediment at Muria peninsula by X RF method

    International Nuclear Information System (INIS)

    Sukirno and Sri Murniasih

    2009-01-01

    he analysis of metals (Fe, Ca, Ti, Ba, Ce, Zr and La) in the sea sediment environmental samples at Muria peninsula has been carried out with X-Ray Fluorescence (XRF) method. The aim of this analysis is to know the distribution metals which accommodate the recent environmental data in supporting the license of site and Environmental Impact Assessment (EIA) for the Nuclear Power Plants (NPP). Samples taken preparation and analysis based on the procedures of environmental analysis. The result analysis that contents of mayor elements in 7 sea sediment location of sampling were Ca, Ti and Fe with concentration are (6.74 – 11.69 ) %; (0.74 – 6.89 ) % and (0.45 -1.94 ) % successively; while minor elements were Ba, Ce, Zr and La with concentration are 451.4 – 1331.6 ) mg/kg; (201.8 – 427.3) mg/kg; (192.3 – 338.5) mg/kg dan (171.7 – 298.4) mg/kg. The statistic test result shows that sampling location there is a significant difference all of element with the level significant of 95 %. (author)

  13. Mesocrystals luminescent BaZrHfO{sub 3} synthesized via hydrothermal process assisted by microwave

    Energy Technology Data Exchange (ETDEWEB)

    Fassbender, Rafael Uarth, E-mail: uarth.fisica@gmail.com

    2016-07-01

    Full text: The Barium Zirconate (BaZrO{sub 3}), is a ceramic oxide belonging to the functional group of perovskites (ABO{sub 3}), this compound can be doped with hafniun (Hf) in solid solution by microwave assisted hydrothermal method (MAH) radioluminescent increases their properties. This method allows to obtain barium zirconate at low temperature as 140 deg C and short times as 160 minutes. The choice of Hafnium (Hf) as a dopant is based on its similarity with Zirconium (Zr), another good reason for this choice is that the Hafnium has intrinsic luminescent characteristics. In general, radioluminescent materials have high density and high atomic mass (atomic number of Hafnium is 72), thereby facilitating the absorption of ionizing radiation to convert it into visible light, this characteristic is strongly dependent on the morphology and especially the electronic structure of (BaZrO{sub 3}). This work consisted in production of barium zirconate powders doped 1-2-4-8-16% (Hf) using (MAH) method. For the characterization of the powders was employed methods : a) X-ray diffraction, b) Raman Spectroscopy, c) Xanes, d) photoluminescence spectroscopy. After the electronic and structural characterization the powders were introduced in a polymeric resin (nylon-BZO), one new characterizations will be performed to validate the results obtained in the production of films to the results already obtained for the powders. We conclude so far, that the powders-doped with 16% Hf has an intense luminescent emission compared to the powders with less concentration of Hf. The small structural change that causes the Hf in (BZO) is considered as a secondary factory. (author)

  14. Synthesis, luminescent properties and white light emitting diode application of Ba{sub 7}Zr(PO{sub 4}){sub 6}:Eu{sup 2+} yellow-emitting phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chenxia; Dai, Jian [College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018 (China); Deng, Degang, E-mail: dengdegang@cjlu.edu.cn [College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China); Shen, Changyu [College of Optical and Electronic Technology, China Jiliang University, Hangzhou 310018 (China); Xu, Shiqing, E-mail: sxucjlu@163.com [College of Materials Science and Engineering, China Jiliang University, Hangzhou 310018 (China)

    2015-10-15

    A yellow-emitting phosphor, Eu{sup 2+}-activated Ba{sub 7}Zr(PO{sub 4}){sub 6} phosphor was synthesized by solid-state reaction method and the luminescence properties were investigated. The phosphor exhibited strong absorption in near ultraviolet (n-UV) region, which matched well with the n-UV chip. Upon excitation at 370 nm, the Ba{sub 7}Zr(PO{sub 4}){sub 6}:Eu{sup 2+} phosphor has a broad yellow emission band with a peak at 585 nm and a full width at half maximum of 178 nm wider than that of the commercial yellow-emitting YAG:Ce{sup 3+} phosphor. The mechanism of concentration quenching of Eu{sup 2+} ions in Ba{sub 7}Zr(PO{sub 4}){sub 6} phosphor is verified to be energy transfer among the nearest neighbor Eu{sup 2+} ions. The CIE value and temperature dependence of photoluminescence were also discussed. Furthermore, a white-LED was fabricated using a 370 nm UV chip pumped with a blend of phosphors consisting of yellow-emitting Ba{sub 6.97}Zr(PO{sub 4}){sub 6}:0.03Eu{sup 2+} and blue-emitting BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} phosphors, which achieved a CIE of (0.3329, 0.3562) with a color-rendering index of 86.4 around the CCT of 5487 K.

  15. Atomic bonding and mechanical properties of Al-Mg-Zr-Sc alloy

    Institute of Scientific and Technical Information of China (English)

    高英俊; 班冬梅; 韩永剑; 钟夏平; 刘慧

    2004-01-01

    The valence electron structures of Al-Mg alloy with minor Sc and Zr were calculated according to the empirical electron theory(EET) in solid. The results show that because of the strong interaction of Al atom with Zr and Sc atom in melting during solidification, the Al3 Sc and Al3 (Sc1-xZrx) particles which act as heterogeneous nuclear are firstly crystallized in alloy to make grains refine. In progress of solidification, the Al-Sc, Al-Zr-Sc segregation regions are formed in solid solution matrix of Al-Mg alloy owing to the strong interaction of Al atom with Zr, Scatoms in bulk of alloy, so in the following homogenization treatment, the finer dispersed Al3 Sc and Al3 (Sc1-x Zrx) second-particles which are coherence with the matrix are precipitated in the segregation region. These finer second particles with the strong Al-Zr, Al-Sc covalent bonds can strengthen the covalent bonds in matrix of the alloy, and also enhance the hardness and strength of Al-Mg alloy. Those finer second-particles precipitated in interface of sub-grains can also strengthen the covalence bonds there, and effectively hinder the interface of sub-grains from migrating and restrain the sub-grains from growing, and cause better thermal stability of Al-Mg alloy.

  16. Effect of Zr on the Corrosion Properties of Mg-Li-Al Alloy

    International Nuclear Information System (INIS)

    Kim, Soon Ho; Choi, Sang Hyun; Kim, In Bae; Kim, Kyung Hyun

    1994-01-01

    Effect of Zr on the electrochemical corrosion characteristics of Mg-Li-Al alloy has been investigated by means of potentiodynamic polarization study. The electrochemical behaviors were evaluated in 0.03% NaCl solution and the solution buffered with KH 2 PO 5 · NaOH at room temperature. It was found that the addition of very small quantity of Zr (0.03wt%) in Mg-Li-Al alloy increased corrosion rates and amount of corrosion products and decreased the pitting resistance of the alloy. From the results it was concluded that Zr which is added to increase the strength of Mg-Li-Al alloy is harmful to corrosion properties of the alloy

  17. A Negative Thermal Expansion Material of ZrMgMo3O12

    International Nuclear Information System (INIS)

    Song Wen-Bo; Liang Er-Jun; Liu Xian-Sheng; Li Zhi-Yuan; Yuan Bao-He; Wang Jun-Qiao

    2013-01-01

    A material with the formula ZrMgMo 3 O 12 having negative thermal expansion is presented and characterized. It is shown that ZrMgMo 3 O 12 crystallizes in an orthorhombic symmetry with space group Pnma(62) or Pna2 1 (33) and exhibits negative thermal expansion in a large temperature range (α l = −3.8 × 10 −6 K −1 from 300K to 1000K by x-ray diffraction and α l = −3.73 × 10 −6 K −1 from 295K to 775K by dilatometer). ZrMgMo 3 O 12 remains the orthorhombic structure without phase transition or decomposition at least from 123K to 1200K and is not hygroscopic. These properties make it an excellent material with negative thermal expansion for a variety of applications

  18. Steam Electrolysis by Proton-Conducting Solid Oxide Electrolysis Cells (SOECs) with Chemically Stable BaZrO3-Based Electrolytes

    KAUST Repository

    Bi, Lei

    2015-07-17

    BaZrO3-based material was applied as the electrolyte for proton-conducting solid oxide fuel cells (SOECs). Compared with the instability of BaCeO3-based proton-conductors, BaZrO3-based material could be a more promising candidate for proton-conducting SOECs due to its excellent chemical stability under H2O conditions, but few reports on this aspect has been made due to the processing difficulty for BaZrO3. Our recent pioneering work has demonstrated the feasibility of using BaZrO3-based electrolyte for SOECs and the fabricated cell achieves relatively high cell performance, which is comparable or even higher than that for BaCeO3-based SOECs and offers better chemical stability. Cell performance can be further improved by tailoring the electrolyte and electrode. © The Electrochemical Society.

  19. Synthesis and Characterization of a Perovskite Barium Zirconate (BaZrO[subscript 3]): An Experiment for an Advanced Inorganic Chemistry Laboratory

    Science.gov (United States)

    Thananatthanachon, Todsapon

    2016-01-01

    In this experiment, the students explore the synthesis of a crystalline solid-state material, barium zirconate (BaZrO3) by two different synthetic methods: (a) the wet chemical method using BaCl[subscript 2]·2H[subscript 2]O and ZrOCl[subscript 2]·8H[subscript 2]O as the precursors, and (b) the solid-state reaction from BaCO[subscript 3] and…

  20. Enhanced critical currents in (Gd,Y)Ba2Cu3Ox superconducting tapes with high levels of Zr addition

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V; Chen, Y; Shi, T; Liu, Y; Khatri, ND; Liu, J; Yao, Y; Xiong, X; Lei, C; Soloveichik, S; Galstyan, E; Majkic, G

    2013-01-21

    The critical current and structural properties of (Gd,Y)BaCuO tapes made by metal organic chemical vapor deposition (MOCVD) with Zr addition levels up to 30 at.% have been investigated. The reduction in critical current beyond the previously optimized Zr addition level of 7.5 at.% was found to be due to structural deterioration of the (Gd,Y)Ba2Cu3Ox film. By a modified MOCVD process,enhanced critical current densities have been achieved with high levels of Zr addition,including 3.83 MA cm(-2) in 15 at.% Zr- added 1.1 mu m thick film at 77 K in zero magnetic field. Critical currents as high as 1072 A/ 12 mm have been reached in (Gd,Y) BaCuO tapes with 15 at.% Zr addition at 30 K in a field of 3 T applied perpendicular to the tape,corresponding to a pinning force value of 268 GN m(-3). The enhanced critical currents achievable with a high density of nanoscale defects by employing high levels of second- phase additions enable the performance targets needed for the use of HTS tapes in coil applications involving high magnetic fields at temperatures below 50 K to be met.

  1. Enhanced critical currents in (Gd,Y)Ba2Cu3Ox superconducting tapes with high levels of Zr addition

    International Nuclear Information System (INIS)

    Selvamanickam, V; Shi, T; Liu, Y; Khatri, N D; Liu, J; Yao, Y; Galstyan, E; Majkic, G; Chen, Y; Xiong, X; Lei, C; Soloveichik, S

    2013-01-01

    The critical current and structural properties of (Gd,Y)BaCuO tapes made by metal organic chemical vapor deposition (MOCVD) with Zr addition levels up to 30 at.% have been investigated. The reduction in critical current beyond the previously optimized Zr addition level of 7.5 at.% was found to be due to structural deterioration of the (Gd,Y)Ba 2 Cu 3 O x film. By a modified MOCVD process, enhanced critical current densities have been achieved with high levels of Zr addition, including 3.83 MA cm −2 in 15 at.% Zr-added 1.1 μm thick film at 77 K in zero magnetic field. Critical currents as high as 1072 A/12 mm have been reached in (Gd,Y)BaCuO tapes with 15 at.% Zr addition at 30 K in a field of 3 T applied perpendicular to the tape, corresponding to a pinning force value of 268 GN m −3 . The enhanced critical currents achievable with a high density of nanoscale defects by employing high levels of second-phase additions enable the performance targets needed for the use of HTS tapes in coil applications involving high magnetic fields at temperatures below 50 K to be met. (paper)

  2. Synthesis strategies for improving the performance of doped-BaZrO 3 materials in solid oxide fuel cell applications

    KAUST Repository

    Bi, Lei; Traversa, Enrico

    2013-01-01

    is lower than that of conventional oxygen-ion conductors, enabling the operating temperature reduction at 600 °C. Among HTPC oxides, doped BaZrO3 materials possess high chemical stability, needed for practical applications. Though, poor sinterability

  3. Synthesis strategies for improving the performance of doped-BaZrO 3 materials in solid oxide fuel cell applications

    KAUST Repository

    Bi, Lei

    2013-08-07

    Solid oxide fuel cells (SOFCs) offer an efficient energy conversion technology for alleviating current energy problems. High temperature proton-conducting (HTPC) oxides are promising electrolytes for this technology, since their activation energy is lower than that of conventional oxygen-ion conductors, enabling the operating temperature reduction at 600 °C. Among HTPC oxides, doped BaZrO3 materials possess high chemical stability, needed for practical applications. Though, poor sinterability and the resulting large volume of highly resistive grain boundaries hindered their deployment for many years. Nonetheless, the recently demonstrated high proton conductivity of the bulk revived the attention on doped BaZrO3, stimulating research on solving the sintering issues. The proper selection of dopants and sintering aids was demonstrated to be successful for improving the BaZrO3 electrolyte sinterability. We here briefly review the synthesis strategies proposed for preparing BaZrO3-based nanostructured powders for electrolyte and electrodes, with the aim to improve the SOFC performance. © Materials Research Society 2013.

  4. BaZrO3 perovskite nanoparticles as emissive material for organic/inorganic hybrid light-emitting diodes

    DEFF Research Database (Denmark)

    Tamulevičius, S.; Ivaniuk, K.; Cherpak, V.

    2017-01-01

    In the present work we have demonstrated double-channel emission from organic exciplexes coupled to inorganic nanoparticles. The process is demonstrated by yellow-green emission in light-emitting diodes based on organic exciplexes hybridized with perovskite-type dispersed BaZrO3 nanoparticles...

  5. Research on aging precipitation in a Cu-Cr-Zr-Mg alloy

    International Nuclear Information System (INIS)

    Su Juanhua; Dong Qiming; Liu Ping; Li Hejun; Kang Buxi

    2005-01-01

    The effects of aging processes on the properties and microstructure of Cu-0.3Cr-0.15Zr-0.05Mg lead frame alloy were investigated. Aging precipitation phase was dealt with by transmission electronic microscope (TEM). After solid solution was treated at 920 deg. C and aged at 470 deg. C for 4 h, the fine precipitation of an ordered compound CrCu 2 (Zr, Mg) is found in copper matrix as well as fine Cr and Cu 4 Zr. Along the grain boundary, there are larger chromium. The hardness and electrical conductivity can reach 109 HV and 80% IACS, respectively. Sixty percent cold-rolled deformation prior to aging at 470 deg. C enhances the hardness of the alloy. The coherent precipitates Cr in copper matrix and the dislocations pinned by the fine precipitates are responsible for maximum strengthening of the alloy. So the hardness 165 HV and electrical conductivity 79.2% IACS are available

  6. The Structural Evolution of (Gd, Y)Ba2Cu3Ox Tapes With Zr Addition Made by Metal Organic Chemical Vapor Deposition

    Energy Technology Data Exchange (ETDEWEB)

    Lei, CH; Galstyan, E; Chen, YM; Shi, T; Liu, YH; Khatri, N; Liu, JF; Xiong, XM; Majkic, G; Selvamanickam, V

    2013-06-01

    Structural analysis of (Gd, Y) Ba2Cu3Ox tapes with Zr addition made by metal organic chemical vapor deposition has been conducted with transmission electron microscopy and X-ray diffraction. Zr content in the films was varied from 0 to 25% in the precursor. In all Zr-doped films, self-assembled nanocolumnar structures of BaZrO3 (BZO) were observed along the c-axis. The amount of BaZrO3 was found to increase steadily with Zr content. Additionally, planar BZO plates were found on the (001) plane of (Gd, Y) Ba2Cu3Ox film. The size and thickness of BZO plates were seen to increase with Zr doping level. Rare-earth copper oxide phases were observed to begin to emerge in the 20% Zr-doped film. Cross-sectional study of the interface between (Gd, Y)Ba2Cu3Ox and LaMnO3 cap layer revealed a thin discrete BZO layer on the LaMnO3 in the 20% Zr doped film.

  7. Equilibrium Crystal Shape of BaZrO{sub 3} and Space Charge Formation in the (011) Surface by Using Ab-Initio Thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji-Su; Kim, Yeong-Cheol [Korea University of Technology and Education, Cheonan (Korea, Republic of)

    2017-01-15

    We investigated the equilibrium crystal shape of BaZrO{sub 3} and the space charge formation in an O-terminated (011) surface by using ab-initio thermodynamics. Twenty-two low-indexed (001), (011), and (111) surfaces were calculated to analyze their surface Gibbs-free energy under the stable condition of BaZrO{sub 3}. Based on the Gibbs-Wulff theorem, the equilibrium crystal shape of BaZrO{sub 3} changed from cubic to decaoctahedral with decreasing Ba chemical potential. The dominant facets of BaZrO{sub 3} were {001} and {011}, which were well consistent with experimental observations. The space charge formation in the (011) surface was evaluated using the space-charge model. We found that the (011) surface was even more resistive than the (001) surface.

  8. Microscopic origins of the large piezoelectricity of leadfree (Ba,Ca)(Zr,Ti)O3.

    Science.gov (United States)

    Nahas, Yousra; Akbarzadeh, Alireza; Prokhorenko, Sergei; Prosandeev, Sergey; Walter, Raymond; Kornev, Igor; Íñiguez, Jorge; Bellaiche, L

    2017-06-20

    In light of directives around the world to eliminate toxic materials in various technologies, finding lead-free materials with high piezoelectric responses constitutes an important current scientific goal. As such, the recent discovery of a large electromechanical conversion near room temperature in (1-x)Ba(Zr 0.2 Ti 0.8 )O 3 -x(Ba 0.7 Ca 0.3 )TiO 3 compounds has directed attention to understanding its origin. Here, we report the development of a large-scale atomistic scheme providing a microscopic insight into this technologically promising material. We find that its high piezoelectricity originates from the existence of large fluctuations of polarization in the orthorhombic state arising from the combination of a flat free-energy landscape, a fragmented local structure, and the narrow temperature window around room temperature at which this orthorhombic phase is the equilibrium state. In addition to deepening the current knowledge on piezoelectricity, these findings have the potential to guide the design of other lead-free materials with large electromechanical responses.

  9. Strain tunable ferroelectric and dielectric properties of BaZrO3

    International Nuclear Information System (INIS)

    Zhang, Yajun; Liu, Man; Shimada, Takahiro; Kitamura, Takayuki; Wang, Jie

    2014-01-01

    The crucial role of epitaxial (in-plane) strain on the structural, electronic, energetic, ferroelectric, and dielectric properties of BaZrO 3 (BZO) is investigated using density-functional theory calculations. We demonstrate that the BZO crystal subjected to a critical compressive (or tensile) strain exhibits non-trivial spontaneous polarization that is higher than that of well-known ferroelectrics BaTiO 3 , while the BZO crystal is essentially paraelectric in the absence of strain. The electronic structure and Born-effective-charge analyses elucidate that the strain-induced paraelectric-to-ferroelectric transition is driven by the orbital hybridization of d-p electrons between zirconium and oxygen. Through the strain-induced paraelectric-to-ferroelectric phase transition, the dielectric response of BZO is significantly enhanced by the in-plane strain. The tensile strain increases the in-plane dielectric constant by a factor of seven with respect to that without the strain, while the compression tends to enhance the out-of-plane dielectric response. Therefore, strain engineering makes BZO an important electromechanical material due to the diversity in ferroelectric and dielectric properties.

  10. Influence of Sc on microstructure and mechanical properties of Al-Si-Mg-Cu-Zr alloy

    Science.gov (United States)

    Li, Yukun; Du, Xiaodong; Zhang, Ya; Zhang, Zhen; Fu, Junwei; Zhou, Shi'ang; Wu, Yucheng

    2018-02-01

    In the present study, the effects of Mg, Cu, Sc and Zr combined additions on the microstructure and mechanical properties of hypoeutectic Al-Si cast alloy were systematically investigated. Characterization techniques such as optical microscopy (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), electron back-scatter diffraction (EBSD), atomic force microscopy (AFM), transmission electron microscope (TEM), Brinell hardness tester and universal testing machine were employed to analyze the microstructure and mechanical properties. The results showed that Sc served as modifier on the microstructure of Al-3Si-0.45Mg-0.45Cu-0.2Zr alloys, including modification of eutectic Si and grains. Extraordinarily, grain refinement was found to be related to the primary particles, which exhibited a close orientation to matrix. After T6 heat treatment, the grain structures were composed of nano-scaled secondary Al3(Sc, Zr) precipitates and spherical eutectic Si. Combined with T6 heat treatment, the highest hardness, yield strength, ultimate tensile strength and elongation were achieved in 0.56 wt.% Sc-modified alloy. Interestingly, the strength and ductility had a similar tendency. This paper demonstrated that combined additions of Mg, Cu, Sc and Zr could significantly improve the microstructure and performance of the hypoeutectic Al-Si cast alloy.

  11. Passivation kinetics of Mg-Nd-Gd-Zn-Zr (EV31A and Mg-Y-Nd-Gd-Zr (WE43C in NaOH solutions

    Directory of Open Access Journals (Sweden)

    Jakraphan Ninlachart

    2017-09-01

    Full Text Available Passivation kinetics of two Mg-RE alloys, such as Mg-Nd-Gd-Zn-Zr (EV31A, and Mg-Y-Nd-Gd-Zr (WE43C were investigated in two different heat treated conditions (solution treated and overaged in 0.01 - 1.0 M NaOH solutions under potentiostatic conditions. Negative reaction order was observed in dilute NaOH which transitioned to positive values as the passivation time increased and in the 1 M NaOH as well. The passive layers showed platelet morphology and the size of the platelets decreased with increase in the NaOH concentration. The hydrogen evolution reaction (HER kinetics was not improved on the passive layer covered surface of the Mg-RE alloys in contrast to the improvements reported on the hydroxide covered pure magnesium. The electrochemical impedance increased with increase in the NaOH concentration in the solution treated condition of both Mg-RE alloys, whereas the overaged EV31A alloy showed a reverse trend. The passive layer of EV31A showed almost 100% higher charge carrier density than the film formed on the WE43C in the overaged condition. A better passivation behavior was observed in the solution treated condition than that in the overaged condition which could be attributed to the uniform distribution of the RE elements in the solution treated specimens. The WE43C alloy revealed better corrosion resistance in the alkaline solution than the EV31A alloy.

  12. Highly constrained ferroelectric [BaTiO3](1−x)Λ/[BaZrO3]xΛ superlattices: X-ray diffraction and Raman spectroscopy

    International Nuclear Information System (INIS)

    Belhadi, J.; El Marssi, M.; Gagou, Y.; El Mendili, Y.; Bouyanfif, H.; Yuzyuk, Yu. I.; Raevski, I. P.; Wolfman, J.

    2014-01-01

    We report an x-ray diffraction (XRD) and a Raman-scattering investigation of ferroelectric/paraelectric superlattices [BaTiO 3 ] (1−x)Λ /[BaZrO 3 ] xΛ for which the composition varied, 0.15 ≤ x ≤ 0.85, while the superlattice (SL) modulation period Λ was kept constant at about 100 Å. The samples were epitaxially grown by pulsed laser deposition on MgO substrates buffered with La 0.5 Sr 0.5 CoO 3 . Based on the XRD analysis and on polarized Raman spectra, we have showed that the large strain in SLs induced ferroelectricity in BaZrO 3 (BZ) for all SLs, a material that is paraelectric in the bulk form at any temperature and in the single film. The induced polar axis in BZ layers is perpendicular to the plane of substrate while BaTiO 3 (BT) layers exhibit in-plane polar orientation. Raman spectroscopy revealed a lattice ordering in SLs due to the misfit strain generated by the large lattice mismatch between the alternating BZ and BT layers. This strain induced a huge upward frequency of the lowest E(1TO) soft mode from 60 cm −1 in the BT single film to 215 cm −1 in the SL with x = 0.85. These results show that in spite of relatively large periodicity of SLs, they are highly constrained and the variation of BZ ratio allowed modifying strains between layers. The temperature dependence of the Raman spectra for BT 0.3Λ /BZ 0.7Λ and BT 0.7Λ /BZ 0.3Λ samples revealed giant shift of the ferroelectric phase transition. The phase transition temperature was found to be upshifted by about 300 °C with respect to BT single crystal.

  13. Growth and scintillation properties of BaMgF{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Yanagida, Takayuki, E-mail: t_yanagi@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Kawaguchi, Noriaki [Tokuyama Corporation, Shibuya 3-chome, Shibuya-ku, Tokyo 150-8383 (Japan); Fujimoto, Yutaka; Sugiyama, Makoto; Furuya, Yuki; Kamada, Kei; Yokota, Yuui [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Chani, Valery [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan)

    2010-09-21

    By using the micro-pulling down ({mu}-PD) method, the barium magnesium fluoride (BaMgF{sub 4}) single crystalline scintillator was produced. The crystal was cut and mirror polished to the physical dimensions of 1x2x10 mm{sup 3} for examination of scintillation properties. BaMgF{sub 4} demonstrated {approx}70% transmittance in wavelength range above 170 nm, and strong emission peaking around 205 nm was observed under X-ray excitation. The absolute light yield of BaMgF{sub 4} was 1300{+-}100 ph/MeV, and the decay time profile showed two components as 0.57{+-}0.01 (70%) and 2.2{+-}0.31 (30%) ns at room temperature.

  14. Phase diagrams for systems Cu2S-AIIS (AII=Mg, Ca, Sr, Ba)

    International Nuclear Information System (INIS)

    Andreev, O.V.; Sikerina, N.V.; Solov'eva, A.V.

    2005-01-01

    By the methods of physicochemical analysis phase diagrams of Cu 2 S-A II S (A II =Mg, Ca, Sr, Ba) systems are studied. The system Cu 2 S-SrS is of eutectic type with eutectic coordinates 1095 K and 21.5 mol.% of SrS. Solubility of SrS in Cu 2 S is 2 mol.% at 1095 K. Regularities of phase diagram changes of Cu 2 S-A II S (A II =Mg, Ca, Sr, Ba) system are determined. Thermodynamic analysis is done [ru

  15. Magnetoelectric effect of (1−x) Ba{sub 0.5}Sr{sub 0.5}Zr{sub 0.5}Ti{sub 0.5}O{sub 3}+(x) Ni{sub 0.12}Mg{sub 0.18}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} composites

    Energy Technology Data Exchange (ETDEWEB)

    Rahaman, Md. D., E-mail: dalilurrahaman1976@gmail.com [Department of Physics, University of Dhaka, Dhaka-1000 (Bangladesh); Saha, S.K.; Ahmed, T.N. [Department of Physics, University of Dhaka, Dhaka-1000 (Bangladesh); Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh); Saha, D.K. [Materials Science Division, Atomic Energy Centre, PO Box 164, Dhaka 1000 (Bangladesh); Hossain, A.K.M. Akther [Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000 (Bangladesh)

    2014-12-15

    The magnetoelectric composites with chemical compositions (1−x) Ba{sub 0.5}Sr{sub 0.5}Zr{sub 0.5}Ti{sub 0.5}O{sub 3}+(x) Ni{sub 0.12}Mg{sub 0.18}Cu{sub 0.2}Zn{sub 0.5}Fe{sub 2}O{sub 4} (x=20, 40, 60 and 80 wt%) was prepared by the conventional solid state reaction method. The presence of a biphase composition was confirmed by X-ray diffraction while the microstructure of the composites was studied by scanning electron microscopy revealing a good mixing of the two phases and a good densification of the bulk ceramics. The dielectric dispersion is observed at lower frequencies due to interfacial polarization arising from the interface of the two phases. At higher frequencies, the dielectric constant is almost constant due to the inability of electric dipoles to follow the first variation of the alternating applied electric field. The dielectric loss shows maxima which are attributed when the hopping frequency of electrons between different ionic sites becomes nearly equal to the frequency of the applied field. The linearity in the log(σ{sub AC}) vs. log(ω{sup 2}) plots confirmed the small polaron hopping type of conduction mechanism. The composite materials are found to exhibit an excellent frequency dependence of magnetic properties. In the high frequency range, with increasing ferrite concentration the initial permeability increases and cut-off frequency decreases. An optimal magnetoelectric coupling responding voltage of about 600 μV cm{sup −1} Oe{sup −1} is obtained for x=20 wt% at room temperature. - Highlights: • XRD patterns confirmed the coexistence of ferroelectric and ferrimagnetic phases. • Dielectric dispersion observed at low frequencies due to interfacial polarization. • Linearity in logσ{sub ac} vs. logω{sup 2} is due to small polaron hopping mechanism. • Maximum ME voltage coefficient 600 μV cm{sup −1} Oe{sup −1} observed for 20% of ferrite.

  16. Composite Fe - BaCe0.2Zr0.6Y0.2O2.9 Anodes for Proton Conductor Fuel Cells

    DEFF Research Database (Denmark)

    Lapina, Alberto; Chatzichristodoulou, Christodoulos; Holtappels, Peter

    2014-01-01

    Symmetrical cells with Fe - BaCe0.2Zr0.6Y0.2O2.9 composite electrodes are produced by screen printing and infiltration, using BaCe0.2Zr0.6Y0.2O2.9 as electrolyte. The electrochemical performance of the composite electrode is studied by impedance spectroscopy at 250–500◦C in dry and wet hydrogen/n...

  17. Simultaneous multi-wavelength ultraviolet excited single-phase white light emitting phosphor Ba1-x(Zr,Ti)Si3O9:xEu

    Science.gov (United States)

    Zhou, Zhenzhen; Liu, Guanghui; Ni, Jia; Liu, Wanlu; Liu, Qian

    2018-05-01

    A kind of novel compound Ba1-x(Zr,Ti)Si3O9:xEu simultaneously activated by different-valence Eu2+ and Eu3+ ions has been successfully synthesized. The existence of Ti4+-O2- charge transfer (CT) transitions in Ba1-xZrSi3O9:xEu is proved by the photoluminescence spectra and first principle calculations, and the Ti4+ ions come from the impurities in commercial ZrO2 raw materials. Under the excitation of multi-wavelength ultraviolet radiation (λEX = 392, 260, 180 nm), Ba1-xZrSi3O9:xEu (x = 0.15) can directly emit nearly white light. The coexistence of multiple luminescent centers and the energy transfer among Zr4+-O2- CT state, Ti4+-O2- CT state, Eu2+ and Eu3+ ions play important roles in the white light emission. Ba1-xZrSi3O9:xEu (x = 0.15) has good thermal stability, in particular, the intensity of emission spectrum (λEX = 392 nm) at 150 °C is ∼96% of that at room temperature. In general, the multi-wavelength ultraviolet-excited single-phase white light emitting phosphor Ba1-x(Zr,Ti)Si3O9:xEu possesses a promise for applications in white light emitting diodes (WLEDs), agriculture, medicine and other photonic fields.

  18. Influence of heat treatment on corrosion behaviour of Al-Zn-Mg-Cu-Zr-Sc alloy

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Y.P.; Liu, X.Y.; He, Y.B. [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Pan, Q.L. [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education, Changsha 410083 (China); Li, W.B. [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); School of Civil Engineering, Hunan City University, Yiyang 413000 (China)

    2012-05-15

    Corrosion behaviour of different tempers (namely NA, UA, PA and OA) of Al-Zn-Mg-Cu-Zr-Sc alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), optical microscopy (OM) and transmission electron microscopy (TEM). Over aged (OA) can decrease the susceptibility to exfoliation due to the discontinuous distribution of the {eta} precipitates at the grain boundaries, cause a negative shift of the corrosion potential (E{sub corr}), and lead to the prolonging of the time of the appearance of two time constants in impedance diagrams. In addition, Al-Zn-Mg-Cu-Zr-Sc alloy with over aged treatment has an enhanced resistance to exfoliation corrosion. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Microstructure Evolution of Mg-Gd-Y-Zn-Zr Magnesium Alloy During Partial Remelting

    Directory of Open Access Journals (Sweden)

    Jianquan TAO

    2014-12-01

    Full Text Available The article deals with the research on the microstructure evolution of Mg-Gd-Y-Zn-Zr magnesium alloy through partial remelting process. It aims at finding out what effects the microstructure of semi-solid Mg-Gd-Y-Zn-Zr alloy will result in under different remelting temperatures and holding times. Based on the results, if to raise the remelting temperature and to prolong the holding time, the size of solid grain will tend to expand and its spheroidization degree also begins to show improvement. In addition, the grain shows tendency of coarsening when the holding time increases. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6483

  20. Computer simulations of nanoindentation in Mg-Cu and Cu-Zr metallic glasses

    DEFF Research Database (Denmark)

    Paduraru, Anca; Andersen, Ulrik Grønbjerg; Thyssen, Anders

    2010-01-01

    The formation of shear bands during plastic deformation of Cu0.50Zr0.50 and Mg0.85Cu0.15 metallic glasses is studied using atomic-scale computer simulations. The atomic interactions are described using realistic many-body potentials within the effective medium theory, and are compared with similar...... simulations using a Lennard-Jones description of the material. The metallic glasses are deformed both in simple shear and in a simulated nanoindentation experiment. Plastic shear localizes into shear bands with a width of approximately 5 nm in CuZr and 8 nm in MgCu. In simple shear, the shear band formation...... is very clear, whereas only incipient shear bands are seen in nanoindentation. The shear band formation during nanoindentation is sensitive to the indentation velocity, indenter radius and the cooling rate during the formation of the metallic glass. For comparison, a similar nanoindentation simulation...

  1. Anisotropy of the irreversibility field for Zr-doped $(Y,Gd)Ba_2Cu_3O_{7-x}$ thin films up to 45T

    OpenAIRE

    Tarantini, C.; Jaroszynski, J.; Kametani, F.; Zuev, Y. L.; Gurevich, A.; Chen, Y.; Selvamanickam, V.; Larbalestier, D. C.; Christen, D. K.

    2012-01-01

    The anisotropic irreversibility field B$_{Irr}$ of two $YBa_2Cu_3O_{7-x}$ thin films doped with additional rare earth (RE)=(Gd,Y) and Zr and containing strong correlated pins (splayed BaZrO$_{3}$ nanorods, and $RE_2O_3$ nanoprecipitates), has been measured over a very broad range up to 45T at temperatures 56 K

  2. Creep behavior and threshold stress of an extruded Al-6Mg-2Sc-1Zr alloy

    International Nuclear Information System (INIS)

    Deshmukh, S.P.; Mishra, R.S.; Kendig, K.L.

    2004-01-01

    Creep experiments were performed on extruded Al-6Mg-2Sc-1Zr (wt.%) alloy in a temperature range of 423-533 K. A threshold type creep behavior was measured and explained by observed dislocation-particle interactions. The experimental threshold stress values at various temperatures were compared with existing theoretical models. None of the available models could account for the decrease in threshold creep strength with increasing temperature

  3. Pure and Y-substituted BaZrO3 ceramics. A possible support material for fabrication of YBa2Cu3O7-x high-Tc superconductors

    International Nuclear Information System (INIS)

    Wang Xiandong.

    1993-01-01

    This thesis concerns the preparation and characterization of cuprate based high-T c superconductors (Y-123 and Bi-2223) and especially development and testing of BaZrO 3 based materials. The formation of YBa 2 Cu 3 O y (Y-123) by a CO 2 -free route involving reaction sintering of stoichiometric mixtures of chemically prepared fine powders of Y 2 BaCuO 5 , BaCuO 2 and CuO have been studied by thermal and XRD analysis. The synthesis and sintering of BaZrO 3 powders prepared by the hydroxide-alkoxide-methanol sol-gel route have been studied. The phase relations in the system BaO-Y 2 O 3 -ZrO 2 have been studied to determine the solid solubility limits for the perovskite phase Ba X Y Y Zr Z O N (X+X+Z=3) at 1500 deg. C. In the binary system Y 2 O 3 -BaZrO 3 the solubility limit was found to be ≅19 mol% Y 2 O 3 , i.e. Ba 0.81 Y 0. 4 2 Zr 0.81 O 3 . along the joint BaYO 2.5 -Ba the boundary was determined to be at BaY 0.21 Zr 0 . 79 O 2.895 . evidence for a new solid solution series between Ba 3 Y 4 O 9 and ZrO 2 are given, and a partial 1500 deg. C phase diagram for the ternary system BaO-Y 2 O 3 -ZrO 2 is presented. The growth of BaZrO 3 single crystals have been attempted both by a laser zone floating technique and flux methods. The compatibility between YBa 2 Cu 3 O 7 -X and BaZrO 3 , Ba X Y Y Zr Z O 3-δ as well as BaHfO 3 have been studied at 950 deg. and 1050 deg. C. The results show the four most promising candidates as support materials for fabrication of YBa 2 Cu 3 O y to be BaHfO 3 , BaY 0.05 Zr 0.95 O 2.975 , , BaZrO 3 and BaY 0.1 Zr 0.9 O 2.95 . (EG)

  4. Structure and properties of Al-Mg-Li-Zr system alloys

    International Nuclear Information System (INIS)

    Fridlyander, I.N.; Dolzhanskij, Yu.M.; Sandler, V.S.; Tyurin, .V.; Nikol'skaya, T.I.

    1977-01-01

    Studied were the structure and mechanical properties of the Al-Mg-Li-Zr alloy system (including 01420 alloy) containing 1.6-5.3%Li and 1.0-8.8%Mg). Electron microscopic studies of 01420 alloy conducted after heating at 450 deg C for 4 hours revealed non-uniformly distributed precipitations of a metastable phase ZrAl 3 , having spherical and needle-like configurations. These precipitations, together with zirconium contained in the solid solution, retard recrystallization. The introduction of 0.1-0.2% Zr decreases the limiting solubility of magnesium and lithium in the aluminium solid solution and leads to the formation of disperse equilibrium (S and, possibly, γ) phases with the size of 0.1-0.5 mcm. These phases were observed in the alloys containing (>=) 4% Mg and 1.9-3.5% Li. The method of planned experiment was used to study the principles governing the variation of the mechanical properties of the alloys subjected to water hardening and after aging at 170 deg C for 16 hours. It was established that the strength properties of the hardened alloys become higher, and the relative elongation decreases with the content of lithium and especially magnesium. It would be more proper to assess strengthening in the course of aging according to variation in the yield point and hardness. The effect of aging determined by the yield point depends on the content of lithium and is practically independent of the concentration of magnesium

  5. Enhanced Proton Conductivity in Y-Doped BaZrO3 via Strain Engineering.

    Science.gov (United States)

    Fluri, Aline; Marcolongo, Aris; Roddatis, Vladimir; Wokaun, Alexander; Pergolesi, Daniele; Marzari, Nicola; Lippert, Thomas

    2017-12-01

    The effects of stress-induced lattice distortions (strain) on the conductivity of Y-doped BaZrO 3 , a high-temperature proton conductor with key technological applications for sustainable electrochemical energy conversion, are studied. Highly ordered epitaxial thin films are grown in different strain states while monitoring the stress generation and evolution in situ. Enhanced proton conductivity due to lower activation energies is discovered under controlled conditions of tensile strain. In particular, a twofold increased conductivity is measured at 200 °C along a 0.7% tensile strained lattice. This is at variance with conclusions coming from force-field simulations or the static calculations of diffusion barriers. Here, extensive first-principles molecular dynamic simulations of proton diffusivity in the proton-trapping regime are therefore performed and found to agree with the experiments. The simulations highlight that compressive strain confines protons in planes parallel to the substrate, while tensile strain boosts diffusivity in the perpendicular direction, with the net result that the overall conductivity is enhanced. It is indeed the presence of the dopant and the proton-trapping effect that makes tensile strain favorable for proton conduction.

  6. Mechanical properties and corrosion behavior of Mg-Gd-Ca-Zr alloys for medical applications.

    Science.gov (United States)

    Shi, Ling-Ling; Huang, Yuanding; Yang, Lei; Feyerabend, Frank; Mendis, Chamini; Willumeit, Regine; Ulrich Kainer, Karl; Hort, Norbert

    2015-07-01

    Magnesium alloys are promising candidates for biomedical applications. In this work, influences of composition and heat treatment on the microstructure, the mechanical properties and the corrosion behavior of Mg-Gd-Ca-Zr alloys as potential biomedical implant candidates were investigated. Mg5Gd phase was observed at the grain boundaries of Mg-10Gd-xCa-0.5Zr (x=0, 0.3, 1.2wt%) alloys. Increase in the Ca content led to the formation of additional Mg2Ca phase. The Ca additions increased both the compressive and the tensile yield strengths, but reduced the ductility and the corrosion resistance in cell culture medium. After solution heat treatment, the Mg5Gd particles dissolved in the Mg matrix. The compressive strength decreased, while the corrosion resistance improved in the solution treated alloys. After ageing at 200°C, metastable β' phase formed on prismatic planes and a new type of basal precipitates have been observed, which improved the compressive and tensile ultimate strength, but decreased the ductility. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Ab initio hybrid DFT calculations of BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Eglitis, Roberts I., E-mail: rieglitis@gmail.com

    2015-12-15

    Highlights: • Surface energies for AO{sub 3}-term (111) surfaces are larger than for Ti (Zr)-term surfaces. • A increase of Ti−O (Zr−O) bond covalency near the ABO{sub 3} (111) surface relative to the bulk is observed. • The ABO{sub 3} (111) surface energy is larger than the earlier calculated (001) surface energy. • Band gap for PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces becomes smaller, but for BaTiO{sub 3} (111) larger with respect to the bulk . - Abstract: The results of ab initio calculations for polar BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces using the CRYSTAL code are presented. By means of the hybrid B3LYP approach, the surface relaxation has been calculated for two possible B (B = Ti or Zr) or AO{sub 3} (A = Ba, Pb or Sr) BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surface terminations. According to performed B3LYP calculations, all atoms of the first surface layer, for both terminations, relax inwards. The only exception is a small outward relaxation of the PbO{sub 3}-terminated PbTiO{sub 3} (111) surface upper layer Pb atom. B3LYP calculated surface energies for BaO{sub 3}, PbO{sub 3}, SrO{sub 3} and PbO{sub 3}-terminated BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces are considerably larger than the surface energies for Ti (Zr)-terminated (111) surfaces. Performed B3LYP calculations indicate a considerable increase of Ti−O (Zr−O) chemical bond covalency near the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surface relative to the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} bulk. Calculated band gaps at the Γ-point near the PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} (111) surfaces are reduced, but near BaTiO{sub 3} (111) surfaces increased, with respect to the BaTiO{sub 3}, PbTiO{sub 3}, SrZrO{sub 3} and PbZrO{sub 3} bulk band gap at the Γ-point values.

  8. PROPERTIES OF Eu3+ LUMINESCENCE IN THE MONOCLINIC Ba2MgSi2O7

    Directory of Open Access Journals (Sweden)

    Shansh an Yao

    2011-09-01

    Full Text Available Red-emitting phosphors Ba2-xMgSi2O7: Eux3+ was prepared by combustion-assisted synthesis method and an efficient red emission under near-ultraviolet (UV was observed. The luminescence and crystallinity were investigated using luminescence spectrometry and X-ray diffractometer. The emission spectrum shows that the most intense peak is located at 614 nm, which corresponds to the 5D0 → 7F2 transitions of Eu3+. The phosphor has two main excitation peaks located at 394 and 465 nm, which match the emission of UV and blue light-emitting diodes, respectively. The effect of Eu3+ concentration on the emission spectrum of Ba2MgSi2O7:Eu3+ phosphor was studied. The results showed that the emission intensity increased with increasing Eu3+ concentration, and then decreased because of concentration quenching. The critical quenching concentration of Eu3+ in Ba2MgSi2O7: Eu3+ phosphor is about 0.05 mol. The mechanism of concentration quenching of Ba2MgSi2O7: Eu3+ luminescence is energy transfer between Eu3+ ions casued by the dipole-dipole interaction.

  9. Crystallization Mechanism and Kinetics of BaO-Li2O-ZrO2-SiO2 Glasses

    Directory of Open Access Journals (Sweden)

    Cristian Berto da Silveira

    2002-03-01

    Full Text Available Differential thermal analysis and scanning electron microscopy were used to determine the influence of the addition of BaO on the crystallization mechanism of Li2O-ZrO2-SiO2 systems. As the concentration of BaO in the samples increased, a transition occurred in the predominant crystallization mechanism, which passed from superficial to volumetric. To determine the maximum nucleation rate, the crystallization kinetics of the sample containing 20 mole % BaO, which showed the most uniform crystallization, was studied by counting the nuclei with an image analyzer. The first nuclei appeared at the first endothermic inflection point (at the start of Tg, at 440 °C, while the maximum number of nuclei was counted at the midpoint of the glass transition region (446 °C. These results are similar to those observed for other materials that crystallize in volume, and confirm scanning electron microscopy data.

  10. Effect of minor Er and Zr on microstructure and mechanical properties of Al-Mg-Mn alloy (5083) welded joints

    Energy Technology Data Exchange (ETDEWEB)

    Dongxia, Yang, E-mail: yangdongxia116@emails.bjut.edu.cn [Department of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China); Xiaoyan, Li; Dingyong, He; Hui, Huang [Department of Materials Science and Engineering, Beijing University of Technology, Beijing 100124 (China)

    2013-01-20

    Samples of Al-Mg-Mn and Al-Mg-Mn-Er-Zr alloys were welded using the method of laser welding. The influence of Er and Zr on microstructure, microhardness and mechanical properties of the Al-Mg-Mn alloy welded joints were investigated. It has been found that addition of Er and Zr refines the grain size in the fusion zone, due to the formation of primary Al{sub 3}Zr and Al{sub 3}Er. Fine equiaxed grains are dominated near the fusion boundary of the Al-Mg-Mn-Er-Zr alloy joint, which is contrary with the columnar crystal in the Al-Mg-Mn alloy joint. Microhardness of the center of the fusion zone rises from 74HV{sub 0.1} to 84HV{sub 0.1} owing to the grain refinement by Er and Zr. The tensile test result shows that the ultimate tensile strength and yield strength are improved by adding Er and Zr. The main reason for this is related to grain refining strengthening.

  11. FRACTIONAL RECRYSTALLIZATION KINETICS IN DIRECTLY COLD ROLLED Al-Mg, Al-Mg-Sc AND Al-Mg-Sc-Zr ALLOY

    Directory of Open Access Journals (Sweden)

    M. S. Kaiser

    2014-12-01

    Full Text Available The evaluation of texture as a function of recrystallization has been characterized for directly cold rolled Al-6Mg, Al-6Mg-0.4Sc and Al-6Mg-0.4Sc-0.2Zr alloys. Samples were annealed isothermally at 400 °C for 1 to 240 minutes to allow recrystallization. Recrystallization kinetics of the alloys is analyzed from the micro-hardness variation. Isothermally annealed samples of aluminum alloys were also studied using JMAK type analysis to see if there exists any correlation between the methods. Recrystallization fraction behavior between two methods the scandium added alloys show the higher variation due to precipitation hardening and higher recrystallization behavior. The scandium and zirconium as a combined shows the more variation due to formation of Al3(Sc, Zr precipitate. From the microstructure it is also observed that the base Al-Mg alloy attained almost fully re-crystallized state after annealing at 400 °C for 60 minutes

  12. Glass formation and physicochemical properties of glasses of Ba(PO3)2-LiRAlF6 (R=Mg, Ca, Sr, Ba) system

    International Nuclear Information System (INIS)

    Khalilev, V.D.; Chkhenkeli, G.D.; Vakhrameev, V.I.

    1987-01-01

    Glass formation regions, crystallizability, optical constants, thermal linear expansion coefficient and IR absorption spectra of glass are studied in Ba(PO) 3 ) 2 - LiRAlF 6 system where R=Mg, Ca, Sr, Ba. The carried out investigation confirms participation of introduced fluorides (as modified cryolites) in structural transformations manifested in increase of glass formation regions and nonlinear variations of properties

  13. Effects of Sm addition on electromagnetic interference shielding property of Mg-Zn-Zr alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chubin [Chongqing University, College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloy, Chongqing (China); Gannan Normal University, Jiangxi Provincial Engineering Research Center for Magnesium Alloy, Ganzhou (China); Pan, Fusheng; Chen, Xianhua [Chongqing University, College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloy, Chongqing (China); Luo, Ning [Gannan Normal University, Jiangxi Provincial Engineering Research Center for Magnesium Alloy, Ganzhou (China)

    2017-06-15

    The electromagnetic interference (EMI) shielding of Sm-containing magnesium alloys in the 30-1500 MHz testing frequency range was investigated by coaxial cable method. The results demonstrated that Mg-3Zn alloys displayed the best electromagnetic shielding property. When 0.5 wt% of Zr was added for crystal grain refinement, the shielding effectiveness (SE) was apparently reduced. The addition of the rare earth element Sm in ZK magnesium alloys can improve the electromagnetic interference shielding of magnesium alloys. The main reason for the differences in electromagnetic interference shielding of magnesium alloys was the change in conductivity. The addition of Zr in Mg-Zn alloys can refine the grains and consequently improve the grain boundary area significantly. Therefore, the number of irregularly arranged atoms at the grain boundaries increased, decreasing the conductivity of magnesium alloys and leading to a decrease in the electromagnetic interference shielding. Following the Sm addition, the Mg-Zn-Sm phase was precipitated at the grain boundaries and in cores. The precipitation of Sm-containing rare earth phases could consume the solid-soluted Zn atoms within the Mg, resulting in an increase in electrical conductivity and electromagnetic interference shielding improvement. (orig.)

  14. Microstructures and mechanical properties of grain refined Al-Li-Mg casting alloy by containing Zr and Ti

    International Nuclear Information System (INIS)

    Saikawa, Seiji; Nakai, Kiyoshi; Sugiura, Yasuo; Kamio, Akihiko.

    1995-01-01

    Mechanical properties and microstructures of various Al-Li-Mg alloy castings containing small amount of Zr and/or Ti were investigated. The δ(AlLi) phase was observed to crystallize in the dendrite-cell gaps as well as on the grain boundaries. Microsegregation of Mg also occurred in the solidified castings. The β(Al 3 Zr) or Al-Zr-Ti compounds crystallize during solidification and remain even after solid solution treatment at 803 K for 36 ks. The grain sizes of Al-2.5%Li-2%Mg alloy castings become finer by the addition of 0.15%Zr and 0.12%Ti compared with each addition of 0.15%Zr or 0.12%Ti. The age hardening is accelerated by the addition of 0.15%Zr. In an Al-2.5%Li-2%Mg-0.15%Zr-0.12%Ti alloy casting poured into a metallic mold and aged at 453 K for 36 ks, ultimate tensile strength, Young's modulus and density were 417 MPa, 80 GPa and was 2.52 g/cm 3 , respectively. Its specific strength and modulus are higher by 50.3 and 13.9% than those of the conventional AC4C-T6 casting. (author)

  15. Impedance spectroscopy studies on lead free Ba1-xMgx(Ti0.9Zr0.1)O3 ceramics

    Science.gov (United States)

    Ben Moumen, S.; Neqali, A.; Asbani, B.; Mezzane, D.; Amjoud, M.; Choukri, E.; Gagou, Y.; El Marssi, M.; Luk'yanchuk, Igor A.

    2018-06-01

    Ba1-xMgx(Ti0.9Zr0.1)O3 (x = 0.01 and 0.02) ceramics were prepared using the conventional solid state reaction. Rietveld refinement performed on X-ray diffraction patterns indicates that the samples are tetragonal crystal structure with P4mm space group. By increasing Mg content from 1 to 2% the unit cell volume decreased. Likewise, the grains size is greatly reduced from 10 μm to 4 μm. The temperature dependence of dielectric constants at different frequencies exhibited typical relaxor ferroelectric characteristic, with sensitive dependence in frequency and temperature for ac conductivity. The obtained activation energy values were correlated to the proposed conduction mechanisms.

  16. Magnesium hexafluoridozirconates MgZrF{sub 6}.5H{sub 2}O, MgZrF{sub 6}.2H{sub 2}O, and MgZrF{sub 6}. Structures, phase transitions, and internal mobility of water molecules

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimenko, Andrey V.; Gaivoronskaya, Kseniya A.; Slobodyuk, Arseny B.; Didenko, Nina A. [Institute of Chemistry, Russian Academy of Sciences, Vladivostok (Russian Federation)

    2017-12-04

    The MgZrF{sub 6}.nH{sub 2}O (n = 5, 2 and 0) compounds were studied by the methods of X-ray diffraction and {sup 19}F, MAS {sup 19}F, and {sup 1}H NMR spectroscopy. At room temperature, the compound MgZrF{sub 6}.5H{sub 2}O has a monoclinic C-centered unit cell and is composed of isolated chains of edge-sharing ZrF{sub 8} dodecahedra reinforced with MgF{sub 2}(H{sub 2}O){sub 4} octahedra and uncoordinated H{sub 2}O molecules and characterized by a disordered system of hydrogen bonds. In the temperature range 259 to 255 K, a reversible monoclinic <-> two-domain triclinic phase transition is observed. The phase transition is accompanied with ordering of hydrogen atoms positions and the system of hydrogen bonds. The structure of MgZrF{sub 6}.2H{sub 2}O comprises a three-dimensional framework consisting of chains of edge-sharing ZrF{sub 8} dodecahedra linked to each other through MgF{sub 4}(H{sub 2}O){sub 2} octahedra. The compound MgZrF{sub 6} belongs to the NaSbF{sub 6} type and is built from regular ZrF{sub 6} and MgF{sub 6} octahedra linked into a three-dimensional framework through linear Zr-F-Mg bridges. The peaks in {sup 19}F MAS spectra were attributed to the fluorine structural positions. The motions of structural water molecules were studied by variable-temperature {sup 1}H NMR spectroscopy. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Zr-based conversion layer on Zn-Al-Mg alloy coated steel sheets: insights into the formation mechanism

    International Nuclear Information System (INIS)

    Lostak, Thomas; Maljusch, Artjom; Klink, Björn; Krebs, Stefan; Kimpel, Matthias; Flock, Jörg; Schulz, Stephan; Schuhmann, Wolfgang

    2014-01-01

    Zr-based conversion layers are considered as environmentally friendly alternatives replacing trication phosphatation in the automotive industry. Based on excellent electronic barrier properties they provide an effective corrosion protection of the metallic substrate. In this work, thin protective layers were grown on novel Zn-Al-Mg alloy coated steel sheets by increasing the local pH-value at the sample surface leading to deposition of a Zr-based conversion layer. For this purpose Zn-Al-Mg alloy (ZM) coated steel sheets were treated in an aqueous model conversion solution containing well-defined amounts of hexafluorozirconic acid (H 2 ZrF 6 ) and characterized after different immersion times with SKPFM and field emission SEM (FE-SEM)/EDX techniques. A deposition mechanism of Zr-based conversion coatings on microstructural heterogeneous Zn-Al-Mg alloy surfaces was proposed

  18. 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.

  19. Broad Temperature Pinning Study of 15 mol.% Zr-Added (Gd, Y)-Ba-Cu-O MOCVD Coated Conductors

    Energy Technology Data Exchange (ETDEWEB)

    Xu, AX; Khatri, N; Liu, YH; Majkic, G; Galstyan, E; Selvamanickam, V; Chen, YM; Lei, CH; Abraimov, D; Hu, XB; Jaroszynski, J; Larbalestier, D

    2015-06-01

    BaZrO3 (BZO) nanocolumns have long been shown to be very effective for raising the pinning force F-p of REBa2Cu3Ox (REBCO, where RE = rare earth) films at high temperatures and recently at low temperatures too. We have successfully incorporated a high density of BZO nanorods into metal organic chemical vapor deposited (MOCVD) REBCO coated conductors via Zr addition. We found that, compared to the 7.5% Zr-added coated conductor, dense BZO nanorod arrays in the 15% Zr-added conductor are effective over the whole temperature range from 77 K down to 4.2 K. We attribute the substantially enhanced J(c) at 30 K to the weak uncorrelated pinning as well as the strong correlated pinning. Meanwhile, by tripling the REBCO layer thickness to similar to 2.8 mu m, the engineering critical current density J(e) at 30 K exceeds J(e) of optimized Nb-Ti wires at 4.2 K.

  20. Thermally stimulated currents in ZrO2:MgO

    International Nuclear Information System (INIS)

    Muccillo, E.N.S.

    1987-01-01

    Thermally Stimulated Depolarization Current measurements between 100 K and 350 K have been performed in ZrO 2 :MgO ceramic samples to discriminate the several kinds of polarization (orientational and interfacial polarization, and extrinsic and intrinsic space charge effects) to allow for the use of the technique in the study of solid solution formation in partially stabilized zirconia. The samples were prepared by conventional ceramic processing methods. Different electrode materials have been used: colloidal graphite, silver, gold, and also insulating electrodes (e.g. mylar foils). The current spectra obtained are strongly dependent upon the electrode material showing the presence of spacial charge phenomenon in these ceramics. (Author) [pt

  1. Thermally stimulated currents in ZrO2:MgO

    International Nuclear Information System (INIS)

    Muccillo, E.N.S.

    1987-01-01

    Thermally Stimulated Depolarization Current measurements between 100 K and 350 K have been performed in ZrO 2 :MgO ceramic samples to discriminate the several Kinds of polarization (orientational and interfacial polarization, and extrinsic and intrinsic space charge effects) to allow for the use of the technique in the study of solid solution formation in partially stabilized zirconia. The samples were prepared by conventional ceramic processing methods. Different electrode materials have been used: colloidal graphite, silver, gold, and also insulating electrodes (e.g. mylar foils). The current spectra obtained are strongly dependent upon the electrode material showing the presence of spacial charge phenomenon in these ceramics. (Author) [pt

  2. Preparation and dielectric properties of Dy, Er-doped BaZr0.2Ti0.8O3 ceramics

    International Nuclear Information System (INIS)

    Hao Sue; Sun Liang; Huang Jinxiang

    2008-01-01

    Ba(Zr x Ti 1-x )O 3 nanopowders and ceramics with different Zr/Ti ratios of 1:9; 2:8; 2.5:7.5; 3.5:6.5 and 4:6 (x = 0.1, 0.2, 0.25, 0.35, 0.4) have been prepared by sol-gel technology using inorganic zirconium as raw materials, and Zr/Ti ratio of 2:8 is determined as the best one according to the measurements of dielectric properties. So the modified Ba(Zr 0.2 ,Ti 0.8 )O 3 ceramics doped by Dy and Er (the additive content is 0.10%, 0.15%, 0.20%, 0.30% and 0.50% molar ratio, respectively) have been prepared, and the effects of rare earth on the microstructure and dielectric properties of Ba(Zr 0.2 ,Ti 0.8 )O 3 ceramics have been studied. The experimental results show that the effect of Er is better than that of Dy in improving the dielectric properties of BaZr 0.2 Ti 0.8 O 3 ceramics. When the content of Er is 0.15 mol%, the dielectric constant is the highest of 12767, while the dielectric loss is lowered to 0.011; the frequency stabilities and the temperature dependence are also better, which is suitable for application in condenser field

  3. Variations of force constants, M-O distances and bond order in solid solutions between Ba/sub 2/MgUO/sub 6/ and Ba/sub 2/MgWO/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Fadini, A [Tuebingen Univ. (Germany, F.R.). Inst. fuer Chemie

    1977-12-01

    In solid solutions between the 1:1 ordered perovskites Ba/sub 2/MgUO/sub 6/ and Ba/sub 2/MgWO/sub 6/ (system Ba/sub 2/MgUsub(1-x)Wsub(x)O/sub 6/) the force constants of the UO/sub 6/ and WO/sub 6/ octahedras are variied. The valence force constants fsub(MO) tend to adjust for each x. The bond order and the M-O distances are reported as well.

  4. Microstructure and Mechanical Properties of an Al-Li-Mg-Sc-Zr Alloy Subjected to ECAP

    Directory of Open Access Journals (Sweden)

    Anna Mogucheva

    2016-10-01

    Full Text Available The effect of post-deformation solution treatment followed by water quenching and artificial aging on microstructure and mechanical properties of an Al-Li-Mg-Sc-Zr alloy subjected to equal-channel angular pressing (ECAP was examined. It was shown that the deformed microstructure produced by ECAP remains essentially unchanged under solution treatment. However, extensive grain refinement owing to ECAP processing significantly affects the precipitation sequence during aging. In the aluminum-lithium alloy with ultrafine-grained (UFG microstructure, the coarse particles of the S1-phase (Al2LiMg precipitate on high-angle boundaries; no formation of nanoscale coherent dispersoids of the δ′-phase (Al3Li occurs within grain interiors. Increasing the number of high-angle boundaries leads to an increasing portion of the S1-phase. As a result, no significant increase in strength occurs despite extensive grain refinement by ECAP.

  5. Effect of Fe2O3 on the sintering and stabilization of ZrO2-MgO system

    International Nuclear Information System (INIS)

    Longo, E.; Paskocimas, C.A.; Ambrosecchia, J.R.; Weffort, L.C.; Baldo, J.B.; Leite, L.R.; Varela, J.A.

    1990-01-01

    Through X-ray diffraction, it was studied the influence of the iron oxide (Fe 2 O 3 ) as a mineralizer in the development of partially stabilized zirconia phases (cubic/tetragonal) within the system ZrO 2 -MgO. In the preparation of the studied compositions it was utilized a Brazilian comercial zirconia powder and different precursors for the MgO and Fe 2 O 3 additives. It was observed that the main effect of iron oxide consisted on the speed up of the solid solution formation process of Mg + 2 in the Zr +4 sub-lattice, as well as being a very effective sintering agent. (author) [pt

  6. On the Precipitation in an Ag-Containing Mg-Gd-Zr Alloy

    Science.gov (United States)

    Zhang, Yu; Zhu, Yuman; Rong, Wei; Wu, Yujuan; Peng, Liming; Nie, Jian-Feng; Birbilis, Nick

    2018-02-01

    The evolution of precipitates in a high-strength Mg-2.4Gd-0.4Ag-0.1Zr (at. pct) alloy was investigated using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The precipitation of Mg-2.4Gd-0.4Ag-0.1Zr includes β- and γ-type precipitates, the latter involving a hitherto unreported precipitation sequence that is the focus of the present study. The β-type precipitation sequence is described as follows: supersaturated solid solution (S.S.S.S.) → ordered solute clusters → zigzag GP zones → β' → βF' → β 1 → β. Compared with the precipitation sequence of the Mg-Gd system, the proposed β-type precipitation sequence includes ordered solute clusters, zigzag GP zones, and βF' , but excludes β″. The strain field around the coarsened β' phase is supposed to stimulate the formation of the β^'F phase. Furthermore, the βF' phase provides preferential nucleation site for the β 1 phase. The γ-type precipitation sequence is proposed as follows: S.S.S.S. → basal GP zones → γ''' → γ″ → γ. The crystal structures, morphologies, and orientations of the basal GP zone, γ''', γ″, γ phases were comprehensively examined and established herein. The results are described in the context of other, but similar, alloy systems. A holistic description of the precipitate evolution in Ag-containing Mg-Gd alloys is discussed and rationalized.

  7. Electron mass anisotropy of BaZrO3 doped YBCO thin films in pulsed magnetic fields up to 30 T

    International Nuclear Information System (INIS)

    Palonen, H; Huhtinen, H; Paturi, P; Shakhov, M A

    2013-01-01

    The high anisotropy of the critical current density in the high-temperature superconductor YBa 2 Cu 3 O 6+x can be compensated by changing the pinning landscape, for example, through doping with BaZrO 3 . We measure the change due to BaZrO 3 doping in the effective electron mass anisotropy, γ, by resistive measurements of the upper critical field in pulsed high magnetic fields. It is found that the angular dependence of the upper critical field follows the Blatter scaling up to 30 T but the irreversibility field does not. We also report a significant reduction in the effective electron mass anisotropy from 6.0 to 3.4 by BaZrO 3 doping. (paper)

  8. Mechanical Properties and Microstructure of TIG and FSW Joints of a New Al-Mg-Mn-Sc-Zr Alloy

    Science.gov (United States)

    Xu, Guofu; Qian, Jian; Xiao, Dan; Deng, Ying; Lu, Liying; Yin, Zhimin

    2016-04-01

    A new Al-5.8%Mg-0.4%Mn-0.25%Sc-0.10%Zr (wt.%) alloy was successfully welded by tungsten inert gas (TIG) and friction stir welding (FSW) techniques, respectively. The mechanical properties and microstructure of the welded joints were investigated by microhardness measurements, tensile tests, and microscopy methods. The results show that the ultimate tensile strength, yield strength, and elongation to failure are 358, 234 MPa, and 27.6% for TIG welded joint, and 376, 245 MPa and 31.9% for FSW joint, respectively, showing high strength and superior ductility. The TIG welded joint fails in the heat-affected zone and the fracture of FSW joint is located in stirred zone. Al-Mg-Mn-Sc-Zr alloy is characterized by lots of dislocation tangles and secondary coherent Al3(Sc,Zr) particles. The superior mechanical properties of the TIG and FSW joints are mainly derived from the Orowan strengthening and grain boundary strengthening caused by secondary coherent Al3(Sc,Zr) nano-particles (20-40 nm). For new Al-Mg-Mn-Sc-Zr alloy, the positive effect from secondary Al3(Sc, Zr) particles in the base metal can be better preserved in FSW joint than in TIG welded joint.

  9. Synthesis and electrical characterization of BaZr0.9Ho0.1O3-δ electrolyte ceramic for IT - SOFCs

    Science.gov (United States)

    Saini, Deepash S.; Singh, Lalit K.; Bhattacharya, D.

    2018-04-01

    A cost-effective modified combustion method using citric acid and glycine has recently been developed to synthesize high quality, and nanosized BaZr0.9Ho0.1O3 ceramic powder. BaZr0.9Ho0.1O3-δ ceramic powder was characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). XRD pattern of BaZr0.9Ho0.1O3-δ ceramic sintered at 1600 °C has shown that pure phase of BaZr0.9Ho0.1O3-δ with cubic Pm3¯m space group symmetry. The transmission electron microscopic investigation has shown that the particle size of the powder calcined at 1100 °C was in the range 30-80 nm. The FESEM image of sintered pellet at 1600 °C for 4 h reveals porous nature of BaZr0.9Ho0.1O3-δ with 83.7 relative density. Impedance analysis reveal three type relaxations in the temperature range 250 °C to 500 °C as studied at different frequencies over 100 Hz to 1 MHz in air. The grain boundary conductivity of BaZr0.9Ho0.1O3-δ ceramic is found lower then grain (bulk) conductivity due to core-space charge layer behavior in grain boundary.

  10. Reactive force field simulation of proton diffusion in BaZrO{sub 3} using an empirical valence bond approach

    Energy Technology Data Exchange (ETDEWEB)

    Raiteri, Paolo; Gale, Julian D [Nanochemistry Research Institute, Department of Chemistry, Curtin University, GPO Box 1987, Perth, WA 6845 (Australia); Bussi, Giovanni, E-mail: paolo@ivec.org, E-mail: julian@ivec.org [Scuola Internazionale Superiore di Studi Avanzati (SISSA), Via Bonomea 265, 34136 Trieste (Italy)

    2011-08-24

    A new reactive force field to describe proton diffusion within the solid oxide fuel cell material BaZrO{sub 3} has been derived. Using a quantum mechanical potential energy surface, the parameters of an interatomic potential model to describe hydroxyl groups within both pure and yttrium-doped BaZrO{sub 3} have been determined. Reactivity is then incorporated through the use of the empirical valence bond model. Molecular dynamics simulations (EVB-MD) have been performed to explore the diffusion of hydrogen using a stochastic thermostat and barostat whose equations are extended to the isostress-isothermal ensemble. In the low concentration limit, the presence of yttrium is found not to significantly influence the diffusivity of hydrogen, despite the proton having a longer residence time at oxygen adjacent to the dopant. This lack of influence is due to the fact that trapping occurs infrequently, even when the proton diffuses through octahedra adjacent to the dopant. The activation energy for diffusion is found to be 0.42 eV, in good agreement with experimental values, though the prefactor is slightly underestimated.

  11. Dielectric behavior of samarium-doped BaZr0.2Ti0.8O3 ceramics

    International Nuclear Information System (INIS)

    Li, Yuanliang; Wang, Ranran; Ma, Xuegang; Li, Zhongqiu; Sang, Rongli; Qu, Yuanfang

    2014-01-01

    Graphical abstract: - Highlights: • We investigate dielectric properties and phase transition of Sm 3+ -doped BaZr 0.2 Ti 0.8 O 3 ceramics. • The additive amount of Sm 2 O 3 can greatly affect the dielectric properties. • The materials undergo a diffuse type ferroelectric phase transition. • There is an alternation of substitution preference of Sm 3+ ion for the host cations in perovskite lattice. - Abstract: The dielectric properties and phase transition of Sm 3+ -doped BaZr 0.2 Ti 0.8 O 3 (BZT20) ceramics were investigated. Room temperature X-ray diffraction study suggested that the compositions had single-phase cubic symmetry. Microstructure studies showed that the grain size decreased and that the Sm 2 O 3 amount markedly affected the dielectric properties of BZT20. A dielectric constant of 5700 at 0.2 mol% Sm 2 O 3 and a dissipation factor of only 0.0011 at 2 mol% Sm 2 O 3 were observed, indicating that BZT20 had significant potential applications. Moreover, the dielectric constant, dissipation factor, phase-transition temperature, and maximum dielectric constant increased with increased Sm 2 O 3 amount at ≤0.2 mol% Sm 2 O 3 but decreased with increased Sm 2 O 3 amount at >0.2 mol% Sm 2 O 3

  12. On the high temperature phase transition in Ba(Zr0.20Ti0.80O3 ceramic

    Directory of Open Access Journals (Sweden)

    K. P. Chandra

    2017-08-01

    Full Text Available Temperature dependent X-ray diffraction (XRD and dielectric properties of perovskite Ba(Zr0.2Ti0.8O3 ceramic prepared using a standard solid-state reaction process is presented. Along with phase transitions at low temperature, a new phase transition at high temperature (873∘C at 20Hz, diffusive in character has been found where the lattice structure changes from monoclinic (space group: P2∕m to hexagonal (space group: P6∕mmm. This result places present ceramic in the list of potential candidate for intended high temperature applications. The AC conductivity data followed hopping type charge conduction and supports jump relaxation model. The experimental value of d33=98pC/N was found. The dependence of polarization and strain on electric field at room temperature suggested that lead-free Ba(Zr0.2Ti0.8O3 is a promising material for electrostrictive applications.

  13. Ferroelectric BaPbO3/PbZr0.53Ti0.47/BaPbO3 heterostructures

    International Nuclear Information System (INIS)

    Liang Chunsheng; Wu Jennming; Chang Mingchu

    2002-01-01

    BaPbO 3 (BPO)/PbZr 0.53 Ti 0.47 (PZT)/BPO heterostructures were fabricated by combining the sol-gel and rf-magnetron sputtering techniques. Experimental results indicate that the BPO bottom electrodes effectively prevent the formation of the rosette structure of PZT, producing smooth surfaces. Additionally, ferroelectric, fatigue, and leakage current properties were markedly improved when both the top and the bottom electrodes were changed from Pt to BPO. These improvements are due to a superior electrode/ferroelectric interface. BPO is better than Pt and other oxide electrodes for use in PZT ferroelectric capacitors due to its remarkably improved properties and quite low growth temperature

  14. Nano-SIMS analysis of Mg, Sr, Ba and U in natural calcium carbonate

    International Nuclear Information System (INIS)

    Sano, Yuji; Shirai, Kotaro; Takahata, Naoto; Hirata, Takafumi; Sturchio, Neil C.

    2005-01-01

    Concentrations of minor (Mg and Sr) and trace (Ba and U) elements in four natural calcium carbonate samples were first analyzed by inductively coupled plasma mass spectrometry (ICP-MS) after chemical dissolution and calibrated against a standard dolomite. Their homogeneities were checked by in situ laser ablation (LA) ICP-MS with 10-20 spots. The carbonate samples were measured by using a high lateral resolution secondary ion mass spectrometer (Nano-SIMS NS50). A ∼4 nA O - primary beam was used to sputter a 5 - 6-μm diameter crater on the sample surface, and secondary positive ions were extracted for mass analysis using an accelerating voltage of 8 kV and a Mattauch-Herzog geometry. A multi-collector system was adjusted to detect 26 Mg + , 43 Ca + , 88 Sr + , 138 Ba + , 238 U 16 O 2 + ions at the same time. A resolving power of 2500 - 5000 at 10% peak height was attained by an entrance slit set at 40 μm, and each exit slit at 50 μm with adequate flat-topped peaks. The observed 26 Mg/ 43 Ca, 88 Sr/ 43 Ca, 138 Ba/ 43 Ca and 238 U 16 O 2 / 43 Ca ratios agreed well with those measured by LA-ICP-MS. Foraminifera shells were analyzed at 5 - 6 μm scale by Nano-SIMS. There was a large variation of the Mg/Ca ratios, up to ±38%, even in a single fragment of the shell, suggesting that although the ratios provide a useful paleoceanographic proxy at bulk scale, they may reflect a more complex pattern at <10 μm scale. (author)

  15. Effect of processing variables on microstructure and properties of two Al-Li-Cu-Mg-Zr alloys

    International Nuclear Information System (INIS)

    Palmer, I.G.; Lewis, R.E.; Crooks, D.D.

    1984-01-01

    Two Al-Li-Cu-Mg-Zr alloys have been prepared in the form of both powder metallurgy (PM) and ingot metallurgy (IM) alloys. The compositions were selected to meet certain program goals based on the results of an alloy development phase, the details of which have been previously published. The target compositions were Al-3Li-1.5Cu-1Mg-0.2Zr and Al-3Cu-2Li-1Mg-0.2Zr. The PM alloys were prepared from chill cast remelt stock by centrifugal atomization in helium, followed by screening, degassing, and extrusion. The IM alloys were prepared by direct chill (DC) casting, homogenization and extrusion. Full details of the production of the alloys are given. The effects of various processing conditions on microstructure and properties were evaluated, including different heat treatments and stretching conditions. These effects are described in detail with particular emphasis on a comparison of the PM and IM alloys. 10 references

  16. Microstructure and mechanical properties of Al-Cu-Mg-Mn-Zr alloy with trace amounts of Ag

    International Nuclear Information System (INIS)

    Liu Xiaoyan; Pan Qinglin; Lu Congge; He Yunbin; Li Wenbin; Liang Wenjie

    2009-01-01

    The microstructure and mechanical properties of Al-Cu-Mg-(Ag)-Mn-Zr alloys were studied by means of tensile testing, optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that small additions of Ag to Al-Cu-Mg-Mn-Zr alloy can accelerate the hardening effect of the aged alloy and reduce the time to peak-aged. The mechanical properties can be improved both at room temperature and at elevated temperatures, which is attributed to the fine and uniform plate-like Ω precipitates. Meanwhile the ductility of the studied alloys remains at relatively high level. The major strengthening phases of the Ag-free alloy are θ' and less S', while that of Al-Cu-Mg-Mn-Zr alloy containing trace amounts of Ag are Ω and less θ'.

  17. Influence of Zr and Ce doping on electromagnetic properties of (Gd,Y)-Ba-Cu-O superconducting tapes fabricated by metal organic chemical vapor deposition

    International Nuclear Information System (INIS)

    Selvamanickam, V.; Chen, Y.; Xie, J.; Zhang, Y.; Guevara, A.; Kesgin, I.; Majkic, G.; Martchevsky, M.

    2009-01-01

    (Gd,Y)Ba 2 Cu 3 O x tapes have been fabricated by metal organic chemical vapor deposition (MOCVD) with Zr-doping levels of 0-15 mol.% and Ce doping levels of 0-10 mol.% in 0.4 μm thick films. The critical current density (J c ) of Zr-doped samples at 77 K, 1 T applied in the orientation of H -parallel c is found to increase with Zr content and shows a maximum at 7.5% Zr doping. The 7.5% Zr-doped sample exhibits a critical current density (J c ) of 0.95 MA/cm 2 at H -parallel c which is more than 70% higher than the J c of the undoped sample. The peak in J c at H -parallel c is 83% of that at H -parallel a-b in the 7.5% Zr-doped sample which is more than twice as that in the undoped sample. Superconducting transition temperature (T c ) values as high as about 89 K have been achieved in samples even with 15% Zr and 10% Ce. Ce-doped samples with and without Ba compensation are found to exhibit substantially different J c values as well as angular dependence characteristics.

  18. Influence of Zr and Ce doping on electromagnetic properties of (Gd,Y)-Ba-Cu-O superconducting tapes fabricated by metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V., E-mail: selva@uh.ed [Department of Mechanical Engineering and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Rd., Houston, TX 77204-4006 (United States); Chen, Y.; Xie, J. [SuperPower Inc., 450 Duane Ave., Schenectady, NY 12304 (United States); Zhang, Y.; Guevara, A.; Kesgin, I.; Majkic, G. [Department of Mechanical Engineering and Texas Center for Superconductivity, University of Houston, 4800 Calhoun Rd., Houston, TX 77204-4006 (United States); Martchevsky, M. [SuperPower Inc., 450 Duane Ave., Schenectady, NY 12304 (United States)

    2009-12-01

    (Gd,Y)Ba{sub 2}Cu{sub 3}O{sub x} tapes have been fabricated by metal organic chemical vapor deposition (MOCVD) with Zr-doping levels of 0-15 mol.% and Ce doping levels of 0-10 mol.% in 0.4 mum thick films. The critical current density (J{sub c}) of Zr-doped samples at 77 K, 1 T applied in the orientation of H -parallel c is found to increase with Zr content and shows a maximum at 7.5% Zr doping. The 7.5% Zr-doped sample exhibits a critical current density (J{sub c}) of 0.95 MA/cm{sup 2} at H -parallel c which is more than 70% higher than the J{sub c} of the undoped sample. The peak in J{sub c} at H -parallel c is 83% of that at H -parallel a-b in the 7.5% Zr-doped sample which is more than twice as that in the undoped sample. Superconducting transition temperature (T{sub c}) values as high as about 89 K have been achieved in samples even with 15% Zr and 10% Ce. Ce-doped samples with and without Ba compensation are found to exhibit substantially different J{sub c} values as well as angular dependence characteristics.

  19. One-step production of biodiesel from Nannochloropsis sp. on solid base Mg-Zr catalyst

    International Nuclear Information System (INIS)

    Li, Yuesong; Lian, Shuang; Tong, Dongmei; Song, Ruili; Yang, Wenyan; Fan, Yong; Qing, Renwei; Hu, Changwei

    2011-01-01

    Nannochloropsis sp., one kind of green microalgae cultivated autotrophically and axenically in laboratory, is used as raw material to produce biodiesel by one-step method in an amended reactor. The effects of several reaction parameters on transesterification over Mg-Zr solid base catalyst were investigated through both conventional method and one-step method. One-step method could give a higher yield of methyl ester than conventional two-step method, which demonstrates that the present one-step method is suitable for biodiesel production from the microalgae Nannochloropsis sp. Moreover, the present one-step method realizes the convenient in situ separation of catalyst from microalgae residue which can be easily used consequently, reducing the procedure units as well as the overall costs.

  20. Physical Characteristics and Sintering Behavior of MgO-Doped ZrO2nanoparticles

    International Nuclear Information System (INIS)

    Muccillo, E.N.S.; Tadokoro, S.K.; Muccillo, R.

    2004-01-01

    Nanosized particles of 13mol% MgO-doped ZrO 2 with a narrow distribution of pore sizes were prepared by the coprecipitation technique using optimized parameters of synthesis. Transmission electron microscopy analysis of the calcined powder reveals that the majority of the particles have grain sizes in the 10-20nm range. From nitrogen adsorption analysis an average particle size of 13nm was estimated, which is similar to the average pore size diameter (12nm). Besides the unimodal distribution of pore sizes, the linear shrinkage curve of a powder compact exhibits several inflexions indicating different rates of densification up to 1600 deg. C. After sintering at 1600 deg. C for 2h, the microstructure features of a compact are characteristics of the intermediate stage with interconnected porosity preferentially observed at grain boundaries. These results are explained as a size effect of nanoparticles of magnesia-doped zirconia during sintering

  1. Fracture resistance and fatigue crack growth characteristics of two Al-Cu-Mg-Zr alloys

    Science.gov (United States)

    Sarkar, Bhaskar; Lisagor, W. B.

    1992-01-01

    The dependence of strength, fracture resistance, and fatigue crack growth rate on the aging conditions of two alloy compositions based on Al-3.7Cu-1.85Mg-0.2Mn is investigated. Mechanical properties were evaluated in two heat treatment conditions and in two orientations (longitudinal and transverse). Compact tension specimens were used to determine fatigue crack growth characteristics and fracture resistance. The aging response was monitored on coupons using hardness measurements determined with a standard Rockwell hardness tester. Fracture resistance is found to increase with increasing yield strength during artificial aging of age-hardenable 2124-Zr alloys processed by powder metallurgy techniques. Fatigue crack growth rate increases with increasing strength. It is argued that these changes are related to deformation modes of the alloys; a homogeneous deformation mode tends to increase fracture resistance and to decrease the resistance to the fatigue crack propagation rate.

  2. Enhanced biocorrosion resistance and biocompatibility of degradable Mg-Nd-Zn-Zr alloy by brushite coating.

    Science.gov (United States)

    Niu, Jialin; Yuan, Guangyin; Liao, Yi; Mao, Lin; Zhang, Jian; Wang, Yongping; Huang, Feng; Jiang, Yao; He, Yaohua; Ding, Wenjiang

    2013-12-01

    To further improve the corrosion resistance and biocompatibility of Mg-Nd-Zn-Zr alloy (JDBM), a biodegradable calcium phosphate coating (Ca-P coating) with high bonding strength was developed using a novel chemical deposition method. The main composition of the Ca-P coating was brushite (CaHPO4·2H2O). The bonding strength between the coating and the JDBM substrate was measured to be over 10 MPa, and the thickness of the coating layer was about 10-30 μm. The in vitro corrosion tests indicated that the Ca-P treatment improved the corrosion resistance of JDBM alloy in Hank's solution. Ca-P treatment significantly reduced the hemolysis rate of JDBM alloy from 48% to 0.68%, and induced no toxicity to MC3T3-E1 cells. The in vivo implantation experiment in New Zealand's rabbit tibia showed that the degradation rate was reduced obviously by the Ca-P treatment and less gas was produced from Ca-P treated JDBM bone plates and screws in early stage of the implantation, and at least 10weeks degradation time can be prolonged by the present coating techniques. Both Ca-P treated and untreated JDBM Mg alloy induced bone growth. The primary results indicate that the present Ca-P treatment is a promising technique for the degradable Mg-based biomaterials for orthopedic applications. © 2013.

  3. Microstructure, mechanical and corrosion properties of Mg-Dy-Gd-Zr alloys for medical applications.

    Science.gov (United States)

    Yang, L; Huang, Y; Feyerabend, F; Willumeit, R; Mendis, C; Kainer, K U; Hort, N

    2013-11-01

    In previous investigations, a Mg-10Dy (wt.%) alloy with a good combination of corrosion resistance and cytocompatibility showed great potential for use as a biodegradable implant material. However, the mechanical properties of Mg-10Dy alloy are not satisfactory. In order to allow the tailoring of mechanical properties required for various medical applications, four Mg-10(Dy+Gd)-0.2Zr (wt.%) alloys were investigated with respect to microstructure, mechanical and corrosion properties. With the increase in Gd content, the number of second-phase particles increased in the as-cast alloys, and the age-hardening response increased at 200°C. The yield strength increased, while the ductility reduced, especially for peak-aged alloys with the addition of Gd. Additionally, with increasing Gd content, the corrosion rate increased in the as-cast condition owing to the galvanic effect, but all the alloys had a similar corrosion rate (~0.5 mm year(-1)) in solution-treated and aged condition. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  4. Strong blue and white photoluminescence emission of BaZrO{sub 3} undoped and lanthanide doped phosphor for light emitting diodes application

    Energy Technology Data Exchange (ETDEWEB)

    Romero, V.H. [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); De la Rosa, E., E-mail: elder@cio.mx [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro, Qro. 76000 (Mexico); Velazquez-Salazar, J.J. [Department of Physics and Astronomy, The University of Texas at San Antonio One UTSA Circle, San Antonio TX 78249 (United States)

    2012-12-15

    In this paper, we report the obtained strong broadband blue photoluminescence (PL) emission centered at 427 nm for undoped BaZrO{sub 3} observed after 266 nm excitation of submicron crystals prepared by hydrothermal/calcinations method. This emission is enhanced with the introduction of Tm{sup 3+} ions and is stronger than the characteristic PL blue emission of such lanthanide. The proposed mechanism of relaxation for host lattice emission is based on the presence of oxygen vacancies produced during the synthesis process and the charge compensation due to the difference in the electron valence between dopant and substituted ion in the host. Brilliant white light emission with a color coordinate of (x=0.29, y=0.32) was observed by combining the blue PL emission from the host with the green and red PL emission from Tb{sup 3+} and Eu{sup 3+} ions, respectively. The color coordinate can be tuned by changing the ratio between blue, green and red band by changing the concentration of lanthanides. - Graphical abstract: Strong blue emission from undoped BaZrO{sub 3} phosphor and white light emission by doping with Tb{sup 3+} (green) and Eu{sup 3+} (red) after 266 nm excitation. Highlights: Black-Right-Pointing-Pointer Blue emission from BaZrO{sub 3} phosphor. Black-Right-Pointing-Pointer Blue emission enhanced with Tm{sup 3+}. Black-Right-Pointing-Pointer White light from BaZrO{sup 3+} phosphor.

  5. Y and Ni Co-Doped BaZrO3 as a Proton-Conducting Solid Oxide Fuel Cell Electrolyte Exhibiting Superior Power Performance

    KAUST Repository

    Shafi, Shahid P.; Bi, Lei; Boulfrad, Samir; Traversa, Enrico

    2015-01-01

    The fabrication of anode supported single cells based on BaZr0.8Y0.2O3-δ (BZY20) electrolyte is challenging due to its poor sinteractive nature. The acceleration of shrinkage behavior, improved sinterability and larger grain size were achieved

  6. A-Site Cation Substitutions in Strained Y-Doped BaZrO3 Multilayer Films Leading to Fast Proton Transport Pathways

    Energy Technology Data Exchange (ETDEWEB)

    Aruta, Carmela [Univ. of Roma Tor Vergata, Rome (Italy); Han, Chu [Georgia Inst. of Technology, Atlanta, GA (United States); Zhou, Si [Dalian Univ. of Technology, Dalian (China); Cantoni, Claudia [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yang, Nan [Univ. of Roma Tor Vergata, Rome (Italy); Tebano, Antonello [Univ. of Roma Tor Vergata, Rome (Italy); Lee, Tien -Lin [Diamond Light Source Ltd., Didcot (United Kingdom); Schlueter, Christoph [Diamond Light Source Ltd., Didcot (United Kingdom); Bongiorno, Angelo [College of Staten Island, Staten Island, NY (United States); The Graduate Center of the City Univ. of New York, New York, NY (United States)

    2016-03-31

    Proton-conducting perovskite oxides form a class of solid electrolytes for novel electrochemical devices operating at moderate temperatures. Here, we use hard X-ray photoelectron spectroscopy, scanning transmission electron microscopy, and density functional theory calculations to investigate the structure and elucidate the origin of the fast proton transport properties of strained ultrathin films of Y-doped BaZrO3 grown by pulsed lased deposition on NdGaO3. Our study shows that our BaZr0.8Y0.2O3 films incorporate a significant amount of Y dopants, and to a lesser extent also Zr ions, substituting for Ba2+, and that these substitutional defects agglomerate forming columnar regions crossing vertically from the surface to the interface the entire film. In conclusion, our calculations also show that, in regions rich in Y substitutions for both Zr and Ba, the proton transfer process involves nearly zero-energy barriers, indicating that A-site cation substitutions by Y lead to fast transport pathways and hence are responsible for the previously observed enhanced values of the proton conductivity of these perovskite oxide films.

  7. Y-doped BaZrO3 as a chemically stable electrolyte for proton-conducting solid oxide electrolysis cells (SOECs)

    KAUST Repository

    Bi, Lei

    2015-01-01

    A proton-conducting solid oxide electrolysis cell using an Y-doped BaZrO3 electrolyte film, which has been demonstrated to be chemically stable, was successfully fabricated for the first time and showed a promising electrolysis performance.

  8. Y and Ni Co-Doped BaZrO3 as a Proton-Conducting Solid Oxide Fuel Cell Electrolyte Exhibiting Superior Power Performance

    KAUST Repository

    Shafi, Shahid P.

    2015-10-16

    The fabrication of anode supported single cells based on BaZr0.8Y0.2O3-δ (BZY20) electrolyte is challenging due to its poor sinteractive nature. The acceleration of shrinkage behavior, improved sinterability and larger grain size were achieved by the partial substitution of Zr with Ni in the BZY perovskite. Phase pure Ni-doped BZY powders of nominal compositions BaZr0.8-xY0.2NixO3-δ were synthesized up to x = 0.04 using a wet chemical combustion synthesis route. BaZr0.76Y0.2Ni0.04O3-δ (BZYNi04) exhibited adequate total conductivity and the open circuit voltage (OCV) values measured on the BZYNi04 pellet suggested lack of significant electronic contribution. The improved sinterability of BZYNi04 assisted the ease in film fabrication and this coupled with the application of an anode functional layer and a suitable cathode, PrBaCo2O5+δ (PBCO), resulted in a superior fuel cell power performance. With humidified hydrogen and static air as the fuel and oxidant, respectively, a peak power density value of 428 and 240 mW cm−2 was obtained at 700 and 600°C, respectively.

  9. Effects of the fabrication process on the grain-boundary resistance in BaZr0.9Y0.1O3-δ

    DEFF Research Database (Denmark)

    Ricote, Sandrine; Bonanos, Nikolaos; Manerbino, A.

    2014-01-01

    This paper reports on the effect of the fabrication process on the conductivity of BZY10 (BaZr0.9Y0.1O3-δ). The dense specimens were prepared by four methods: (1) solid-state reactive sintering (SSRS), (2) conventional sintering using powder prepared by solid-state reaction and NiO as sintering a...

  10. Isothermal sections of Eu(Ca, Zr, Ba)-Mn-Al ternary phase diagrams at 770 K

    International Nuclear Information System (INIS)

    Manyako, N.B.; Yanson, T.I.; Zarechnyuk, O.S.

    1988-01-01

    Isothermal cross sections of Eu(Ca, Sr, Ba)-Mn-Al state diagrams at 770 K are plotted by means of X-ray structural analysis. EuMn 2.3-3.6 Al 9.7-8.4 (ThMn 12 structure type) and Eu 2 Mn 5 Al 12 (eigenstructure type) two compound are found within Eu-Mn-Al system. Existance of CaMn 0.16- 0 .32 Al 1.84-1.68 compound (MgNi 2 structure type) is proved and CaMn 3.2-2.1 Al 8.8-9.9 compound (ThMn 12 type partially ordered structure) is found within Ca-Mn-Al system. Ternary compounds are not formed within Sr(Ba)-Mn-Al systems. Regions of stratification, occurring within Eu(Ca, Sr, Ba)-Mn systems, penetrate in ternary system

  11. Microemulsion and Sol-Gel Synthesized ZrO2-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural

    Directory of Open Access Journals (Sweden)

    Almudena Parejas

    2017-12-01

    Full Text Available Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively. Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO2 (especially Zr-SG are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps.

  12. Microemulsion and Sol-Gel Synthesized ZrO₂-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural.

    Science.gov (United States)

    Parejas, Almudena; Montes, Vicente; Hidalgo-Carrillo, Jesús; Sánchez-López, Elena; Marinas, Alberto; Urbano, Francisco J

    2017-12-18

    Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively). Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water) reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO₂ (especially Zr-SG) are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps.

  13. Atomic layer deposited ZrO2 nanofilm on Mg-Sr alloy for enhanced corrosion resistance and biocompatibility.

    Science.gov (United States)

    Yang, Qiuyue; Yuan, Wei; Liu, Xiangmei; Zheng, Yufeng; Cui, Zhenduo; Yang, Xianjin; Pan, Haobo; Wu, Shuilin

    2017-08-01

    The biodegradability and good mechanical property of magnesium alloys make them potential biomedical materials. However, their rapid corrosion rate in the human body's environment impairs these advantages and limits their clinical use. In this work, a compact zirconia (ZrO 2 ) nanofilm was fabricated on the surface of a magnesium-strontium (Mg-Sr) alloy by the atomic layer deposition (ALD) method, which can regulate the thickness of the film precisely and thus also control the corrosion rate. Corrosion tests reveal that the ZrO 2 film can effectively reduce the corrosion rate of Mg-Sr alloys that is closely related to the thickness of the film. The cell culture test shows that this kind of ZrO 2 film can also enhance the activity and adhesion of osteoblasts on the surfaces of Mg-Sr alloys. The significance of the current work is to develop a zirconia nanofilm on biomedical MgSr alloy with controllable thickness precisely through atomic layer deposition technique. By adjusting the thickness of nanofilm, the corrosion rate of Mg-Sr alloy can be modulated, thereafter, the degradation rate of Mg-based alloys can be controlled precisely according to actual clinical requirement. In addition, this zirconia nanofilm modified Mg-Sr alloys show excellent biocompatibility than the bare samples. Hence, this work provides a new surface strategy to control the degradation rate while improving the biocompatibility of substrates. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Superconductivity in dense Mg1–xMxB2 (M= Zr, Nb, Mo; x= 0⋅ 05 ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 28; Issue 3. Superconductivity in dense Mg1–MB2 (M = Zr, Nb, Mo; = 0.05) materials sintered under pressure. S Kalavathi C Divakar. Superconductors Volume 28 Issue 3 June 2005 pp 249-252 ...

  15. Effects of ageing treatment on microstructures and properties of Mg-Gd-Y-Zr alloys with and without Zn additions

    International Nuclear Information System (INIS)

    Liu, X.B.; Chen, R.S.; Han, E.H.

    2008-01-01

    Mg-10Gd-3Y-0.5Zr alloys with and without 1% Zn additions have been investigated using optical microscopy, scanning electron microscope and X-ray diffraction. The microstructures, ageing hardening behaviors and mechanical properties of the two alloys are compared. The extruded-T5 specimens exhibit remarkable age hardening responses during ageing from 200 to 250 deg. C. The highest peak hardness and strength of the two alloys are obtained when they are aged at 200 deg. C. Addition of 1% Zn to Mg-10Gd-3Y-0.5Zr alloy results in the greater magnitude ageing effect and better mechanical properties as well as better heat resistance. Furthermore, secondary ageing is carried out at 200 deg. C following preliminary ageing at 250 deg. C for both Mg-10Gd-3Y-0.5Zr and Mg-10Gd-3Y-1Zn-0.5Zr alloys. The ultimate tensile strength values after secondary ageing are slightly lower compared with the highest strength of the two alloys, but secondary ageing offers a better combination of high strength and ductility

  16. A superplastic Al-Li-Cu-Mg-Zr powder alloy with high hardness and modulus

    International Nuclear Information System (INIS)

    Phillips, V.A.

    1986-01-01

    Structure/property studies were made on an experimental Al-3.18% Li-4.29% Cu-1.17% Mg-0.18% Zr powder alloy, which is of the low density/high modulus type. Alloy powder was made by the P and W/GPD rapid solidification rate (RSR) process, canned, and extruded to bar. The density was 2.458 x 10/sup 6/ g/m/sup 3/. The material was solution-treated, and aged at 149 0 C(300 0 F), 171 0 C(340 0 F), and 193 0 C(380 0 F), using hardness tests to determine the aging curves. Testpieces solution-treated at 516 0 C(961 0 F) showed an average yield strength (0.2% offset) of 43.3 ksi (299 MPa) and ultimate tensile strength of 50.0 ksi (345 MPa), with 1% elongation, which increased to 73.0 ksi (503 MPa) and 73.1 ksi (504 MPa), respectively, with only 0.2% elongation, on peak aging at 193 0 C(380 0 F), with a modulus of elasticity of 11.4 x 10/sup 6/ psi (78.3 GPa). Hardness values reached 90-92 R/sub B/ on aging at 149-193 0 C(300-380 0 F). The as-extruded alloy showed superplastic behavior at 400-500 0 C(752-932 0 F) with elongations of 80-185% on 25.6 mm, peaking at 450 0 C(842 0 F). An RSR Al-2.53% Li-2.82% Mn-0.02% Zr extruded allow showed only 18-23% elongation at 400-500 0 C(752-932 0 F)

  17. Combined experimental and theoretical investigations of the photoluminescent behavior of Ba(Ti, Zr)O3 thin films

    International Nuclear Information System (INIS)

    Cavalcante, L.S.; Gurgel, M.F.C.; Paris, E.C.; Simoes, A.Z.; Joya, M.R.; Varela, J.A.; Pizani, P.S.; Longo, E.

    2007-01-01

    The correlation between experimental data and theoretical calculations have been investigated to explain the photoluminescence at room temperature of Ba(Ti 0.75 Zr 0.25 )O 3 (BTZ) thin films prepared by the polymeric precursor method. The degree of structural order-disorder was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible absorption spectroscopy and photoluminescence (PL) measurements. First-principles quantum mechanical calculations based on density functional theory (B3LYP level) were employed to study the electronic structure of ordered and deformed asymmetric models. The electronic properties are analyzed and the relevance of the present theoretical and experimental results on the PL behavior is discussed. The presence of localized electronic levels and a charge gradient in the band gap due to a break in symmetry, are responsible for the PL in disordered BTZ lattice

  18. Large electrical manipulation of permittivity in BaTiO3 and Pb(Zr,Ti)O3 bimorph heterostructure

    International Nuclear Information System (INIS)

    Ci, Penghong; Liu, Guoxi; Dong, Shuxiang; Zhang, Li

    2014-01-01

    We report a strain-mediated electric field manipulation of permittivity in BaTiO 3 (barium titanate, BT) ceramic by a Pb(Zr,Ti)O 3 (PZT) bimorph. This BT/PZT heterostructure exhibited a relatively large permittivity tunability of BT up to ±10% in a wide frequency range under an electric field of ±4 kV/cm applied to the PZT bimorph. The permittivity tunability is attributed to the strain in BT produced by the PZT bimorph. Calculations of the relationship between permittivity and applied electric field were developed, and corresponded well with measurements. The BT/PZT heterostructure has potential for applications in broadband field tunable smart electronic devices.

  19. Structures, phase transitions and microwave dielectric properties of the 6H perovskites Ba3BSb2O9, B=Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    Ling, Chris D.; Rowda, Budwy; Avdeev, Maxim; Pullar, Robert

    2009-01-01

    We present a complete temperature-composition phase diagram for Ba 3 BSb 2 O 9 , B=Mg, Ca, Sr, Ba, along with their electrical behavior as a function of B. These compounds have long been recognized as 6H-type perovskites, but (with the exception of B=Mg) their exact structures and properties were unknown due to their low symmetries, temperature-dependent phase transitions, and difficulties in synthesizing pure samples. The full range of possible space group symmetries is observed, from ideal hexagonal P6 3 /mmc to monoclinic C2/c to triclinic P1-bar. Direct second-order transitions between these phases are plausible according to group theory, and no evidence was seen for any further intermediate phases. The phase diagram with respect to temperature and the effective ionic radius of B is remarkably symmetrical for B=Mg, Ca, and Sr. For B=Ba, a first-order phase transition to a locally distorted phase allows a metastable hexagonal phase to persist to lower temperatures than expected before decomposing around 600 K. Electrical measurements revealed that dielectric permittivity corrected for porosity does not change significantly as a function of B and is in a good agreement with the values predicted by the Clausius-Mossotti equation. - Graphical abstract: Thermodynamic phase diagram for Ba 3 BSb 2 O 9 , B=Mg, Ca, and Sr, as a function of temperature T and effective ionic radius (IR) of the B 2+ cation

  20. Improvement of mechanical properties and corrosion resistance of biodegradable Mg-Nd-Zn-Zr alloys by double extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaobo, E-mail: xbxbzhang2003@163.com [School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167 (China); Wang, Zhangzhong [School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167 (China); Yuan, Guangyin [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, Shanghai, 200240 (China); Xue, Yajun [School of Materials Science and Engineering, Nanjing Institute of Technology, Nanjing, 211167 (China)

    2012-08-01

    Highlights: Black-Right-Pointing-Pointer Microstructure of Mg-Nd-Zn-Zr alloys was refined and homogenized by double extrusion process. Black-Right-Pointing-Pointer The mechanical properties of the alloys were significantly enhanced by double extrusion. Black-Right-Pointing-Pointer The biocorrosion resistance of the alloys was improved by double extrusion. - Abstract: Mg-Nd-Zn-Zr alloy is a novel and promising biodegradable magnesium alloy due to good biocompatibility, desired uniform corrosion mode and outstanding corrosion resistance in simulated body fluid (SBF). However, the corrosion resistance and mechanical properties should be improved to meet the requirement of the biodegradable implants, such as plates, screws and cardiovascular stents. In the present study, double extrusion process was adopted to refine microstructure and improve mechanical properties of Mg-2.25Nd-0.11Zn-0.43Zr and Mg-2.70Nd-0.20Zn-0.41Zr alloys. The corrosion resistance of the alloys after double extrusion was also studied. The results show that the microstructure of the alloys under double extrusion becomes much finer and more homogeneous than those under once extrusion. The yield strength, ultimate tensile strength and elongation of the alloys under double extrusion are over 270 MPa, 300 MPa and 32%, respectively, indicating that outstanding mechanical properties of Mg-Nd-Zn-Zr alloy can be obtained by double extrusion. The results of immersion experiment and electrochemical measurements in SBF show that the corrosion resistance of Alloy 1 and Alloy 2 under double extrusion was increased by 7% and 8% respectively compared with those under just once extrusion.

  1. Influence of small additions of Sc and Zr on structure and mechanical properties of Al-Zn-Mg-Cu alloy

    International Nuclear Information System (INIS)

    Kajgorodova, L.I.; Sel'nikhina, E.I.; Tkachenko, E.A.; Senatorova, O.G.

    1996-01-01

    A study was made into Sc and Zr addition effects on grain structure formation, supersaturated solid solution decomposition and mechanical properties of Al-7%Zn-2%Mg-1.2%Cu alloy. It is shown that grain structure is determined by volume fraction and distribution character of disperse particles of Al 3 Sc and Al 3 (Sc 1-x Zr x ). The reason for additives influence on decomposition kinetics during natural and artificial ageing are revealed. The structural factors responsible for the enhancement of mechanical properties on alloying are discussed. 17 refs.; 5 figs.; 2 tabs

  2. Ionic conductivity of Ca and Mg doped NdGdZr1.95Sc0.05O7

    International Nuclear Information System (INIS)

    Anithakumari, P.; Mandal, B.P.; Grover, V.; Tyagi, A.K.; Mishra, A.K.

    2014-01-01

    The ionic conductivity of pyrochlore based materials makes them promising candidates for fuel-cell applications where high ionic conductivity and low activation energy are desired. Earlier it has been reported that 5%Sc doped GdNdZr 2 O 7 shows highest ionic conductivity. In this present work, an attempt has been made to further increase the oxygen vacancy concentration by the incorporation of Ca 2+ and Mg 2+ ions at A site of NdGdZr 1.95 Sc 0.05 O 7 (NGZS)

  3. Electrical properties and structure of glasses in the Ba(PO3)2-MF2 systems, where M = Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    Sokolov, I.A.; Tarlakov, Yu.P.; Murin, I.V.; Pronkin, A.A.

    2000-01-01

    Using the methods of conductometry and IR spectroscopy the concentrational dependences of electric conductivity are studied, the nature of current carriers is determined, the concentrational dependence of transfer numbers is ascertained and structural changes in glasses of the system Ba(PO 3 ) 2 -MF 2 (M = Mg, Ca, Sr, Ba), depending on MF 2 content, are considered. It is shown that F - ions take part in electric current transfer. Influence of crystallochemical nature of alkaline-earth cations on physicochemical properties and structure of the glasses studied is analyzed [ru

  4. Crystal structure and thermal expansion of the low- and high-temperature forms of Ba MIV(PO 4) 2 compounds ( M=Ti, Zr, Hf and Sn)

    Science.gov (United States)

    Bregiroux, D.; Popa, K.; Jardin, R.; Raison, P. E.; Wallez, G.; Quarton, M.; Brunelli, M.; Ferrero, C.; Caciuffo, R.

    2009-05-01

    The crystal structure of β-BaZr(PO 4) 2, archetype of the high-temperature forms of Ba M(PO 4) 2 phosphates (with M=Ti, Zr, Hf and Sn), has been solved ab initio by Rietveld analysis from synchrotron X-ray powder diffraction data. The phase transition appears as a topotactic modification of the monoclinic (S.G. C2/m) lamellar α-structure into a trigonal one (S.G. P3¯m1) through a simple mechanism involving the unfolding of the [Zr)]n2- layers. The thermal expansion is very anisotropic (e.g., -4.1< α i<34.0×10 -6 K -1 in the case of α-BaZr(PO 4) 2) and quite different in the two forms, as a consequence of symmetry. It stems from a complex combination of several mechanisms, involving bridging oxygen rocking in M-O-P linkages, and "bond thermal expansion".

  5. Effect of Zr on microstructures and mechanical properties of an Al-Mg-Si-Cu-Cr alloy prepared by low frequency electromagnetic casting

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Yi, E-mail: yimonmy@sina.com; Cui, Jianzhong; Zhao, Zhihao; He, Lizi

    2014-06-01

    The Al-1.6Mg-1.2Si-1.1Cu-0.15Cr (all in wt. %) alloys with and without Zr addition prepared by low frequency electromagnetic casting process were investigated by using the optical microscope, scanning electron microscope and transmission electron microscope equipped with energy dispersive analytical X-ray. The effects of Al{sub 3}Zr phases on the microstructures and mechanical properties during solidification, homogenization, hot extrusion and solid solution were studied. The results show that Al{sub 3}Zr phases reduce the grain size by ∼ 29% and promote the formation of an equiaxed grain structure during solidification. Numerous spherical Al{sub 3}Zr dispersoids with 35–60 nm in diameters precipitate during homogenization, and these fine dispersoids change little during subsequent hot extrusion and solid solution. Adding 0.15 wt. % Zr results in no recrystallization after hot extrusion and partial recrystallization after solid solution, while the recrystallized grain size is 400–550 μm in extrusion direction in the Zr-free alloy. In addition, adding 0.15 wt. % Zr can obviously promote Q′ phase precipitation, while the β″ phases are predominant in the alloy without Zr. Adding 0.15 wt. % Zr, the ultimate tensile strength of the T6 treated alloy increases by 45 MPa, while the elongation remains about 16.7%. - Highlights: • Minor Zr can refine as-cast grains of the LFEC Al-Mg-Si-Cu-Cr alloy. • L1{sub 2} Al{sub 3}Zr phases with 35–60 nm in diameter precipitate during homogenization. • L1{sub 2} and DO{sub 22} Al{sub 3}Zr phases result in partial recrystallization after solid solution. • Minor Zr can promote the precipitation of Q′ phases. • Mechanical properties of Al-Mg-Si-Cu-Cr-Zr alloy are higher than those of AA7005.

  6. Effect of Zr on microstructures and mechanical properties of an Al-Mg-Si-Cu-Cr alloy prepared by low frequency electromagnetic casting

    International Nuclear Information System (INIS)

    Meng, Yi; Cui, Jianzhong; Zhao, Zhihao; He, Lizi

    2014-01-01

    The Al-1.6Mg-1.2Si-1.1Cu-0.15Cr (all in wt. %) alloys with and without Zr addition prepared by low frequency electromagnetic casting process were investigated by using the optical microscope, scanning electron microscope and transmission electron microscope equipped with energy dispersive analytical X-ray. The effects of Al 3 Zr phases on the microstructures and mechanical properties during solidification, homogenization, hot extrusion and solid solution were studied. The results show that Al 3 Zr phases reduce the grain size by ∼ 29% and promote the formation of an equiaxed grain structure during solidification. Numerous spherical Al 3 Zr dispersoids with 35–60 nm in diameters precipitate during homogenization, and these fine dispersoids change little during subsequent hot extrusion and solid solution. Adding 0.15 wt. % Zr results in no recrystallization after hot extrusion and partial recrystallization after solid solution, while the recrystallized grain size is 400–550 μm in extrusion direction in the Zr-free alloy. In addition, adding 0.15 wt. % Zr can obviously promote Q′ phase precipitation, while the β″ phases are predominant in the alloy without Zr. Adding 0.15 wt. % Zr, the ultimate tensile strength of the T6 treated alloy increases by 45 MPa, while the elongation remains about 16.7%. - Highlights: • Minor Zr can refine as-cast grains of the LFEC Al-Mg-Si-Cu-Cr alloy. • L1 2 Al 3 Zr phases with 35–60 nm in diameter precipitate during homogenization. • L1 2 and DO 22 Al 3 Zr phases result in partial recrystallization after solid solution. • Minor Zr can promote the precipitation of Q′ phases. • Mechanical properties of Al-Mg-Si-Cu-Cr-Zr alloy are higher than those of AA7005

  7. Enhanced Age Strengthening of Mg-Nd-Zn-Zr Alloy via Pre-Stretching

    Directory of Open Access Journals (Sweden)

    Erjun Guo

    2016-08-01

    Full Text Available Pre-stretching was carried out to modify the microstructure of Mg-Nd-Zn-Zr alloy to enhance its age strengthening. The results indicated that more heterogeneous nucleation sites can be provided by the high density of dislocations caused by the plastic pre-stretching deformation, as well as speeding up the growth rate of precipitates. Comparison of microstructure in non-pre-stretched specimens after artificial aging showed that pre-stretched specimens exhibited a higher number density of precipitates. The fine and coarse plate-shaped precipitates were found in the matrix. Due to an increase in the number density of precipitates, the dislocation slipping during the deformation process is effectively hindered, and the matrix is strengthened. The yield strength stabilizes at 4% pre-stretching condition, and then the evolution is stable within the error bars. The 8% pre-stretched specimens can achieve an ultimate tensile strength of 297 MPa. However, further pre-stretching strains after 8% cannot supply any increase in strength. Tensile fracture surfaces of specimens subjected to pre-stretching strain mainly exhibit a trans-granular cleavage fracture. This work indicated that a small amount of pre-stretching strain can further increase strength of alloy and also effectively enhance the formation of precipitates, which can expand the application fields of this alloy.

  8. Reforming of Ethanol to Produce Hydrogen over PtRuMg/ZrO2 Catalyst

    Directory of Open Access Journals (Sweden)

    Josh Y. Z. Chiou

    2012-01-01

    Full Text Available A modified PtRu/ZrO2 catalyst with Mg is evaluated for the oxidative steam reforming of ethanol (OSRE and the steam reforming of ethanol (SRE. In order to understand the variation in the reaction mechanism on OSRE and SRE, further analysis of both fresh and used catalyst is concentrated on for TEM, TG, Raman, and TPR characterization. The results show that the OSRE reaction requires a higher temperature (∼390°C to achieve 100% ethanol conversion than the SRE reaction (∼2500°C. The distribution of CO is minor for both reactions (< 5% for OSRE, < 1% for SRE. This demonstrates that the water gas shift (WGS reaction is an important side-reaction in the reforming of ethanol to produce H2 and CO2. A comparison of the temperature of WGS (WGS shows it is lower for the SRE reaction (WGS∼250°C for SRE, ~340°C for OSRE.

  9. Precipitation Behavior and Quenching Sensitivity of a Spray Deposited Al-Zn-Mg-Cu-Zr Alloy

    Directory of Open Access Journals (Sweden)

    Xiaofei Sheng

    2017-09-01

    Full Text Available Precipitation behavior and the quenching sensitivity of a spray deposited Al-Zn-Mg-Cu-Zr alloy during isothermal heat treatment have been studied systematically. Results demonstrate that both the hardness and the ultimate tensile strength of the studied alloy decreased with the isothermal treatment time at certain temperatures. More notably, the hardness decreases rapidly after the isothermal heat treatment. During isothermal heat treatment processing, precipitates readily nucleated in the medium-temperature zone (250–400 °C, while the precipitation nucleation was scarce in the low-temperature zone (<250 °C and in the high-temperature zone (>400 °C. Precipitates with sizes of less than ten nanometers would contribute a significant increase in yield strength, while the ones with a larger size than 300 nm would contribute little strengthening effect. Quenching sensitivity is high in the medium-temperature zone (250–400 °C, and corresponding time-temperature-property (TTP curves of the studied alloy have been established.

  10. Superplasticity and grain boundary character distribution in overaged Al-Li-Cu-Mg-Zr alloy

    International Nuclear Information System (INIS)

    Avramovic-Cingara, G.; Aust, K.T.; Perovic, D.D.; McQueen, H.J.

    1995-01-01

    Samples of 8091 alloy were subjected to a thermomechanical processing (TMP) treatment that included the following stages: overaging before deformation, multistage deformation at 300 deg C and strain rate change tests for superplasticity. Torsional deformation was utilized both to develop the refined microstructure and to test for superplasticity. The strain rate sensitivity, m, of the material ranged between 0.30 and 0.45 at 450 deg C for strain rates between 8 x 10 -2 and 10 -3 s -1 . The grain boundary character distribution (GBCD) of thermomechanically processed Al-Li-Cu-Mg-Zr (8091) alloy, which develops good superplastic response, has been determined by an electron backscattering diffraction technique (EBSD). All grain boundaries have been classified into one of three categories in terms of Σ values : low angle, coincidence site lattice and random high angle boundaries. Quantitative studies of grain boundary character were done after various processing stages to obtain evidence about structure evolution and indicate an increase in Σ boundary frequency following TMP. Selected area electron diffraction examination (SAD) gave evidence about the refined structure, in which the grain boundary misorientation increased EBSD how the grain boundary character was changed to high Σ values. TEM analyses indicate that the T 2 phase is responsible for substructure stabilization. There is no evidence of cavity formation during superplastic deformation by torsion, which suggests that cavity nucleation is strongly influenced by the nature of stress. (author). 32 refs., 3 tabs., 9 figs

  11. Thermal conductivity of M-Si-N (M = Mg, Ca, Sr, Ba) compounds with varying M/Si ratio

    NARCIS (Netherlands)

    Hintzen, H.T.J.M.; Bruls, R.J.; Delsing, A.C.A.; Itatani, K.; Tanaka, S.; With, de G.; Metselaar, R.

    2002-01-01

    The thermal cond. of M-Si-N (M = Mg, Ca, Sr, Ba) compds. was examd. The emphasis is on MgSiN2 (a material which can be derived from AlN by replacing systematically 2Al3+ by Mg2+/Si4+), and Si3N4 (the well known b-modification as well as the recently discovered cubic modification with the spinel

  12. Effects of Sr2+ substitution on photoluminescence characteristics of Ba1−x−ySryZrSi3O9:xEu2+ phosphors

    International Nuclear Information System (INIS)

    Chiang, Chung-Hao; Gong, Syuan-Jhih; Lin, Han-Yu; Zhan, Ting-Shi; Chu, Sheng-Yuan

    2014-01-01

    In this work, single-phase Ba 1−x−y Sr y ZrSi 3 O 9 :xEu 2+ phosphors were synthesized via the solid-state reaction method. The crystal structure and luminescence properties were investigated using X-ray diffraction and photoluminescence measurements, respectively. An increase of the dopant Sr 2+ increased the emission intensity of the phosphors. The peak intensity of the samples was at y = 0.4 under near-ultraviolet light excitation (397 nm). The wavelength of the emission peaks red-shifts slightly from 477 to 483 nm due to the splitting of the 5d energy level. Sr 2+ ions have a smaller ionic radius than that of Ba 2+ ions, and thus the dopant changes the crystal structure, improving the energy transfer efficiency between luminescence centers. More Eu 2+ solid solubility was found in Ba 0.6−x Sr 0.4 ZrSi 3 O 9 :xEu 2+ phosphors (10 mol. %) than in the host BaZrSi 3 O 9 (6 mol. %), which enhanced the emission intensity. In addition, the thermal reliability of the phosphors was studied

  13. Predictive calculation of phase formation in Al-rich Al-Zn-Mg-Cu-Sc-Zr alloys using a thermodynamic Mg-alloy database

    International Nuclear Information System (INIS)

    Groebner, J.; Rokhlin, L.L.; Dobatkina, T.V.; Schmid-Fetzer, R.

    2007-01-01

    Three series of Al-rich alloys in the system Al-Zn-Mg-Cu-Sc-Zr and the subsystems Al-Zn-Mg-Cu-Sc and Al-Zn-Mg-Sc were studied by thermodynamic calculations. Phase formation was compared with experimental data obtained by DTA and microstructural analysis. Calculated phase diagrams, phase amount charts and enthalpy charts together with non-equilibrium calculations under Scheil conditions reveal significant details of the complex phase formation. This enables consistent and correct interpretation of thermal analysis data. Especially the interpretation of liquidus temperature and primary phase is prone to be wrong without using this tool of computational thermodynamics. All data are predictions from a thermodynamic database developed for Mg-alloys and not a specialized Al-alloy database. That provides support for a reasonable application of this database for advanced Mg-alloys beyond the conventional composition ranges

  14. Predictive calculation of phase formation in Al-rich Al-Zn-Mg-Cu-Sc-Zr alloys using a thermodynamic Mg-alloy database

    Energy Technology Data Exchange (ETDEWEB)

    Groebner, J. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch Strasse 42, D-38678 Clausthal-Zellerfeld (Germany); Rokhlin, L.L. [Baikov Institute of Metallurgy and Materials Science, Leninsky prosp. 49, 119991 GSP-1, Moscow (Russian Federation); Dobatkina, T.V. [Baikov Institute of Metallurgy and Materials Science, Leninsky prosp. 49, 119991 GSP-1, Moscow (Russian Federation); Schmid-Fetzer, R. [Institute of Metallurgy, Clausthal University of Technology, Robert-Koch Strasse 42, D-38678 Clausthal-Zellerfeld (Germany)]. E-mail: schmid-fetzer@tu-clausthal.de

    2007-05-16

    Three series of Al-rich alloys in the system Al-Zn-Mg-Cu-Sc-Zr and the subsystems Al-Zn-Mg-Cu-Sc and Al-Zn-Mg-Sc were studied by thermodynamic calculations. Phase formation was compared with experimental data obtained by DTA and microstructural analysis. Calculated phase diagrams, phase amount charts and enthalpy charts together with non-equilibrium calculations under Scheil conditions reveal significant details of the complex phase formation. This enables consistent and correct interpretation of thermal analysis data. Especially the interpretation of liquidus temperature and primary phase is prone to be wrong without using this tool of computational thermodynamics. All data are predictions from a thermodynamic database developed for Mg-alloys and not a specialized Al-alloy database. That provides support for a reasonable application of this database for advanced Mg-alloys beyond the conventional composition ranges.

  15. Incorporation of Mg, Sr, Ba, U, and B in High-Mg Calcite Benthic Foraminifers Cultured Under Controlled pCO2

    Science.gov (United States)

    Not, C.; Thibodeau, B.; Yokoyama, Y.

    2018-01-01

    Measurement of elemental ratios (E/Ca) has been performed in two symbiont-bearing species of high-Mg calcite benthic foraminifers (hyaline, Baculogypsina sphaerulata and porcelaneous, Amphisorus hemprichii), cultured under five pCO2 levels, representing preindustrial, modern, and three predicted future values. E/Ca ratios were analyzed by Laser Ablation coupled with Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS). We measured several E/Ca, such as Mg/Ca, Sr/Ca, Ba/Ca, U/Ca, and B/Ca simultaneously. We observed that high-Mg calcite benthic foraminifers possess higher E/Ca than low-Mg calcite foraminifers, irrespective of their calcification mode (hyaline or porcelaneous). In both modes of calcification, Mg, Sr, Ba, U, and B incorporation could be controlled by Rayleigh fractionation. However, more data are needed to validate and quantify the relative importance of this process and closely investigate the presence/absence of other mechanism. Therefore, it highlights the need for a multielemental approach when looking at trace element incorporation. Finally, no significant relationship was observed between the different ratios and the pCO2 of the water, suggesting that none of the Mg/Ca, Sr/Ca, Ba/Ca, U/Ca, and B/Ca is sensitive to bottom water pCO2 or pH for these species.

  16. Thermal stability of (AlSi)x(ZrVTi) intermetallic phases in the Al–Si–Cu–Mg cast alloy with additions of Ti, V, and Zr

    International Nuclear Information System (INIS)

    Shaha, S.K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D.L.

    2014-01-01

    Highlights: • Al–Si–Cu–Mg alloy was modified by introducing Zr, V, and Ti. • The chemistry of the phases was identified using SEM/EDX. • The crystal lattice parameters of the phases were characterized using EBSD. • To investigate the phase stability, XRD was performed up to 600 °C. • Thermal analysis was done to find out the possible phase transformation reactions. - Abstract: The Al–Si–Cu–Mg cast alloy was modified with additions of Ti–V–Zr to improve the thermal stability of intermetallics at increased temperatures. A combination of electron microscopy, electron backscatter diffraction, and high temperature X-ray diffraction was explored to identify phases and temperatures of their thermal stability. The micro-additions of transition metals led to formation of several (AlSi) x (TiVZr) phases with D0 22 /D0 23 tetragonal crystal structure and different lattice parameters. While Cu and Mg rich phases along with the eutectic Si dissolved at temperatures from 300 to 500 °C, the (AlSi) x (TiVZr) phases were stable up to 696–705 °C which is the beneficial to enhance the high temperature properties. Findings of this study are useful for selecting temperatures during melting and heat treatment of Al–Si alloys with additions of transition metals

  17. Super-microporous solid base MgO-ZrO2 composite and their application in biodiesel production

    Science.gov (United States)

    Su, Jiaojiao; Li, Yongfeng; Wang, Huigang; Yan, Xiaoliang; Pan, Dahai; Fan, Binbin; Li, Ruifeng

    2016-10-01

    The super-microporous microcrystalline MgO-ZrO2 nanomaterials (pore size 1-2 nm) was prepared successfully via a facile one-pot evaporation-induced self-assembly (EISA) method and employed in the transesterification of soybean oil and methanol. X-ray diffraction, transmission electron microscope, temperature programmed desorption of CO2, and N2 adsorption porosimetry were employed to characterize the nanocomposites. Nitrogen sorption isotherms revealed that these materials had large surface areas of more than 200 m2/g. Moreover, the sample with a Mg/Zr molar ratio of 0.5 and calcined at 400 °C showed high biodiesel yield (around 99% at 150 °C).

  18. Mechanical properties and biocorrosion resistance of the Mg-Gd-Nd-Zn-Zr alloy processed by equal channel angular pressing.

    Science.gov (United States)

    Zhang, Junyi; Kang, Zhixin; Wang, Fen

    2016-11-01

    A Mg-Gd-Nd-Zn-Zr alloy was processed by equal channel angular pressing (ECAP) at 375°C. The grain size of Mg-Gd-Nd-Zn-Zr alloy was refined to ~2.5μm with the spherical precipitates (β1 phase) distributing in the matrix. The mechanical properties of ECAPed alloy were significantly improved as a result of the grain refinement and precipitation strengthening. The corrosion rate of the ECAPed magnesium alloy in simulated body fluid dramatically decreased from 0.236mm/a to 0.126mm/a due to the strong basal texture and refined microstructure. This wrought magnesium alloy shows potentials in biomedical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. The role of structural order-disorder for visible intense photoluminescence in the BaZr0.5Ti0.5O3 thin films

    International Nuclear Information System (INIS)

    Anicete-Santos, M.; Cavalcante, L.S.; Orhan, E.; Paris, E.C.; Simoes, L.G.P.; Joya, M.R.; Rosa, I.L.V.; Lucena, P.R. de; Santos, M.R.M.C.; Santos-Junior, L.S.; Pizani, P.S.; Leite, E.R.; Varela, J.A.; Longo, E.

    2005-01-01

    The nature of the intense visible room temperature photoluminescence of BaZr 0.5 Ti 0.5 O 3 non-crystalline thin films is discussed in the light of experimental results and theoretical calculations. The photoluminescence measurements reveal that the emission intensity changes with the degree of disorder in the BaZr 0.5 Ti 0.5 O 3 lattice. First principles quantum mechanical techniques, based on density functional theory at B3LYP level, have been employed to study the electronic structure of a crystalline model and of structurally disordered models in order to detect the influence of disorder on the electronic structure. An analysis of the electronic charge distribution reveals local polarization in the disordered structures. The relevance of the present theoretical and experimental results on the photoluminescence behavior of BZT is discussed

  20. Influence of 45S5 Bioglass addition on microstructure and properties of ultrafine grained (Mg-4Y-5.5Dy-0.5Zr) alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, K., E-mail: kamil.kowalski@put.poznan.pl [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland); Jurczyk, M.U. [Division of Mother’s and Child’s Health, Poznan University of Medical Sciences, Polna 33, 60-535 Poznan (Poland); Wirstlein, P.K. [Department of Gynecology and Obstetrics, Division of Reproduction, Poznan University of Medical Sciences, Polna 33, 60-535 Poznan (Poland); Jakubowicz, J.; Jurczyk, M. [Institute of Materials Science and Engineering, Poznan University of Technology, Jana Pawla II 24, 61-138 Poznan (Poland)

    2017-05-15

    Highlights: • Ultrafine grained composites were formed by consolidating mechanically alloyed powders. • Mechanical properties were sensitive to the content of 45S5 Bioglass in Mg-4Y-5.5Dy-0.5Zr alloy. • Fluoride treated composites displayed superior corrosion resistance in Ringer solution. • Composites modified with MgF{sub 2} have a higher degree of biocompatibility in comparison with the unmodified reference material. - Abstract: Bulk samples of an ultrafine grained (Mg-4Y-5.5Dy-0.5Zr)-x wt% 45S5 Bioglass (x = 0, 5) and (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass-1 wt% Ag composites have been synthesized by consolidating mechanically alloyed powders. The influence of the chemical composition on the microstructure, mechanical properties and corrosion behavior of bulk composites were studied. The sintering of (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass powders led to the formation of a bulk composite with grain size of approx. 95 nm. The corrosion behavior of Mg-based composites before and after hydrofluoric acid treatment was also investigated. The ultrafine grained (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass composite was more corrosion resistant than the bulk Mg-4Y-5.5Dy-0.5Zr alloy after HF treatment. The in vitro biocompatibility of synthesized composites was evaluated and compared with microcrystalline magnesium. Magnesium, (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass and (Mg-4Y-5.5Dy-0.5Zr)-5 wt% 45S5 Bioglass-1 wt% Ag composites modified with MgF{sub 2} have a higher degree of biocompatibility in comparison with the unmodified reference material.

  1. Some observations on the synthesis and electrolytic properties of (Ba1-xCax (M0.9Y0.1O3, M = Ce, Zr-based samples modified with calcium

    Directory of Open Access Journals (Sweden)

    Dudek Magdalena

    2016-03-01

    Full Text Available In this paper, the impact of partial substitution of calcium for barium in (Ba1-xCax (M0.9Y0.1 O3, M = Ce, Zr on physicochemical properties of the powders and sintered samples was investigated. The powders, with various contents of calcium (x = 0, 0.02, 0.05, 0.1, were prepared by means of thermal decomposition of organometallic precursors containing EDTA. All of the BaCeO3-based powders synthesised at 1100 °C were monophasic with a rhombohedral structure, however, completely cubic BaZrO3-based solid solutions were obtained at 1200 °C. A study of the sinterability of BaZr0.9Y0.1O3 and BaCe0.9Y0.1O3-based pellets was performed under non-isothermal conditions within a temperature range of 25 to 1200 °C. The partial substitution of barium for calcium in the (Ba1-xCax (M0.9Y0.1 O3, M = Ce, Zr solid solution improved the sinterability of the samples in comparison to the initial BaCe0.9Y0.1O3 or BaZr0.9Y0.1O3. The relative density of calcium-modified BaCe0.9Y0.1O3-based samples reached approximately 95 to 97 % after sintering at 1500 °C for 2 h in air. The same level of relative density was achieved after sintering calcium-modified BaZr0.9Y0.1O3 at 1600 °C for 2 h. Analysis of the electrical conductivity from both series of investigated materials showed that the highest ionic conductivity, in air and wet 5 % H2 in Ar, was attained for the compositions of x = 0.02 to 0.05 (Ba1-xCax(M0.9Y0.1O3, M = Zr, Ce. The oxygen reduction reaction on the interface Pt│BaM0.9Y0.1O3, M = Ce, Zr was investigated using Pt microelectrodes. Selected samples of (Ba1-xCax (M0.9Y0.1O3, M = Zr, Ce were tested as ceramic electrolytes in hydrogen-oxygen solid oxide fuel cells operating at temperatures of 700 to 850 °C.

  2. Perovskite phases of the system Ba/sub 2/MgUsub(1-x)Wsub(x)O/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Seemann, I [Tuebingen Univ. (Germany, F.R.). Inst. fuer Anorganische Chemie

    1976-08-01

    The series Ba/sub 2/MgUsub(1-x)Wsub(x)O/sub 6/ shows complete miscibility. The Vegard rule is obeyed. Deviations from the ideal properties of solid solutions are observed: The replacement of Usup 9vi0 by Wsup(VI) leads to a deformation of the UO/sub 6/ octahedra and vice versa.

  3. Blue and red emission in wide band gap BaZrO{sub 3}:Yb{sup 3+},Tm{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Borja-Urby, R. [Centro de Investigaciones en Optica, A. C., C. P. 37150 Leon, Gto. (Mexico); Diaz-Torres, L.A., E-mail: ditlacio@cio.mx [Centro de Investigaciones en Optica, A. C., C. P. 37150 Leon, Gto. (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A. P. 1-1010, Queretaro 76000 (Mexico); Vega-Gonzalez, 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, Cd. Mexico D.F. 07730 (Mexico)

    2010-10-25

    Under NIR excitation at 967 intense blue and red photoluminescence (PL) emissions are observed at room temperature in codoped Tm{sup 3+}-Yb{sup 3+} barium zirconate (BaZrO{sub 3}:Yb,Tm) powders. Powders were prepared by a simple hydrothermal method, and present a wide band gap that depends on the total rare earth content due to the degree of disorder induced in the BaZrO{sub 3} lattice by the substitution of the rare earth ions. Rietveld refinements of the XRD patterns indicated the presence of primary nanocrystallites with sizes between 50 and 70 nm depending on the Tm{sup 3+} content. Scanning transmission electron microscopy (STEM) shows that these primary particles self-aggregated in larger secondary particles which present a regular morphology with sizes around 1 {mu}m. The intense blue and red PL emissions in BaZrO{sub 3} powders under 967 nm excitation are governed by energy transfer processes from Yb{sup 3+} ions to Tm{sup 3+} ions and crossrelaxation among Tm{sup 3+} ions.

  4. The low-temperature, high-magnetic-field critical current characteristics of Zr-added (Gd, Y)Ba2Cu3Ox superconducting tapes

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V; Yao, Y; Chen, Y; Shi, T; Liu, Y; Khatri, ND; Liu, J; Lei, C; Galstyan, E; Majkic, G

    2012-10-26

    Critical current performances of state-of-the-art Zr-added (Gd, Y)BaCuO tapes have been investigated over a temperature range of 20-77 K, in magnetic fields up to 9 T and over a wide angular range of magnetic field orientations. The peak in critical current that is commonly observed in the field orientation perpendicular to the tape in BaZrO3 (BZO) containing superconducting tapes is found to vanish at 30 K in magnetic fields at 1-9 T. While the critical current of 15% Zr-added tapes was about 40% lower than that of 7.5% Zr-added tapes at 77 K, the pinning force values of the former were found to be 18-23% higher than those of the latter in the temperature range of 20-40 K and in magnetic fields of 3-5 T. The results from this study emphasize the importance of optimization of coated conductor fabrication processes for optimum performance not just in low magnetic fields at 77 K but also at the operating conditions of low temperatures and high magnetic fields that are of interest, especially for rotating superconducting machinery applications.

  5. The low-temperature, high-magnetic-field critical current characteristics of Zr-added (Gd,Y)Ba2Cu3Ox superconducting tapes

    International Nuclear Information System (INIS)

    Selvamanickam, V; Yao, Y; Shi, T; Liu, Y; Khatri, N D; Liu, J; Galstyan, E; Majkic, G; Chen, Y; Lei, C

    2012-01-01

    Critical current performances of state-of-the-art Zr-added (Gd, Y)BaCuO tapes have been investigated over a temperature range of 20–77 K, in magnetic fields up to 9 T and over a wide angular range of magnetic field orientations. The peak in critical current that is commonly observed in the field orientation perpendicular to the tape in BaZrO 3 (BZO) containing superconducting tapes is found to vanish at 30 K in magnetic fields at 1–9 T. While the critical current of 15% Zr-added tapes was about 40% lower than that of 7.5% Zr-added tapes at 77 K, the pinning force values of the former were found to be 18–23% higher than those of the latter in the temperature range of 20–40 K and in magnetic fields of 3–5 T. The results from this study emphasize the importance of optimization of coated conductor fabrication processes for optimum performance not just in low magnetic fields at 77 K but also at the operating conditions of low temperatures and high magnetic fields that are of interest, especially for rotating superconducting machinery applications. (paper)

  6. Laser cladding of a Mg based Mg–Gd–Y–Zr alloy with Al–Si powders

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Erlei [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zhang, Kemin, E-mail: zhangkm@sues.edu.cn [School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Zou, Jianxin [National Engineering Research Center of Light Alloys Net Forming & School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2016-03-30

    Graphical abstract: A Mg based Mg–Gd–Y–Zr alloy was treated by laser cladding with Al–Si powders at different laser scanning speeds. The laser clad layer mainly contains Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases distributed in the Mg matrix. After laser cladding, the corrosion resistance of the Mg alloy was significantly improved together with increased microhardness in the laser clad layers. - Highlights: • A Mg based Mg–Gd–Y–Zr alloy was laser clad with Al–Si powders. • The microstructure and morphology vary with the depth of the clad layer and the laser scanning speed. • Hardness and corrosion resistance were significantly improved after laser cladding. - Abstract: In the present work, a Mg based Mg–Gd–Y–Zr alloy was subjected to laser cladding with Al–Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg{sub 2}Si, Mg{sub 17}Al{sub 12} and Al{sub 2}(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from −1.77 V for the untreated alloy to −1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10{sup −5} A cm{sup −2} to 1.64 × 10{sup −6} A cm{sup −2}. The results show that laser cladding is an efficient method to improve

  7. Laser cladding of a Mg based Mg–Gd–Y–Zr alloy with Al–Si powders

    International Nuclear Information System (INIS)

    Chen, Erlei; Zhang, Kemin; Zou, Jianxin

    2016-01-01

    Graphical abstract: A Mg based Mg–Gd–Y–Zr alloy was treated by laser cladding with Al–Si powders at different laser scanning speeds. The laser clad layer mainly contains Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases distributed in the Mg matrix. After laser cladding, the corrosion resistance of the Mg alloy was significantly improved together with increased microhardness in the laser clad layers. - Highlights: • A Mg based Mg–Gd–Y–Zr alloy was laser clad with Al–Si powders. • The microstructure and morphology vary with the depth of the clad layer and the laser scanning speed. • Hardness and corrosion resistance were significantly improved after laser cladding. - Abstract: In the present work, a Mg based Mg–Gd–Y–Zr alloy was subjected to laser cladding with Al–Si powders at different laser scanning speeds in order to improve its surface properties. It is observed that the laser clad layer mainly contains Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases distributed in the Mg matrix. The depth of the laser clad layer increases with decreasing the scanning speed. The clad layer has graded microstructures and compositions. Both the volume fraction and size of Mg_2Si, Mg_1_7Al_1_2 and Al_2(Gd,Y) phases decreases with the increasing depth. Due to the formation of these hardening phases, the hardness of clad layer reached a maximum value of HV440 when the laser scanning speed is 2 mm/s, more than 5 times of the substrate (HV75). Besides, the corrosion properties of the untreated and laser treated samples were all measured in a NaCl (3.5 wt.%) aqueous solution. The corrosion potential was increased from −1.77 V for the untreated alloy to −1.13 V for the laser clad alloy with scanning rate of 2 mm/s, while the corrosion current density was reduced from 2.10 × 10"−"5 A cm"−"2 to 1.64 × 10"−"6 A cm"−"2. The results show that laser cladding is an efficient method to improve surface properties of Mg–Rare earth alloys.

  8. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    International Nuclear Information System (INIS)

    Jiang, S.T.; Zhang, J.; Shun, S.Z.; Chen, M.F.

    2016-01-01

    Highlights: • Use a two-step chemical treatment method for formation of FHA coating on biodegradable Mg-Zn-Zr alloy;. • We reported the formation mechanism of FHA coating on Mg-Zn-Zr alloy and achieved optimum properties;. • The MgF_2 coating and FHA coating provide effective protection for the Mg alloy substrate and the FHA coating showed better corrosion resistance. - Abstract: To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO_3).4H_2O and 0.06 mol/L NH_4H_2PO_4 at 90 °C to prepare the Ca-P coating. The concentrations of Mg"2"+, F"− ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF_2 nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After immersion for 60 min, the FHA coating with

  9. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, S.T.; Zhang, J.; Shun, S.Z. [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin (China); Chen, M.F., E-mail: mfchentj@126.com [School of Materials Science and Engineering, Tianjin University of Technology, Tianjin (China); Tianjin Key Laboratory of Display Materials and Photoelectric Device, Tianjin University of Technology , Tianjin (China)

    2016-12-01

    Highlights: • Use a two-step chemical treatment method for formation of FHA coating on biodegradable Mg-Zn-Zr alloy;. • We reported the formation mechanism of FHA coating on Mg-Zn-Zr alloy and achieved optimum properties;. • The MgF{sub 2} coating and FHA coating provide effective protection for the Mg alloy substrate and the FHA coating showed better corrosion resistance. - Abstract: To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO{sub 3}).4H{sub 2}O and 0.06 mol/L NH{sub 4}H{sub 2}PO{sub 4} at 90 °C to prepare the Ca-P coating. The concentrations of Mg{sup 2+}, F{sup −} ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF{sub 2} nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After

  10. Protonic defects in pure and doped La2Zr2O7 pyrochlore oxide

    DEFF Research Database (Denmark)

    Björketun, Mårten; Knee, Christopher S.; Nyman, B. Joakim

    2008-01-01

    migration pathway that enables long-range transport is proposed. In addition, the interaction energies between protons and divalent Ba, Sr, Ca, and Mg dopants located on the La- and Zr-sites have been calculated. All interactions are found to be attractive; they are strong in the case of Ba and Mg and quite...

  11. Photoionization behavior of Eu2+-doped BaMgSiO4 long-persisting phosphor upon UV irradiation

    International Nuclear Information System (INIS)

    Li, Y.; Wang, Y.; Gong, Y.; Xu, X.; Zhang, F.

    2011-01-01

    Highlights: → Photoionization behavior of BaMgSiO 4 :Eu 2+ long persistent phosphor upon UV irradiation. → Green phosphorescence was obtained from BaMgSiO 4 :Eu 2+ . → The ionization of Eu 2+ to Eu 3+ was observed in BaMgSiO 4 :Eu 2+ . → The photogenerated Eu 3+ cannot change back to its divalent state at room temperature. → The phosphorescence is associated with the formation forming Eu 3+ -e - pairs. - Abstract: The fluorescence, phosphorescence and thermoluminescence properties of Eu-doped BaMgSiO 4 phosphors sintered in air and in a reducing atmosphere were investigated. Phosphorescence of phosphor sintered in a reducing atmosphere can last for 1.5 h at a recognizable intensity level, whereas phosphorescence of air-sintered phosphor can only persist for 6 min. In addition, a distinction between the shape of the fluorescence spectrum and its corresponding phosphorescence spectrum is observed in the former case. Ionization of Eu 2+ to Eu 3+ upon UV irradiation is observed in the phosphor prepared in a reducing atmosphere, but there is no indication that the photogenerated Eu 3+ cannot change back to its divalent state at room temperature after the excitation source is switched off. In addition, phosphor sintered in a reducing atmosphere shows photochromism upon UV irradiation. No such photoionization and photochromism behavior is observed for the air-sintered phosphor. A possible Eu 2+ photoionization mechanism is constructed on the basis of these experimental observations. The photoionization mechanism presented can also successfully explain the fluorescence and phosphorescence behavior of Eu in BaMgSiO 4 .

  12. Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program. II. Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu

    Science.gov (United States)

    Delgado Mena, E.; Tsantaki, M.; Adibekyan, V. Zh.; Sousa, S. G.; Santos, N. C.; González Hernández, J. I.; Israelian, G.

    2017-10-01

    Aims: To understand the formation and evolution of the different stellar populations within our Galaxy it is essential to combine detailed kinematical and chemical information for large samples of stars. The aim of this work is to explore the chemical abundances of neutron capture elements which are a product of different nucleosynthesis processes taking place in diverse objects in the Galaxy, such as massive stars, asymptotic giant branch (AGB) stars and supernovae (SNe) explosions. Methods: We derive chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd, and Eu for a large sample of more than 1000 FGK dwarf stars with high-resolution (R 115 000) and high-quality spectra from the HARPS-GTO program. The abundances are derived by a standard local thermodynamic equilibrium (LTE) analysis using measured equivalent widths (EWs) injected to the code MOOG and a grid of Kurucz ATLAS9 atmospheres. Results: We find that thick disc stars are chemically disjunct for Zn and Eu and also show on average higher Zr but lower Ba and Y than the thin disc stars. We also discovered that the previously identified high-α metal-rich population is also enhanced in Cu, Zn, Nd, and Eu with respect to the thin disc but presents lower Ba and Y abundances on average, following the trend of thick disc stars towards higher metallities and further supporting the different chemical composition of this population. By making a qualitative comparison of O (pure α), Mg, Eu (pure r-process), and s-process elements we can distinguish between the contribution of the more massive stars (SNe II for α and r-process elements) and the lower mass stars (AGBs) whose contribution to the enrichment of the Galaxy is delayed, due to their longer lifetimes. The ratio of heavy-s to light-s elements of thin disc stars presents the expected behaviour (increasing towards lower metallicities) and can be explained by a major contribution of low-mass AGB stars for s-process production at disc metallicities. However, the

  13. Characterization of oxygen vacancies and their migration in Ba-doped Pb(Zr0.52Ti0.48)O3 ferroelectrics

    Science.gov (United States)

    Zhang, M. F.; Wang, Y.; Wang, K. F.; Zhu, J. S.; Liu, J.-M.

    2009-03-01

    We investigate in detail the migration kinetics of oxygen vacancies (OVs) in Ba-doped Pb(Zr0.52Ti0.48)O3 (PZT) ferroelectrics by complex impedance spectroscopy. The temperature dependent dc-electrical conductivity σdc suggests that Ba doping into PZT can lower significantly the density of OVs, leading to the distinctly decreased σdc and slightly enhanced activation energy U for the migration of OVs, thus benefiting the polarization fatigue resistance. Furthermore, the polarization fluctuation induced by the relaxation of OVs is reduced by the Ba doping. The Cole-Cole fitting to the dielectric loss manifests strong correlation among OVs, and the migration of OVs appears to be a collective behavior.

  14. Defects or charge transfer: Different possibilities to explain the photoluminescence in crystalline Ba(Zr{sub x}Ti{sub 1−x})O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Agda E., E-mail: agda@fct.unesp.br [Universidade Estadual Paulista, Faculdade de Ciências e Tecnologia, Presidente Prudente, SP (Brazil); Sasaki, Guilherme S.; Camacho, Sabrina A.; Teixeira, Silvio R. [Universidade Estadual Paulista, Faculdade de Ciências e Tecnologia, Presidente Prudente, SP (Brazil); Li, Maximo S. [Universidade de São Paulo, Instituto de Física, São Carlos, SP (Brazil); Longo, Elson [Universidade estadual Paulista, Instituto de Química, Araraquara, SP (Brazil)

    2016-11-15

    In this work, BZT (Ba (Zr{sub x}Ti{sub 1−x})O{sub 3}), composite ceramic powder with x=0, 0.25, 0.50, 0.75 and 1 (mol) was prepared by the microwave-assisted hydrothermal method. The structural, morphological and optical properties of the compounds were determined by XRD, SEM, Raman, UV–vis and photoluminescence analysis. The results showed that the stability of the BZ phase was strongly influenced by the isomorphic Zr/Ti substitution, and that the BZ sample had the greatest structural order for short and long distances compared to the other. The BZT ceramic composite showed optical behavior also influenced by the concentration of Zr, resulting in a growing photoluminescence emission with increasing Zr ion in the network. The BZ sample showed higher photoluminescent intensity in a region including the entire visible spectrum. Although the effect of photoluminescence in these materials is dependent on the presence of defects, which produce excitons for radiative recombination, in the BZ compound, there might have been other effects causing the intense photoluminescence. In this case, high emission is associated with the a charge transfer between neighboring clusters [ZrO{sub 6}] in a nanoparticle surface interface, which in turn are joined to form BZ mesocrystals on a micrometer scale. The photoluminescence observed in the BZT compound had a predominantly white color, a feature that gives it high potential for applications in white light-emitting devices.

  15. Electrical and mechanical properties of 0.5Ba (Zr0.2Ti0.8)O3-0.5 (Ba0.7Ca0.3)TiO3 (BZT-BCT) lead free ferroelectric ceramics reinforced with Al2O3 nano-oxide

    International Nuclear Information System (INIS)

    Adhikari, Prativa; Mazumder, R.

    2014-01-01

    Piezoelectric ceramics are widely used as actuator, resonator, and spark igniter. Recently, much attention has been paid to prepare 0.5Ba (Zr 0.2 Ti 0.8 )O 3 -0.5 (Ba 0.7 Ca 0.3 )TiO 3 (BZT-BCT) piezoelectric ceramics because of its good dielectric, piezoelectric properties and environment friendly nature. However, piezoelectric ceramics based on BaTiO 3 suffer from low reliability and poor mechanical properties such as strength and toughness. For practical application improvement of the mechanical properties of BaTiO 3 -based ceramics is strongly required. A novel method has been used to improve the mechanical properties of structural ceramics by reinforcement of oxide (Al 2 O 3 , MgO, ZrO 2 and Stabilized-ZrO 2 ) or non-oxide (SiC) particles. It is well known that electrical properties of ferroelectric ceramics generally degrade with non-ferroelectric additives and decrease in sinterability usually encountered with refractory oxide additives. Use of nano-oxide additives may drastically reduce the amount of additive and electrical property may not degrade much. In this report we would show the electrical and mechanical properties of BZT-BCT with Al 2 O 3 nano oxide additive. Modified BZT-BCT nanocomposites were prepared by mixing and sintering of solid state synthesized Zr, Ca modified barium titanate powder and small amount (0.1-2.0 vol %) of nano-oxides, i.e. Al 2 O 3 . Effect of sintering temperature, time, particle size of the nano-oxide additives on electrical (dielectric constant, loss factor, Curie temperature, d 33 ) and mechanical (flexural strength, fracture toughness, hardness) properties were studied. We obtained ∼ 94% dense BZT-BCT reinforced with Al 2 O 3 nano-oxide at 1300℃ without degrading electrical properties (dielectric constant (4850), low dissipation factor (0.0242)) and superior mechanical properties (flexural strength - 60.3 MPa, Vickers hardness-750-800 MPa). (author)

  16. Textures and mechanical properties in rare-earth free quasicrystal reinforced Mg-Zn-Zr alloys prepared by extrusion

    International Nuclear Information System (INIS)

    Ohhashi, S.; Kato, A.; Demura, M.; Tsai, A.P.

    2011-01-01

    Highlights: → Powder-metallurgical warm extrusion made quasicrystal dispersing Mg alloys. → Mg extrusions containing quasicrystals showed randomized textures. → These extrusion showed the enhancement of mechanical properties at 150 deg. C. - Abstract: Microstructure and mechanical properties of quasicrystals dispersed Mg alloys prepared by warm extrusion of the mixtures of Mg and Zn-Mg-Zr quasicrystalline (Qc) powders have been studied. Strong texture oriented along a [101-bar 0] direction observed in pure Mg was reduced in Qc-dispersed samples, as verified by pole figure method and electron back scattering diffraction. The ultimate tensile strengths at 150 deg. C for Qc-dispersed extrusions were much higher than 110 MPa for pure Mg, which drastically reached 156 MPa for 15 wt.% Qc by preventing the motion of dislocations. Elongation was improved by the randomization of grain orientation: from 5.7% for pure Mg to 12.9% for 10 wt.% Qc at room temperature; from 15% for pure Mg to 37.1% for 5 wt.% Qc at 150 deg. C.

  17. Effects of homogenization on microstructures and properties of a new type Al-Mg-Mn-Zr-Ti-Er alloy

    International Nuclear Information System (INIS)

    He, L.Z.; Li, X.H.; Liu, X.T.; Wang, X.J.; Zhang, H.T.; Cui, J.Z.

    2010-01-01

    Research highlights: These new type alloys are very potential for increased use in aerospace and automobile industries. However, most of published reports have focused on the effects of Cu, Sc, Zr, Ag, rare metals and Si additions, Portevin-LeChatelier effect, corrosion properties, friction stir welding and superplasticity in 5000-series aluminum alloy, few investigated on Er and stepped homogenization on the precipitation of dispersoids in Al-Mg-Mn alloy. The purpose of this work was to study the effects of Er and homogenization treatment on mechanical properties and microstructural evolution in new type Al-Mg-Mn-Er alloy. - Abstract: Microstructural evolutions and mechanical properties of Al-Mg-Mn-Zr-Ti-Er alloy after homogenization were investigated in detail by optical microscope (OM), scanning electronic microscope (SEM), transmission electronic microscope (TEM), energy dispersive spectrum (EDS) and tensile test. A maximum tensile strength is obtained when the alloy homogenized at 510 deg. C for 16 h. With increasing preheating temperature (200-400 deg. C), the strength of the alloy finial homogenized at 490 deg. C for 16 h increases. When the preheating temperature is ≥300 deg. C, the strengths of the two-step homogenized alloys are higher than those of the single homogenized alloys. The preheating stage plays an important role in the microstructures and properties of the final homogenized alloy. Many fine (Mn,Fe)Al 6 precipitates when the preheating temperature is 400 deg. C. ErAl 3 phase cannot be observed during preheating stage. Plenty of fine (Mn,Fe)Al 6 and ErAl 3 precipitate in finial homogenized alloy when the preheating temperature is ≥300 deg. C. The Al-Mg-Mn-Zr-Ti-Er alloy is effectively strengthened by substructure and dispersoids of (Mn,Fe)Al 6 and ErAl 3 .

  18. In vitro and in vivo corrosion, mechanical properties and biocompatibility evaluation of MgF2-coated Mg-Zn-Zr alloy as cancellous screws.

    Science.gov (United States)

    Li, Zhen; Shizhao, Sun; Chen, Minfang; Fahlman, Bradley Dean; Debao Liu; Bi, Hongwei

    2017-06-01

    Magnesium (Mg) and its alloys as biodegradable materials have received much attention in the orthopedics applications; however, the corrosion behavior of these metals in vivo remains challenging. In this work, a dense and nanoscale magnesium fluoride (MgF 2 ) coating was deposited on the surface of Mg-Zn-Zr (MZZ) alloy cancellous screw. The MZZ cancellous screw with MgF 2 coating maintained an integrated shape and high yield tensile stress after 30days immersion in SBF, comparing with the bare screw. Hydrogen releasing rate of the MZZ samples was suppressed at a lower level at the initial stage, which is in favour of the adhesion of the cells. And in vivo experiments indicated that MgF 2 -coated MZZ screws presented advantages in cytocompatibility, osteoconductivity and osteogenesis of cancellous bone in rabbits. Corrosion rate in vivo perfusion environment increased very slowly with time in long-term study, which was an opposite trend in vitro static immersion test. Moreover, maximum corrosion rate (CR max ), a critical calculation method of corrosion rate was introduced to predict fracture regions of the sample. The MZZ alloy with MgF 2 coating possesses a great potential for clinical applications for internal fracture fixation repair. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. The effect of nano-size ZrO2 powder addition on the microstructure and superconducting properties of single-domain Y-Ba-Cu-O bulk superconductors

    International Nuclear Information System (INIS)

    Iida, K; Babu, N H; Reddy, E S; Shi, Y-H; Cardwell, D A

    2005-01-01

    The effect of nano-size ZrO 2 powder addition on the microstructure and superconducting properties of Y-Ba-Cu-O single grain bulk superconductors has been investigated. Significant pushing phenomena of Y 2 BaCuO 5 (Y-211) particles, particularly in the c growth sector, were observed even with a small amount of ZrO 2 added to the precursor powder. An increase in Y-211 particle pushing was observed with increasing ZrO 2 content, leading to an inhomogeneous bulk microstructure. In addition, a growth cycle consisting of a Y-211 free layer-porous narrow layer-Y-211 high concentration layer was observed for samples prepared with 0.25 wt% ZrO 2 in both the a and c growth sectors. The extent of the growth of single grain Y-Ba-Cu-O (YBCO) decreased with increasing ZrO 2 content due to increased pushing of Y-211 particles towards molten liquid. The superconducting transition temperature, T c , of the ZrO 2 containing YBCO samples was sharp but depressed slightly (by up to 1 K) compared with an undoped YBCO grain, indicating a relative insensitivity of T c to ZrO 2 content. Finally, the sensitivity of critical current density, J c , to applied magnetic field in large grain bulk YBCO containing ZrO 2 was observed to depend critically on position due to the inhomogeneous sample microstructure

  20. Enhanced flux pinning by BaZrO3 and (Gd,y)2O3 nano-structures in metal organic chemical vapor deposited GdYBCO high temperature superconductor tapes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y [SuperPower Incorporated, Schenectady, New York; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York; Paranthaman, Mariappan Parans [ORNL; Cantoni, Claudia [ORNL; Aytug, Tolga [ORNL; Goyal, Amit [ORNL; Lee, Dominic F [ORNL; Specht, Eliot D [ORNL; Zuev, Yuri L [ORNL; Zhang, Yifei [ORNL

    2009-01-01

    We have formed BaZrO3 nano-columns and (Gd,Y)2O3 nano-precipitates in reel-to-reel MOCVD processed (Gd,Y)Ba2Cu3O7-x coated conductors and increased the critical currents (Ic) of the conductors in applied magnetic fields to remarkable levels. A (Gd,Y)Ba2Cu3O7-x tape of 1m length with 6.5% Zr-additions and 30% composition rich in both Gd and Y showed Ic values of 813 A/cm-width at (self-field, 77K) and above 186 A/cm-width at (1T, 77K). The strongly enhanced flux pinning over a wide range of magnetic field orientations can be attributed to the bidirectionally aligned defect structures of BaZrO3 and (Gd,Y)2O3 created by optimized MOCVD conditions.

  1. Quantitative determination of phases in ZrO2 (MgO) (Y2O3) using the Rietveld method

    International Nuclear Information System (INIS)

    Castro, Antonio Carlos de

    2007-01-01

    The key objective of this work is the crystallographic characterization of the zircon co-doped with Yttria and magnesium with the application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon monoclinic, tetragonal, and cubic). Samples of zircon polymorph were obtained from zircon doped with Yttria and magnesium at defined molar concentrations. The zircon polymorph stability during subeutetoid aging at 1350 deg C were investigated to determine ZrO 2 - MgO - Y 2 0 3 phases degradation and to define the solid solutions stability environment. ZrO 2 powders doped with 8 mol por cent of MgO and 1 mol por cent of Y 2 O 3 , and 9 mol por cent of MgO and 0 mol por cent of Y 2 O 3 have been prepared by chemical route using the co-precipitation method. These samples have been calcinate at 550 deg C, sintered at 1500 deg C and characterized by the Rietveld method using the X-ray diffraction data. The variation of the lattice parameter, changes in the phase composition and their microstructures are discussed. The application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon tetragonal and cubic) reveals no formation of tetragonal phase and indicating that the matrix is the cubic phase with low concentration of monoclinic phase.(author)

  2. The hot deformation behavior and microstructure evolution of HA/Mg-3Zn-0.8Zr composites for biomedical application.

    Science.gov (United States)

    Liu, Debao; Liu, Yichi; Zhao, Yue; Huang, Y; Chen, Minfang

    2017-08-01

    The hot deformation behavior of nano-sized hydroxylapatite (HA) reinforced Mg-3Zn-0.8Zr composites were performed by means of Gleeble-1500D thermal simulation machine in a temperature range of 523-673K and a strain rate range of 0.001-1s -1 , and the microstructure evolution during hot compression deformation were also investigated. The results show that the flow stress increases increasing strain rates at a constant temperature, and decreases with increasing deforming temperatures at a constant strain rate. Under the same processing conditions, the flow stresses of the 1HA/Mg-3Zn-0.8Zr specimens are higher than those of the Mg-3Zn-0.8Zr alloy specimens, and the difference is getting closer with increasing deformation temperature. The hot deformation behaviors of Mg-3Zn-0.8Zr and 1HA/Mg-3Zn-0.8Zr can be described by constitutive equation of hyperbolic sine function with the hot deformation activation energy being 124.6kJ/mol and 125.3kJ/mol, respectively. Comparing with Mg-3Zn-0.8Zr alloy, the instability region in the process map of 1HA/Mg-3Zn-0.8Zr expanded to a bigger extent at the same conditions. The optimum process conditions of 1HA/Mg-3Zn-0.8Zr composite is concluded as between the temperature window of 573-623K with a strain rate range of 0.001-0.1s -1 . A higher volume fraction and smaller grain size of dynamic recrystallization (DRX) grains was observed in 1HA/Mg-3Zn-0.8Zr specimens after the hot compression deformation compared with Mg-3Zn-0.8Zr alloy, which was ascribed to the presence of the HA particles that play an important role in particle-stimulated nucleation (PSN) mechanism and can effectively hinder the migration of interfaces. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Effects of chemical synthesis parameters on the Zr O2: 8% mol Mg O solid electrolytes electric conductivity and microstructure

    International Nuclear Information System (INIS)

    Avila, D.M.; Muccillo, E.N.S.

    1996-01-01

    Electrical conductivity measurements and scanning electron microscope observations have been done in Zr O 2 - 8 mol % Mg O solid electrolytes. The main purpose was to investigate to what extent some processing variables can influence the electrical behaviour and microstructural characteristics of the sintered ceramic. Zirconia powders have been prepared under different pH and temperature of precipitation, and washing media conditions. The results show that many structural characteristics of the calcined powders are 'lost' during sintering, giving rise to ceramics with similar electrical properties, besides minor differences in the final microstructure. The washing media play the major role on both microstructural development and electrical conductivity. (author)

  4. In situ martensitic transformation in a ternary MgO-Y/sub 2/O/sub 3/-ZrO/sub 2/ alloy: II, transformation in tetragonal ZrO/sub 2/ precipitates

    International Nuclear Information System (INIS)

    Lee, R.R.; Heuer, A.H.

    1988-01-01

    The stress-induced martensitic transformation of t-ZrO/sub 2/ precipitates in a ternary MgO-Y/sub 2/O/sub 3/-ZrO/sub 2/ alloy has been studied in situ in the transmission electron microscope. The transformation occurs autocatalytically and takes place by piecewise growth of two twin-related m-ZrO/sub 2/ variants. Unloading causes retransformation of partially transformed precipitates, but this reverse (m → t) transformation of fully transformed precipitates only occurs on heating. The martensitic transformation in this system is clearly thermoeleastic

  5. Refractory materials based on compounds of Mg, Zr, Si and Ca

    International Nuclear Information System (INIS)

    Drygalska, E.; Piech, J.; Szczerba, J.

    2003-01-01

    Basic refractory materials modified with zirconium oxide or calcium zirconate find application in metallurgy and ceramic industry. Fundamental raw material for ZrO 2 production is zirconia sand, while synthetic calcium zirconate is produced in reaction of zirconium oxide with calcium oxide. Regarding these facts new highly refractory composite materials CZ and DZ were obtained from mixtures of zirconia sand and limestone of dolomite. These composite materials may contain stabilised ZrO 2 and/or calcium zirconate. Among other important components are periclase and calcium orthosilicates. All these phases have high melting points (above 2000 o C). This work describes thermal and technological properties and microstructure of CZ and DZ materials. The use of calcareous raw materials (limestone and dolomite) yields materials with good hydration resistance. These composites may be used as an additive modifying properties of magnesia products. (author)

  6. Synthesis and crystal structure of nanocrystalline phase: Ca1-xMxZr4P6O24 (M = Sr, Ba and x = 0.0-1.0)

    International Nuclear Information System (INIS)

    Rashmi, Ch.; Shrivastava, O.P.

    2011-01-01

    The structure of strontium and barium substituted nano crystalline calcium zirconium phosphate (CZP) was determined on the basis of crystal data of solid solutions. It was found that up to 2.42 mol % of strontium and 1.62 mol % of barium could be loaded into CZP formulations without significant changes of the three-dimensional framework structure. The crystal chemistry of Ca 1-x M x Zr 4 P 6 O 24 (M = Sr, Ba and x = 0.0-1.0) phases has been investigated using General Structure Analysis System (GSAS) programming. The Sr and Ba substituted CZP phases crystallize in the space group R-3 and Z = 6. Powder diffraction data have been subjected to Rietveld refinement to arrive at a satisfactory structural convergence of R-factors. The unit cell volume and polyhedral (ZrO 6 and PO 4 ) distortion increases with rise in the size and mole % of loaded cation in the CZP matrix. The PO 4 stretching and bending vibrations in the Infra red (IR) region have been assigned. SEM, TEM and EDAX analysis provide evidence of Sr and Ba in the matrix. (authors)

  7. Yttrium and Nickel Co-Doped BaZrO3 as a Proton-Conducting Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells

    KAUST Repository

    Shafi, S. P.

    2015-07-17

    High temperature proton conducting oxides, due to their lower activation energy for proton conduction, can achieve high conductivity at relatively low temperatures (500-700°C). Though BaZr0.8Y0.2O3-δ (BZY) perovskite exhibits good chemical stability and high bulk conductivity, high grain boundary resistance decreases its total conductivity. This work focuses on substitution of Zr4+ with Ni2+ in the perovskite B-site in a targeted fashion in order to promote the sinterability of BZY. Powder X-ray diffraction analysis showed the formation of single phases for Ba0.8-xY0.2NixO3-δ compositions up to x = 0.04. Scanning electron microscopy (SEM) image analysis demonstrated that densification is promoted by increasing the Ni-content, reaching a fully dense microstructure for Ba0.76Y0.2Ni0.04O3-δ (BZYNi04). An anode supported single cell based on BZYNi04 electrolyte showed superior power performance, achieving 240 and 428 mW cm-2 at 600 and 700°C, respectively. © The Electrochemical Society.

  8. Pushing and trapping phenomena in YBa2Cu3O7 melt-textured composites with BaZrO3 and Ag additions

    International Nuclear Information System (INIS)

    Carrillo, A E; Puig, T; Obradors, X

    2005-01-01

    A new Ag trapped particle morphology has been discovered in melt-textured YBa 2 Cu 3 O 7 /Ag composites where the interface energy between particle inclusions and a solid matrix has been enhanced with BaZrO 3 additives. The enhanced pushing effect generates square-like macrosegregation bands where the secondary additives Y 2 BaCuO 5 , BaZrO 3 , and Ag are accumulated. It is shown that elongated Ag particles with a long axis ∼ 60-120 μm and aspect ratios as high as a ∼ 12 can be trapped in the YBa 2 Cu 3 O 7 matrix free of any other additive with a very anisotropic orientation. It is demonstrated that the elongated Ag particles lie with the long axis parallel to the growth direction in all the growth sectors generated by the top seeding growth. The pushing-trapping theory is used to explain qualitatively the unusual phenomenon of a growth-induced morphological shaping of inclusion particles

  9. Yttrium and Nickel Co-Doped BaZrO3 as a Proton-Conducting Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells

    KAUST Repository

    Shafi, S. P.; Bi, Lei; Boulfrad, S.; Traversa, Enrico

    2015-01-01

    High temperature proton conducting oxides, due to their lower activation energy for proton conduction, can achieve high conductivity at relatively low temperatures (500-700°C). Though BaZr0.8Y0.2O3-δ (BZY) perovskite exhibits good chemical stability and high bulk conductivity, high grain boundary resistance decreases its total conductivity. This work focuses on substitution of Zr4+ with Ni2+ in the perovskite B-site in a targeted fashion in order to promote the sinterability of BZY. Powder X-ray diffraction analysis showed the formation of single phases for Ba0.8-xY0.2NixO3-δ compositions up to x = 0.04. Scanning electron microscopy (SEM) image analysis demonstrated that densification is promoted by increasing the Ni-content, reaching a fully dense microstructure for Ba0.76Y0.2Ni0.04O3-δ (BZYNi04). An anode supported single cell based on BZYNi04 electrolyte showed superior power performance, achieving 240 and 428 mW cm-2 at 600 and 700°C, respectively. © The Electrochemical Society.

  10. Single-Crystal X-Ray Diffraction Studies of Homologues in the Series nBa(Nb,Zr)O 3+3 mNbO with n=2, 3, 4, 5 and m=1

    Science.gov (United States)

    Nilsson, G.; Svensson, G.

    2001-01-01

    Single crystals of four homologues in the series nBa(Nb,Zr)O3+3mNbO, with n:m=2:1, 3:1, 4:1, and 5:1, were found in the reduced Ba-Nb-Zr-O system. Single-crystal X-ray diffraction data were collected for all the crystals. For all homologues the space group was found to be P4/mmm. The structures can be described as intergrowths of Ba(Nb,Zr)O3 perovskite and NbO slabs. The refined cell parameters and compositions of the 2:1, 3:1, and 4:1 homologues are a=4.1768(5) Å and c=12.269(2) Å for Ba2Nb4.5(1)Zr0.5(1)O9, a=4.1769(5) Å and c=16.493(3) Å for Ba3+δNb4.8(2)-δ Zr1.2(2)O12-δ (δ=0.098(4)), and a=4.1747(6) Å and c= 20.619(4) Å for Ba4+δNb5.1(4)-δZr1.9(4)O15-δ (δ=0.270(9)). The refined cell parameters of the 5:1 homologue are a=4.1727(3) Å and c=24.804(3) Å. Zr replaces Nb only in the NbO6 octahedra found in the perovskite slabs.

  11. Effect of the Size of Al3(Sc,Zr) Precipitates on the Structure of Multi-Directionally Isothermally Forged Al-Mg-Sc-Zr Alloy

    Science.gov (United States)

    Sitdikov, O. Sh.; Avtokratova, E. V.; Mukhametdinova, O. E.; Garipova, R. N.; Markushev, M. V.

    2017-12-01

    The effect of Al3(Sc,Zr) dispersoids on the evolution of the cast Al-Mg-Sc-Zr alloy structure under multi-directional isothermal forging (MIF) has been investigated. The alloy, which has an equiaxed grain structure with a grain size of 25 μm and contains dispersoids 5-10 and 20-50 nm in size after onestage (at 360°C for 6 h) and two-stage (360°C for 6 h + 520°C for 1 h) annealing, respectively, was deformed at 325°C ( 0.65 T m) up to cumulative strains of e = 8.4. In the initial stages of MIF, new fine (sub)grains surrounded by low-angle and high-angle boundaries (HABs) were formed near the initial grain boundaries. With increasing strain, the volume fraction and misorientation of these crystallites increased, which led to the replacement of a coarse-grained structure with a fine-grained one with a grain size of 1.5-2.0 μm. Dynamic recrystallization occurred in accordance to a continuous mechanism and was controlled by the interaction of lattice dislocations and/or (sub)grain boundaries with dispersoids that effectively inhibited the migration of boundaries, as well as the rearrangement of lattice dislocations and their annihilation. The particle size and the density of their distribution significantly affected the parameters of the evolved structure; in an alloy with smaller particles, a structure with a smaller grain size and a larger HAB fraction developed.

  12. Evaluation of the photocatalytic ability of a sol-gel-derived MgO-ZrO2 oxide material

    Directory of Open Access Journals (Sweden)

    Ciesielczyk Filip

    2017-02-01

    Full Text Available This paper deals with the synthesis and characterization of a novel group of potential photocatalysts, based on sol-gel-derived MgO-ZrO2 oxide material. The material was synthesized in a typical sol-gel system using organic precursors of magnesia and zirconia, ammonia as a promoter of hydrolysis and methanol as a solvent. All materials were thoroughly analyzed, including morphology and particle sizes, chemical composition, identification of characteristic functional groups, porous structure parameters and crystalline structure. The proposed methodology of synthesis resulted in obtaining pure MgO-ZrO2 oxide material with micrometric-sized particles and a relatively high surface area. The samples underwent an additional calcination process which led to the crystalline phase of zirconia being formed. The key element of the study was the evaluation of the effectiveness of decomposition of C.I. Basic Blue 9 dye. It was shown that the calcined materials exhibit both satisfactory adsorption and photocatalytic activity with respect to the decomposition of a selected model organic impurity. Total dye removal varied in the range of 50-70%, and was strongly dependent on process parameters such as quantity of photocatalyst, time of irradiation, and the addition of promoters.

  13. A study on microstructure and corrosion resistance of ZrO{sub 2}-containing PEO coatings formed on AZ31 Mg alloy in phosphate-based electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, J.J.; Guo, Y.Q.; Xiang, N. [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China); Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China); Xiong, Y.; Hu, Q. [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China); College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310032 (China); Song, R.G., E-mail: songrg@hotmail.com [Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou University, Changzhou 213164 (China); Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, Jiangsu (China)

    2015-12-01

    Graphical abstract: - Highlights: • PEO coatings were formed in K{sub 2}ZrF{sub 6}-containing electrolyte. • K{sub 2}ZrF{sub 6} is capable to optimize the microstructure of PEO coating. • Corrosion resistance of PEO coatings is effected by K{sub 2}ZrF{sub 6} concentration in the electrolyte. • Potentiodynamic polarization results are well matched with the EIS test results. • Long time immersion test confirmed the electrochemical results. - Abstract: ZrO{sub 2}-containing ceramic coatings formed on the AZ31 Mg alloy were fabricated in an alkaline electrolyte containing sodium phosphate and potassium fluorozirconate (K{sub 2}ZrF{sub 6}) by plasma electrolytic oxidation (PEO). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) techniques were used to study the phase structure and composition of the coatings. It is indicated that the coatings formed in the K{sub 2}ZrF{sub 6}-containing electrolyte were composed of MgO, MgF{sub 2} and t-ZrO{sub 2}. Morphological investigation carried out by scanning electron microscopy (SEM) and stereoscopic microscopy, revealed that the uniformity of coatings increased and roughness of coatings decreased after the addition of K{sub 2}ZrF{sub 6}. Electrochemical investigation was achieved by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coating formed in K{sub 2}ZrF{sub 6}-containing electrolyte exhibited an improved corrosion resistance than that of the coating formed in K{sub 2}ZrF{sub 6}-free electrolyte. In addition, the polarization and EIS tests results both showed that the suitable concentration (2.5 g/l) of K{sub 2}ZrF{sub 6} is of significant ability to improve the corrosion resistance of coatings. However, 5 g/l and 10 g/l K{sub 2}ZrF{sub 6} has a negative effect on improving the corrosion resistance of PEO coatings compared with the coating formed in 2.5 g/l K{sub 2}ZrF{sub 6}-containing electrolyte.

  14. A study on microstructure and corrosion resistance of ZrO2-containing PEO coatings formed on AZ31 Mg alloy in phosphate-based electrolyte

    International Nuclear Information System (INIS)

    Zhuang, J.J.; Guo, Y.Q.; Xiang, N.; Xiong, Y.; Hu, Q.; Song, R.G.

    2015-01-01

    Graphical abstract: - Highlights: • PEO coatings were formed in K 2 ZrF 6 -containing electrolyte. • K 2 ZrF 6 is capable to optimize the microstructure of PEO coating. • Corrosion resistance of PEO coatings is effected by K 2 ZrF 6 concentration in the electrolyte. • Potentiodynamic polarization results are well matched with the EIS test results. • Long time immersion test confirmed the electrochemical results. - Abstract: ZrO 2 -containing ceramic coatings formed on the AZ31 Mg alloy were fabricated in an alkaline electrolyte containing sodium phosphate and potassium fluorozirconate (K 2 ZrF 6 ) by plasma electrolytic oxidation (PEO). X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) techniques were used to study the phase structure and composition of the coatings. It is indicated that the coatings formed in the K 2 ZrF 6 -containing electrolyte were composed of MgO, MgF 2 and t-ZrO 2 . Morphological investigation carried out by scanning electron microscopy (SEM) and stereoscopic microscopy, revealed that the uniformity of coatings increased and roughness of coatings decreased after the addition of K 2 ZrF 6 . Electrochemical investigation was achieved by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) test. The results showed that the PEO coating formed in K 2 ZrF 6 -containing electrolyte exhibited an improved corrosion resistance than that of the coating formed in K 2 ZrF 6 -free electrolyte. In addition, the polarization and EIS tests results both showed that the suitable concentration (2.5 g/l) of K 2 ZrF 6 is of significant ability to improve the corrosion resistance of coatings. However, 5 g/l and 10 g/l K 2 ZrF 6 has a negative effect on improving the corrosion resistance of PEO coatings compared with the coating formed in 2.5 g/l K 2 ZrF 6 -containing electrolyte.

  15. GdCuMg with ZrNiAl-type structure. An 82.2 K ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Stein, Sebastian; Heletta, Lukas; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2017-08-01

    GdCuMg has been synthesized by induction-melting of the elements in a sealed niobium ampoule followed by annealing in a muffle furnace. The sample was studied by powder and single crystal X-ray diffraction: ZrNiAl type, P anti 62m (a=749.2(4), c=403.3(1) pm), wR2=0.0242, 315 F{sup 2} values and 15 variables. Temperature dependent magnetic susceptibility measurements have revealed an experimental magnetic moment of 8.54(1) μ{sub B} per Gd atom. GdCuMg orders ferromagnetically below T{sub C}=82.2(5) K and based on the magnetization isotherms it can be classified as a soft ferromagnet.

  16. Ionic conductivity of ZrF4-BaF2-MFsub(n) fluoride glasses (M : The group I--V metal elements)

    International Nuclear Information System (INIS)

    Kawamoto, Yoji; Nohara, Ichiro

    1985-01-01

    To glass transition temperature in argon atmosphere using the complex capacitance and complex impedance methods. The ionic conductivity of glasses, represented by log σ = log σ 0 - ΔE/2.303 kT, was nearly dependent only upon the activation energy. The polarizability of cation was found to be a dominant factor which governs activation energy. Thus, glasses with high meanpolarizability of glass-constituting cations exhibited high ionic conductivity, and the ZrF 4 -BaF 2 -CsF system was suggested to be a promising system that may provide a glass with higher fluoride-ion conduction. (author)

  17. The formation of FHA coating on biodegradable Mg-Zn-Zr alloy using a two-step chemical treatment method

    Science.gov (United States)

    Jiang, S. T.; Zhang, J.; Shun, S. Z.; Chen, M. F.

    2016-12-01

    To improve the corrosion resistance of the biomedical magnesium alloy, a two-step chemical treatment method has been employed to prepare an FHA coating on the alloy surface. Prior to forming an FHA layer, the samples of Mg-3 wt% Zn-0.5 wt% Zr alloy were soaked in HF with concentration of 20% (v/v) at 37 °C temperature for 2 h, and were then placed into an aqueous solution with 0.1 mol/L Ca(NO3).4H2O and 0.06 mol/L NH4H2PO4 at 90 °C to prepare the Ca-P coating. The concentrations of Mg2+, F- ions, and pH variation with immersing time in the solution were investigated to explore the growth mechanism of FHA. The surface morphologies and compositions of the coatings were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the alloy surface treated with acid formed a layer of MgF2 nanoparticles with a thickness of 0.7 μm. The corrosion resistance of coatings in SBF solution was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The results showed that the substrate with FHA coating had good corrosion resistance. After immersing into the calcium phosphate solution, some small spherical particles were first formed on the surface; these then cover the surface completely after 20 min. Some clusters consisting of needle-like crystal were observed in the spherical particles covering the surface, and the Ca/P ratio of the needle-like crystal was 1.46, clearly growing along the c axis preferred orientation growth. After immersion for 60 min, the FHA coating with completely uniform growth was obtained on the Mg-Zn-Zr alloy surface with its thickness reaching about 120 μm.

  18. Study of chromites YbMIICr2O5,5 (MII - Mg, Ca, Sr, Ba by X-ray diffraction

    Directory of Open Access Journals (Sweden)

    B. Kasenov

    2012-03-01

    Full Text Available Compounds of composition YbMeMnFeO5,5 (Me – Mg, Ca, Sr, Ba are synthesized from Yb2O3, , Cr2O3 and MgCO3, CaCO3, SrCO3, BaCO3 by solid phase method. X-ray powder diffraction showed that the compound YbMgCr2O5,5, YbCaCr2O5,5, YbSrCr2O5,5, YbBaCr2O5,5 crystallizes in the tetragonal crystal system.

  19. Microstructure Evolution in Mg-Zn-Zr-Gd Biodegradable Alloy: The Decisive Bridge Between Extrusion Temperature and Performance.

    Science.gov (United States)

    Yao, Huai; Wen, Jiu-Ba; Xiong, Yi; Lu, Yan; Huttula, Marko

    2018-01-01

    Being a biocompatible metal with similar mechanical properties as bones, magnesium bears both biodegradability suitable for bone substitution and chemical reactivity detrimental in bio-ambiences. To benefit its biomaterial applications, we developed Mg-2.0Zn-0.5Zr-3.0Gd (wt%) alloy through hot extrusion and tailored its biodegradability by just varying the extrusion temperatures during alloy preparations. The as-cast alloy is composed of the α-Mg matrix, a network of the fish-bone shaped and ellipsoidal (Mg, Zn) 3 Gd phase, and a lamellar long period stacking ordered phase. Surface content of dynamically recrystallized (DRXed) and large deformed grains increases within 330-350°C of the extrusion temperature, and decreases within 350-370°C. Sample second phase contains the (Mg, Zn) 3 Gd nano-rods parallel to the extrusion direction, and Mg 2 Zn 11 nanoprecipitation when temperature tuned above 350°C. Refining microstructures leads to different anticorrosive ability of the alloys as given by immersion and electrochemical corrosion tests in the simulated body fluids. The sample extruded at 350°C owns the best anticorrosive ability thanks to structural impacts where large DRXed portions and uniform nanosized grains reduce chemical potentials among composites, and passivate the extruded surfaces. Besides materials applications, the in vitro mechanism revealed here is hoped to inspire similar researches in biometal developments.

  20. Microstructure evolution in Mg-Zn-Zr-Gd biodegradable alloy: the decisive bridge between extrusion temperature and performance

    Science.gov (United States)

    Yao, Huai; Wen, Jiu-Ba; Xiong, Yi; Lu, Yan; Huttula, Marko

    2018-03-01

    Being a biocompatible metal with similar mechanical properties as bones, magnesium bears both biodegradability suitable for bone substitution and chemical reactivity detrimental in bio-ambiences. To benefit its biomaterial applications, we developed Mg-2.0Zn-0.5Zr-3.0Gd (wt%) alloy through hot extrusion and tailored its biodegradability by just varying the extrusion temperatures during alloy preparations. The as-cast alloy is composed of the α-Mg matrix, a network of the fish-bone shaped and ellipsoidal (Mg, Zn)3Gd phase, and a lamellar long period stacking ordered phase. Surface content of dynamically recrystallized (DRXed) and large deformed grains increases within 330-350 C of the extrusion temperature, and decreases within 350-370 C. Sample second phase contains the (Mg, Zn)3Gd nano-rods parallel to the extrusion direction, and Mg2Zn11 nanoprecipitation when temperature tuned above 350 C. Refining microstructures leads to different anticorrosive ability of the alloys as given by immersion and electrochemical corrosion tests in the simulated body fluids. The sample extruded at 350 C owns the best anticorrosive ability thanks to structural impacts where large DRXed portions and uniform nanosized grains reduce chemical potentials among composites, and passivate the extruded surfaces. Besides materials applications, the in vitro mechanism revealed here is hoped to inspire similar researches in biometal developments.

  1. Microstructure Evolution in Mg-Zn-Zr-Gd Biodegradable Alloy: The Decisive Bridge Between Extrusion Temperature and Performance

    Directory of Open Access Journals (Sweden)

    Huai Yao

    2018-03-01

    Full Text Available Being a biocompatible metal with similar mechanical properties as bones, magnesium bears both biodegradability suitable for bone substitution and chemical reactivity detrimental in bio-ambiences. To benefit its biomaterial applications, we developed Mg-2.0Zn-0.5Zr-3.0Gd (wt% alloy through hot extrusion and tailored its biodegradability by just varying the extrusion temperatures during alloy preparations. The as-cast alloy is composed of the α-Mg matrix, a network of the fish-bone shaped and ellipsoidal (Mg, Zn3Gd phase, and a lamellar long period stacking ordered phase. Surface content of dynamically recrystallized (DRXed and large deformed grains increases within 330–350°C of the extrusion temperature, and decreases within 350–370°C. Sample second phase contains the (Mg, Zn3Gd nano-rods parallel to the extrusion direction, and Mg2Zn11 nanoprecipitation when temperature tuned above 350°C. Refining microstructures leads to different anticorrosive ability of the alloys as given by immersion and electrochemical corrosion tests in the simulated body fluids. The sample extruded at 350°C owns the best anticorrosive ability thanks to structural impacts where large DRXed portions and uniform nanosized grains reduce chemical potentials among composites, and passivate the extruded surfaces. Besides materials applications, the in vitro mechanism revealed here is hoped to inspire similar researches in biometal developments.

  2. Effect of europium ion concentration on the structural and photoluminescence properties of novel Li2BaZrO4: Eu3+ nanocrystals

    Science.gov (United States)

    Ahemen, I.; Dejene, F. B.; Kroon, R. E.; Swart, H. C.

    2017-12-01

    This work reports the influence of Eu3+ ion concentration on the structure and photoluminescence properties of Li2BaZrO4 nanocrystals including its intrinsic quantum efficiency (IQE). Chemical bath method was employed in the synthesis procedure. X-ray diffraction results showed tetragonal phase for Eu3+ ion concentration in the range 1 and 7 mol% and cubic phase at 8 mol%. The presence of barium oxide (BaO) was confirmed from selected area electron diffraction (SAED). The excitation spectra for these phosphors consisted of broad charge transfer (CT) bands due to the combination of Zr4+ - O2- and Eu3+-O2- charge transfer states. Superimposed on the CT band were direct excitation levels of Eu3+ and Ba2+ ions, in the range 320-450 nm. At high Eu3+ ions concentrations, the intensities of CT bands decreased because some of the ions were coordinated with Ba2+ ions. Photoluminescence emissions for all the doped samples at room temperature appeared to be entirely from intraconfigurational Eu3+ emissions and depended both on the site symmetry as well as the ion concentration. The quadrupole-quadrupole multipolar process was found to be solely responsible for the luminescence quenching. The intensity parameters (Ω2 ,Ω4), asymmetry ratio, R0 and the average decay lifetime of the nanocrystals showed dependence on concentration. High internal quantum efficiency (IQE) values were obtained at low Eu3+ ion concentrations, but efficiency decreased with increasing ion concentration. The CIE coordinates values were comparable to existing red phosphors and in combination with the high IQE make this phosphor a good candidate for red light emitting applications.

  3. Compounds of the type Ba/sub 3/Bsup(II)M/sub 2/sup(V)O/sub 9/ with Bsup(II) = Mg, Ca, Sr, Ba, and Msup(V) = Nb, Ta

    Energy Technology Data Exchange (ETDEWEB)

    Kemmler-Sack, S; Thumm, I; Herrmann, M [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1981-08-01

    The hexagonal perovskites Ba/sub 3/Bsup(II)M/sub 2/sup(V)O/sub 9/ (Msup(V) = Nb, Ta) crystallize with Bsup(II) = Mg, Ca in a 3 L structure (sequence (c)/sub 3/) and Bsup(II) = Sr in the hexagonal BaTiO/sub 3/ type (6 L; sequence (hcc)/sub 2/) with an 1:2 order for the B and M ions. Intensity calculations for Ba/sub 3/SrNb/sub 2/O/sub 9/ and Ba/sub 3/SrTa/sub 2/O/sub 9/ gave in the space group P6/sub 3//mmc a refined, intensity related R' value of 8.4% (Nb) and 9.0% (Ta) respectively. For Bsup(II) = Ba the perovskite Ba/sub 3/BaTa/sub 2/O/sub 9/ has an orthorhombic distorted 6 L structure and forms with Ba/sub 3/SrTa/sub 2/O/sub 9/ a continuous series of mixed crystals (Ba/sub 3/Srsub(1-x)Basub(x)Ta/sub 2/O/sub 9/). In the system Ba/sub 3/Srsub(1-x)Basub(x)Nb/sub 2/O/sub 9/ the range of existence of the hexagonal BaTiO/sub 3/ type is confined to the Sr richer end. The pure Ba compound posesses a proper structure type (5 L: Ba/sub 5/BaNb/sub 3/vacantOsub(13.5)vacantsub(1.5)).

  4. Effects of Sc and Zr on mechanical property and microstructure of tungsten inert gas and friction stir welded aerospace high strength Al–Zn–Mg alloys

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Ying, E-mail: csudengying@163.com [School of Metallurgy and Environment, Central South University, Hunan, Changsha 410083 (China); School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China); State Key Laboratory for Power Metallurgy, Central South University, Hunan, Changsha 410083 (China); Peng, Bing [School of Metallurgy and Environment, Central South University, Hunan, Changsha 410083 (China); Xu, Guofu, E-mail: csuxgf66@csu.edu.cn [School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China); State Key Laboratory for Power Metallurgy, Central South University, Hunan, Changsha 410083 (China); Pan, Qinglin; Yin, Zhimin; Ye, Rui [School of Materials Science and Engineering, Central South University, Hunan, Changsha 410083 (China); Wang, Yingjun; Lu, Liying [Northeast Light Alloy Co. Ltd., Hei Longjiang, Harbin 150060 (China)

    2015-07-15

    New aerospace high strength Al–Zn–Mg and Al–Zn–Mg–0.25Sc–0.10Zr (wt%) alloys were welded by tungsten inert gas (TIG) process using a new Al–6.0Mg–0.25Sc–0.10Zr (wt%) filler material, and friction stir welding (FSW) process, respectively. Mechanical property and microstructure of the welded joints were investigated comparatively by tensile tests and microscopy methods. The results show that Sc and Zr can improve the yield strength and ultimate tensile strength of Al–Zn–Mg alloy by 59 MPa (23.3%) and 16 MPa (4.0%) in TIG welded joints, and by 77 MPa (23.8%) and 54 MPa (11.9%) in FSW welded joints, respectively. The ultimate tensile strength and elongation of new Al–Zn–Mg–Sc–Zr alloy FSW welded joint are 506±4 MPa and 6.34±0.2%, respectively, showing superior post welded performance. Mechanical property of welded joint is mainly controlled by its “weakest microstructural zone”. TIG welded Al–Zn–Mg and Al–Zn–Mg–Sc–Zr alloys reinforced with weld bead both failed at fusion boundaries. Secondary Al{sub 3}Sc{sub x}Zr{sub 1−x} particles originally present in parent alloy coarsen during TIG welding process, but they can restrain the grain growth and recrystallization here, thus improving welding performance. For two FSW welded joints, fracture occurred in weld nugget zone. Secondary Al{sub 3}Sc{sub x}Zr{sub 1−x} nano-particles almost can keep unchangeable size (20–40 nm) across the entire FSW welded joint, and thus provide effective Orowan strengthening, grain boundary strengthening and substructure strengthening to strengthen FSW joints. The positive effect from Sc and Zr additions into base metals can be better preserved by FSW process than by TIG welding process.

  5. Effects of Sc and Zr on mechanical property and microstructure of tungsten inert gas and friction stir welded aerospace high strength Al–Zn–Mg alloys

    International Nuclear Information System (INIS)

    Deng, Ying; Peng, Bing; Xu, Guofu; Pan, Qinglin; Yin, Zhimin; Ye, Rui; Wang, Yingjun; Lu, Liying

    2015-01-01

    New aerospace high strength Al–Zn–Mg and Al–Zn–Mg–0.25Sc–0.10Zr (wt%) alloys were welded by tungsten inert gas (TIG) process using a new Al–6.0Mg–0.25Sc–0.10Zr (wt%) filler material, and friction stir welding (FSW) process, respectively. Mechanical property and microstructure of the welded joints were investigated comparatively by tensile tests and microscopy methods. The results show that Sc and Zr can improve the yield strength and ultimate tensile strength of Al–Zn–Mg alloy by 59 MPa (23.3%) and 16 MPa (4.0%) in TIG welded joints, and by 77 MPa (23.8%) and 54 MPa (11.9%) in FSW welded joints, respectively. The ultimate tensile strength and elongation of new Al–Zn–Mg–Sc–Zr alloy FSW welded joint are 506±4 MPa and 6.34±0.2%, respectively, showing superior post welded performance. Mechanical property of welded joint is mainly controlled by its “weakest microstructural zone”. TIG welded Al–Zn–Mg and Al–Zn–Mg–Sc–Zr alloys reinforced with weld bead both failed at fusion boundaries. Secondary Al 3 Sc x Zr 1−x particles originally present in parent alloy coarsen during TIG welding process, but they can restrain the grain growth and recrystallization here, thus improving welding performance. For two FSW welded joints, fracture occurred in weld nugget zone. Secondary Al 3 Sc x Zr 1−x nano-particles almost can keep unchangeable size (20–40 nm) across the entire FSW welded joint, and thus provide effective Orowan strengthening, grain boundary strengthening and substructure strengthening to strengthen FSW joints. The positive effect from Sc and Zr additions into base metals can be better preserved by FSW process than by TIG welding process

  6. Perovskites with noble metals of type Ba/sub 3/BM/sub 2/O/sub 9/; B = Mg, Fe, Co, Ni, Zn, Cd; M = Ru, Ir

    Energy Technology Data Exchange (ETDEWEB)

    Treiber, U; Kemmler-Sack, S; Ehmann, A [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1982-04-01

    The perovskites Ba/sub 3/BM/sub 2/O/sub 9/ crystallize in a hexagonal BaTiO/sub 3/ structure and could be prepared for M = Ru; B = Mg, Fe, Co, Ni, Zn, Cd and M = Ir; B = Co, Ni. According to intensity calculations on powder data of Ba/sub 3/MgRu/sub 2/O/sub 9/ and Ba/sub 3/NiIr/sub 2/O/sub 9/ (refined intensity related R' value 6.7% (Ba/sub 3/MgRu/sub 2/O/sub 9/) and 6.9% (Ba/sub 3/NiIr/sub 2/O/sub 9/)) an 1:2 order is present and both lattices contain face connected M/sub 2/O/sub 9/ double octahedra linked by another via common corners through BO/sub 6/ single octahedra. The occurrence of this typ of cationic order results for B = Mg, Co, Ni, Zn, Cd from the analysis of the vibrational spectra. For B = Mg, Zn, Cd and presumable with B = Ni the charge distribution is B/sup 2 +// 2 M/sup 5 +/; for B = Co deviation can not be excluded. On the opposite in Ba/sub 3/FeRu/sub 2/O/sub 9/ an electron delocalisation is present.

  7. In-situ observation of recrystallization in an AlMgScZr alloy using confocal laser scanning microscopy

    International Nuclear Information System (INIS)

    Taendl, J.; Nambu, S.; Orthacker, A.; Kothleitner, G.; Inoue, J.; Koseki, T.; Poletti, C.

    2015-01-01

    In this work we present a novel in-situ approach to study the recrystallization behavior of age hardening alloys. We use confocal laser scanning microscopy (CLSM) at 400 °C to investigate the static recrystallization of an AlMg4Sc0.4Zr0.12 alloy in-situ. The results are combined with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses. It was found that CLSM is a powerful tool to visualize both the local initiation and temporal sequence of recrystallization. After fast nucleation and initial growth, the grain growth rate decreases and the grain boundary migration stops after some minutes due to Zener pinning from Al 3 (Sc,Zr) precipitates produced during the heat treatment. EBSD and TEM analyses confirm both the boundary movements and the particle-boundary interactions. - Highlights: • First time that CLSM is used to study recrystallization in-situ. • The start and end of recrystallization can be directly observed. • The procedure is easy to apply and requires only simple data interpretation. • In-situ observations on the surface correlate to modifications inside the bulk. • In-situ observations correlate to EBSD and EFTEM analyses.

  8. Superplasticity behaviors of Al-Zn-Mg-Zr cold-rolled alloy sheet with minor Sc addition

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, H. [School of Materials Science and Engineering, Central South University (Light Alloy Research Institute, Central South University), Changsha 410083 (China); Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Changsha 410083 (China); Pan, Q.L., E-mail: pql2016@126.com [School of Materials Science and Engineering, Central South University (Light Alloy Research Institute, Central South University), Changsha 410083 (China); Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Changsha 410083 (China); Yu, X.H.; Huang, X.; Sun, X.; Wang, X.D.; Li, M.J.; Yin, Z.M. [School of Materials Science and Engineering, Central South University (Light Alloy Research Institute, Central South University), Changsha 410083 (China); Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Changsha 410083 (China)

    2016-10-31

    A refined microstructure of Al-Zn-Mg-Sc-Zr alloy sheet was produced by simple hot and cold rolling to an average grain size of 3 µm. Experiments were completed in electro-fluid servo-fatigue tester and results were investigated by means of optical microscope (OM), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Superplastic deformation was conducted and superplastic ductility of ≥200% was achieved at a testing temperature range from 425 ºC to 500 ºC and relative high strain rate range of 1×10{sup −3} s{sup −1}~1×10{sup −1} s{sup −1}. The maximum elongation of 539% was obtained at 500 ºC and 1×10{sup −2} s{sup −1}. In addition, the scanning electron microscopy (SEM) and transmission electron microscope (TEM) analyses showed that the presence of Al{sub 3} (Sc, Zr) particles in pinning grain boundaries and dislocations had a great influence on the superplastic deformation. The analyses of superplastic test data calculated out the coherent strain rates sensitivity parameter of 0.43 and the average activation energy of 143.762 kJ/mol. The data interpreted that the dominant deformation mechanism was grain boundary sliding controlled by lattice self-diffusion.

  9. In-situ observation of recrystallization in an AlMgScZr alloy using confocal laser scanning microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Taendl, J., E-mail: johannes.taendl@tugraz.atl [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria); Nambu, S. [Department of Materials Engineering, The University of Tokyo, Tokyo 113-8656 (Japan); Orthacker, A.; Kothleitner, G. [Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, Graz (Austria); Graz Center for Electron Microscopy, Graz (Austria); Inoue, J.; Koseki, T. [Department of Materials Engineering, The University of Tokyo, Tokyo 113-8656 (Japan); Poletti, C. [Institute of Materials Science and Welding, Graz University of Technology, Graz (Austria)

    2015-10-15

    In this work we present a novel in-situ approach to study the recrystallization behavior of age hardening alloys. We use confocal laser scanning microscopy (CLSM) at 400 °C to investigate the static recrystallization of an AlMg4Sc0.4Zr0.12 alloy in-situ. The results are combined with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses. It was found that CLSM is a powerful tool to visualize both the local initiation and temporal sequence of recrystallization. After fast nucleation and initial growth, the grain growth rate decreases and the grain boundary migration stops after some minutes due to Zener pinning from Al{sub 3}(Sc,Zr) precipitates produced during the heat treatment. EBSD and TEM analyses confirm both the boundary movements and the particle-boundary interactions. - Highlights: • First time that CLSM is used to study recrystallization in-situ. • The start and end of recrystallization can be directly observed. • The procedure is easy to apply and requires only simple data interpretation. • In-situ observations on the surface correlate to modifications inside the bulk. • In-situ observations correlate to EBSD and EFTEM analyses.

  10. Growth of Ca, Zr co-doped BaTiO3 lead-free ferroelectric single crystal and its room-temperature piezoelectricity

    Directory of Open Access Journals (Sweden)

    Donglin Liu

    2017-09-01

    Full Text Available Lead-free Ca, Zr co-doped BaTiO3 (BCZT single crystal with a dimension up to 2mm×2mm×2mm was grown by a spontaneous nucleation technique using KF as the flux. The composition of the studied single crystal was defined to be Ba0.798Ca0.202Zr0.006Ti0.994O3, corresponding to a tetragonal phase at room temperature. The oriented single crystal exhibited a quasi-static piezoelectric constant of approximately 232 pC/N. The effective piezoelectric coefficient d33* of the single domain crystal obtained under a unipolar electric field of 35 kV/cm was 179 pm/V. Rayleigh analysis was used to identify the intrinsic and extrinsic contributions to the room-temperature piezoelectricity of BCZT single crystal. The extrinsic contribution was estimated up to 40% due to the irreversible domain wall movement. Furthermore a sixth-order polynomial of Landau expansion was employed to analyze the intrinsic contribution to piezoelectricity of BCZT single crystal. The large energy barriers inhibited polarization rotations, leading to the relatively low piezoelectricity.

  11. Correlation between in-field critical currents in Zr-added (Gd, Y)Ba2Cu3Ox superconducting tapes at 30 and 77 K

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V; Xu, A; Liu, Y; Khatri, ND; Lei, C; Chen, Y; Galstyan, E; Majkic, G

    2014-03-11

    Critical current (I-c) values of 1384 Lambda/12 mm, corresponding to a critical current density of 12.47 MA cm(-2) and a pinning force of 374 GN m(-3), have been achieved at 30 K, 3 T in the orientation of field parallel to the c axis (B parallel to c) in (Gd, Y)BaCuO tapes with 15 mol% Zr addition made by metal organic chemical vapor deposition (MOCVD). These tapes show pinning force levels as high as 453 GN m(-3) at 30 K. An analysis of the properties of 24-28 (Gd, Y)BaCuO tapes with 15 mol% Zr addition showed a lack of correlation between their critical currents at 30 K, 3 T (B parallel to c) and I-c values both at 77 K, zero field and at 77 K, 1 T (B parallel to c). However, a strong correlation was found between the critical currents at 30 K, 3 T and at 77 K, 3 T (B parallel to c). It has also been discovered that the minimum critical current (I-c, (min)) value at 77 K, 3 T has no influence on the I-c,I- (min) value at 30 K, 3 T, and it in turn depends on the ratio of the I-c values in the orientations of field parallel and perpendicular to the c axis at 77 K, 3 T.

  12. Impedance spectroscopy studies on lead free (Ba0.85Ca0.15(Ti0.9Zr0.1O3 ceramics

    Directory of Open Access Journals (Sweden)

    Ahcène Chaouchi

    2012-12-01

    Full Text Available The AC complex impedance spectroscopy technique has been used to obtain the electrical parameters of polycrystalline sample of (Ba0.85Ca0.15(Ti0.9Zr0.1O3 in a wide frequency range at different temperatures. This sample was prepared by a high temperature solid-state reaction technique and single phase formation was confirmed by X-ray diffraction technique. This study was carried out by the means of simultaneous analysis of impedance, modulus, and electrical conductivity. The Cole-Cole (Nyquist plots suggest that the grains and grain boundaries are responsible in the conduction mechanism of the material at high temperature. The ColeCole (Nyquist plot studies revealed the presence of grain and grain boundary effect at 485 °C. On the other hand, it showed only the presence of grain boundary component of the resistivity at 535 °C. Complex impedance analysis indicated the presence of non-Debye type dielectric relaxation. The bulk resistance of the material decreases with rise in temperature similar to a semiconductor, and the Cole-Cole (Nyquist plot showed the negative temperature coefficient of resistance (NTCR character of (Ba0.85Ca0.15(Ti0.9Zr0.1O3. The value of activation energy is found to be 0.7433 eV, which suggests that the conduction may be the result of defect and charge carriers present in the materials.

  13. Optical and vibrational spectroscopy of Ba0.85Ca0.15Zr0.1Ti0.9O3 modified lithium borate glass ceramics

    Science.gov (United States)

    Viswanath, Pamarti; Prashanth, Sadhu Sai Pavan; Molli, Muralikrishna; Wicram, Jaschin Prem; Sai Muthukumar, V.

    2018-04-01

    Glass ceramics are excellent replacement for single crystalline materials which are expensive and difficult to fabricate. In this context, we have attempted to fabricate glass nanocomposites comprising of Lithium Borate glass matrix embedded with lead free ferroelectric Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT). Both of these functional materials are known to exhibit excellent ferroelectric behavior and are currently explored for various device applications. We have prepared these novel glass nanocomposite using melt-quenching techniquein various chemical composition involving different molar ratio. x(Ba0.85Ca0.15Zr0.1Ti0.9O3)-(1-x)(Li2O.2B2O3) where (x=0.1,0.2,0.3,0.4). The as-quenched samples exhibited amorphous nature as revealed by X-ray Diffraction studies. With the increase in BCZT content we have observed significant alteration in optical bandgap and Urbach energy. The tailoring of optical properties by tuning the structure was probed by Raman vibrational spectroscopy which confirmed the dominant role played by BCZT as a network modifier in these borate glasses. Concomitantly, these glass nanocomposites were found to be excellent UV absorbers.

  14. Analysis of (Ba,Ca,Sr)3MgSi2O8:Eu2+, Mn2+ phosphors for application in solid state lighting

    International Nuclear Information System (INIS)

    Han, J.K.; Piqutte, A.; Hannah, M.E.; Hirata, G.A.; Talbot, J.B.; Mishra, K.C.; McKittrick, J.

    2014-01-01

    The luminescence properties of Eu 2+ and Mn 2+ co-activated (Ba,Ca,Sr) 3 MgSi 2 O 8 phosphors prepared by combustion synthesis were studied. Eu 2+ -activated (Ba,Ca,Sr) 3 MgSi 2 O 8 has a broad blue emission band centered at 450–485 nm and Eu 2+ –Mn 2+ -activated (Ba,Ca,Sr) 3 MgSi 2 O 8 exhibits a red emission around 620–703 nm, depending on the relative concentrations of Ba, Ca and Sr. The particle size of Eu 2+ and Mn 2+ co-activated (Ba,Ca) 3 MgSi 2 O 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 3 MgSi 2 O 8 originates from secondary phases (Ba 2 SiO 4 and BaMgSiO 4 ) confirmed by emission spectra and X-ray diffraction patterns. The secondary phases of Ba 3 MgSi 2 O 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 3 MgSi 2 O 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) 3 MgSi 2 O 8 :Eu 2+ , Mn 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

  15. Effect of BaZrO3/Ag hybrid doping to the microstructure and performance of fluorine-free MOD method derived YBa2Cu3O7−x superconducting thin films

    DEFF Research Database (Denmark)

    Tang, Xiao; Yue, Zhao; Wu, W.

    2015-01-01

    It is known that BaZrO3 and Ag can improve the magnetic and transport performance of YBCO thin film through totally disparate ways. BaZrO3 plays the role of flux pinning centers and Ag improves the transparency of the YBCO grain boundaries. However, similar research is rare on the fluorine-free d...

  16. Two-step process of regeneration of acid(s) from ZrF{sub 4} containing spent pickle liquor and recovery of zirconium metal

    Energy Technology Data Exchange (ETDEWEB)

    Nersisyan, Hayk [Graduate School of Department of Materials Science & Engineering, Chungnam National University, 99 Daehakro, Yuseong-gu, Daejeon (Korea, Republic of); RASOM, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Han, Seul Ki; Choi, Jeong Hun [Graduate School of Department of Materials Science & Engineering, Chungnam National University, 99 Daehakro, Yuseong-gu, Daejeon (Korea, Republic of); Graduate School of Energy Science & Technology, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Young-Jun; Yoo, Bung Uk [Graduate School of Energy Science & Technology, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); Ri, Vladislav E. [Graduate School of Department of Materials Science & Engineering, Chungnam National University, 99 Daehakro, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Jong Hyeon, E-mail: jonglee@cnu.ac.kr [Graduate School of Department of Materials Science & Engineering, Chungnam National University, 99 Daehakro, Yuseong-gu, Daejeon (Korea, Republic of); Graduate School of Energy Science & Technology, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of); RASOM, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon (Korea, Republic of)

    2017-04-01

    In this paper we describe a progressive two-step process that allows zirconium fluoride (ZrF{sub 4}) contained in spent baths for etched zirconium alloys to be effectively recycled on a pilot scale and produce a high purity regenerated pickling acid. In the first step, a spent pickling liquor is treated by a BaF{sub 2} suspension to produce water insoluble Ba{sub 2}ZrF{sub 8}. After filtration of Ba{sub 2}ZrF{sub 8} more than 99.9 wt % purity pickling acid is regenerated. The precipitation mechanism of Ba{sub 2}ZrF{sub 8} is discussed and the role of BaF{sub 2} particles size on the precipitation process is demonstrated. In the second step the as-precipitated Ba{sub 2}ZrF{sub 8} is mixed with Mg and Cu metal powders and heat-treated at 1200 °C (or above) to produce CuZr alloy ingot. The characteristics of the ingot are discussed in regard to Cu concentration and the heating temperature. - Highlights: •Two-step process for recycling ZrF{sub 4} containing pickling acid on a pilot scale is developed. •Water insoluble Ba{sub 2}ZrF{sub 8} is precipitated by mixing spent pickling liquor with BaF{sub 2}. •The recycled pickling acid demonstrates more than 99.9 wt % purity. •The processing of Ba{sub 2}ZrF{sub 8} with Cu and Mg metals at 1200 °C yielded CuZr alloy. •The recovery depth of Zr was more than 95 wt%.

  17. Effect of rare-earth composition on microstructure and pinning properties of Zr-doped (Gd,Y)Ba2Cu3Ox superconducting tapes

    International Nuclear Information System (INIS)

    Selvamanickam, V; Zhang, Y; Guevara, A; Shi, T; Yao, Y; Majkic, G; Galtsyan, E; Chen, Y; Lei, C; Miller, D J

    2012-01-01

    The effect of changing Gd + Y content from 1.2 to 1.6 in the precursor of (Gd,Y)Ba 2 Cu 3 O 7 superconducting thin film tapes made by metal organic chemical vapor deposition (MOCVD) at a constant Gd:Y ratio and a fixed Zr content of 7.5% has been studied. The influence of changing the Gd:Y ratio from Gd = 0 to Y= 0 in 0.2 mol steps at a constant Gd + Y content of 1.2 in the precursor has also been investigated at a fixed Zr content of 7.5%. The critical current of these films is found to vary significantly as a function of rare-earth content as well as a function of rare-earth type. Even for a fixed Zr content, it is found that the critical current in the orientation of magnetic field parallel to the a–b plane and that in the orientation of field perpendicular to the a–b plane can be systematically varied with changing Gd + Y content as well as with changing Gd:Y ratio. The nanoscale defect structures along the a–b plane and along the c-axis are found to be sensitive to these changes in rare-earth content and type. (paper)

  18. Piezoelectric properties and temperature stability of Mn-doped Pb(Mg1/3Nb2/3)-PbZrO3-PbTiO3 textured ceramics

    OpenAIRE

    Yan, Yongke; Cho, Kyung-Hoon; Priya, Shashank

    2012-01-01

    In this letter, we report the electromechanical properties of textured 0.4Pb(Mg1/3Nb2/3) O-3-0.25PbZrO(3)-0.35PbTiO(3) (PMN-PZT) composition which has relatively high rhombohedral to tetragonal (R-T) transition temperature (TR-T of 160 degrees C) and Curie temperature (T-C of 234 degrees C) and explore the effect of Mn-doping on this composition. It was found that MnO2-doped textured PMN-PZT ceramics with 5 vol.% BaTiO3 template (T-5BT) exhibited inferior temperature stability. The coupling f...

  19. Monolithic translucent BaMgAl10O17:Eu2+ phosphors for laser-driven solid state lighting

    Directory of Open Access Journals (Sweden)

    Clayton Cozzan

    2016-10-01

    Full Text Available With high power light emitting diodes and laser diodes being explored for white light generation and visible light communication, thermally robust encapsulation schemes for color-converting inorganic phosphors are essential. In the current work, the canonical blue-emitting phosphor, high purity Eu-doped BaMgAl10O17, has been prepared using microwave-assisted heating (25 min and densified into translucent ceramic phosphor monoliths using spark plasma sintering (30 min. The resulting translucent ceramic monoliths convert UV laser light to blue light with the same efficiency as the starting powder and provide superior thermal management in comparison with silicone encapsulation.

  20. Low sintering temperature and high piezoelectric properties of Li-doped (Ba,Ca)(Ti,Zr)O3 lead-free ceramics

    International Nuclear Information System (INIS)

    Chen, Xiaoming; Ruan, Xuezheng; Zhao, Kunyun; He, Xueqing; Zeng, Jiangtao; Li, Yongsheng; Zheng, Liaoying; Park, Chul Hong; Li, Guorong

    2015-01-01

    Highlights: • Li-doped Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 (BCZT) lead-free piezoceramics were prepared by the two-step synthesis and solid-state reaction method. • Their sintering temperature decreases from about 1540 °C down to about 1400 °C. • With the proper addition of Li, the densities and grain sizes of ceramics increase. • The ceramics not only have the characteristics of hard piezoceramics but also possesses the features of soft piezoceramics at low sintering temperature. - Abstract: Li-doped Ba 0.85 Ca 0.15 Ti 0.9 Zr 0.1 O 3 (BCZT) lead-free piezoelectric ceramics were prepared by the two-step synthesis and the solid-state reaction method. The density and grain size of ceramics sufficiently increases by Li-doped sintering aid, and their sintering temperature decreases from about 1540 °C down to about 1400 °C. X-ray diffraction reveals that the phase structure of Li-doped BCTZ ceramics is changed with the sintering temperature, which is consistent with their phase transition observed by the temperature-dependent dielectric curves. The well-poled Li-doped BCZT ceramics show a high piezoelectric constant d 33 (512 pC/N) and a planar electromechanical coupling factor k p (0.49), which have the characteristics of soft Pb(Zr,Ti)O 3 (PZT) piezoceramic, on the other hand, the mechanical quality factor Q m is about 190, which possesses the features of hard PZT piezoceramics. The enhanced properties of the Li-doped BCZT are explained by the combination of Li-doped effect and sintering effect on the microstructure and the phase transition around room temperature

  1. Synergetic effects of Sc and Zr microalloying and heat treatment on mechanical properties and exfoliation corrosion behavior of Al-Mg-Mn alloys

    International Nuclear Information System (INIS)

    Peng, Yongyi; Li, Shu; Deng, Ying; Zhou, Hua; Xu, Guofu; Yin, Zhimin

    2016-01-01

    Mechanical properties, exfoliation corrosion behavior and microstructure of Al-5.98Mg-0.47Mn and Al-6.01Mg-0.45Mn-0.25Sc-0.10Zr (wt%) alloy sheets under various homogenizing and annealing processes were investigated comparatively by tensile tests, electrochemical measurements, X-ray diffraction technique and microscopy methods. The as-cast alloys mainly consist of Fe and Mn enriched impurity phases, Mg and Mn enriched non-equilibrium aluminides and Mg 3 Al 2 phases. During homogenization treatment, solvable intermetallics firstly precipitate and then dissolve into matrix. The optimized homogenization processes for removing micro-segregation and obtaining maximum precipitation strengthening of secondary Al 3 (Sc, Zr) particles are 440 °C×8 h and 300 °C×8 h, respectively. Sc and Zr additions can make the yield strength of Al-Mg-Mn alloy increase by 21 MPa (6.9%), 120 MPa (61.2%) and 127 MPa (68.3%), when annealed at 270 °C, 300 °C and 330 °C, respectively, indicating that Orowan precipitation strengthening caused by secondary Al 3 (Sc, Zr) nano-particles is much greater than grain boundary strengthening from primary Al 3 (Sc, Zr) micro-particles. Increasing homogenization and annealing degrees and adding Sc and Zr all can decrease corrosion current density and improve exfoliation corrosion resistance. The exfoliation corrosion behavior is dominant by anodic dissolution occurring at the interface between intermetallics and α(Al) matrix. After homogenizing at 440 °C for 8 h and annealing at 300 °C for 1 h, yield strength, ultimate strength, elongation to failure and exfoliation corrosion rank are 196 MPa, 360 MPa, 20.2% and PA (slight pitting corrosion) in Al-Mg-Mn alloy, and reach to 316 MPa, 440 MPa, 17.0% and PA in Al-Mg-Mn-Sc-Zr alloy, respectively, revealing that high strength, high ductility and admirable corrosion resistance of Al-Mg-Mn alloys can be achieved by the synergetic effects of Sc and Zr microalloying and heat treatment.

  2. Exfoliation corrosion of Al-Zn-Mg-Cu-Zr alloy containing Sc examined by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Y.P.; Liu, X.Y.; He, Y.B.; Li, C.L. [School of Materials Science and Engineering, Central South University, Changsha (China); Pan, Q.L. [School of Materials Science and Engineering, Central South University, Changsha (China); The Key Laboratory of Nonferrous Materials Science and Engineering of Ministry of Education, Changsha (China); Li, W.B. [School of Materials Science and Engineering, Central South University, Changsha (China); School of Civil Engineering, Hunan City University, Yiyang (China)

    2012-02-15

    The exfoliation corrosion behavior of an Al-Zn-Mg-Cu-Zr alloy containing Sc artificially aged at 120 C for 24 h is studied by macroscopic observation techniques and electrochemical impedance spectroscopy (EIS) measurements. After 48 h immersion, the blisters start bursting and delamination initiates, along with the appearance of two time constants in the impedance diagrams. According to the simulation by equivalent circuit, the corrosion rate decreases sharply and then reaches a steady state, which is due to the change of the solution pH and oxide layer thickness, as well as the accumulation of corrosion products. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Kinetics of thermal dehydration of sol-gel derived MgO-ZrO{sub 2} composite hydrogel

    Energy Technology Data Exchange (ETDEWEB)

    Das, Sudip; Das, Sukhen [Jadavpur Univ., Kolkata (India). Dept. of Physics; Mitra, N.K. [Calcutta Univ., Kolkata (India). Dept. of Chemical Technology

    2013-06-15

    The kinetics of thermal dehydration of mixed hydroxide hydrogels in MgO-ZrO{sub 2} system was studied as a function of composition by following the isothermal heat treatment route. Kinetic parameters were calculated through the application of the Guggenheim equation. The expulsion of both loosely bound water and constitutional OH groups were not continuous processes but proceeded in steps. The applicability of 1st order reaction kinetics for the major portion of the reaction for all compositions suggests that during the dehydroxylation process the dehydration is essentially controlled by the orientation of H{sub 2}O molecules and the mutual interaction of hydroxyl groups. Due to a decrease in the concentration of the reacting species the activation energy was always higher at the final stage of dehydration. (orig.)

  4. Numerical analysis of residual stress of Al-Mg-Mn-Sc-Zr alloy subjected to surface strengthening by shot peening

    Directory of Open Access Journals (Sweden)

    Mariusz Stegliński

    2015-03-01

    Full Text Available In this paper, we presented the results of the analysis of the stresses in the Al-Mg5%-Mn1,5%-Sc0,8%-Zr0,4% alloy after shot peening process using solver ANSYSANSYSANSYS LS-Dyna. The computational model illustrates the phenomena occurring as a result of plastic deformation caused by hitting a steel ball on the surface of the analyzed aluminium alloy. We analyzed two input variables: diameter and speed of a ball. The resulting normal stress distribution centred exposes the minimum compressive stress at a position located at a depth point of Belayev 0.125 mm with a value of σ = –345 MPa. Variable parameter shows the correlation of the boundary conditions of minimum stress increase with increasing ball’s diameter and its speed. Selected points of numerical analysis were verified with experimental results.[b]Keywords[/b]: materials science, numerical analysis, metal forming, shot peening, aluminium

  5. Studies on Al-Cu-Li-Mg-Ag-Zr alloy processed through vacuum induction melting (VIM) technique

    International Nuclear Information System (INIS)

    Nayan, Niraj; Govind; Nair, K. Suseelan; Mittal, M.C.; Sudhakaran, K.N.

    2007-01-01

    A new technique of lithium addition has been adapted for the processing of Al-Cu-Li-Ag-Mg-Zr alloy, which gives more than 90% recovery of lithium throughout the billet. Processing studies on this alloy include casting, three step homogenization, to avoid incipient melting, and mechanical working particularly forging and rolling. The products in the form of sheets were subjected to various T6 (solution treatment + water quenching + aging) tempers. Mechanical properties were evaluated at room temperature and correlated with microstructure. Characterizations using optical microscope and post-fracture analysis have been carried out using Scanning electron microscope (SEM). Experimental investigation shows highest mechanical properties for the Al-1.3%Li alloy in T6 (500 deg. C/1 h + WQ + 190 deg. C/24 h) condition

  6. Microstructure and high temperature stability of age hardenable AA2219 aluminium alloy modified by Sc, Mg and Zr additions

    Energy Technology Data Exchange (ETDEWEB)

    Naga Raju, P. [Metallurgical and Materials Engineering Department, IIT-Madras, Chennai 600036 (India)], E-mail: puvvala_nagaraju@yahoo.com; Srinivasa Rao, K. [Metallurgical Engineering Department, Andhra University, Visakapatnam 530003 (India); Reddy, G.M. [Defence Metallurgical Research Laboratory, Hyderabad 500258 (India); Kamaraj, M.; Prasad Rao, K. [Metallurgical and Materials Engineering Department, IIT-Madras, Chennai 600036 (India)

    2007-08-25

    The present work pertains to the improvement of high temperature stability of age hardenable AA2219 aluminium-copper (6.3%) alloy. Addition of scandium, magnesium and zirconium to the base metal AA2219 was adopted to improve this high temperature stability. These additions were systematically varied by preparing alloys of different composition using gas tungsten arc melting. Long time ageing studies and impression creep technique were used to study the high temperature stability of the alloys. These modified compositions of the alloy resulted in fine equiaxed grains, refined eutectics, large number of high temperature stable and finer precipitates. Among all the compositions, 0.8% Sc + 0.45% Mg + 0.2% Zr addition was found to be significant in improving the high temperature stability of AA2219 alloy. This may be attributed to the possible microstructural changes, solute enrichment of the matrix and pinning of the grain boundaries by the finer precipitates.

  7. Hot deformation of particulate reinforced Al-4Li-1Mg-0.5Ge-0.2Zr

    International Nuclear Information System (INIS)

    Chanda, T.; Lavernia, E.J.; Wolfenstine, J.

    1991-01-01

    Lithium additions to aluminum give the greatest reduction in density and increase in elastic modulus per wt.% of any known alloying element. The potential for aluminum alloy density reduction through lithium additions is evident by comparing its atomic weight (6.94) to that of aluminum (26.98). Over the past decade, considerable research efforts have been directed towards developing aluminum-lithium alloys, with lithium contents of up to 2.5 wt.%, for aircraft applications, where their low density and increased stiffness can lead to significant improvements in payload capacity. A recent notable example has been the development of a quarternary aluminum-lithium alloy containing silver, (A1-(4.5-6.3) Cu-1.3Li-0.4Ag-0.4Mg-0.14Zr, in wt.%). In an effort to further decrease the density and increase the modulus of aluminum-lithium alloys, research efforts have progressively shifted towards alloys containing higher concentrations of lithium (>3.0 wt.%). Furthermore, aluminum-lithium alloys are being studied as potential candidate matrix materials in metal matrix composites (MMCs), as a result of the observation that lithium effectively enhances the ability of the aluminum matrix to wet the ceramic reinforcement. The extreme reactivity associated with high additions of lithium, and the difficulties associated with processing MMCs, have prompted the development of alternate synthesis approaches. One such approach, spray atomization and co-deposition, is actively being studied as a result of its ability to rapidly quench, reinforce, and consolidate in a single step, thus avoiding the difficulties associated with the handling of fine reactive particulates. The object of the paper is to provide insight into the elevated temperature deformation behavior of high lithium (4 wt.%) aluminum alloys reinforced with SiC particles prepared by spray atomization and co-deposition. The selection of the A1-4Li-1Mg-0.5Ge-0.2Zr wt

  8. Enhancement of osteogenesis and biodegradation control by brushite coating on Mg-Nd-Zn-Zr alloy for mandibular bone repair.

    Science.gov (United States)

    Guan, Xingmin; Xiong, Meiping; Zeng, Feiyue; Xu, Bin; Yang, Lingdi; Guo, Han; Niu, Jialin; Zhang, Jian; Chen, Chenxin; Pei, Jia; Huang, Hua; Yuan, Guangyin

    2014-12-10

    To diminish incongruity between bone regeneration and biodegradation of implant magnesium alloy applied for mandibular bone repair, a brushite coating was deposited on a matrix of a Mg-Nd-Zn-Zr (hereafter, denoted as JDBM) alloy to control the degradation rate of the implant and enhance osteogenesis of the mandible bone. Both in vitro and in vivo evaluations were carried out in the present work. Viability and adhesion assays of rabbit bone marrow mesenchyal stem cells (rBM-MSCs) were applied to determine the biocompatibility of a brushite-coated JDBM alloy. Osteogenic gene expression was characterized by quantitative real-time polymerase chain reaction (RT-PCR). Brushite-coated JDBM screws were implanted into mandible bones of rabbits for 1, 4, and 7 months, respectively, using 316L stainless steel screws as a control group. In vivo biodegradation rate was determined by synchrotron radiation X-ray microtomography, and osteogenesis was observed and evaluated using Van Gieson's picric acid-fuchsin. Both the naked JDBM and brushite-coated JDBM samples revealed adequate biosafety and biocompatibility as bone repair substitutes. In vitro results showed that brushite-coated JDBM considerably induced osteogenic differentiation of rBM-MSCs. And in vivo experiments indicated that brushite-coated JDBM screws presented advantages in osteoconductivity and osteogenesis of mandible bone of rabbits. Degradation rate was suppressed at a lower level at the initial stage of implantation when new bone tissue formed. Brushite, which can enhance oeteogenesis and partly control the degradation rate of an implant, is an appropriate coating for JDBM alloys used for mandibular repair. The Mg-Nd-Zn-Zr alloy with brushite coating possesses great potential for clinical applications for mandibular repair.

  9. Microstructure, corrosion resistance and cytocompatibility of Mg-5Y-4Rare Earth-0.5Zr (WE54) alloy

    Energy Technology Data Exchange (ETDEWEB)

    Smola, Bohumil, E-mail: bohumil.smola@mff.cuni.cz [Charles University Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Joska, Ludek [Institute of Chemical Technology Prague, Faculty of Chemical Technology, Technicka 5, 166 28 Praha 6 (Czech Republic); Brezina, Vitezslav [University of South Bohemia, Institute of Physical Biology, Zamek 136, 373 33 Nove Hrady (Czech Republic); Stulikova, Ivana [Charles University Prague, Faculty of Mathematics and Physics, Ke Karlovu 5, 121 16 Praha 2 (Czech Republic); Hnilica, Frantisek [Czech Technical University in Prague, Faculty of Mechanical Engineering, Karlovo namesti 13, 121 35 Praha 2 (Czech Republic)

    2012-05-01

    Conventionally cast Mg-5Y-4Rare Earth-0.5Zr alloy (WE54) was solution treated (525 Degree-Sign C/8 h - T4) and one part subsequently aged (200 Degree-Sign C/16 h - T6). Powder from the cast WE54 alloy prepared by gas atomizing was consolidated by extrusion at 250 Degree-Sign C or 400 Degree-Sign C. Dense triangular arrangement of prismatic plates of transient D0{sub 19} and C-base centered orthorhombic phases precipitated in the {alpha}-Mg matrix during the T6 treatment. Both alloys prepared by powder metallurgy exhibit similar microstructure consisting of {approx} 4-6 {mu}m {alpha}-Mg matrix fibers surrounded by particles of the equilibrium Mg{sub 5}(Y, Nd) phase and of oxides. Open circuit potential and polarization resistance in the isotonic saline (9 g/l NaCl/H{sub 2}O) were monitored for 24 h. The corrosion rate of the T4 and T6 treated alloys was about 80 times lower than that of commercial Mg. Both alloys prepared by powder metallurgy exhibited approximately 8 times higher corrosion resistance than commercial Mg. The human MG-63 osteoblast-like cells spreading and division in the extracts (0.28 g in 28 ml of EMEM) of all 4 alloys were monitored by cinemicrography for 24 h. The MG-63 cells proliferate without cytotoxicity in all extracts. - Highlights: Black-Right-Pointing-Pointer T6 treated WE54 alloy exhibit dense triangular arrangement of {beta} Double-Prime and {beta} Prime phase prismatic plates. Black-Right-Pointing-Pointer Microstructure of PM prepared WE54 alloy consists of {alpha}-Mg phase cells surrounded by {beta} phase particles. Black-Right-Pointing-Pointer PM produced WE54 corroded 10 times faster in physiological solution thanT4 and T6 treated WE54. Black-Right-Pointing-Pointer MG63 cell spreading in EMEM extracts of PM prepared WE54 is comparable to that in control EMEM. Black-Right-Pointing-Pointer Cell mitosis is enhanced in PM WE54 extracts compared to the control and extracts of T4 and T6 WE54.

  10. Effects of Ce and Zr addition on microstructure and hardness of Al-Si-Cu-Mg alloy

    International Nuclear Information System (INIS)

    Bevilaqua, William Lemos; Reguly, Afonso; Froehlich, Andre Ronaldo; Stadtlander, Antonio Ricardo

    2016-01-01

    The effects of cerium and zirconium contents (0.3%-0.16%Zr; 0.3%-0.27%Zr e 0.3%-0.36%Zr) to aluminum alloy 354.0 was investigated by microstructural analysis and hardness measurements in as-cast and heat-treated conditions. The macrostructure show an excellent grain refinement for all Ce and Zr contents used. Additionally, the Cu-Ce reaction during solidification changes significantly the age hardening process of modified alloys. (author)

  11. High dielectric constant observed in (1 − x)Ba(Zr0.07Ti0.93)O3–xBa(Fe0.5Nb0.5)O3 binary solid-solution

    International Nuclear Information System (INIS)

    Kruea-In, Chatchai; Eitssayeam, Sukum; Pengpat, Kamonpan; Rujijanagul, Gobwute

    2012-01-01

    Binary solid-solutions of the (1 − x)Ba(Zr 0.07 Ti 0.93 )O 3 –xBa(Fe 0.5 Nb 0.5 O 3 ) system, with 0.1 ≤ x ≤ 0.9,were fabricated via a solid-state processing technique. X-ray diffraction analysis revealed that all samples exhibited a single perovskite phase. The BaFe 0.5 Nb 0.5 O 3 also promoted densification and grain growth of the system. Dielectric measurements showed that all samples displayed a relaxor like behavior. The x = 0.1 sample presented a dielectric-frequency and temperature with low loss tangent ( 0.2 samples, the dielectric data showed a broad dielectric constant–temperature curve with a giant dielectric characteristic. In addition, a high dielectric constant > 50,000 (at 10 kHz and temperature > 150 °C) was observed for the x = 0.9 sample.

  12. Crystallisation of Ba1-xSrxZn2Si2O7 from BaO/SrO/ZnO/SiO2 glass with different ZrO2 and TiO2 concentrations

    Science.gov (United States)

    Vladislavova, Liliya; Kracker, Michael; Zscheckel, Tilman; Thieme, Christian; Rüssel, Christian

    2018-04-01

    The effect of different nucleation agents such as ZrO2 and TiO2 was investigated for a first time with respect to their crystallisation behaviour in the glass system BaO-SrO-ZnO-SiO2. In all studied glasses, a Ba1-xSrxZn2Si2O7 (0.1 ≤ x ≤ 0.9) solid solution crystallized. This phase was first described in 2015 to possess a similar structure as the high temperature phase of BaZn2Si2O7 and a thermal expansion close to zero or even negative. It may find applications e.g. as cook panels, telescope mirrors, and furnace windows. Kinetic parameters of the crystallisation process were determined by supplying different heating rates in a differential scanning calorimeter (DSC). The results were evaluated using the equations of Ozawa and Kissinger with respect to the activation energies. Furthermore, the Ozawa method was used for the determination of Avrami parameters, which provides further information on the nucleation and crystallisation processes. Scanning electron microscopy including electron backscatter diffraction (EBSD) was used to characterise the microstructure, to determine the crystallite size and the crystal orientation. For the characterisation of the occurring crystalline phases, X-ray diffraction was used.

  13. In vitro and in vivo corrosion, cytocompatibility and mechanical properties of biodegradable Mg-Y-Ca-Zr alloys as implant materials.

    Science.gov (United States)

    Chou, Da-Tren; Hong, Daeho; Saha, Partha; Ferrero, Jordan; Lee, Boeun; Tan, Zongqing; Dong, Zhongyun; Kumta, Prashant N

    2013-11-01

    This study introduces a class of biodegradable Mg-Y-Ca-Zr alloys novel to biological applications and presents evaluations for orthopedic and craniofacial implant applications. Mg-Y-Ca-Zr alloys were processed using conventional melting and casting techniques. The effects of increasing Y content from 1 to 4 wt.% as well as the effects of T4 solution treatment were assessed. Basic material phase characterization was conducted using X-ray diffraction, optical microscopy and scanning electron microscopy. Compressive and tensile tests allowed for the comparison of mechanical properties of the as-cast and T4-treated Mg-Y-Ca-Zr alloys to pure Mg and as-drawn AZ31. Potentiodynamic polarization tests and mass loss immersion tests were used to evaluate the corrosion behavior of the alloys. In vitro cytocompatibility tests on MC3T3-E1 pre-osteoblast cells were also conducted. Finally, alloy pellets were implanted into murine subcutaneous tissue to observe in vivo corrosion as well as local host response through H&E staining. SEM/EDS analysis showed that secondary phase intermetallics rich in yttrium were observed along the grain boundaries, with the T4 solution treatment diffusing the secondary phases into the matrix while increasing the grain size. The alloys demonstrated marked improvement in mechanical properties over pure Mg. Increasing the Y content contributed to improved corrosion resistance, while solution-treated alloys resulted in lower strength and compressive strain compared to as-cast alloys. The Mg-Y-Ca-Zr alloys demonstrated excellent in vitro cytocompatibility and normal in vivo host response. The mechanical, corrosion and biological evaluations performed in this study demonstrated that Mg-Y-Ca-Zr alloys, especially with the 4 wt.% Y content, would perform well as orthopedic and craniofacial implant biomaterials. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Ion channeling study of epitaxially grown HoBa2Cu3Ox thin films on MgO(001)

    International Nuclear Information System (INIS)

    Watamori, Michio; Shoji, Fumiya; Hanawa, Teruo; Oura, Kenjiro; Itozaki, Hideo.

    1990-01-01

    The crystalline quality of high-T c superconducting HoBa 2 Cu 3 O x thin films formed on MgO(001) has been investigated by a high-energy ion channeling technique. Analysis was performed at 3 depth regions (surface, inside, and interface), and the degree of crystalline quality at each depth was estimated. Based on ion channeling measurements carried out with the normal and off-normal and directions, it has been found that (1) the crystalline quality at the film surface is much better than that at the interface, (2) the crystalline disorder can be seen mainly along the c-axis, and (3) the film consists of two domains, 90deg rotated from each other about the c-axis of the film. The crystalline quality of the MgO substrates has also been investigated. (author)

  15. Quasi-2D silicon structures based on ultrathin Me2Si (Me = Mg, Ca, Sr, Ba) films

    Science.gov (United States)

    Migas, D. B.; Bogorodz, V. O.; Filonov, A. B.; Borisenko, V. E.; Skorodumova, N. V.

    2018-04-01

    By means of ab initio calculations with hybrid functionals we show a possibility for quasi-2D silicon structures originated from semiconducting Mg2Si, Ca2Si, Sr2Si and Ba2Si silicides to exist. Such a 2D structure is similar to the one of transition metal chalcogenides where silicon atoms form a layer in between of metal atoms aligned in surface layers. These metal surface atoms act as pseudo passivation species stabilizing crystal structure and providing semiconducting properties. Considered 2D Mg2Si, Ca2Si, Sr2Si and Ba2Si have band gaps of 1.14 eV, 0.69 eV, 0.33 eV and 0.19 eV, respectively, while the former one is also characterized by a direct transition with appreciable oscillator strength. Electronic states of the surface atoms are found to suppress an influence of the quantum confinement on the band gaps. Additionally, we report Sr2Si bulk in the cubic structure to have a direct band gap of 0.85 eV as well as sizable oscillator strength of the first direct transition.

  16. Crystal structure and thermal expansion of the low- and high-temperature forms of BaMIV(PO4)2 compounds (M=Ti, Zr, Hf and Sn)

    International Nuclear Information System (INIS)

    Bregiroux, D.; Popa, K.; Jardin, R.; Raison, P.E.; Wallez, G.; Quarton, M.; Brunelli, M.; Ferrero, C.; Caciuffo, R.

    2009-01-01

    The crystal structure of β-BaZr(PO 4 ) 2 , archetype of the high-temperature forms of BaM(PO 4 ) 2 phosphates (with M=Ti, Zr, Hf and Sn), has been solved ab initio by Rietveld analysis from synchrotron X-ray powder diffraction data. The phase transition appears as a topotactic modification of the monoclinic (S.G. C2/m) lamellar α-structure into a trigonal one (S.G. P3-barm1) through a simple mechanism involving the unfolding of the [Zr(PO 4 ) 2 ] n 2- layers. The thermal expansion is very anisotropic (e.g., -4.1 i -6 K -1 in the case of α-BaZr(PO 4 ) 2 ) and quite different in the two forms, as a consequence of symmetry. It stems from a complex combination of several mechanisms, involving bridging oxygen rocking in M-O-P linkages, and 'bond thermal expansion'. - Graphical abstract: The layered high-temperature form of BaM(PO 4 ) 2 , only expands along the c-axis.

  17. Morphology and the structure of quasicrystal phase in as-cast and melt-spun Mg-Zn-Y-Zr alloys

    International Nuclear Information System (INIS)

    Tang, Y.L.; Zhao, D.S.; Shen, N.F.

    1993-01-01

    During recent years, many researchers have investigated the experimental and theoretical aspects of quasicrystal materials. In some Mg alloys (Mg 32 Al 17 Zn 32 , Mg 32 (Al,Zn) 49 , Mg 32 (Al,Zn,Cu) 49 , Mg 4 CuAl 6 and Ga 16 Mg 32 Zn 52 ), icosahedral quasicrystals (IQC) have been found. However, most of the quasicrystals in these alloys were formed under a rapid solidification condition. In the recent study on Mg-Zn-(Zr,Y) as-cast alloys, the authors identified a new Mg-rich and a Zn-rich IQC by X-ray diffraction (XRD) and electron microscopy (EM). The discovery of Mg-Zn-Y IQC is of interest because it formed in an as-cast ingot and did not contain the element Al, which is the major constituent of nearly all IQC forming alloys reported. Also, analyses on IQC in as-cast and RS Mg alloys with the composition have not previously been carried out. In this paper, TEM and XRD investigations were completed on IQC formed in a Mg-Zn-Y-Zr cast ingot and melt-spun ribbons for microstructure comparison

  18. Influence of SrTiO3 modification on dielectric properties of Mg(Zr0.05Ti0.95)O3 ceramics at microwave frequency

    International Nuclear Information System (INIS)

    Tseng, Ching-Fang; Lu, Shu-Cheng

    2013-01-01

    Highlights: ► The microwave dielectric properties of (1−x)Mg(Zr 0.05 Ti 0.95 )O 3 –xSrTiO 3 system have been discussed. ► The dielectric constant and τ f increased; nevertheless, the Q × f decreased with an increase in x. ► Second phases were formed and affected the microwave dielectric properties of (1−x)MZT–xST system. ► ε r of 20.8, Q × f of 257,000, and τ f of 0.2 ppm/°C were obtained for the 0.06Mg(Zr 0.05 Ti 0.95 )O 3 –0.04SrTiO 3 ceramics. ► Due to high-quality factor and near-zero τ f , MZT–ST demonstrate a good potential for use in microwave devices. -- Abstract: The microwave dielectric properties and microstructures were investigated in the (1−x)Mg(Zr 0.05 Ti 0.95 )O 3 –xSrTiO 3 (hereafter referred to as (1−x)MZT–xST) system. The compounds were prepared via the conventional solid-state reaction. Compositions in the (1−x)Mg(Zr 0.05 Ti 0.95 )O 3 –xSrTiO 3 system were designed to compensate the negative temperature coefficient of the resonant frequency of Mg(Zr 0.05 Ti 0.95 )O 3 . The values displayed nonmonotonic mixture-like behavior, because the TiO 2 phase was formed in the MZT composite ceramics with increasing x. A close zero τ f of 0.2 ppm/°C could be achieved at 0.96MZT–0.04ST with ε r = 20.8 and Q × f = 257,000 GHz

  19. Passive behavior of magnesium alloys (Mg-Zr) containing rare-earth elements in alkaline media

    International Nuclear Information System (INIS)

    Pinto, R.; Ferreira, M.G.S.; Carmezim, M.J.; Montemor, M.F.

    2010-01-01

    The passive behavior of magnesium alloys ZK31, EZ33 and WE54 was studied in alkaline media (NaOH - pH 13) in the presence and absence of chloride ions. The electrochemical properties were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and capacitance measurements. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed for the study of the chemical composition and surface morphology of the surface films, respectively. The electrochemical impedance results revealed that the film formed on the surface of the three alloys is characterized by an increasing resistance, which stabilized with time. In the absence of chloride the film resistance was identical for all the three alloys. However, in the presence of chloride, the resistance of the film formed on the EZ33 alloy dropped nearly one order of magnitude comparatively to the other alloys. Generally, in the presence of chloride there was a decrease of the conductive character of the film. The films are homogeneous and, according to the XPS results, the outer layer seemed mainly composed of Mg(OH) 2 and the internal layer composed of MgO, independently of the presence of chloride. The AFM study revealed that the presence of chloride affected film morphology, namely nano-crystallites dimensions and aggregates size that increased.

  20. Influence of Applied Voltage and Film-Formation Time on Microstructure and Corrosion Resistance of Coatings Formed on Mg-Zn-Zr-Ca Bio-magnesium Alloy

    Science.gov (United States)

    Yandong, Yu; Shuzhen, Kuang; Jie, Li

    2015-09-01

    The influence of applied voltage and film-formation time on the microstructure and corrosion resistance of coatings formed on a Mg-Zn-Zr-Ca novel bio-magnesium alloy has been investigated by micro-arc oxidation (MAO) treatment. Phase composition and microstructure of as-coated samples were analyzed by the x-ray diffraction, energy dispersive x-ray spectroscopy and scanning electron microscopy. And the porosity and average of micro-pore aperture of the surface on ceramic coatings were analyzed by general image software. Corrosion microstructure of as-coated samples was caught by a microscope digital camera. The long-term corrosion resistance of as-coated samples was tested in simulated body fluid for 30 days. The results showed that the milky white smooth ceramic coating formed on the Mg-Zn-Zr-Ca novel bio-magnesium alloy was a compound of MgO, Mg2SiO4 and MgSiO3, and its corrosion resistance was significantly improved compared with that of the magnesium substrate. In addition, when the MAO applied voltage were 450 V and 500 V and film-formation time were 9 min and 11 min, the surface micro-morphology and the corrosion resistance of as-coated samples were relatively improved. The results provided a theoretical foundation for the application of the Mg-Zn-Zr-Ca novel bio-magnesium alloy in biomedicine.

  1. Effects of minor Zr and Sr on as-cast microstructure and mechanical properties of Mg-3Ce-1.2Mn-0.9Sc (wt.%) magnesium alloy

    International Nuclear Information System (INIS)

    Pan Fusheng; Yang Mingbo; Shen Jia; Wu Lu

    2011-01-01

    Research highlights: → Minor Zr and/or Sr additions can effectively refine the grains of the Mg-3Ce-1.2Mn-0.9Sc alloy. → Minor Zr and/or Sr additions can improve the tensile properties of the Mg-3Ce-1.2Mn-0.9Sc alloy. → Minor Zr and/or Sr additions can improve the creep properties of the Mg-3Ce-1.2Mn-0.9Sc alloy. - Abstract: The effects of minor Zr and Sr on the as-cast microstructure and mechanical properties of the Mg-3Ce-1.2Mn-0.9Sc (wt.%) alloy were investigated by using optical and electron microscopies, differential scanning calorimetry (DSC) analysis, and tensile and creep tests. The results indicate that adding minor Zr and/or Sr to the Mg-3Ce-1.2Mn-0.9Sc alloy does not cause an obvious change in the morphology and distribution of the Mg 12 Ce phase. However, the grains of the Zr and/or Sr-containing alloys are effectively refined. Among the Zr and/or Sr-containing alloys, the grains of the alloy with the addition of 0.5 wt.%Zr + 0.1 wt.%Sr are the finest, followed by the alloys with the additions of 0.5 wt.%Zr and 0.1 wt.%Sr, respectively. In addition, small additions of Zr and/or Sr can improve the tensile and creep properties of the Mg-3Ce-1.2Mn-0.9Sc alloy. Among the Zr and/or Sr-containing alloys, the alloy with the addition of 0.5 wt.%Zr + 0.1 wt.%Sr obtains the optimum tensile and creep properties.

  2. Preparation and dielectric properties of Ba0.95Ca0.05Ti0.8Zr0.2O3-polyethersulfone composites

    International Nuclear Information System (INIS)

    Wang Fajun; Li Wen; Jiang Hongliu; Xue Mingshan; Lu Jinshan; Yao Junping

    2010-01-01

    We report the preparation and dielectric properties of ceramic-polymer composites using Ba 0.95 Ca 0.05 Ti 0.8 Zr 0.2 O 3 (BCTZ) as a ceramic filler and polyethersulfone (PES) as a polymer matrix. The BCTZ powders were synthesized by a sol-gel method to fabricate BCZT-PES composites. The composites with various BCTZ volume fractions were prepared by a solution mixing and hot-pressing method. The composite with 50 vol % BCTZ showed high dielectric constant (ε=48.80) and low loss (tan δ=0.042) at 1 kHz and room temperature. Such excellent dielectric properties of the composites displayed an acceptable stability within a wide range of temperature (from 20 to 150 deg. C) and frequency (from 100 Hz to 100 kHz). The present work indicates that the BCTZ-PES composite can be a candidate for embedded capacitors.

  3. Characterization of highly (110)- and (111)-oriented Pb(Zr,Ti)O3 films on BaPbO3 electrode using Ru conducting barrier

    International Nuclear Information System (INIS)

    Liang, C.-S.; Wu, J.-M.

    2005-01-01

    Highly non-(001)-oriented Pb(Zr,Ti)O 3 (PZT) films have been fabricated by rf-magnetron sputtering. The preferential (110)-oriented BaPbO 3 (BPO) deposited on Ru buffer layer induces the growth of (110)-oriented PZT film. With the aid of self-organized growth of PZT, the orientation of the film deposited on random-oriented BPO/Pt(111)/Ru(002) is (111)-preferred. The insertion of Pt layer between BPO and Ru changes the orientation of PZT from (110) to (111) and prevents the oxygen diffusion. These non-(001)-oriented PZT films possess more superior ferroelectric, fatigue, and retention properties than those of (001)-oriented PZT films

  4. Structural, microstructural, dielectric and ferroelectric properties of lead free Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramic

    Science.gov (United States)

    Sharma, Sarita; Sharma, Hakikat; Negi, N. S.

    2018-05-01

    Lead free Ba0.85Ca0.15Zr0.1Ti0.9O3(BCTZ) ceramic has been synthesized by sol-gel method. Properties of material are studied at different sintering temperatures for 5 hours. Structural and microstructural properties are analyzed by using X-ray diffractrometer (XRD) and scanning electron microscopy (SEM) at annealing temperature of 850°C and 1050°C XRD pattern confirm the perovskite structure of the material without any unwanted phases crystalinity increased with increase of sintering temperature so as roughness and porosity is decreased as shown by SEM micrographs. There is large improvement in density with rise of sintering temperature which also leads to drastic change in ferroelectric and dielectric properties.

  5. Scanning/friction force microscopy study of YBa2Cu3O7-δ single crystals grown in BaZrO3 crucibles

    International Nuclear Information System (INIS)

    Lang, H.P.; Jess, P.; Hubler, U.

    1996-01-01

    Very pure YBa 2 Cu 3 O 7-δ (YBCO) single crystals grown in BaZrO 3 crucibles are studied in the as-grown and the oxidized state by scanning force (SFM), friction force (FFM) and scanning tunneling microscopies (STM). The images show clean terraces with step-heights of one unit cell along YBCO(001), i.e. 1.2 nm. Only close to step edges is material contrast observed by FFM indicating traces of flux. Some crystal surfaces exhibit over-layer features, such as star-like, ribbon-like and checkerboard-like structures, which exhibit friction contrast implying the presence of different materials on the surface. Tunneling spectroscopy at 4-7 K in high vacuum reveals a superconducting energy gap of 2Δ ∼ 26 meV

  6. Cube textured CeO2, BaZrO3 and LaAlO3 buffer layers on Ni based Substrates

    International Nuclear Information System (INIS)

    Deinhofer, C; Gritzner, G

    2006-01-01

    CeO 2 , BaZrO 3 as well as LaAlO 3 buffer layers were deposited on {100} Ni + 5 weight-% W substrates by a wet chemical technique. The solutions were prepared by dissolving the metal nitrates or acetates and zirconiumacetylacetonate, respectively, in mixtures of acetic acid, methanol and water. The solutions were applied by dip- or spincoating, dried at 135 deg. C and annealed at temperatures between 900 and 1 400 deg. C depending on the buffer layer for 15 min. under Ar-5% H 2 gas flow. Pole-figure measurements proved the exact texture of each buffer layer. Electron microscopy showed dense and smooth buffer layers

  7. Structures and Spectroscopy Studies of Two M(II-Phosphonate Coordination Polymers Based on Alkaline Earth Metals (M = Ba, Mg

    Directory of Open Access Journals (Sweden)

    Kui-Rong Ma

    2013-01-01

    Full Text Available The two examples of alkaline-earth M(II-phosphonate coordination polymers, [Ba2(L(H2O9]·3H2O (1 and [Mg1.5(H2O9]·(L-H21.5·6H2O (2 (H4L = H2O3PCH2N(C4H8NCH2PO3H2, N,N′-piperazinebis(methylenephosphonic acid, (L-H2 = O3PH2CHN(C4H8NHCH2PO3 have been hydrothermally synthesized and characterized by elemental analysis, FT-IR, PXRD, TG-DSC, and single-crystal X-ray diffraction. Compound 1 possesses a 2D inorganic-organic alternate arrangement layer structure built from 1D inorganic chains through the piperazine bridge, in which the ligand L−4 shows two types of coordination modes reported rarely at the same time. In 1, both crystallographic distinct Ba(1 and Ba(2 ions adopt 8-coordination two caps and 9-coordination three caps triangular prism geometry structures, respectively. Compound 2 possesses a zero-dimensional mononuclear structure with two crystallographic distinct Mg(II ions. Free metal cations   [MgO6]n2+ and uncoordinated anions (L-H2n2- are joined together by static electric force. Results of photoluminescent measurement indicate three main emission bands centered at 300 nm, 378.5 nm, and 433 nm for 1 and 302 nm, 378 nm, and 434.5 nm for 2 (λex=235 nm, respectively. The high energy emissions could be derived from the intraligand π∗-n transition stations of H4L (310 nm and 382 nm, λex=235 nm, while the low energy emission (>400 nm of 1-2 may be due to the coordination effect with metal(II ions.

  8. Improving High-Temperature Tensile and Low-Cycle Fatigue Behavior of Al-Si-Cu-Mg Alloys Through Micro-additions of Ti, V, and Zr

    Science.gov (United States)

    Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

    2015-07-01

    High-temperature tensile and low-cycle fatigue tests were performed to assess the influence of micro-additions of Ti, V, and Zr on the improvement of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in the as-cast condition. Addition of transition metals led to modification of microstructure where in addition to conventional phases present in the Al-7Si-1Cu-0.5Mg base, new thermally stable micro-sized Zr-Ti-V-rich phases Al21.4Si4.1Ti3.5VZr3.9, Al6.7Si1.2TiZr1.8, Al2.8Si3.8V1.6Zr, and Al5.1Si35.4Ti1.6Zr5.7Fe were formed. The tensile tests showed that with increasing test temperature from 298 K to 673 K (25 °C to 400 °C), the yield stress and tensile strength of the present studied alloy decreased from 161 to 84 MPa and from 261 to 102 MPa, respectively. Also, the studied alloy exhibited 18, 12, and 5 pct higher tensile strength than the alloy A356, 354 and existing Al-Si-Cu-Mg alloy modified with additions of Zr, Ti, and Ni, respectively. The fatigue life of the studied alloy was substantially longer than those of the reference alloys A356 and the same Al-7Si-1Cu-0.5Mg base with minor additions of V, Zr, and Ti in the T6 condition. Fractographic analysis after tensile tests revealed that at the lower temperature up to 473 K (200 °C), the cleavage-type brittle fracture for the precipitates and ductile fracture for the matrix were dominant while at higher temperature fully ductile-type fracture with debonding and pull-out of cracked particles was identified. It is believed that the intermetallic precipitates containing Zr, Ti, and V improve the alloy performance at increased temperatures.

  9. Correlative characterization of primary Al{sub 3}(Sc,Zr) phase in an Al–Zn–Mg based alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, J.H., E-mail: jie-hua.li@hotmail.com [Institute of Casting Research, Montanuniversität Leoben, A-8700 Leoben (Austria); Wiessner, M. [Materials Center Leoben Forschung GmbH, A-8700 Leoben (Austria); Albu, M. [Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Center for Electron Microscopy (Austria); Wurster, S. [Department of Materials Physics, Montanuniversität Leoben, Erich Schmid Institute of Materials Science of the Austrian Academy of Sciences, A-8700 Leoben (Austria); Sartory, B. [Materials Center Leoben Forschung GmbH, A-8700 Leoben (Austria); Hofer, F. [Institute for Electron Microscopy and Nanoanalysis, Graz University of Technology, Center for Electron Microscopy (Austria); Schumacher, P. [Institute of Casting Research, Montanuniversität Leoben, A-8700 Leoben (Austria); Austrian Foundry Research Institute, A-8700 Leoben (Austria)

    2015-04-15

    Three-dimensional electron backscatter diffraction, focused ion beam, transmission electron microscopy and energy filtered transmission electron microscopy were employed to investigate the structural information of primary Al{sub 3}(Sc,Zr) phase, i.e. size, shape, element distribution and orientation relationship with the α-Al matrix. It was found that (i) most primary Al{sub 3}(Sc,Zr) phases have a cubic three-dimensional morphology, with a size of about 6–10 μm, (ii) most primary Al{sub 3}(Sc,Zr) phases are located within the α-Al matrix, and exhibit a cube to cube orientation relationship with the α-Al matrix, and (iii) a layer by layer growth was observed within primary Al{sub 3}(Sc,Zr) phases. Al, Cu, Si and Fe are enriched in the α-Al matrix between the layers of cellular eutectic Al{sub 3}(Sc,Zr) phase, while Sc, Ti and Zr are enriched in small Al{sub 3}(Sc,Zr) phases. A peritectic reaction and subsequent eutectic reaction between Al{sub 3}Sc and Al was proposed to interpret the observed layer by layer growth. This paper demonstrates that the presence of impurities (Fe, Si, Cu, Ti) in the diffusion field surrounding the growing Al{sub 3}(Sc,Zr) particle enhances the heterogeneous nucleation of Al{sub 3}(Sc,Zr) phases. - Highlights: • Most fine cubic primary Al{sub 3}(Sc,Zr) phases were observed within the α-Al matrix. • A layer by layer growth within primary Al{sub 3}(Sc,Zr) phase was observed. • A peritectic and subsequent eutectic reaction between Al{sub 3}Sc and Al was proposed. • Impurities in diffusion fields enhance heterogeneous nucleation of Al{sub 3}(Sc,Zr)

  10. Photoluminescence and thermoluminescence properties of Eu2+ doped and Eu2+ ,Dy3+ co-doped Ba2 MgSi2 O7 phosphors.

    Science.gov (United States)

    Sao, Sanjay Kumar; Brahme, Nameeta; Bisen, D P; Tiwari, Geetanjali

    2016-11-01

    In this work, we report the preparation, characterization, comparison and luminescence mechanisms of Eu 2 + -doped and Eu 2 + ,Dy 3 + -co-doped Ba 2 MgSi 2 O 7 (BMSO) phosphors. Prepared phosphors were synthesized via a high temperature solid-state reaction method. All prepared phosphors appeared white. The phase structure, particle size, and elemental analysis were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) analysis. The luminescence properties of the phosphors were investigated by thermoluminescence (TL) and photoluminescence (PL). The PL excitation and emission spectra of Ba 2 MgSi 2 O 7 :Eu 2 + showed the peak to be around 381 nm and 490 nm respectively. The PL excitation spectrum of Ba 2 MgSi 2 O 7 :Eu 2 + Dy 3 + showed the peak to be around 341 nm and 388 nm, and the emission spectrum had a broad band around 488 nm. These emissions originated from the 4f 6 5d 1 to 4f 7 transition of Eu 2 + . TL analysis revealed that the maximum TL intensity was found at 5 mol% of Eu 2 + doping in Ba 2 MgSi 2 O 7 phosphors after 15 min of ultraviolet (UV) light exposure. TL intensity was increased when Dy 3 + ions were co-doped in Ba 2 MgSi 2 O 7 :Eu 2 + and maximum TL intensity was observed for 2 mol% of Dy 3 + . TL emission spectra of Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors were found at 500 nm. TL intensity increased with UV exposure time up to 15 min, then decreased for the higher UV radiation dose for both Eu doping and Eu,Dy co-doping. The trap depths were calculated to be 0.54 eV for Ba 1.95 MgSi 2 O 7 :0.05Eu 2 + and 0.54 eV and 0.75 eV for Ba 1.93 MgSi 2 O 7 :0.05Eu 2 + ,0.02Dy 3 + phosphors. It was observed that co-doping with small amounts of Dy 3 + enhanced the thermoluminescence properties of Ba 2 MgSi 2 O 7 phosphor. Copyright © 2016 John Wiley & Sons, Ltd. [Correction added on 5 April 2016, after first online publication: The

  11. Gigantic terahertz magnetochromism via electromagnons in the hexaferrite magnet Ba2Mg2Fe12O22

    Science.gov (United States)

    Kida, N.; Kumakura, S.; Ishiwata, S.; Taguchi, Y.; Tokura, Y.

    2011-02-01

    Effects of temperature (6-225 K) and magnetic field (0-7 T) on the low-energy (1.2-5 meV) electrodynamics of the electromagnon, the magnetic resonance driven by the light electric field, have been investigated for a hexaferrite magnet Ba2Mg2Fe12O22 by using terahertz time-domain spectroscopy. We find the gigantic terahertz magnetochromism via electromagnons; the magnetochromic change, as defined by the difference of the absorption intensity with and without magnetic field, exceeds 500% even at 0.6 T. The results arise from the fact that the spectral intensity of the electromagnon critically depends on the magnetic structure. With changing the conical spin structures in terms of the conical angle θ from the proper screw (θ=0°) to the ferrimagnetic (θ=90°) through the conical spin-ordered phases (0°origin of this electromagnon is argued in terms of the exchange-striction mechanism.

  12. Effect of Cr, Ti, V, and Zr Micro-additions on Microstructure and Mechanical Properties of the Al-Si-Cu-Mg Cast Alloy

    Science.gov (United States)

    Shaha, S. K.; Czerwinski, F.; Kasprzak, W.; Friedman, J.; Chen, D. L.

    2016-05-01

    Uniaxial static and cyclic tests were used to assess the role of Cr, Ti, V, and Zr additions on properties of the Al-7Si-1Cu-0.5Mg (wt pct) alloy in as-cast and T6 heat-treated conditions. The microstructure of the as-cast alloy consisted of α-Al, eutectic Si, and Cu-, Mg-, and Fe-rich phases Al2.1Cu, Al8.5Si2.4Cu, Al5.2CuMg4Si5.1, and Al14Si7.1FeMg3.3. In addition, the micro-sized Cr/Zr/Ti/V-rich phases Al10.7SiTi3.6, Al6.7Si1.2TiZr1.8, Al21.4Si3.4Ti4.7VZr1.8, Al18.5Si7.3Cr2.6V, Al7.9Si8.5Cr6.8V4.1Ti, Al6.3Si23.2FeCr9.2V1.6Ti1.3, Al92.2Si16.7Fe7.6Cr8.3V1.8, and Al8.2Si30.1Fe1.6Cr18.8V3.3Ti2.9Zr were present. During solution treatment, Cu-rich phases were completely dissolved, while the eutectic silicon, Fe-, and Cr/Zr/Ti/V-rich intermetallics experienced only partial dissolution. Micro-additions of Cr, Zr, Ti, and V positively affected the alloy strength. The modified alloy in the T6 temper during uniaxial tensile tests exhibited yield strength of 289 MPa and ultimate tensile strength of 342 MPa, being significantly higher than that for the Al-Si-Cu-Mg base. Besides, the cyclic yield stress of the modified alloy in the T6 state increased by 23 pct over that of the base alloy. The fatigue life of the modified alloy was substantially longer than that of the base alloy tested using the same parameters. The role of Cr, Ti, V, and Zr containing phases in controlling the alloy fracture during static and cyclic loading is discussed.

  13. In situ transmission electron microscopy studies of microstructure evolution in Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 piezoceramic

    International Nuclear Information System (INIS)

    Zakhozheva, Marina

    2016-01-01

    The purpose of this work is to understand the microstructural features which contribute to the strong electromechanical properties of the lead-free Ba (Zr 0.2 Ti 0.8 )O 3 -x(Ba 0.7 Ca 0.3 )TiO 3 (BZT-xBCT) piezoelectric ceramic. Detailed conventional transmission electron microscopy (TEM) studies on a broad variety of BZT - xBCT were performed in order to demonstrate the composition dependent structural changes. Moreover, several in situ TEM techniques, including in situ hot- and cold-stage, in situ electric field and in situ electric field with simultaneous cooling, were successfully applied in order to monitor the domain morphology evolution in real time. By means of in situ temperature dependent TEM experiments it was shown that during rhombohedral → orthorhombic → tetragonal phase transition the domain morphology changed according to the crystal structure present. During in situ electric field investigations the displacement of the domain walls and changes in the domain configuration during electrical poling were observed, which indicates a high extrinsic contribution to the piezoelectric response in all BZT - xBCT compositions studied. From the results of in situ electric field TEM experiments with simultaneous cooling, we obtained experimental evidence that the further the composition deviates from the polymorphic phase boundary, the higher the electric field required to fully pole the material.

  14. Significant increase of Curie temperature and large piezoelectric coefficient in Ba(Ti0.80Zr0.20)O3-0.5(Ba0.70Ca0.30)TiO3 nanofibers

    Science.gov (United States)

    Fu, Bi; Yang, Yaodong; Gao, Kun; Wang, Yaping

    2015-07-01

    Ba(Ti0.80Zr0.20)O3-0.5(Ba0.7Ca0.3)TiO3 (abbreviated as BTZ-0.5BCT) is a piezoelectric ceramic with a high piezoelectric coefficient d33 (˜620 pC N-1) and has been regarded as one of the most promising candidates to replace PZT-based materials (200-710 pC N-1). However, its Curie temperature TC is relatively low (93 °C) limiting its application. In this letter, we found a temperature dependent Raman spectrum in BTZ-0.5BCT nanofibers (NFs), demonstrating a diffused tetragonal-to-cubic phase transition at 300 °C. This means that the TC of the NFs is nearly 207 °C higher than that of the normal bulk material. The increased TC is considered to be associated with the size effect of BTZ-0.5BCT nanoceramic subunits and the nanoporous nature of the fiber, resulting in discontinuous physical properties. The variation of the ferro/piezoelectricity over the fiber surface is attributed to the polycrystalline structure. The d33 (173.32 pm V-1) is improved in terms of the decreased Q factor result in an increase in d33 of 236.54 pm V-1 after polarization. With a high TC and a very large d33, BTZ-0.5BCT NFs are capable of providing electromechanical behavior used in moderate temperatures.

  15. Investigation of structural, ferroelectric, piezoelectric and dielectric properties of Ba0.92Ca0.08TiO3-BaTi0.96Zr0.04O3 lead-free electroceramics

    Science.gov (United States)

    Keswani, Bhavna C.; Patil, S. I.; Kolekar, Y. D.

    2018-04-01

    Lead free ferroelectric with composition 0.55Ba0.92Ca0.08TiO3-0.45BaTi0.96Zr0.04O3 (BCT8-BZT4) was synthesized by solid state reaction method and investigated their structural, ferroelectric, piezoelectric and dielectric properties. X-ray diffraction analysis shows that BCT8-BZT4 ceramic possess both tetragonal (space group P4mm) and orthorhombic (space group Amm2) crystal structure which was further confirmed from Raman spectra spectroscopy. The micronized grains were observed from scanning electron micrographs while the presence of polarization-electric field hysteresis loop confirms ferroelectric nature of BCT8-BZT4 ceramic. Higher values of maximum polarization (Pmax = 22.27 μC/cm2), remnant polarization (Pr = 11.61 μC/cm2), coercive electric field (Ec = 4.77 kV/cm) and direct piezoelectric coefficient (d33) approximately 185 pC/N were observed. The real part of dielectric constant with frequency shows the usual dielectric dispersion behaviour at RT. The observed properties show that the lead free BCT8-BZT4 ceramic is suitable for ferroelectric memory device, piezoelectric sensor, capacitor, etc. applications.

  16. A brief review of Ba(Ti0.8Zr0.2)O3-(Ba0.7Ca0.3)TiO3 based lead-free piezoelectric ceramics: Past, present and future perspectives

    Science.gov (United States)

    Zhang, Yong; Sun, Huajun; Chen, Wen

    2018-03-01

    As one kind of most crucial and emerging lead-free piezoelectric systems, Ba(Ti0.8Zr0.2)O3-(Ba0.7Ca0.3)TiO3 (BCZT) based lead-free piezoceramics have attracted worldwide attention in recent years. Much progress has been made, however, a summary which covers both the recent progress and the remained problems is urgently needed to further push this field forward. In this review, a brief background of the development of BCZT based lead-free piezoceramics was illustrated firstly. Then, the internal mechanism for the high piezoelectric response would be elaborated. Current research status was discussed in detail in the third section. Various strategies including: (1) Using distinct synthesis routes, (2) adopting different sintering techniques, (3) doping with foreign ions and/or second components, (4) grain size control, were exploited to improve the comprehensive performance and in turn broaden their application areas. In this part, some recently representative works were touched in detail and several existing problems were pointed out. Last, some critical comments (some thoughts related to the potential and future development of BCZT system) were given based on the current research status and existing problems. All in all, this review is devoted to summarizing the milestones in the past, classifying selected recent works and analyzing the prospects of BCZT based ceramics. It can be expected that, this first review that concentrates on BCZT based ceramics obviously would provide useful guidance for the research community.

  17. Electromagnetic and microwave absorption properties of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19}

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jing [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Meng, Pingyuan [Huzhou Innovation Center of Advanced Materials, Shanghai Institute of Ceramics Chinese Academy of Sciences, Huzhou 215100 (China); Wang, Meiling [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Zhou, Guanchen [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Wang, Xinqing [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Xu, Guangliang, E-mail: xuguangliang@swust.edu.cn [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China)

    2016-09-15

    To improve the impedance matching and then achieve a better microwave absorption performance in electromagnetic absorber, the Mg{sup 2+} was added to occupy the sites of Co{sup 2+} in hexagonal-type ferrite BaCoTiFe{sub 10}O{sub 19}. BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} were synthesized by a simple sol-gel combustion technique and the phase of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} was confirmed by X-ray diffraction analysis (XRD). The grain size of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} was in the range of 100–400 nm and crystal particles were refined with the augment of doped Mg{sup 2+}. Based on the static magnetic measurement, the coercivity (H{sub c}) increased and the saturation magnetization (M{sub s}) decreased as the x increased. Moreover, it was found that BaMg{sub 0.4}Co{sub 0.6}TiFe{sub 10}O{sub 19} possessed a maximum reflection loss of −33.7 dB with a matching thickness of 2.0 mm measured by the vector net-analyzer in the frequency of 0.5–18 GHz, which also had a bandwidth below −20 dB ranging from 11.5 GHz to 17.2 GHz. Meanwhile, the permeability of the prepared ferrites could be adjusted and a proper match was provided between dielectric and magnetic properties by controlling the doped content of Mg{sup 2+}, which would be significant to the application of BaMg{sub x}Co{sub 1−x}TiFe{sub 10}O{sub 19} in the field of the microwave absorbing materials. - Highlights: • The Mg{sup 2+} ions were first employed to occupy the place of Co{sup 2+} ions in BaCoTiFe{sub 10}O{sub 19}. • The grains were refined as Co substitution by Mg in ferrite. • The peaks of complex permeability shift to high frequency with Mg{sup 2+} substituted. • The coercivity increased and saturation magnetization slightly decreased. • Substitution of Mg{sup 2+} enhanced microwave absorption and broadened bandwidth.

  18. In situ screen-printed BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} electrolyte-based protonic ceramic membrane fuel cells with layered SmBaCo{sub 2}O{sub 5+x} cathode

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Bin; Dong, Yingchao; Zhang, Shangquan; Hu, Mingjun; Zhou, Yang; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China); Yan, Ruiqiang [Department of Materials Engineering, Taizhou University, Linhai, Zhejiang 317000 (China)

    2009-01-15

    In order to develop a simple and cost-effective route to fabricate protonic ceramic membrane fuel cells (PCMFCs) with layered SmBaCo{sub 2}O{sub 5+x} (SBCO) cathode, a dense BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY) electrolyte was fabricated on a porous anode by in situ screen printing. The porous NiO-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (NiO-BZCY) anode was directly prepared from metal oxide (NiO, BaCO{sub 3}, ZrO{sub 2}, CeO{sub 2} and Y{sub 2}O{sub 3}) by a simple gel-casting process. An ink of metal oxide (BaCO{sub 3}, ZrO{sub 2}, CeO{sub 2} and Y{sub 2}O{sub 3}) powders was then employed to deposit BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY) thin layer by an in situ reaction-sintering screen printing process on NiO-BZCY anode. The bi-layer with 25 {mu}m dense BZCY electrolyte was obtained by co-sintering at 1400 C for 5 h. With layered SBCO cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H{sub 2} as fuel and the static air as oxidant. A high open-circuit potential of 1.01 V, a maximum power density of 382 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.15 {omega} cm{sup 2} was achieved at 700 C. (author)

  19. Annealing behavior of a cast Mg-Gd-Y-Zr alloy with necklace fine grains developed under hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yi [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yang, Xuyue, E-mail: yangxuyue@mail.csu.edu.cn [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Central South University, Changsha 410083 (China); Xiao, Zhenyu; Zhang, Duxiu [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Wang, Jun [Institute for Frontier Materials, Deakin University, Geelong, VIC 3216 (Australia); Sakai, Taku [UEC Tokyo (The University of Electro-Communications), Chofu, Tokyo 182-8585 (Japan)

    2017-03-14

    The microstructure and texture development of a cast Mg-Gd-Y-Zr alloy during hot deformation and subsequent annealing were investigated by optical microscopy (OM) and electron backscattered diffraction (EBSD) technology. Initial microstructures with partially and fully developed new fine grains (NFGs), separately attended by continuous or interrupted hot forging, were various mixed grain structures composed of NFGs in necklace and retained coarse grains. It is shown that, during annealing, the development of grain size can be divided into three stages: i.e. an incubation of grain growth, a rapid coarsening and a normal grain growth. After a long time annealing of over 10{sup 4} ks at 693 K, the average grain size for samples continuous compressed to ε=1.2 and those interrupted compressed to ε=1.6 were close. Moreover, orientations of such strain-induced fine grains were relatively randomly distributed, leading to a weakened basal texture, while the basal plane of retained coarse grains were perpendicular to the forging direction. Such texture even became weaker during subsequent annealing. The results show that the development of necklace NFGs during hot deformation can be effective for homogeneous grain refinement under subsequent annealing.

  20. Precipitation sequence and kinetics in a Mg-4Sm-1Zn-0.4Zr (wt%) alloy

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Xiangyu, E-mail: xxia5@wisc.edu [Materials Science Program, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States); Department of Materials Science and Engineering, University of Wisconsin – Madison, 1509 University Ave, Madison, WI 53706 (United States); Luo, Alan A. [Department of Materials Science and Engineering, University of Wisconsin – Madison, 1509 University Ave, Madison, WI 53706 (United States); Department of Materials Science and Engineering, The Ohio State University, 116 W. 19th Ave, Columbus, OH 43210 (United States); Stone, Donald S. [Materials Science Program, University of Wisconsin – Madison, 1509 University Ave., Madison, WI 53706 (United States); Department of Materials Science and Engineering, University of Wisconsin – Madison, 1509 University Ave, Madison, WI 53706 (United States)

    2015-11-15

    The present research presents a series of investigations into phase identification and precipitation sequence in Mg-4Sm-1Zn-0.4Zr alloy, using differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The precipitation sequence is: super saturated solid solution (S.S.S.S) → solute atom clusters → γ″ → γ′ (→stacking faults) → γ. Structure of γ″ has been determined as an ordered hexagonal GP zone, a = 0.556 nm, c = 0.414 nm γ′ is composed of several γ″ layers. Kinetic studies show that quenched-in vacancies play an important role in the formation of solute clusters, while the growth of both precipitates are diffusion controlled. Analysis of microstructure evolution suggests that nucleation of γ′ happens near existing γ″ precipitates. - Highlights: • Precipitation sequence in a high-zinc magnesium-samarium-zinc-zirconium alloy has been identified. • Structures of metastable precipitates are modified directly with HAADF-STEM. • Kinetic calculations were performed to understand nucleation/growth mechanisms of these precipitates.

  1. Effect of the substrate temperature on the microstructure and texture of Mg90Zr10 (at.%) films deposited by sputtering

    International Nuclear Information System (INIS)

    Garces, Gerardo; Landais, Stephan; Adeva, Paloma

    2006-01-01

    The microstructure of Mg 90 Zr 10 (at.%) films obtained by sputtering onto copper substrate at three different temperatures (180, 320 and 350 deg. C) has been studied. Films exhibited an intense (0 0 0 1) basal plane fibre texture with the fibre axis parallel to the growth direction. Their microstructure consisted of columnar grains growing from the copper substrate to the free surface which is typical of the zone II of the Movchan and Demchishin zone model developed for PVD materials. Nevertheless, the microstructure of films was dependent on the substrate temperature. The grain diameter increased as the substrate temperature was increased. Moreover, the dislocation density inside the grains as well as that piled-up forming sub-grain boundaries decreased as the deposition temperature increased. Although the film growth in zone II is controlled by surface diffusion the larger surface mobility of the atoms as the substrate temperature increased led to changes in the solubility of zirconium. At low substrate temperatures all zirconium was in solid solution. However, at 350 deg. C the formation of small zirconium particles occurred at grain boundaries

  2. Improvement of the field-trapping capabilities of bulk Nd Ba Cu O superconductors using Ba Cu O substrates

    Science.gov (United States)

    Matsui, Motohide; Nariki, Shinya; Sakai, Naomichi; Iwafuchi, Kengo; Murakami, Masato

    2006-07-01

    We used Ba-Cu-O substrates to fabricate bulk Nd-Ba-Cu-O superconductors using a top-seeded melt-growth method. There were several advantages for the use of Ba-Cu-O substrate compared to conventional substrate materials such as MgO, ZrO2, Al2O3, RE123 and RE211 (RE = rare earth). The Ba-Cu-O did not react with the precursor and minimized liquid loss. Accordingly, the introduction of large-sized cracks was suppressed. We also found that Tc values were high at the bottom regions, which was ascribed to the beneficial effect of Ba-Cu-O in suppressing Nd/Ba substitution. As a result, we obtained bulk Nd-Ba-Cu-O superconductors that exhibited fairly good field-trapping capabilities, even at the bottom surfaces.

  3. Exceptionally High Piezoelectric Coefficient and Low Strain Hysteresis in Grain-Oriented (Ba, Ca)(Ti, Zr)O3 through Integrating Crystallographic Texture and Domain Engineering.

    Science.gov (United States)

    Liu, Yingchun; Chang, Yunfei; Li, Fei; Yang, Bin; Sun, Yuan; Wu, Jie; Zhang, Shantao; Wang, Ruixue; Cao, Wenwu

    2017-09-06

    Both low strain hysteresis and high piezoelectric performance are required for practical applications in precisely controlled piezoelectric devices and systems. Unfortunately, enhanced piezoelectric properties were usually obtained with the presence of a large strain hysteresis in BaTiO 3 (BT)-based piezoceramics. In this work, we propose to integrate crystallographic texturing and domain engineering strategies into BT-based ceramics to resolve this challenge. [001] c grain-oriented (Ba 0.94 Ca 0.06 )(Ti 0.95 Zr 0.05 )O 3 (BCTZ) ceramics with a texture degree as high as 98.6% were synthesized by templated grain growth. A very high piezoelectric coefficient (d 33 ) of 755 pC/N, and an extremely large piezoelectric strain coefficient (d 33 * = 2027 pm/V) along with an ultralow strain hysteresis (H s ) of 4.1% were simultaneously achieved in BT-based systems for the first time, which are among the best values ever reported on both lead-free and lead-based piezoceramics. The exceptionally high piezoelectric response is mainly from the reversible contribution, and can be ascribed to the piezoelectric anisotropy, the favorable domain configuration, and the formation of smaller sized domains in the BCTZ textured ceramics. This study paves a new pathway to develop lead-free piezoelectrics with both low strain hysteresis and high piezoelectric coefficient. More importantly, it represents a very exciting discovery with potential application of BT-based ceramics in high-precision piezoelectric actuators.

  4. Low sintering temperature and high piezoelectric properties of Li-doped (Ba,Ca)(Ti,Zr)O{sub 3} lead-free ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xiaoming [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Ruan, Xuezheng; Zhao, Kunyun [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); He, Xueqing [School of Materials and Metallurgy, Northeastern University, Shenyang 110004 (China); Zeng, Jiangtao, E-mail: zjt@mail.sic.ac.cn [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Li, Yongsheng [School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Zheng, Liaoying [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Park, Chul Hong [Department of Physics Education, Pusan National University, Pusan 609735 (Korea, Republic of); Li, Guorong [Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2015-05-25

    Highlights: • Li-doped Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.9}Zr{sub 0.1}O{sub 3} (BCZT) lead-free piezoceramics were prepared by the two-step synthesis and solid-state reaction method. • Their sintering temperature decreases from about 1540 °C down to about 1400 °C. • With the proper addition of Li, the densities and grain sizes of ceramics increase. • The ceramics not only have the characteristics of hard piezoceramics but also possesses the features of soft piezoceramics at low sintering temperature. - Abstract: Li-doped Ba{sub 0.85}Ca{sub 0.15}Ti{sub 0.9}Zr{sub 0.1}O{sub 3} (BCZT) lead-free piezoelectric ceramics were prepared by the two-step synthesis and the solid-state reaction method. The density and grain size of ceramics sufficiently increases by Li-doped sintering aid, and their sintering temperature decreases from about 1540 °C down to about 1400 °C. X-ray diffraction reveals that the phase structure of Li-doped BCTZ ceramics is changed with the sintering temperature, which is consistent with their phase transition observed by the temperature-dependent dielectric curves. The well-poled Li-doped BCZT ceramics show a high piezoelectric constant d{sub 33} (512 pC/N) and a planar electromechanical coupling factor k{sub p} (0.49), which have the characteristics of soft Pb(Zr,Ti)O{sub 3} (PZT) piezoceramic, on the other hand, the mechanical quality factor Q{sub m} is about 190, which possesses the features of hard PZT piezoceramics. The enhanced properties of the Li-doped BCZT are explained by the combination of Li-doped effect and sintering effect on the microstructure and the phase transition around room temperature.

  5. Kinetic studies of oxidation of MgAlON and a comparison of the oxidation behaviour of AlON, MgAlON, O'SiAlON-ZrO{sub 2}, and BN-ZCM ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xidong; Seetharaman, S. [Div. of Metallurgy, Royal Inst. of Tech., Stockholm (Sweden); Li Wenchao [Dept. of Physical Chemistry, Univ. of Science and Technology Beijing (USTB), Beijing, BJ (China)

    2002-06-01

    The kinetics and morphology of the oxidation process of magnesium-aluminium oxynitride (MgAlON), aluminium oxynitride (AlON), O'SiAlON-ZrO{sub 2}, and BN-ZCM have been studied in the temperature range 1373-1773 K (ZCM=30 wt% ZrO{sub 2}, 52 wt% Al{sub 2}O{sub 3} and 18 wt% 3 Al{sub 2}O{sub 3}.2 SiO{sub 2}). Oxidation experiments with powder and plate samples of the above materials have been carried out in air. MgAlON shows the best resistance to oxidation at lower temperatures (< 1473 K), whereas at higher temperatures ({proportional_to} 773 K), AlON shows the best resistance. O'SiAlON-ZrO{sub 2} shows very good oxidation resistance up to 1673 K. But its oxidation rate increases strongly above 1673 K, presumably due to the formation of liquid phase. BN-ZCM has the poorest oxidation resistance due to the evaporation of B{sub 2}O{sub 3}. The activation energies for the chemical oxidation reaction of AlON, MgAlON, and O'SiAlON-ZrO{sub 2} are 214, 330 and 260 kJ/mol, respectively. The overall diffusion activation energies for AlON, MgAlON, O'SiAlON-ZrO{sub 2} and BN-ZCM are 227, 573, 367 and 289 kJ/mol, respectively. (orig.)

  6. Deformation Behavior of Ultra-Strong and Ductile Mg-Gd-Y-Zn-Zr Alloy with Bimodal Microstructure

    Science.gov (United States)

    Xu, C.; Fan, G. H.; Nakata, T.; Liang, X.; Chi, Y. Q.; Qiao, X. G.; Cao, G. J.; Zhang, T. T.; Huang, M.; Miao, K. S.; Zheng, M. Y.; Kamado, S.; Xie, H. L.

    2018-02-01

    An ultra-strong and ductile Mg-8.2Gd-3.8Y-1Zn-0.4Zr (wt pct) alloy was developed by using hot extrusion to modify the microstructure via forced-air cooling and an artificial aging treatment. A superior strength-ductility balance was obtained that had a tensile yield strength of 466 MPa and an elongation to failure of 14.5 pct. The local strain evolution during the in situ testing of the ultra-strong and ductile alloy was quantitatively analyzed with high-resolution electron backscattered diffraction and digital image correlation. The fracture behavior during the tensile test was characterized by synchrotron X-ray tomography along with SEM and STEM observations. The alloy showed a bimodal microstructure, consisting of dynamically recrystallized (DRXed) grains with random orientations and elongated hot-worked grains with parallel to the extrusion direction. The DRXed grains were deformed by the basal slip and the hot-worked grains were deformed by the prismatic slip dominantly. The strain evolution analysis indicated that the multilayered structure relaxed the strain localization via strain transfer from the DRXed to the hot-worked regions, which led to the high ductility of the alloy. Precipitation of the γ' on basal planes and the β' phases on the prismatic planes of the α-Mg generated closed volumes, which enhanced the strength by pinning dislocations effectively, and contributed to the high ductility by impeding the propagation of micro-cracks inside the grains. The deformation incompatibility between the hot-worked grains and the arched block-shaped long-period stacking ordered (LPSO) phases induced the crack initiation and propagation, which fractured the alloy.

  7. Epitaxial YBa2Cu3O7-x nanocomposite films and coated conductors from BaMO3 (M = Zr, Hf) colloidal solutions

    Science.gov (United States)

    Obradors, X.; Puig, T.; Li, Z.; Pop, C.; Mundet, B.; Chamorro, N.; Vallés, F.; Coll, M.; Ricart, S.; Vallejo, B.; Pino, F.; Palau, A.; Gázquez, J.; Ros, J.; Usoskin, A.

    2018-04-01

    Superconducting nanocomposites are the best material choice to address the performance required in power applications and magnets working under high magnetic fields. However, it is still challenging to sort out how to achieve the highest superconducting performance using attractive and competitive manufacturing processes. Colloidal solutions have been recently developed as a novel and very promising low cost route to manufacture nanocomposite coated conductors. Well dispersed and stabilized preformance nanoparticle solutions are first prepared with high concentrations and then mixed with the YBa2Cu3O7 metalorganic precursor solutions to generate colloidal solutions to grow the nanocomposite films. Here we demonstrate, for the first time, that non-reactive BaZrO3 and BaHfO3 perovskite preformed nanoparticles are suitable for growing high quality thin and thick films, and coated conductors with a homogeneous distribution and controlled particle size using this fabrication method. Additionally, we extend the nanoparticle content of the nanocomposites up to 20%-25% mol without any degradation of the superconducting properties. Thick nanocomposite films, up to 0.8 μm, have been prepared with a single deposition of low-fluorine solutions using an ink jet printing dispenser and we demonstrate that the preformed nanoparticles display only a very limited coarsening during the growth process and so high critical current densities J c (B) under high magnetic fields. These films show the highest critical currents achieved so far based on the colloidal solution approach, I c = 220 A/cm-w at 77 K and self-field, and they still have a high potential for further increase in the film thickness. Finally, we also show that nanocomposite YBa2Cu3O7-BaZrO3 coated conductors based on an alternating beam assisted deposited YSZ buffer layer on stainless steel metallic substrates can be developed based on these novel colloidal solutions. Non-reactive preformed oxide perovskite

  8. Production by thermo-mechanical process and stability in crude petroleum studies of Ba{sub 2}AlZrO{sub 5,5} ceramics; Producao por processo termo-mecanico e estudos de estabilidade em petroleo cru da ceramica Ba{sub 2}AlZrO{sub 5,5}

    Energy Technology Data Exchange (ETDEWEB)

    Yadava, Y.P.; Bezerra, L.P.; Ferreira, R.A.S., E-mail: yadava@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Engenharia Mecanica

    2010-07-01

    The necessity of developing technologies that makes possible the petroleum wells exploration is very important. Knowing that those are hostile environments is necessary ta find materials that are able to resist to those environment conditions. In this way we worked on the fabrication of ceramic embedding temperature sensors for petroleum industry. The present work looks for the fabrication of Ba{sub 2}AlZrO{sub 5,5} ceramic by thermo-mechanical process and the study of it's stability in crude petroleum. The Ba{sub 2}AlZrO{sub 5,5} was fabricated by thermo-mechanical process. The ceramic powder was calcined and then the granulometry was analyzed by laser. The samples were compacted, sintered and the microstructure and mechanical properties were characterized. The ceramic stability study in crude petroleum was done and the ceramic was analyzed by X-Ray diffraction and Vickers micro hardness The results shows that the ceramic is stable in crude petroleum. (author)

  9. Dependence of transfer number of fluorine on cation type in glasses of Ba(PO3)2-MeF2 systems (Me=Ba,Sr,Ca,Mg)

    International Nuclear Information System (INIS)

    Pronkin, A.A.

    1978-01-01

    The influence of Ba, Sr, Ca, Mg cations on transfer numbers of fluorine in glasses of Ba(PO 3 ) 2 - MeF 2 pseudobinary systems is studied. Transfer numbers are essentially different in one and the same fluorine ion concentration in glasses, containing various alkali-earth cations: increase of the cation field force brings about decrease of the transfer numbers of fluorine, and the glass-formation region in the Ba-Sr-Ca-Mg series rises. The dependence of transfer numbers of fluorine on the fluorine concentration logarithm is presented. It is established, that alkali-earth metals influence the transfer numbers of fluorine on account of selective interaction with the phosphate constituent of glass structure

  10. Phase, microstructure and microwave dielectric properties of Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics

    Directory of Open Access Journals (Sweden)

    Manan Abdul

    2015-03-01

    Full Text Available Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics was prepared via conventional solid-state mixed-oxide route. The phase, microstructure and microwave dielectric properties of the sintered samples were characterized using X-ray diffraction (XRD, scanning electron microscopy (SEM and a vector network analyzer. The microstructure comprised of circular and elongated plate-like grains. The semi quantitative analysis (EDS of the circular and elongated grains revealed the existence of Mg0:95Ni0:05T2O5 as a secondary phase along with the parent Mg0:95Ni0:05Ti0:98Zr0:02O3 phase, which was consistent with the XRD findings. In the present study, εr ~17.1, Qufo~195855 ± 2550 GHz and τf ~ -46 ppm/K was achieved for the synthesized Mg0:95Ni0:05Ti0:98Zr0:02O3 ceramics sintered at 1325 °C for 4 h.

  11. The effect of Bi2 O3 on the electrical properties of Zr O2: 3 wt% Mg O ceramic solid electrolytes

    International Nuclear Information System (INIS)

    Cosentino, I.C.

    1991-01-01

    Zr O 2 : 3 wt% Mg O ceramic solid electrolytes have been prepared to study the effect of Bi 2 O 3 addition on densification and electrical conductivity. Microstructural characterization have been done by X-ray diffractometry, scanning electron microscopy and electron microprobe analyses. Electrical conductivity measurements have been done by two probe dc technique in the 400 0 C - 700 0 C temperature range. The results show that 5 wt% Bi 2 O 3 addition improves densification: 93% TD and 98% TD specimens are obtained from zirconia stabilized by powder mixture and by coprecipitation of oxides, respectively. Moreover, electrical conductivity values are found to be two orders of magnitude higher for Zr O 2 : 3 wt% Mg O with 5% Bi 2 O 3 . (author)

  12. The ambient and high temperature deformation behavior of Al–Si–Cu–Mg alloy with minor Ti, Zr, Ni additions

    International Nuclear Information System (INIS)

    Hernandez-Sandoval, J.; Garza-Elizondo, G.H.; Samuel, A.M.; Valtiierra, S.; Samuel, F.H.

    2014-01-01

    Highlights: • Characterization on the precipitation of Ni- and Zr-based intermetallics. • High temperature tensile properties of 354 alloy containing Zr and Ni below 0.5%. • Quality index charts as a function of heat treatment. • Yield strength and ductility color contours as a function of aging temperature and aging time. - Abstract: The principal aim of the present work was to investigate the effects of minor additions of nickel and zirconium on the strength of cast aluminum alloy 354 at ambient and high temperatures. Tensile properties of the as-cast and heat-treated alloys were determined at room temperature and at high temperatures (190 °C, 250 °C, 350 °C). The results show that Zr reacts only with Ti, Si and Al. From the quality index charts constructed for these alloys, the quality index attains minimum and maximum values of 259 MPa and 459 MPa, in the as-cast and solution-treated conditions; also, maximum and minimum values of yield strength are observed at 345 MPa and 80 MPa, respectively, within the series of aging treatments applied. A decrease in tensile properties of ∼10% with the addition of 0.4 wt.% nickel is attributed to a nickel–copper reaction. The reduction in mechanical properties due to addition of different elements is attributed principally to the increase in the percentage of intermetallic phase particles formed during solidification; such particles act as stress concentrators, decreasing the alloy ductility. Tensile test results at ambient temperatures show a slight increase (∼10%) in alloys with Zr and Zr/Ni additions, particularly at aging temperatures above 240 °C. Additions of Zr and Zr + Ni increase the high temperature tensile properties, in particular for the alloy containing 0.2 wt.% Zr + 0.2 wt.% Ni, which exhibits an increase of more than 30% in the tensile properties at 300 °C compared with the base 354 alloy

  13. Resistência química de vitro-cerâmicos pertencentes a sistemas Li2O-ZrO2-BaO-SiO2 frente ao tratamento com soluções ácidas e básicas Chemical durability of the Li2O-ZrO2-BaO-SiO2 glass-ceramic treated with acidic and basic solution

    Directory of Open Access Journals (Sweden)

    Silvia Denofre de Campos

    2002-05-01

    Full Text Available The chemical durability of the Li2O-ZrO2-BaO-SiO2 system was examined by determination of the Vickers hardness. The dependence of hardness and of the chemical resistance with BaO addition was investigated. The experimental results indicate that the hardness increases with the BaO content. The samples surface's morphology submitted to the chemical treatment in acidic (H2SO4 and basic (KOH solution was accompanied by scanning electron microscopy. The chemical durability of the materials with BaO showed better than the glass ceramic without this content. These materials treated with H2SO4 solution showed a preferential attack to the silica rich sites.

  14. Electronic structure and O vacancy formation/migration in La0.825(Mg/Ca/Ba)0.125CoO3

    KAUST Repository

    Omotayo Akande, Salawu; Gan, Li-Yong; Schwingenschlö gl, Udo

    2016-01-01

    The effect of A-site hole doping (Mg2+, Ca2+ or Ba2+) on the electronic and magnetic properties as well as the O vacancy formation and migration in perovskite LaCoO3 is studied using first-principles calculations. All three dopants are found

  15. Luminescence Properties of Self-Activated Mm(VO4)2 (M = Mg, Ca, Sr, and Ba) Phosphors Synthesized by Solid-State Reaction Method.

    Science.gov (United States)

    Min, Xin; Huang, Zhaohui; Fang, Minghao; Liu, Yan'gai; Tang, Chao; Wu, Xiaowen

    2016-04-01

    In this paper, M3(VO4)2 (M = Mg, Ca, Sr, and Ba) self-activated phosphors were prepared by a solid-state reaction method at 1,000 °C for 5 h. The phase formation and micrographs were analyzed by X-ray diffraction and scanning electron microscopy. The Ca3(VO4)2 phosphor does not show any emission peaks under excitation with ultraviolet (UV) light. However, the M3(VO4)2 (M = Mg, Sr, and Ba) samples are effectively excited by UV light chips ranging from 200 nm to 400 nm and exhibit broad emission bands due to the charge transfer from the oxygen 2p orbital to the vacant 3d orbital of the vanadium in the VO4. The color of these phosphors changes from yellow to light blue via blue-green with increasing ionic radius from Mg to Sr to Ba. The luminescence lifetimes and quantum yield decrease with the increasing unit cell volume and V-V distance, in the order of Mg3(VO4)2 to Sr3(VO4)2 to Ba3(VO4)2. The emission intensity decreases with the increase of temperatures, but presents no color shift. This confirms that these self-activated M3(VO4)2 phosphors can be suggested as candidates of the single-phase phosphors for light using UV light emitting diodes (LEDs).

  16. Microstructure, mechanical properties, in vitro degradation and cytotoxicity evaluations of Mg-1.5Y-1.2Zn-0.44Zr alloys for biodegradable metallic implants.

    Science.gov (United States)

    Fan, Jun; Qiu, Xin; Niu, Xiaodong; Tian, Zheng; Sun, Wei; Liu, Xiaojuan; Li, Yangde; Li, Weirong; Meng, Jian

    2013-05-01

    Mg-1.5Y-1.2Zn-0.44Zr alloys were newly developed as degradable metallic biomaterials. A comprehensive investigation of the microstructure, mechanical properties, in vitro degradation assessments and in vitro cytotoxicity evaluations of the as-cast state, as-heat treated state and as-extruded state alloys was done. The microstructure observations show that the Mg-1.5Y-1.2Zn-0.44Zr alloys are mainly composed of the matrix α-Mg phases and the Mg12ZnY secondary phases (LPS structure). The hot extrusion method significantly refined the grains and eliminated the defects of both as-cast and heat treated alloys and thereby contributed to the better mechanical properties and biodegradation resistance. The values of tensile strength and tensile yield strength of the alloy in the as-extruded condition are about 236 and 178 MPa respectively, with an excellent elongation of 28%. Meanwhile, the value of compressive strength is about 471 MPa and the value of bending strength is about 501 MPa. The superior bending strength further demonstrates the excellent ductility of the hot extruded alloys. The results of immersion tests and electrochemical measurements in the SBF indicate that a protective film precipitated on the alloy's surface with the extension of degradation. The protective film contains Mg(OH)2 and hydroxyapatite (HA) which can reinforce osteoblast activity and promote good biocompatibility. No significant cytotoxicity towards L-929 cells was detected and the immersion extracts of alloy samples could enhance the cell proliferation with time in the cytotoxicity evaluations, implying that the Mg-1.5Y-1.2Zn-0.44Zr alloys have the potential to be used for biomedical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Energetic prediction on the stability of A2Mg12Si7, A2Mg4Si3, and AMgSi in the A2Si–Mg2Si system (A = Ca, Sr and Ba) and their calculated electronic structures

    International Nuclear Information System (INIS)

    Imai, Yoji; Mori, Yoshihisa; Nakamura, Shigeyuki; Takarabe, Ken-ichi

    2014-01-01

    Highlights: • Formation energies of A 2 Mg 4 Si 3 , A 2 Mg 12 Si 7 , and AMgSi (A = Ca,Sr,Ba) were calculated. • All AMgSi are quite stable compared to mixture of A 2 Si and Mg 2 Si. • Ba 2 Mg 4 Si 3 and Sr 2 Mg 4 Si 3 are predicted to be stable, but Ca 2 Mg 4 Si 3 is not. • Ca 2 Mg 12 Si 7 and Sr 2 Mg 12 Si 7 are energetically unstable. • Stability of Ba 2 Mg 12 Si 7 is a tender subject. -- Abstract: In order to evaluate the relative stability of A 2 Mg 4 Si 3 , A 2 Mg 12 Si 7 , and AMgSi (A = Ca, Sr, and Ba) in the A 2 Si–Mg 2 Si system, electronic energy changes in the formation of these compounds were calculated using a density-functional theory with the Perdew–Wang generalized gradient approximations. It was found that (1) AMgSi’s are quite stable compared to equi-molar mixture of A 2 Si and Mg 2 Si, (2) Ba 2 Mg 4 Si 3 and Sr 2 Mg 4 Si 3 are also stable, (3) Ca 2 Mg 4 Si 3 and Ca 2 Mg 12 Si 7 are less stable than the mixture of CaMgSi and Mg 2 Si, and (4) Stability of Ba 2 Mg 12 Si 7 is a tender subject and Sr 2 Mg 12 Si 7 is energetically unstable compared to the mixture of Sr 2 Mg 4 Si 3 (or, SrMgSi) and Mg 2 Si. The presence of Sr 2 Mg 12 Si 7 may be due to the vibrational and/or configurational entropy, which are not treated in the present study. From the calculated electronic densities of state, complex compounds of SrMgSi and Mg 2 Si have both p-type and n-type character, depending on the ratio of SrMgSi and Mg 2 Si in that compound

  18. Chemical, structural and magnetic studies of new mono- and diphosphates appearing in ternary diagrams AO-CuO-(P2O5); A= Mg, Ca, Sr, Ba

    International Nuclear Information System (INIS)

    Moqine, A.

    1990-01-01

    A systematic study of mixed mono- and diphosphates of AO-CuO-(P 2 O 5 ) systems (A= Mg, Ca, Sr, Ba) has been carried out. This study showed up, on one hand, continuous and wide ranges in magnesium system and on the other hand, eight new phases in the other systems: Sr sub 18 Cu sub 3 (PO 4 ) 14 , A 2 Cu (PO 4 ) 2 , (A= Sr, Ba), Sr 3 Cu 3 (PO 4 ) 4 , BaCu 2 (PO 4 ) 2 and ACu(P 2 O 7 ) (A= Ca, Sr, Ba). The crystalline structures of SrCu(P 2 O 7 ), BaCu(P 2 O 7 ),Sr 3 Cu 3 (PO 4 ) 4 and BaCu 2 (PO 4 ) 2 phosphates have been described and discussed. The first compound presents a Tunnel structure and the three others have Foliation structures. The magnetic behaviours of some Cu sup 2+ ions phos-phates have been correlated to their crystalline structures. The experimental data have been parametered using the Ising model and/or the Heisenberg model. In this work, three Ising theoretical models have been developed. This magnetic study showed up new chains of antiferro- or ferrimagnetic Cu sup 2+ ions. 59 figs., 32 tabs., 113 refs. (author)

  19. The importance of passive smoking in the accumulation of Pb, Be, Ba, Mg, Ca, Sr in the children adenoid

    Directory of Open Access Journals (Sweden)

    Maria Gerycka

    2014-09-01

    Full Text Available Introduction. The quality of our life is determined by the quality of the air that we breathe. Hence the influence of cigarette smoking and secondary exposure of persons within the smoking environment is significant. Previous studies have confirmed the influence of passive smoking to on the accumulation of given elements in the tonsils. The subject of the study is to determine the importance of ETS exposure for the accumulation of Pb, Be, Ba, Ca, Mg and Sr in the pharyngeal tonsils. Material and methods. The study involved 162 adenoids from boys and girls living in Tychy and Chorzów. exposed and not exposed to passive smoking. All biological samples were subjected to mineralization with nitric acid (V from Merck. The chemical composition of the samples was determined by the ICP – AES method. Results. The statistical analysis of the elements in the tonsils of children exposed and not exposed to ETS is performed taking into account as an additional criterion of distribution the place of residence and gender of the children. Conclusions. There was no significant effect of passive smoking on the increase of the examined metals in the adenoid. However the role of gender and place of residence to the process of accumulation of elements in this organ remains significant.

  20. Electronic structure, magnetic, mechanical and thermo-physical behavior of double perovskite Ba2MgOsO6

    Science.gov (United States)

    Dar, Sajad Ahmad; Srivastava, Vipul; Sakalle, Umesh Kumar; Parey, Vanshree

    2018-02-01

    The electronic structure, the magnetic, elasto-mechanical and thermodynamic belongings of cubic double oxide perovskites Ba2MgOsO6 have been successfully investigated within the full potential linearized augmented plane wave method (FP-LAPW), based upon the density functional theory (DFT). The structural examination reveals ferromagnetic stability and the spin polarized electronic band structure and density of states display half-metallic nature of the compound. The calculated magnetic moment was found to have an integer value of 2μ_B. From the knowledge of obtained elastic constants mechanical properties like Young's modulus ( E), shear modulus ( G), Poisson ratio (ν) and the anisotropic factor have been predicted. The calculated B/ G and Cauchy pressure ( C_{12}-C_{44}) both portray the ductile nature of the compound. For a complete understanding of the thermo-physical behavior of vital parameters like heat capacity, thermal expansion, Grüneisen parameter and Debye temperature were predicted using quasi harmonic Debye approximation.

  1. Influence of minor combined addition of Cr and Pr on microstructure, mechanical properties and corrosion behaviors of an ultrahigh strength Al-Zn-Mg-Cu-Zr alloy.

    Science.gov (United States)

    Wang, Ming; Huang, Lanping; Chen, Kanghua; Liu, Wensheng

    2018-01-01

    This work focuses on controlling grain boundary structure in an ultra-high strength Al-8.6Zn-2.5Mg-2.2Cu-0.16Zr (wt.%) alloy by the combined addition of trace Cr (0.1wt.%) and Pr (0.14wt.%), and evaluating mechanical properties and localized corrosion behaviors of the alloy in the peak aged condition. The introduction of trace Cr and Pr leads to the formation of nanoscale Cr, Pr-containing Al 3 Zr and Zr-containing PrCr 2 Al 20 dispersoids which can obviously inhibit the recrystallization and sub-grain growth of the super-high strength Al-Zn-Mg-Cu alloys, and retain the deformation-recovery microstructure dominated by low-angle grain boundaries. The nearly ellipsoidal dispersoids with a size of 10-35nm are discretely distributed and precipitate free zones are hardly formed in low-angle grain boundaries. This new alloy composition exhibits better combined properties, higher resistance to stress corrosion, exfoliation corrosion and inter-granular corrosion with the undamaged strength, ductility and fracture toughness. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Effect of isothermal aging on the microstructure and properties of as-cast Mg-Gd-Y-Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liang Shuquan [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Guan Dikai, E-mail: gdk199@126.com [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Tan Xiaoping; Chen Liang; Tang Yan [School of Material Science and Engineering, Central South University, Changsha 410083 (China)

    2011-01-25

    Research highlights: {yields} The improvement of the hardness of the peak-aged alloys at 200 deg. C, 225 deg. C and 250 deg. C is mainly ascribed to the presence of the {beta}' phase. {yields} The alloy peak-aged at 200 deg. C displays the highest hardness owing to the existence of a great many {beta}' precipitates with a quite small size and uniform distribution in the matrix. {yields} The corrosion rates of the peak-aged samples increase as the isothermal aging temperature rise. The {beta}' precipitates are larger and appear to be more active as galvanic cathodes for the alloy peak-aged at the higher aging temperatures. {yields} Therefore, in our paper, optimal mechanical properties and good corrosion resistance in 5% NaCl solutions are obtained simultaneously when the alloy is aged at 200 deg. C for 120 h. - Abstract: The microstructure of Mg-7Gd-3Y-0.4Zr (wt.%) alloy during isothermal aging at 200 deg. C, 225 deg. C and 250 deg. C was investigated using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction. The mechanical properties of the peak-aged materials were evaluated by using Vickers hardness values, and their corrosion resistance was studied by using immersion tests, salt spray tests and electrochemical measurements in 5% NaCl solutions (wt.%). The results show that owing to the existence of a great many {beta}' precipitates with a quite small size and uniform distribution in the matrix, optimal mechanical properties and good corrosion resistance in 5% NaCl solutions are obtained when the alloy is aged at 200 deg. C for 120 h. The potentiodynamic polarization curves show that the corrosion current densities of the cathodic hydrogen evolution on the alloy peak-aged at 200 deg. C is lower than those for specimens of the alloy aged at 225 deg. C and 250 deg. C, which agrees fairly well with the microstructures of the alloys.

  3. Structural and dielectric properties of (001) and (111)-oriented BaZr0.2Ti0.8O3 epitaxial thin films

    International Nuclear Information System (INIS)

    Ventura, J.; Fina, I.; Ferrater, C.; Langenberg, E.; Coy, L.E.; Polo, M.C.; Garcia-Cuenca, M.V.; Fabrega, L.; Varela, M.

    2010-01-01

    We have grown and characterized BaZr 0.2 Ti 0.8 O 3 (BZT) epitaxial thin films deposited on (001) and (111)-oriented SrRuO 3 -buffered SrTiO 3 substrates by pulsed laser deposition. Structural and morphological characterizations were performed using X-ray diffractometry and atomic force microscopy, respectively. A cube-on-cube epitaxial relationship was ascertained from the θ-2θ and φ diffractograms in both (001) and (111)-oriented films. The (001)-oriented films showed a smooth granular morphology, whereas the faceted pyramid-like crystallites of the (111)-oriented films led to a rough surface. The dielectric response of BZT at room temperature was measured along the growth direction. The films were found to be ferroelectric, although a well-saturated hysteresis loop was obtained only for the (001)-oriented films. High leakage currents were observed for the (111) orientation, likely associated to charge transport along the boundaries of its crystallites. The remanent polarization, coercive field, dielectric constant, and relative change of dielectric permittivity (tunability) of (111)-oriented BZT were higher than those of (001)-oriented BZT.

  4. Isotropic and anisotropic pinning in TFA-grown YBa2Cu3O7−x films with BaZrO3 nanoparticles

    International Nuclear Information System (INIS)

    Palau, A; Llordés, A; Puig, T; Obradors, X; Bartolomé, E

    2011-01-01

    YBCO films grown by the trifluoroacetate (TFA) method with increasing number of BaZrO 3 (BZO) nanoparticles have been measured by in-field angular transport measurements to investigate changes in the pinning landscape. The isotropic and anisotropic contributions to the critical current density, J c (H), with the magnetic field applied in H||c and H||ab orientation have been determined, allowing us to characterize the population of isotropic and correlated defects along the c axis and ab planes. First, the influence of the YBCO oxygenation process on the formation of different sorts of anisotropic defects in standard films is demonstrated. Next, we show that the addition of non-coherent BZO nanoparticles to the YBCO matrix produces an expansion of the single-vortex pinning regime toward higher fields, due to the presence of isotropic pinning centers. Moreover, by increasing the amount of isotropic defects in the BZO nanocomposites it is possible to extend the region dominated by strong isotropic pinning centers to large magnetic fields and thus enhance the irreversibility line.

  5. Controlling BaZrO3 nanostructure orientation in YBa2Cu3O{}_{7-\\delta } films for a three-dimensional pinning landscape

    Science.gov (United States)

    Wu, J. Z.; Shi, J. J.; Baca, F. J.; Emergo, R.; Wilt, J.; Haugan, T. J.

    2015-12-01

    The orientation phase diagram of self-assembled BaZrO3 (BZO) nanostructures in c-oriented YBa2Cu3O{}7-δ (YBCO) films on flat and vicinal SrTiO3 substrates was studied experimentally with different dopant concentrations and vicinal angles and theoretically using a micromechanical model based on the theory of elasticity. The organized BZO nanostructure configuration was found to be tunable, between c-axis to ab-plane alignment, by the dopant concentration in the YBCO film matrix strained via lattice mismatched substrates. The correlation between the local strain caused by the BZO doping and the global strain on the matrix provides a unique approach for controllable growth of dopant nanostructure landscapes. In particular, a mixed phase of the c-axis-aligned nanorods and the ab-plane-aligned planar nanostructures can be obtained, leading to a three-dimensional pinning landscape with single impurity doping and much improved J c in almost all directions of applied magnetic field.

  6. Ba2NdZrO5.5 as a potential substrate material for YBa2Cu3O7-δ superconducting films

    International Nuclear Information System (INIS)

    Tovar, H.; Ortiz Diaz, O.; Landinez Tellez, D.A.; Roa-Rojas, J.

    2007-01-01

    The new oxide Ba 2 NdZrO 5.5 (BNZO) has been produced by the standard solid state reaction method. X-ray diffraction analysis (XRD) revealed that this synthesized material has an ordered complex cubic perovskite structure characteristic of A 2 BB'O 6 crystalline structure with a lattice parameter of a = 8.40 Aa. It was established through EDX analysis that there is no trace of impurities. Chemical stability of BNZO with YBa 2 Cu 3 O 7-δ (YBCO) has been studied by means of Rietveld analysis of experimental XRD data on several samples of BNZO-YBCO composites. Quantitative analysis of phases on XRD patterns show that all peaks have been indexed for both BNZO and YBCO, and no extra peak is detectable. YBCO and BNZO remain as two different separate phases in the composites with no chemical reaction. Electrical measurements also revealed that superconducting transition temperature of pure YBCO and BNZO-YBCO composites is 90 K. These favorable characteristics of BNZO show that it can be used as a potential substrate material for deposition of YBCO superconducting films. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. Ferroelectric properties of BaTiO3/PbZr0.2Ti.08O3 bilayer thin film

    Science.gov (United States)

    Salev, Pavel; Yang, Chun; Grigoriev, Alexei

    2014-03-01

    The thin film ferroelectric BaTiO3/PbZr0.2Ti0.8O3 bilayer was epitaxially grown on SrRuO3/SrTiO3 substrate by RF sputtering. Electrical measurements of polarization switching revealed two different switching regimes - a small ferroelectric hysteresis loop at low applied voltage and a larger loop at a high voltage. The measured dielectric permittivity corresponds to weak electrostatic coupling between two layers according to Landau-Ginsburg-Devonshire theory. This weak coupling may allow for independent polarization states to exist in individual layers. This can lead to stable head-to-head and tail-to-tail polarization domain configurations, which would explain the two switching regimes observed in electrical measurements. The compensation of polarization gradient across the interface can be explained by the enhancement of interface charge carrier density due to strong bending of electron energy bands. This work was supported by NSF award DMR-1057159.

  8. Phase development and dielectric properties of (1-x)Pb(Zr0.52Ti0.48)O3-xBaTiO3 ceramics

    International Nuclear Information System (INIS)

    Chaisan, Wanwilai; Yimnirun, Rattikorn; Ananta, Supon; Cann, David P.

    2006-01-01

    (1-x)Pb(Zr 0.52 Ti 0.48 )O 3 -xBaTiO 3 ceramics were prepared by a modified mixed-oxide method. The phase formation was studied by XRD analysis. All compositions exhibit complete solid solutions of perovskite-like phase in the (1-x)PZT-xBT system. The (2 0 0)/(0 0 2) peak was found to split at the composition x = 0.6 and the co-existence of tetragonal-rhombohedral phases occurs with x ≤ 0.6. The possible range of compositions which correspond to a phase transition is 0.6 < x < 0.7. While pure BT ceramics exhibited a sharp phase transformation expected for normal ferroelectrics, phase transformation behavior of the (1-x)PZT-xBT solid solutions became more diffuse with increasing BT contents. This was primarily evidenced by an increased broadness in the dielectric peak, with a maximum peak width occurring at x = 0.5

  9. Citrate precursor synthesis, characterization and dielectric properties of Ba1-xSrxZrO3 (0 ≤ x ≤1)

    International Nuclear Information System (INIS)

    Ubaidullah, Mohd; Ahmad, Tokeer; Al-Hartomy, Omar A.

    2012-01-01

    Barium Strontium Zirconate (BSZ) nanoparticles of the general formula Ba 1-x Sr x ZrO 3 over the composition range of (x= 0.0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.50, 0.75 and 1.0) have been successfully synthesized by simple and most elegant method known as Polymeric citrate precursor route using citric acid and ethylene glycol for the first time. These solid solutions were investigated by means of powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and BET surface area studies. XRD studies revealed the monophasic nature of the powders after heating the precursor at 1000 ℃. The particle size obtained from TEM studies were found to be in the range of 13.8-40 nm. Specific surface area of the solid solutions comes out to be in the range of 49 to 94 m 2 g -1 . The average particle size of these nanoparticles could also be calculated using the equation: D BET = 6000/(ρ.S w ), where the symbols D BET , ρ, S w stand for average diameter of the spherical particle, theoretical density, and specific surface area of the sample in m 2 /g respectively

  10. Improved high temperature refractory. [MgCr/sub 2/O/sub 4/ composite with ZrO/sub 2/

    Science.gov (United States)

    Singh, J.P.; James, J.; Picciolo, J.J.

    1985-12-10

    A high chromia refractory composite has been developed with improved thermal shock resistance and containing about 5 to 30 wt % of unstabilized ZrO/sub 2/ having a temperature-dependent phase change resulting in large expansion mismatch between the ZrO/sub 2/ and the chromia matrix which causes microcracks to form during cooling in the high chromia matrix. The particle size preferably is primarily between about 0.6 to 5 microns and particularly below about 3 microns with an average size in the order of 1.2 to 1.8 microns.

  11. Fusibility diagram and phase composition of special section ZrO2-MgCr2O4 in oxidative and inert atmospheres

    International Nuclear Information System (INIS)

    Sennikov, S.G.; Revzin, G.E.; Chistyakova, M.V.

    1982-01-01

    Using the differential-thermal and microroentgenospectral analyses fusibility diagram is built and phase transformations in subsolidus region of partial cross-section ZrO 2 -MgCr 2 O 4 in the air and in argon atmosphere are studied. It is established that the system studied is attributed to simple eutectics, with the eutectics composition 43 mol.%ZrO 2 and temperature 2005+-15 deg C. Mutual solubility of components is of a limited character. Using the methods of roentgenography and by thermodynamical calculations it has been shown that above 1300 K in oxidative atmosphere enrichment of samples with magnesium oxide and their composition sift to the field of elementary triangle take place

  12. NO and NO{sub 2} adsorption on subsurface doped MgO (100) and BaO (100) surfaces. A density functional study

    Energy Technology Data Exchange (ETDEWEB)

    Añez, Rafael, E-mail: ranez@ivic.gob.ve [Laboratorio de Química Física y Catálisis Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Apartado 21827, Caracas (Venezuela, Bolivarian Republic of); Sierraalta, Aníbal [Laboratorio de Química Física y Catálisis Computacional, Centro de Química, Instituto Venezolano de Investigaciones Científicas, Apartado 21827, Caracas (Venezuela, Bolivarian Republic of); Soto, Lenin J. Díaz [Pontifícia Universidade Católica do Rio de Janeiro, Departamento de Física, 22451-900 Rio de Janeiro, RJ (Brazil); Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, CT Bloco A sala 412, Rio de Janeiro, RJ 21949-900 (Brazil)

    2017-05-15

    Highlights: • Subsurface doped BaO(100) and MgO(100) surfaces. • NO and NO{sub 2} adsorption on doped BaO(100) and MgO(100) surfaces. • Surface distortion produced by the doped improves the interaction with the surface. • NO and NO{sub 2} adsorption energies displayed good correlation with the transferred charge. - Abstract: A periodic DFT approach was used to study the energetic, electronic and structural changes produced by the V, Fe and Ni sub layer doped of the MgO (100) and BaO (100) surfaces and the effect of these changes over the adsorption of NO and NO{sub 2}. Results indicate that the higher capacity of donating charge of the transition metal atoms improves the ability of the surfaces to transfer charge to the molecules. The charge transferred goes to NO and NO{sub 2} antibonding orbitals which makes them more reactive hence the interaction becomes stronger. A good lineal correlation between the charge transferred and the calculated adsorption energy was found, that is, as the charge transferred increases the adsorption energy increases. The interaction between the NO or NO{sub 2} molecule on doped surfaces not only depends of the charge transferred, surface structural changes produced by the doping with transition metal atoms increase the adsorption energy specially on the BaO (100) surface where the surface structural changes were more noticeable. Calculated stretching frequency of a NO in a η{sup 1} –N configuration indicates that this is the most stable specie found for the adsorption of NO on terraces of the MgO (100) surface around 77 K and that the sub layer Ni doped BaO (100) surface could be a promising material for the decomposition of NO{sub 2}.

  13. Sinterização de filmes espessos de Ba(Ti0,85Zr0,15O3 por varredura laser Laser scanning sintering of Ba(Ti0.85Zr0.15O3 thick films

    Directory of Open Access Journals (Sweden)

    E. Antonelli

    2009-03-01

    Full Text Available São apresentados os resultados de sinterização de filmes espessos de BaTi0,85Zr0,15O3 (BTZ15, depositados pela técnica de eletroforese, utilizando como fonte de calor um laser de CO2. A montagem experimental foi otimizada de modo a permitir a sinterização de filmes com dimensões de até 70 mm de comprimento por 10mm de largura e espessuras variáveis. Os processos térmicos envolvidos durante a varredura contínua a laser atuaram de modo similar à sinterização em duas etapas. Os tempos de patamares em cada etapa foram dependentes da velocidade e do número de varreduras. A temperatura máxima que se pode atingir no filme espesso, durante cada varredura e para uma potência nominal do laser fixa, foi correlacionada com a densidade relativa. Após sinterizados, os filmes apresentaram homogeneidade microestrutural e uma porosidade aparente de ~7%.The results for sintering of BaTi0.85Zr0.15O3 (BTZ15 thick films, deposited by electrophoresis, using as heat source a CO2 laser are presented. The characteristics of the experimental apparatus were optimized in such a way as to allow the sintering of thick films whose dimensions were up to 70 mm in length, 10 mm in width and variable thicknesses. The related thermal process during the continuous laser scanning acted in a similar way as a two-step sintering. The step times in each stage were dependent on the speed and scan number. The maximum temperature that can be achieved in the thick film, during each scanning, and for a fixed rated laser power, was correlated with the relative density. After sintering the films presented a microstructural homogeneity and an apparent porosity of ~7%.

  14. Thermal stability of (AlSi){sub x}(ZrVTi) intermetallic phases in the Al–Si–Cu–Mg cast alloy with additions of Ti, V, and Zr

    Energy Technology Data Exchange (ETDEWEB)

    Shaha, S.K. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada); Czerwinski, F., E-mail: Frank.Czerwinski@nrcan.gc.ca [CanmetMATERIALS, Natural Resources Canada, 183 Longwood Road South, Hamilton, Ontario L8P 0A5 (Canada); Kasprzak, W. [CanmetMATERIALS, Natural Resources Canada, 183 Longwood Road South, Hamilton, Ontario L8P 0A5 (Canada); Friedman, J.; Chen, D.L. [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3 (Canada)

    2014-11-10

    Highlights: • Al–Si–Cu–Mg alloy was modified by introducing Zr, V, and Ti. • The chemistry of the phases was identified using SEM/EDX. • The crystal lattice parameters of the phases were characterized using EBSD. • To investigate the phase stability, XRD was performed up to 600 °C. • Thermal analysis was done to find out the possible phase transformation reactions. - Abstract: The Al–Si–Cu–Mg cast alloy was modified with additions of Ti–V–Zr to improve the thermal stability of intermetallics at increased temperatures. A combination of electron microscopy, electron backscatter diffraction, and high temperature X-ray diffraction was explored to identify phases and temperatures of their thermal stability. The micro-additions of transition metals led to formation of several (AlSi){sub x}(TiVZr) phases with D0{sub 22}/D0{sub 23} tetragonal crystal structure and different lattice parameters. While Cu and Mg rich phases along with the eutectic Si dissolved at temperatures from 300 to 500 °C, the (AlSi){sub x}(TiVZr) phases were stable up to 696–705 °C which is the beneficial to enhance the high temperature properties. Findings of this study are useful for selecting temperatures during melting and heat treatment of Al–Si alloys with additions of transition metals.

  15. Multi-proxy Reconstructions of the Eastern Equatorial Pacific: Measuring Sr/Ca, Ba/Ca, and Li/Mg in Modern Corals Using ICP-OES

    Science.gov (United States)

    Cheung, A. H.; Cole, J. E.; Vetter, L.; Jimenez, G.; Thompson, D. M.; Tudhope, A. W.

    2017-12-01

    Sea surface temperature (SST) in the Eastern Equatorial Pacific (EEP) exhibits large variability on multiple timescales. These variations are often related to modes of climate variability that exert significant influence on global climate, such as the El Niño Southern Oscillation. However, the short length and sparsity of instrumental data in the EEP limits our ability to discern changes in this region. Geochemical signals in corals can help extend instrumental data further back in time. While δ18O and Sr/Ca are the most commonly analyzed geochemical tracers of SST in corals, they often have site-specific complications. Several alternatives (e.g., Li/Mg) have been proposed to overcome these challenges, but have yet to be applied to long climate records, in part due to the cost and time required to measure these elements. Here, we develop a new method that uses Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) to analyze Li/Mg, Sr/Ca, and Ba/Ca ratios in coral aragonite. We apply this method to two Porites spp. corals collected from the northern Galapagos archipelago (Wolf and Darwin Islands). We specifically assess the fidelity of Li/Mg and Sr/Ca to reconstruct SST, and Ba/Ca to reconstruct upwelling conditions. Our results confirm that both Li/Mg and Sr/Ca track SST. We show that despite analytical noise, downcore reconstructions of Li/Mg have the potential to provide additional information about SST that is not present in reconstructions generated from Sr/Ca alone. Skeletal Ba/Ca shows little relationship with upwelling, perhaps because of the distance of our sites from the center of upwelling in the southern Galapagos. These results demonstrate the potential for analyzing Sr, Li, Ba, Mg simultaneously in corals with a cost- and time- efficient method, which may be applied to coral paleoclimate sites worldwide.

  16. Introduction of BaSnO3 and BaZrO3 artificial pinning centres into 2G HTS wires based on PLD-GdBCO films. Phase I of the industrial R&D programme at SuperOx

    Science.gov (United States)

    Chepikov, V.; Mineev, N.; Degtyarenko, P.; Lee, S.; Petrykin, V.; Ovcharov, A.; Vasiliev, A.; Kaul, A.; Amelichev, V.; Kamenev, A.; Molodyk, A.; Samoilenkov, S.

    2017-12-01

    An industrial R&D programme is ongoing at SuperOx, aimed at improving 2G HTS wire performance in magnetic field. We introduce perovskite artificial pinning centres (APC) into the HTS layer matrix. In contrast to most studies described in the literature, we use the high rate production processing parameters and PLD equipment at SuperOx. This paper reports the results of Phase I of this programme. We fabricated 2G HTS wires by pulsed laser deposition of GdBCO films doped with 6%, 12% and 18% (molar) of BaSnO3 and 6% (molar) of BaZrO3, and compared their performance with an undoped reference sample. The depositions were carried out at production growth rates of 375, 560 and 750 nm min-1 by varying laser pulse frequency. BaZrO3 and BaSnO3 formed columnar semi-coherent nanoinclusions in the GdBCO film matrix. The average transverse size of the nanocolumns was about 5 nm, and their volume density correlated with the dopant concentration. All doped samples exhibited much lower angular anisotropy of in-field critical current and higher lift-factors than the undoped sample. Samples containing 6% BaSnO3 and deposited at the lower growth rates, had higher I c than the undoped sample in the entire temperature range, in a wide range of magnetic field (B//c). The sample containing 6% BaZrO3 had higher I c than the undoped sample at 20 and 4.2 K. These results are an encouraging start of our programme, as they show a positive impact of APC introduced into 2G HTS wires fabricated at production throughput. Phase II work will be focussed on maximising the improvements in specific temperature and field conditions, as well as on the verification of reproducibility of the improvements in production wires.

  17. Microstructure and Mechanical Properties of Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca-x Y Alloys.

    Science.gov (United States)

    Kim, Yong-Ho; Yoo, Hyo-Sang; Son, Hyeon-Taek

    2018-09-01

    Magnesium and its alloys are potential candidates for many automotive and aerospace applications due to their low density and high specific strength. However, the use of magnesium as wrought products is limited because of its poor workability at ambient temperatures. Mg-Li alloys containing 5-11 wt.% Li exhibit a two-phase structure consisting of a α (hcp) Mg-rich phase and a β (bcc) Li-rich phase. Mg-Li alloys with Li content greater than 11 wt.% exhibit a single-phase structure consisting of only the β phase. In the present study, we studied the effects of Y addition on the microstructure and mechanical properties of Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca based alloys. The melt was maintained at 720 °C for 20 min and poured into a mold. Then, the as-cast Mg alloys were homogenized at 350 °C for 4 h and were hot-extruded onto a 4-mm-thick plate with a reduction ratio of 14:1. The as-cast Mg-11Li-6Zn-0.6Zr-0.4Ag-0.2Ca-xY (x 0, 1, 3, and 5 wt.%) alloys were composed of α-Mg, β-Li, γ-Mg2Zn3Li, I-Mg3YZn6, W-Mg3Y2Zn3, and X-Mg12YZn phases. By increasing the Y content from 0 to 5 wt.%, the composition of the W-Mg3Y2Zn3 phase increased. With increasing Y content, from 0 to 1, 3, and 5 wt.%, the average grain size and ultimate tensile of the as-extruded Mg alloys decreased slightly, from 8.4, to 3.62, 3.56, and 3.44 μm and from 228.92 to 215.57, 187.47, and 161.04 MPa, respectively, at room temperature.

  18. A high performance BaZr0.1Ce0.7Y0.2O3-δ-based solid oxide fuel cell with a cobalt-free Ba0.5Sr0.5FeO3-δ–Ce0.8Sm0.2O2-δ composite cathode

    NARCIS (Netherlands)

    Sun, Wenping; Shi, Zhen; Fang, S.; Yan, Litao; Zhu, Zhiwen; Liu, Wei

    2010-01-01

    A cobalt-free Ba0.5Sr0.5FeO3-δ–Ce0.8Sm0.2O2-δ (BSF–SDC) composite is employed as a cathode for an anode-supported proton-conducting solid oxide fuel cells (H-SOFCs) using BaZr0.1Ce0.7Y0.2O3-δ (BZCY) as the electrolyte. The chemical compatibility between BSF and SDC is evaluated. The XRD results show

  19. Dielectric and magnetic properties of xCoFe{sub 2}O{sub 4}–(1 − x)[0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}] composites

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Jyoti [Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Yadav, K.L., E-mail: klyadav35@yahoo.com [Smart Materials Research Laboratory, Department of Physics, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Prakash, Satya [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India)

    2014-12-15

    Highlights: • Spinel–perovskite xCoFe{sub 2}O{sub 4}–(1 − x)(0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}) composites have been synthesized by solid state reaction method. • Two anomalies in dielectric constant have been identified, and the composites show relaxor behaviour. • The magnetic properties of the composites improve with increasing concentration of CoFe{sub 2}O{sub 4}. • Enhanced magnetodielectric effect is found, and magnetoelectric coupling has been confirmed by Δϵ ∼ γM{sup 2} relation. • Optical band gap energy of these composites has been reported for the first time. - Abstract: xCoFe{sub 2}O{sub 4}–(1 − x)(0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3}) composites with x = 0.1, 0.2, 0.3 and 0.4 have been synthesized by solid state reaction method. X-ray diffraction analysis and field emission secondary electron microscopy have been used for structural and morphological analysis, respectively. The spinel CoFe{sub 2}O{sub 4} and perovskite 0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} phase could be identified in the composites. Two anomalies in dielectric constant have been identified: first one is close to ferroelectric to paraelectric phase transition of 0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} ceramic and the other lies near the magnetic transition temperature of CoFe{sub 2}O{sub 4}. There is an increase in magnetocapacitance and saturation magnetization of the composites at room temperature with increase in CoFe{sub 2}O{sub 4} content. The magnetoelectric coupling coefficient (γ) was approximated by Δϵ ∼ γM{sup 2} relation. The optical band gap energy of the composites decreases with increase in CoFe{sub 2}O{sub 4} content.

  20. The degradation and transport mechanism of a Mg-Nd-Zn-Zr stent in rabbit common carotid artery: A 20-month study.

    Science.gov (United States)

    Zhang, Jian; Li, Haiyan; Wang, Wu; Huang, Hua; Pei, Jia; Qu, Haiyun; Yuan, Guangyin; Li, Yongdong

    2018-03-15

    Mg-based stent is a promising candidate of the next generation fully degradable vascular stents. The latest progress includes the CE approval of the Magmaris ® WE43 based drug eluting stent. However, so far, the long term (more than 1 year implantation) in vivo degradation and the physiological effects caused by the degradation products were still unclear. In this study, a 20 month observation was carried out after the bare Mg-Nd-Zn-Zr (abbr. JDBM) stent prototype was implanted into the common carotid artery of New Zealand white rabbit in order to evaluate its safety, efficacy and especially degradation behavior. The degradation of the main second phase Mg 12 Nd was also studied. Results showed that the bare JDBM stent had good safety and efficacy with a complete re-endothelialization within 28 days. The JDBM stent struts were mostly replaced in situ by degradation products in 4 month. The important finding was that the volume and Ca concentration of the degradation products decreased in the long term, eliminating the clinicians' concern of possible vessel calcification. In addition, the alloying elements Mg and Zn in the stent could be safely metabolized as continuous enrichment in any of the main organs were not detected although Nd and Zr showed an abrupt increase in spleen and liver after 1 month implantation. Collectively, the long term in vivo results showed the rapid re-endothelialization of JDBM stent and the long term safety of the degradation products, indicating its great potential as the backbone of the fully degradable vascular stent. Mg-based stent is a promising candidate of the next generation fully degradable stents, especially after the recent market launch of one of its kind (Magmaris). However the fundamental question about the long term degradation and metabolic mechanism of Mg-based stent and its degradation products remain unanswered. We implanted our patented Mg-Nd-Zn-Zr bare stent into the common carotid artery of rabbits and

  1. Comparison of electrochemical corrosion behaviour of MgO and ZrO2 coatings on AM50 magnesium alloy formed by plasma electrolytic oxidation

    International Nuclear Information System (INIS)

    Liang, J.; Srinivasan, P. Bala; Blawert, C.; Dietzel, W.

    2009-01-01

    Two types of PEO coatings were produced on AM50 magnesium alloy using pulsed DC plasma electrolytic oxidation process in an alkaline phosphate and acidic fluozirconate electrolytes, respectively. The phase composition and microstructure of these PEO coatings were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The corrosion behaviour of the coated samples was evaluated by open circuit potential (OCP) measurements, potentiodynamic polarization tests, and electrochemical impedance spectroscopy (EIS) in neutral 0.1 M NaCl solution. The results showed that PEO coating prepared from alkaline phosphate electrolyte consisted of only MgO and on the other hand the one formed in acidic fluozirconate solution was mainly composed of ZrO 2 , MgF 2 . Electrochemical corrosion tests indicated that the phase composition of PEO coating has a significant effect on the deterioration process of coated magnesium alloy in this corrosive environment. The PEO coating that was composed of only MgO suffered from localized corrosion in the 50 h exposure studies, whereas the PEO coating with ZrO 2 compounds showed a much superior stability during the corrosion tests and provided an efficient corrosion protection. The results showed that the preparation of PEO coating with higher chemical stability compounds offers an opportunity to produce layers that could provide better corrosion protection to magnesium alloys.

  2. Elucidating of the microstructure of ZrO2 ceramics with additions of 1200 deg. C heat treated ultrafine MgO powders: Aging at 1420 deg. C

    International Nuclear Information System (INIS)

    Brito-Chaparro, J.A.; Reyes-Rojas, A.; Bocanegra-Bernal, M.H.; Aguilar-Elguezabal, A.; Echeberria, J.

    2007-01-01

    The microstructure and phase transformations in the pressureless sintered composite ZrO 2 with additions of 3.11 wt% high purity and ultrafine MgO powder (9.25 mol% Mg-PSZ) heat treated at 1200 deg. C were investigated by using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction, before and after of eutectoid aging treatment at 1420 deg. C during 4 h. The phases in the as-sintered ceramics were t, c, and m, and was not evident under the experimental conditions of this work, the formation of typical disk-like shape tetragonal precipitates aligned at right angles, meanwhile the microstructure resulting in aged samples was majority monoclinic stable phase showing a banded structure which appear to be twin related. When is used MgO previously heat treated as stabilizer of ZrO 2 , strong differences in SEM microstructures compared to the shown by other investigators in very similar compositions have been found

  3. Electronic structure and O vacancy formation/migration in La0.825(Mg/Ca/Ba)0.125CoO3

    KAUST Repository

    Omotayo Akande, Salawu

    2016-05-05

    The effect of A-site hole doping (Mg2+, Ca2+ or Ba2+) on the electronic and magnetic properties as well as the O vacancy formation and migration in perovskite LaCoO3 is studied using first-principles calculations. All three dopants are found to facilitate O vacancy formation. Substitution of La3+ with Ba2+/Mg2+ yields the lowest O vacancy formation energy for low/intermediate spin Co, implying that not only the structure but also the spin state of Co is a key parameter. Only for low spin Co the ionic radius is correlated with the O migration barrier. Enhanced migration for intermediate spin Co is ascribed to the availability of additional space at the transition state. © CopyrightEPLA, 2016.

  4. Structural, elastic and electronic properties of C14-type Al{sub 2}M (M=Mg, Ca, Sr and Ba) Laves phases

    Energy Technology Data Exchange (ETDEWEB)

    Lishi, Ma; Yonghua, Duan, E-mail: duanyh@kmust.edu.cn; Runyue, Li

    2017-02-15

    The structural and mechanical properties, Debye temperatures and anisotropic sound velocities of the Laves phases Al{sub 2}M (M=Mg, Ca, Sr and Ba) with C14-type structure were investigated using the first-principles corresponding calculations. The corresponding calculated structural parameters and formation enthalpies are in good agreement with the available theoretical values, and Al{sub 2}Ca has the best phase stability. The mechanical properties, including elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, and Poisson ratio ν, were deduced within the Voigt-Reuss-Hill approximation. The brittleness and ductility were estimated by the values of Poisson ratio, B/G and Cauchy pressure. Moreover, the elastic anisotropy was investigated by calculating and discussing several anisotropy indexes. Finally, the electronic structures were used to illustrate the bonding characteristics of C14-Al{sub 2}M (M=Mg, Ca, Sr and Ba) phases.

  5. Spectroscopic and thermal degradation behavior of Mg(II, Ca(II, Ba(II and Sr(II complexes with paracetamol drug

    Directory of Open Access Journals (Sweden)

    Moamen S. Refat

    2017-05-01

    Full Text Available Complexes of Mg(II, Ca(II, Ba(II and Sr(II with paracetamol drug were synthesized and characterized by elemental analysis, conductivity, UV–Vis, IR, and 1H NMR spectroscopy and thermal analysis, as well as screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as paracetamol behaves as a neutral bidentate ligand coordinated to the metal ions via the lone pair of electrons of nitrogen and carbonyl-O atoms of the amide group. From the microanalytical data, the stoichiometry of the complexes reacts with Mg(II, Ca(II, Ba(II and Sr(II by molar ratios (2:1 (paracetamol:metal ion. The thermal behavior (TG/DTG of the complexes was studied. The ligand and their metal complexes were screened against both of antibacterial and fungicidal activities.

  6. Infrared emissions in MgSrAl10O17:Er3+ phosphor co-doped with Yb3+/Ba2+/Ca2+ obtained by solution combustion route

    International Nuclear Information System (INIS)

    Singh, Vijay; Kumar Rai, Vineet; Venkatramu, V.; Chakradhar, R.P.S.; Hwan Kim, Sang

    2013-01-01

    An intense infrared emitting MgSrAl 10 O 17 :Er 3+ phosphor co-doped with Yb 3+ , Ba 2+ and Ca 2+ ions have been prepared by a solution combustion method. Phase purity of the derived compounds was confirmed by X-ray diffraction technique. The vibrational properties of MgSrAl 10 O 17 phosphor was studied by Fourier transform infrared spectroscopy. The broad and strong infrared emission of Er 3+ ions at around 1.53 μm was observed upon excitation at 980 nm. Effect of co-doping with the Yb 3+ , Ba 2+ and Ca 2+ ions on the infrared luminescence intensity of Er 3+ ions and the mechanism responsible for the variation in the infrared intensity have been discussed. The results indicate that these materials may be suitable for the optical telecommunication window and wavelength division multiplexing applications. - Highlights: ► The hexagonal phase of MgSrAl 10 O 17 could be obtained by the low temperature combustion method. ► The broad and strong infrared emission of Er 3+ ions at around 1.53 μm was observed. ► Effect of co-doping with the Yb 3+ , Ba 2+ and Ca 2+ ions on the infrared luminescence intensity of Er 3+ were reported.

  7. Temperature dependence of partial conductivities of the BaZr0.7Ce0.2Y0.1O3-δ proton conductor

    Science.gov (United States)

    Heras-Juaristi, Gemma; Pérez-Coll, Domingo; Mather, Glenn C.

    2017-10-01

    Partial conductivities are presented for BaZr0.7Ce0.2Y0.1O3-δ, an important proton conductor for protonic-ceramic fuel cells and membrane reactors. Atmospheric dependencies of impedance performed in humidified and dry O2, air, N2 and H2(10%)/N2(90%) in the temperature range 300-900 °C, supported by the modified emf method, confirm significant electron-hole and protonic contributions to transport. For very reducing and wet atmospheres, the conductivity is predominantly ionic, with a higher participation of protons with decreasing temperature and increasing water-vapour partial pressure (pH2O). From moderately reducing conditions of wet N2 to wet O2, however, the conductivity is considerably influenced by electron holes as revealed by a significant dependence of total conductivity on oxygen partial pressure (pO2). With higher pH2O, proton transport increases, with a concomitant decrease of holes and oxygen vacancies. However, the effect of pH2O is also influenced by temperature, with a greater protonic contribution at both lower temperature and pO2. Values of proton transport number tH ≈ 0.63 and electronic transport number th ≈ 0.37 are obtained at 600 °C for pH2O = 0.022 atm and pO2 = 0.2 atm, whereas tH ≈ 0.95 and th ≈ 0.05 for pO2 = 10-5 atm. A hydration enthalpy of -109 kJ mol-1 is obtained in the range 600-900 °C.

  8. Effect of rare earth doping on optical and spectroscopic characteristics of BaZrO3:Eu3+,Tb3+ perovskites

    Science.gov (United States)

    Katyayan, Shambhavi; Agrawal, Sadhana

    2018-06-01

    This paper reports structural investigations of rare earth doped BaZrO3 phosphors synthesized by Solid state reaction technique with varying concentrations of Eu3+ and Tb3+ from 0 mol% to 2 mol%. The synthesized phosphors show enhanced variable emissions in the visible region corresponding to different hypersensitive electronic transitions of Eu3+ and Tb3+ ions. With cubic structure confirmed in XRD analysis, the FESEM images show uniform grain connectivity and homogeneity of prepared samples. The TEM micrographs of the synthesized phosphors show agglomerated irregular structures. The synthesized phosphors were also subjected to FTIR, Raman, EDXS analysis along with studies of thermoluminescent and photoluminescent characteristics. On subjecting to 229 nm (UV) excitation, the phosphors show enhanced PL emissions corresponding to 571 nm (5D0-7F0), 591 nm (5D0-7F1), 615 nm (5D0-7F2) and 678 nm (5D0-7F4) hypersensitive transitions of Eu3+ ions and emission peaks at 489 nm (5D4-7F6), 539 nm (5D4-7F5), 589 nm (5D4-7F4) and 632 nm (5D4-7F3) accounting for electronic transitions of Tb3+ ions respectively. The computed average PL lifetime is 14.014 s. In the TL analysis, the second order of kinetics with the activation energy varying from 5.0 × 10‑1 eV to 6.6 × 10‑1 eV is reported. The maximum TL lifetime is estimated as 19.4985 min in the TL lifetime analysis.

  9. Experimental evidence of hydrogen–oxygen decoupled diffusion into BaZr0.6Ce0.25Y0.15O3−δ

    International Nuclear Information System (INIS)

    Lim, D.-K.; Im, H.-N.; Jeon, S.-Y.; Park, J.-Y.; Song, S.-J.

    2013-01-01

    The electrical properties of BaZr 0.6 Ce 0.25 Y 0.15 O 3−δ (BZCY) were studied as a function of both oxygen partial pressure (-2.65⩽log(P O 2 atm -1 )⩽-0.62) and water vapor activity (-3.33⩽log(P H 2 O atm -1 ⩽-1.3)) in the temperature range of 973–1073 K. The total conductivity slightly increased in reducing atmospheres with increasing water vapor activity because of the relative contribution to the total conductivity by the redox reaction at the given thermodynamic conditions. The partial conductivities of protons, holes and oxygen vacancies were successfully calculated, and the activation energy determined for proton transport was 0.3 ± 0.1 eV. The chemical diffusivity of oxygen at a fixed water vapor activity, D ∼ vO , could only be evaluated from Fick’s second law during oxidation and reduction at the fixed water vapor activity. However, twofold nonmonotonic conductivity relaxation behaviors were clearly confirmed in the temperature range investigated during hydration/dehydration. If P O 2 represents the fixed oxygen partial pressure, D ∼ iH is the hydrogen chemical diffusivity at P O 2 and D ∼ vH is the oxygen chemical diffusivity at P O 2 , it was observed that D ∼ iH >D ∼ vH at all experimental conditions, suggesting that the hydrogen chemical diffusion is always faster than oxygen on hydration/dehydration in the temperature range studied

  10. Role of A-site Ca and B-site Zr substitution in BaTiO3 lead-free compounds: Combined experimental and first principles density functional theoretical studies

    Science.gov (United States)

    Keswani, Bhavna C.; Saraf, Deepashri; Patil, S. I.; Kshirsagar, Anjali; James, A. R.; Kolekar, Y. D.; Ramana, C. V.

    2018-05-01

    We report on the combined experimental and theoretical simulation results of lead-free ferroelectrics, Ba(1-x)CaxTiO3 (x = 0.0-0.3) and BaTi(1-y)ZryO3 (y = 0.0-0.2), synthesized by standard solid state reaction method. First principles density functional calculations are used to investigate the electronic structure, dynamical charges, and spontaneous polarization of these compounds. In addition, the structural, ferroelectric, piezoelectric, and dielectric properties are studied using extensive experiments. The X-ray diffraction and temperature dependent Raman spectroscopy studies indicate that the calcium (Ca) substituted compositions exhibit a single phase crystal structure, while zirconium (Zr) substituted compositions are biphasic. The scanning electron micrographs reveal the uniform and highly dense microstructure. The presence of polarization-electric field and strain-electric field hysteresis loops confirms the ferroelectric and piezoelectric nature of all the compositions. Our results demonstrate higher values for polarization, percentage strain, piezoelectric coefficients, and electrostrictive coefficient compared to those existing in the literature. For smaller substitutions of Ca and Zr in BaTiO3, a direct piezoelectric coefficient (d33) is enhanced, while the highest d33 value (˜300 pC/N) is observed for BaTi0.96Zr0.04O3 due to the biphasic ferroelectric behavior. Calculation of Born effective charges indicates that doping with Ca or Zr increases the dynamical charges on Ti as well as on O and decreases the dynamical charge on Ba. An increase in the dynamical charges on Ti and O is ascribed to the increase in covalency of Ti-O bond that reduces the polarizability of the crystal. A broader range of temperatures is demonstrated to realize the stable phase in the Ca substituted compounds. The results indicate enhancement in the temperature range of applicability of these compounds for device applications. The combined theoretical and experimental study is

  11. Seasonal Trends and Inter-Individual Heterogeneity: A multi-species record of Mg, Sr, Ba, & Mn in Planktic Foraminifera from the Modern Cariaco Basin

    Science.gov (United States)

    Davis, C. V.; Thunell, R.; Astor, Y. M.

    2017-12-01

    The trace element to calcium ratios (TE/Ca) of planktic foraminifera shells are a valuable tool for paleoceanographic reconstructions, and represent a combination of environmental, ecological and biological signals. We present here a three-year record (2010-2013) of TE/Ca (Mg, Sr, Ba, Mn) from four species of foraminifera (Orbulina universa, Globigerina ruber, Globigerinella siphonifera, and Globorotalia menardii) collected by plankton tow in the modern Cariaco basin. Each tow is paired with in situ measurements of water column properties, allowing a direct comparison between shell geochemistry and calcification environment. A combination of Laser Ablation and solution ICP-MS analyses are used to document seasonality, primarily due to the alternating influence of wind-driven coastal upwelling and riverine inputs, in shell TE/Ca. Individual shell data further allows for the quantification of trace element heterogeneity among individual shells within single tows. All TE/Ca ratios vary temporally and show inter-individual variability within single tows. The spread in TE/Ca differs between element and species, with Mg/Ca ratios being the most variable. Despite this, Mg/Ca still tracks temperature changes in G. ruber, O. universa, and G. menardii, with G. ruber most closely reproducing sea surface temperature. Some species show chamber-to-chamber differences in trace element ratios, with G. ruber Mg/Ca and Ba/Ca decreasing in younger chambers (but not other elements) and Mg/Ca, Mn/Ca and Ba/Ca decreasing in younger chambers in G. siphonifera. We find the original Mn/Ca to be variable both temporally and between species, with G. menardii in some samples having extremely high ratios (100 μmol/mol). Assessing seasonal trends and environmental drivers of TE/Ca variability and quantifying the extent of inter-individual heterogeneity in these species will inform the use of their shells as geochemical proxies.

  12. Study of the structural and electrical behavior of Bi(Mg,TiO3 modified (Ba,CaTiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Md. Kashif Shamim

    2016-12-01

    Full Text Available The ability of BaTiO3 to form solid solutions with different dopants (both iso- and aliovalent makes it versatile for various applications. In the present study, (Ba,CaTiO3 (BCT is modified with Bi(MgTiO3 (BMT in search for new lead-free ferroelectric material and improve their properties. For this purpose, BCT acts as a main base material and BMT acts as a modifier to fabricate a multifunctional material. In this study, we report the structural and electrical properties of lead free piezo-ceramics (1−x(Ba0.8Ca0.2TiO3–xBi(Mg0.5Ti0.5O3 with x=0.2, 0.4, 0.5 prepared by solid-state sintering technique. Single perovskite phase with tetragonal structure is obtained for all the compositions, which is reconfirmed by the Raman Spectroscopic study. Dielectric study confirm the temperature stable behavior of the dielectric permittivity values above 300∘C. The dielectric constant value decreases with increase in BMT doping content. Impedance Spectroscopic study confirms non-Debye type dielectric relaxation in the specimen. The Nyquist plot and conductivity studies show the negative temperature coefficient of resistance behavior (NTCR of the samples.

  13. Effects of Er3+ and Pr3+ Substitution on Structural, Dielectric, Ferroelectric and Photoluminescence Properties of the BaTi0.9Zr0.1O3 Ceramic

    Science.gov (United States)

    Zouari, I.; Sassi, Z.; Seveyrat, L.; Perrin, V.; Zghal, S.; Abdelmoula, N.; Lebrun, L.; Khemakhem, H.

    2017-07-01

    BaTi0.9Zr0.1O3 (BZT), Ba1- x Ln2 x/3□ x/3Ti0.9Zr0.1O3 (with x = 0.5% mol and Ln = Er3+) (BZT-Er) and Ba1- x Ln2 x/3□ x/3Ti0.9Zr0.1O3 (with x = 0.5% mol and Ln = Pr3+) (BZT-Pr) were prepared via the conventional solid-state reaction method. X-ray diffraction showed that all these ceramics were in the single perovskite phase at room temperature (RT). The temperature dependence of dielectric behavior was investigated in the temperature range 25-225°C and exhibited a classical ferroelectric behavior. A slight decrease of the Curie temperature ( T C) with Pr3+ and Er3+ substitution was observed in addition to an increase in the maximum dielectric permittivity ( \\varepsilon_{r {max} }^' }} ) of about 40% for the BZT-Er. At RT, the ferroelectric and piezoelectric coefficients were decreased for BZT-Pr, but were maintained for BZT-Er with a piezoelectric coefficient ( d 33) of 185 pC/N, a planar electromechanical coupling factor of 30%, and a remanent polarization of 11.6 μC/cm2. The Raman bands as a function of temperature confirmed the paraelectric-ferroelectric phase transition of all those ceramics. The photoluminescence spectra showed that strong red (615 nm and 645 nm) and bright green (523 nm and 545 nm) emission bands were obtained, under excitation by laser at 488 nm at RT, for BZT-Pr and BZT-Er, respectively. These multifunctional materials showed a significant technological promise in coupling device applications.

  14. Air Plasma-Sprayed La2Zr2O7-SrZrO3 Composite Thermal Barrier Coating Subjected to CaO-MgO-Al2O3-SiO2 (CMAS)

    Science.gov (United States)

    Cai, Lili; Ma, Wen; Ma, Bole; Guo, Feng; Chen, Weidong; Dong, Hongying; Shuang, Yingchai

    2017-08-01

    La2Zr2O7-SrZrO3 composite thermal barrier coatings (TBCs) were prepared by air plasma spray (APS). The La2Zr2O7-SrZrO3 composite TBCs covered with calcium-magnesium-aluminum-silicate (CMAS) powder, as well as the powder mixture of CMAS and spray-dried La2Zr2O7-SrZrO3 composite powder, were heat-treated at 1250 °C in air for 1, 4, 8, and 12 h. The phase constituents and microstructures of the reaction products were characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. Experimental results showed that the La2Zr2O7-SrZrO3 composite TBCs had higher CMAS resistance than 8YSZ coating. A dense new layer developed between CMAS and La2Zr2O7-SrZrO3 composite TBCs during interaction, and this new layer consisted mostly of apatite (Ca2La8(SiO4)6O2) and c-ZrO2. The newly developed layer effectively protected the La2Zr2O7-SrZrO3 composite TBCs from further CMAS attack.

  15. Anisotropy of the Irreversibility Field for Zr-doped (Y,Gd)Ba2<\\sub>Cu3<\\sub>O<7-x<\\sub> Thin Films up to 45 T

    Energy Technology Data Exchange (ETDEWEB)

    Tarantini, C. [Florida State University; Jaroszynski, J. [Florida State University; Kametani, F. [Florida State University; Zuev, Yuri L [ORNL; Gurevich, A. [Florida State University; Chen, Y [SuperPower Incorporated, Schenectady, New York; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York; Larbalestier, D. C. [Florida State University; Christen, David K [ORNL

    2011-01-01

    The anisotropic irreversibility fieldBIrr of twoYBa2Cu3O7 x thin films dopedwith additional rare earth (RE)= (Gd, Y) and Zr and containing strong correlated pins (splayed BaZrO3 nanorods and RE2O3 anoprecipitates) has been measured over a very broad range up to 45 T at temperatures 56 K < T < Tc. We found that the experimental angular dependence of BIrr ( ) does not follow the mass anisotropy scaling BIrr ( ) = BIrr (0)(cos2 + 2 sin2 ) 1/2, where = (mc/mab)1/2 = 5 6 for the RE-doped Ba2Cu3O7 x (REBCO) crystals, mab and mc are the effective masses along the ab plane and the c-axis, respectively, and is the angle between B and the c-axis. For B parallel to the ab planes and to the c-axis correlated pinning strongly enhances BIrr , while at intermediate angles, BIrr ( ) follows the scaling behavior BIrr ( ) (cos2 + 2 RP sin2 ) 1/2 with the effective anisotropy factor RP 3 significantly smaller than the ass anisotropy would suggest. In spite of the strong effects of c-axis BaZrO3 nanorods, we found even greater enhancements of BIrr for fields along the ab planes than for fields parallel to the c-axis, as well as different temperature dependences of the correlated pinning contributions to BIrr for B//ab and B//c. Our results show that the dense and strong pins, which can now be incorporated into REBCO thin films in a controlled way, exert major and diverse effects on the measured vortex pinning anisotropy and the irreversibility field over wide ranges of B and T . In particular, we show that the relative contribution of correlated pinning to BIrr for B//c increases as the temperature increases due to the suppression of thermal fluctuations of vortices by splayed distribution of BaZrO3 nanorods.

  16. Effect of porosity on the ferroelectric and piezoelectric properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 piezoelectric ceramics

    DEFF Research Database (Denmark)

    Yap, Emily W.; Glaum, Julia; Oddershede, Jette

    2018-01-01

    The ferroelectric and piezoelectric properties of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT) ceramics were measured as a function of porosity. Porous BCZT ceramics were fabricated using the sacrificial fugitive technique. Two different pore morphologies were induced by adding polymeric microspheres...... and fibres as the pore-forming agents. Increasing porosity led to decreasing ferroelectric and piezoelectric properties due to a reduction of polarisable BCZT ceramic available. With the benefit of being a lead-free piezoelectric material, porous BCZT ceramics may be considered for acoustic impedance...

  17. Effect of heat treatment on the optical properties of perovskite BaZr0.5Ce0.3Y0.2O3-δ ceramic prepared by spark plasma sintering

    Science.gov (United States)

    Xing, Bohang; Cheng, Zhi; Wang, Cao; Zhao, Zhe

    2017-09-01

    The effect of heat treatment on the in-line transmittance of BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) ceramics prepared by spark plasma sintering method was investigated. The loss of Ba in transparent BZCY532 ceramics is the key reason for the loss of transmittance during the annealing process. This problem can be effectively alleviated by using a powder bed of BZCY532. Heat treatment atmospheres, wet air and dry air, were also found to be critical for obtaining high quality transparent ceramics. A highly transparent BZCY532 ceramic with the in-line transmittance (Tin) of 71.4% at 2000 nm can be obtained by using SPS method followed by an annealing in powder bed at 1500 °C in wet air.

  18. Effect of heat treatment on corrosion behavior of low pressure sand cast Mg-10Gd-3Y-0.5Zr alloys

    Directory of Open Access Journals (Sweden)

    Qian-qian Wu

    2016-07-01

    Full Text Available The corrosion behaviors of low-pressure sand cast Mg-10Gd-3Y-0.5Zr (wt.% alloys in as-cast, solution treated (T4 and aged (T6 conditions were studied by means of immersion test and electrochemical measurements in 5wt.% NaCl solution saturated with Mg(OH2. It was observed that the corrosion rate in the T4 condition was lower than that of the as-cast and T6 conditions by both sand casting and permanent mold casting with the same order of as-cast>T6>T4; while the corrosion resistance of the permanent mold casting is superior to the sand casting. The morphologies of the corrosion products are similar porous structures consisting of tiny erect flakes perpendicular to the corroded surface of the alloy, irrespective of the heat treatment conditions. Especially, the corrosion film in T4 condition is more compact than that in the other two conditions. In addition, the severer corrosion happening to the as-cast condition is correlated with the galvanic corrosion between the matrix and the eutectic compounds; while improved corrosion resistance for the T4 and T6 conditions is ascribed to the dissolution of the secondary eutectic compounds. The measured corrosion current densities of Mg-10Gd-3Y-0.5Zr alloys in as-cast, T4, and T6 conditions are 36 μA·cm-2, 10 μA·cm-2, and 33 μA·cm-2, respectively. The proposed equivalent circuit [Rs(CPE1(Rt(RfCPE2] by Zview software matches well with the tested electrochemical impedance spectra (EIS data.

  19. Effect of Mg(2+), Ca(2+), Sr(2+) and Ba(2+) metal ions on the antifungal activity of ZnO nanoparticles tested against Candida albicans.

    Science.gov (United States)

    Haja Hameed, Abdulrahman Syedahamed; Karthikeyan, Chandrasekaran; Senthil Kumar, Venugopal; Kumaresan, Subramanian; Sasikumar, Seemaisamy

    2015-01-01

    The antifungal ability of pure and alkaline metal ion (Mg(2+), Ca(2+), Sr(2+) and Ba(2+)) doped ZnO nanoparticles (NPs) prepared by the co-precipitation method was tested against the pathogenic yeast, Candida albicans (C. albicans), and the results showed that the Mg-doped ZnO NPs possessed greater effect than the other alkaline metal ion doped ZnO NPs. The impact of the concentration of Mg doped ZnO sample on the growth of C. albicans was also studied. The Minimal Fungicidal Concentration (MFC) of the Mg doped ZnO NPs was found to be 2000 μg/ml for which the growth of C. albicans was completely inhibited. The ZnO:Mg sample (1.5mg/ml) with various concentrations of histidine reduced the fungicidal effect of the nanoparticles against C. albicans, which was deliberately explained by the role of ROS. The ZnO:Mg sample added with 5mM of histidine scavenged the ample amount of generated ROS effectively. The binding of the NPs with fungi was observed by their FESEM images and their electrostatic attraction is confirmed by the zeta potential measurement. Copyright © 2015. Published by Elsevier B.V.

  20. Effect of composition on thermal conductivity of MgO–Nd2Zr2O7 composites for inert matrix materials

    International Nuclear Information System (INIS)

    Nelson, A.T.; Giachino, M.M.; Nino, J.C.; McClellan, K.J.

    2014-01-01

    Inert matrix fuels based on magnesium oxide (MgO) as the inert phase have been of historic interest due to its high thermal conductivity. Minor actinide-bearing phases possessing an A 2 B 2 O 7 pyrochlore structure are also believed to contain a range of favorable attributes, suggesting a possible pairing with MgO to yield a high performance inert matrix fuel. The thermal diffusivity, heat capacity, and thermal expansion of MgO–Nd 2 Zr 2 O 7 composites were measured from room temperature to 1273 K, where the MgO phase content was varied from 40 to 70 volume percent. The thermal conductivity of each composition was calculated using these results and then compared to widely employed methods to approximate the thermal conductivity of composite materials based upon the properties of the constituent phases. Results suggest that use of either a rule of mixtures or geometric mean approximation for the thermal conductivity of composite systems such as this one would be subject to significant uncertainties when the constituent properties widely differ. A sigmoidal average of the upper and lower Hashin–Shtrikman bounds was found to be in good agreement with the thermal conductivity of the composites as determined experimentally

  1. Sinterización de vidrios del sistema RO-BaO-SiO2 (R= Mg, Zn para el sellado de SOFC

    Directory of Open Access Journals (Sweden)

    Lara, C.

    2007-04-01

    Full Text Available Glasses of composition 50SiO2•30BaO•20ZnO, mol% (Zn1.5-50, 55SiO2•27BaO•18ZnO, mol% (Zn1.5-55, and 55SiO2•27BaO•18MgO, mol% (Mg1.5-55 present good properties for application in sealing planar solid oxide fuel cells with an intermediate temperature of operation (850ºC (IT-SOFC. The sealing must take place on sintering the glass powder during the start-up of the cell between 700 and 850ºC. Further treatment at the operation temperature provokes the crystallisation of barium silicates with the subsequent increase of viscosity and seal rigidity. This work is a study of the sintering behaviour of these glasses using different heating rates and particle-size distributions of the glass powder in order to obtain dense and homogeneous seals. The glasses Zn1.5-55 and Mg1.5-55 with a particle size less than 63 μm heated at 2ºC/min reach final densities higher than 95%. A good agreement has been demonstrated between the measured sintering kinetics and those predicted with the sintering model of Clusters formation in the absence of concurrent crystallisation.

    Los vidrios de composición molar 50SiO2•30BaO•20ZnO (Zn1.5-50, 55SiO2•27BaO•18ZnO (Zn1.5-55, y 55SiO2•27BaO•18MgO (Mg1.5-55 presentan buenas propiedades para su aplicación en el sellado de pilas de combustible de óxido sólido de configuración plana y temperatura de operación intermedia (850ºC (IT-SOFC. El sellado debe producirse a través de la sinterización del polvo de vidrio, durante el arranque de la pila, a temperaturas entre 700 y 850ºC. El tratamiento posterior a la temperatura de operación da lugar a la cristalización de silicatos de bario con el consiguiente aumento de viscosidad y rigidez del sello. Este trabajo es un estudio del comportamiento de sinterización de estos vidrios utilizando diferentes velocidades de calentamiento y distribuciones de tamaño de partícula del polvo de vidrio, para la obtención final de sellos densos y homog

  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. Mechanism of Dynamic Recrystallization and Evolution of Texture in the Hot Working Domains of the Processing Map for Mg-4Al-2Ba-2Ca Alloy

    Directory of Open Access Journals (Sweden)

    Kalidass Suresh

    2017-12-01

    Full Text Available The occurrence of dynamic recrystallization (DRX and its effect on the evolution of texture during uniaxial compression of a creep-resistant cast Mg-4Al-2Ba-2Ca alloy in the temperature range of 260–500 °C and strain rate range of 0.0003–10 s−1 has been studied using transmission electron microscopy and electron backscatter diffraction techniques with a view to understand its mechanism. For this purpose, a processing map has been developed for this alloy, which revealed two domains of DRX in the temperature and strain rate ranges of: (1 300–390 °C/0.0003–0.001 s−1 and (2 400–500 °C/0.0003–0.5 s−1. In Domain 1, DRX occurs by basal slip and recovery by dislocation climb, as indicated by the presence of planar slip bands and high dislocation density leading to tilt boundary formation and a low-intensity basal texture. On the other hand, DRX in Domain 2 occurs by second order pyramidal slip and recovery by cross-slip since the microstructure revealed tangled dislocation structure with twist boundaries and randomized texture. The high volume content of intermetallic phases Mg21Al3Ba2 and (Al,Mg2Ca eutectic phase is considered to be responsible for the observed hot deformation behavior.

  4. Effect of concurrent Mg/Nb-doping on dielectric properties of Ba0.45Sr0.55TiO3 thin films

    Science.gov (United States)

    Alema, Fikadu; Reich, Michael; Reinholz, Aaron; Pokhodnya, Konstantin

    2013-08-01

    Composition, microstructure, and dielectric properties of undoped and Ba(Mg1/3Nb2/3)O3 (BMN) doped Ba0.45Sr0.55TiO3 (BST) thin films deposited via rf. magnetron sputtering on platinized alumina substrates have been investigated. The analysis of microstructure has shown that despite the sizable effect of doping on the residual stress, the latter is partially compensated by the thermal expansion coefficient mismatch, and its influence on the BST film crystal structure is insignificant. It was revealed that BMN doped film demonstrated an average (over 2000 devices) of 52.5% tunability at 640 kV/cm, which is ˜8% lower than the value for the undoped film. This drop is associated with the presence of Mg ions in BMN; however, the effect of Mg doping is partially compensated by that of Nb ions. The decrease in grain size upon doping may also contribute to the tunability drop. Doping with BMN allows achievement of a compensation concentration yielding no free carriers and resulting in significant leakage current reduction when compared with the undoped film. In addition, the presence of large amounts of empty shallow traps related to NbTi• allows localizing free carriers injected from the contacts thus extending the device control voltage substantially above 10 V.

  5. Far-infrared spectroscopy in ordered and disordered BaMg1/3Nb2/3O3 microwave ceramics

    Science.gov (United States)

    Dias, Anderson; Moreira, Roberto Luiz

    2003-09-01

    Ba(Mg1/3Nb2/3)O3 ceramics with suitable microwave dielectric properties for application in wireless communications and information access technologies were studied by far-infrared spectroscopy. Samples with different B-site ordering degrees, obtained by hydrothermal synthesis followed by sintering at various temperatures, were employed in this investigation. The sixteen infrared modes predicted by factor-group analysis were observed and adjusted according to a four-parameter semiquantum model. The dispersion parameters were determined in order to calculate the real part of the dielectric permittivity and the quality factors associated with the dielectric losses in the microwave region. The materials exhibited increasing ɛ0 and Q values up to 1100 °C, increasing more substantially when the temperature attained 1300 °C. The B-site ordering played an important role on this behavior along with the microstructural evolution above 1100 °C (grain growth), which also increased the phonon lifetime and contributed to the Q improvement. Kramers-Kronig analyses were carried out in all experimental data and the contributions of the main optical polar modes to the dielectric and microwave properties were carefully analyzed in order to identify and attribute the Ba-BO3 external mode, the inner modes related to the O-Mg-O and O-Nb-O bending vibrations, and the stretching modes of each MgO6 and NbO6 octahedron.

  6. Spectroscopic and thermal degradation behavior of Mg(II), Ca(II), Ba(II) and Sr(II) complexes with paracetamol drug

    OpenAIRE

    Moamen S. Refat; Gehad G. Mohamed; Mohamed Y. El-Sayed; Hamada M.A. Killa; Hammad Fetooh

    2017-01-01

    Complexes of Mg(II), Ca(II), Ba(II) and Sr(II) with paracetamol drug were synthesized and characterized by elemental analysis, conductivity, UV–Vis, IR, and 1H NMR spectroscopy and thermal analysis, as well as screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as paracetamol behaves as a neutral bidentate ligand coordinated to the metal ions via the lone pair of electrons of nitrogen and carbonyl-O atoms of the amide group. From the microanalytical dat...

  7. Raman spectroscopy of DNA-metal complexes. I. Interactions and conformational effects of the divalent cations: Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd

    OpenAIRE

    Duguid, J.; Bloomfield, V.A.; Benevides, J.; Thomas Jr, G.J.

    1993-01-01

    Interactions of divalent metal cations (Mg2+, Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) with DNA have been investigated by laser Raman spectroscopy. Both genomic calf-thymus DNA (> 23 kilobase pairs) and mononucleosomal fragments (160 base pairs) were employed as targets of metal interaction in solutions containing 5 weight-% DNA and metal:phosphate molar ratios of 0.6:1. Raman difference spectra reveal that transition metal cations (Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) ind...

  8. Correlation of microstructures, aging treatments, and properties of Al-Li-Cu-Mg-Zr I/M and P/M alloys

    International Nuclear Information System (INIS)

    Kar, R.J.; Bohlen, J.W.; Chanani, G.R.

    1984-01-01

    In a Northrop research program on Al-Li based alloys, the microstructures and heat treatment characteristics of two Al-Li-Cu-Mg-Zr alloys, one I/M (ingot metallurgy) and one P/M (powder metallurgy), were examined and correlated with properties obtained. Prior work had shown that this alloy system has a high payoff potential for aircraft applications. Following solution-heat-treatments, the artificial aging response of these alloys was determined, using hardness measurements. Microstructural characterization of these alloys was carried out using optical metallography and transmission electron microscopy (TEM) and phases were identified using X-ray methods, electron diffraction and Auger electron spectroscopy. The tensile and fracture toughness properties of the alloys were determined for selected tempers. Scanning electron microscopic (SEM) fracture examination was carried out on fractured tensile and fracture toughness coupons. The mechanical properties obtained and fracture behavior observed were correlated with significant microstructural features. 16 references

  9. Modification of the temperatures of phase transformations of alumina by the insertion of MgO and ZrO2

    International Nuclear Information System (INIS)

    Rosario, D.C.C.; Gouvea, D.

    2010-01-01

    Due to the stability and diversity of alumina polymorph, it becomes a very interesting material for stability studies considering changes in surface energy. The gamma phase is metastable and extensively studied due its properties and applications in catalysis. Studies have been conducted with the purpose to changing the transformation temperature gamma-alpha, considering modification on surface energy of nanomaterials. Thereby, this study aims to understand the phase transition amorphous-gamma of alumina by inserting additives (MgO and ZrO 2 ), taking into account the effects on specific surface area and surface energy. The assessment of stability was performed by analysis of DTA, X-ray diffraction and measurements of specific surface area, showing an increase in surface area with additives concentration, followed by a decrease of surface energy, then stability of gamma phase. (author)

  10. Local and average structures of 0.7Pb(Mg1/3Nb2/3)O3 - 0.3PbZrO3

    International Nuclear Information System (INIS)

    Krishna, P.S.R.; Shinde, A.B.; Narasimhan, S.L.; Tiwari, V.S.; Singh, G.

    2005-01-01

    The local and average structure of 0.7Pb(Mg 1/3 Nb 2/3 )O 3 - 0.3PbZrO 3 (PMN-PZ) was studied by neutron diffraction. The Rietveld refinement was carried out to determine the average, long-range crystallographic structure, while the pair density function (PDF) analysis was used in studying the local atomic structure. The local atomic structure determined by the PDF analysis, was found to be significantly different from the average crystallographic structure determined by the Rietveld analysis. These results show that the conflict between the local structural preference and the average structure is not limited to relax or ferroelectric oxides, but may be widely prevalent in mixed-ion ferroelectrics. (author)

  11. LaCoO3: Promising cathode material for protonic ceramic fuel cells based on a BaCe0.2Zr0.7Y0.1O3−δ electrolyte

    DEFF Research Database (Denmark)

    Ricote, Sandrine; Bonanos, Nikolaos; Lenrick, Filip

    2012-01-01

    Symmetric cells (cathode/electrolyte/cathode) were prepared using BaCe0.2Zr0.7Y0.1O3−δ (BCZY27) as proton conducting electrolyte and LaCoO3 (LC) infiltrated into a porous BCZY27 backbone as cathode. Single phased LC was formed after annealing in air at 600 °C for 2 h. Scanning electron micrograph...... that the presence of oxide ion conduction in the cathode material is not necessary for good performance.......Symmetric cells (cathode/electrolyte/cathode) were prepared using BaCe0.2Zr0.7Y0.1O3−δ (BCZY27) as proton conducting electrolyte and LaCoO3 (LC) infiltrated into a porous BCZY27 backbone as cathode. Single phased LC was formed after annealing in air at 600 °C for 2 h. Scanning electron micrographs...... showed the presence of the infiltrated LC in the full cathode depth. Transmission electron micrographs revealed LC grains (60–80 nm) covering partly the BCZY27 grains (200 nm–1 μm). Impedance spectra were recorded at 500 °C and 600 °C, varying the oxygen partial pressure and the water vapour pressure...

  12. Synthesis, structural and electrical studies of Ba1-xSrxCe0.65Zr0.25Pr0.1O3-δ electrolyte materials for solid oxide fuel cells

    Science.gov (United States)

    Madhuri Sailaja, J.; Murali, N.; Margarette, S. J.; Mammo, Tulu Wegayehu; Veeraiah, V.

    2018-03-01

    This paper is discussed Sr doping effect on the microstructure, chemical stability and conductivity of Ba1-xSrxCe0.65Zr0.25Pr0.1O3-δ (0 ≤ x ≤ 0.2) electrolyte prepared by sol-gel method. The lattice constants and unit cell volumes are found to decrease as Sr atomic percentage increased in accordance with the Vegard law, confirming the formation of solid solution with orthorhombic structure. Among them all the synthesized samples are showed a conductivity with different atmosphere values at 500 °C. Ba0.92Sr0.08Ce0.65Zr0.25Pr0.1O3-δ recorded highest conductivity with a value of 3.3 × 10-6 S/cm (dry air) & 3.41 × 10-6 S/cm (wet air with 3% relative humidity) at 500 °C due to its smaller lattice volume, larger grain size and lower activation energy that led to excessive increase in conductivity. All pellets exhibited good chemical stability when exposed to air and H2O atmospheres. This study elucidates that the composition will be a promising electrolyte material for use as SOFC at intermediate temperatures if Sr doping is limited to small amounts.

  13. Z-contrast imaging of ordered structures in Pb(Mg1/3Nb2/3)O3 and Ba(Mg1/3Nb2/3)O3

    International Nuclear Information System (INIS)

    Yan, Y.; Pennycook, S.J.; Xu, Z.; Viehland, D.

    1998-02-01

    Lead-based cubic perovskites such as Pb(B 1/3 2+ B 2/3 5+ )O 3 (B 2+ Mg, Co, Ni, Zn; B 5+ = Nb, Ta) are relaxor ferroelectrics. Localized order and disorder often occur in materials of this type. In the Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) family, previous studies have proposed two models, space-charge and charge-balance models. In the first model, the ordered regions carry a net negative charge [Pb(Mg 1/2 Nb 1/2 )O 3 ], while in the second model it does not carry a net charge [Pb((Mg 2/3 Nb 1/3 ) 1/2 Nb 1/2 )O 3 ]. However, no direct evidence for these two models has appeared in the literature yet. In this paper the authors report the first direct observations of local ordering in undoped and La-doped Pb(Mg 1/3 Nb 2/3 )O 3 , using high-resolution Z-contrast imaging. Because the ordered structure in Ba(Mg 1/3 Nb 2/3 )O 3 is well known, the Z-contrast image from an ordered domain is used as a reference for this study

  14. Piezoelectric properties and temperature stability of Mn-doped Pb(Mg1/3Nb2/3)-PbZrO3-PbTiO3 textured ceramics

    Science.gov (United States)

    Yan, Yongke; Cho, Kyung-Hoon; Priya, Shashank

    2012-03-01

    In this letter, we report the electromechanical properties of textured 0.4Pb(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3 (PMN-PZT) composition which has relatively high rhombohedral to tetragonal (R-T) transition temperature (TR-T of 160 °C) and Curie temperature (TC of 234 °C) and explore the effect of Mn-doping on this composition. It was found that MnO2-doped textured PMN-PZT ceramics with 5 vol. % BaTiO3 template (T-5BT) exhibited inferior temperature stability. The coupling factor (k31) of T-5BT ceramic started to degrade from 75 °C while the random counterpart showed a very stable tendency up to 180 °C. This degradation was associated with the "interface region" formed in the vicinity of BT template. MnO2 doped PMN-PZT ceramics textured with 3 vol. % BT and subsequently poled at 140 °C (T-3BT140) exhibited very stable and high k31 (>0.53) in a wide temperature range from room temperature to 130 °C through reduction in the interface region volume. Further, the T-3BT140 ceramic exhibited excellent hard and soft combinatory piezoelectric properties of d33 = 720 pC/N, k31 = 0.53, Qm = 403, tan δ = 0.3% which are very promising for high power and magnetoelectric applications.

  15. Microstructure and elevated-temperature tensile properties of differential pressure sand cast Mg-4Y-3Nd-0.5Zr alloy

    Directory of Open Access Journals (Sweden)

    Hong-hui Liu

    2016-01-01

    Full Text Available The microstructures of an Mg-4Y-3Nd-0.5Zr alloy by differential pressure casting were investigated using scanning electron microscopy (SEM and transmission electron microscopy (TEM, and its tensile deformation behavior was measured using a Gleeble1500D themo-simulation machine in the temperature range of 200 to 400 °C at initial strain rates of 5×10-4 to 10-1 s-1. Results show that the as-cast microstructure consists of primary α-Mg phase and bone-shaped Mg5RE eutectic phase distributed along the grain boundary. The eutectic phase is dissolved into the matrix after solution treatment and subsequently precipitates during peak aging. Tensile deformation tests show that the strain rate has little effect on stress under 300 °C. Tensile stress decreases with an increase in temperature and the higher strain rate leads to an increase in stress above 300 °C. The fracture mechanism exhibits a mixed quasi-cleavage fracture at 200 °C, while the fracture above 300 °C is a ductile fracture. The dimples are melted at 400 °C with the lowest strain rate of 10-4 s-1.

  16. Microstructure, mechanical properties, biocorrosion behavior, and cytotoxicity of as-extruded Mg-Nd-Zn-Zr alloy with different extrusion ratios.

    Science.gov (United States)

    Zhang, Xiaobo; Yuan, Guangyin; Niu, Jialin; Fu, Penghuai; Ding, Wenjiang

    2012-05-01

    Recently, commercial magnesium (Mg) alloys containing Al (such as AZ31 and AZ91) or Y (such as WE43) have been studied extensively for biomedical applications. However, these Mg alloys were developed as structural materials, not as biomaterials. In this study, a patented Mg-Nd-Zn-Zr (denoted as JDBM) alloy was investigated as a biomedical material. The microstructure, mechanical properties, biocorrosion behavior, and cytotoxicity of the alloy extruded at 320 °C with extrusion ratios of 8 and 25 were studied. The results show that the lower extrusion ratio results in finer grains and higher strength, but lower elongation, while the higher extrusion ratio results in coarser grains and lower strength, but higher elongation. The biocorrosion behavior of the alloy was investigated by hydrogen evolution and mass loss tests in simulated body fluid (SBF). The results show that the alloy extruded with lower extrusion ratio exhibits better corrosion resistance. The corrosion mode of the alloy is uniform corrosion, which is favorable for biomedical applications. Aging treatment on the as-extruded alloy improves the strength and decreases the elongation at room temperature, and has a small positive influence on the corrosion resistance in SBF. The cytotoxicity test indicates that the as-extruded JDBM alloy meets the requirement of cell toxicity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Quantitative determination of phases in ZrO{sub 2} (MgO) (Y{sub 2}O{sub 3}) using the Rietveld method; Determinacao quantitativa de fases em ZrO{sub 2} - MgO - Y{sub 2}O{sub 3} utilizando o metodo de Rietveld

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Antonio Carlos de

    2007-07-01

    The key objective of this work is the crystallographic characterization of the zircon co-doped with Yttria and magnesium with the application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon monoclinic, tetragonal, and cubic). Samples of zircon polymorph were obtained from zircon doped with Yttria and magnesium at defined molar concentrations. The zircon polymorph stability during subeutetoid aging at 1350 deg C were investigated to determine ZrO{sub 2} - MgO - Y{sub 2}0{sub 3} phases degradation and to define the solid solutions stability environment. ZrO{sub 2} powders doped with 8 mol por cent of MgO and 1 mol por cent of Y{sub 2}O{sub 3}, and 9 mol por cent of MgO and 0 mol por cent of Y{sub 2}O{sub 3} have been prepared by chemical route using the co-precipitation method. These samples have been calcinate at 550 deg C, sintered at 1500 deg C and characterized by the Rietveld method using the X-ray diffraction data. The variation of the lattice parameter, changes in the phase composition and their microstructures are discussed. The application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon tetragonal and cubic) reveals no formation of tetragonal phase and indicating that the matrix is the cubic phase with low concentration of monoclinic phase.(author)

  18. Effect of rare-earth composition on microstructure and pinning properties of Zr-doped (Gd, Y)Ba{sub 2}Cu{sub 3}O{subx} superconducting tapes.

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, V.; Chen, Y.; Zhang, Y.; Guevara, A.; Shi, T.; Yao, Y.; Majkic, G.; Lei, C.; Galtsyan, E.; Miller, D. J. (Materials Science Division); (Univ. Houston); (SuperPower Inc.)

    2012-01-01

    The effect of changing Gd + Y content from 1.2 to 1.6 in the precursor of (Gd,Y)Ba{sub 2}Cu{sub 3}O{sub 7} superconducting thin film tapes made by metal organic chemical vapor deposition (MOCVD) at a constant Gd:Y ratio and a fixed Zr content of 7.5% has been studied. The influence of changing the Gd:Y ratio from Gd = 0 to Y= 0 in 0.2 mol steps at a constant Gd + Y content of 1.2 in the precursor has also been investigated at a fixed Zr content of 7.5%. The critical current of these films is found to vary significantly as a function of rare-earth content as well as a function of rare-earth type. Even for a fixed Zr content, it is found that the critical current in the orientation of magnetic field parallel to the a-b plane and that in the orientation of field perpendicular to the a-b plane can be systematically varied with changing Gd + Y content as well as with changing Gd:Y ratio. The nanoscale defect structures along the a-b plane and along the c-axis are found to be sensitive to these changes in rare-earth content and type.

  19. Tunability, dielectric, and piezoelectric properties of Ba{sub (1−x)}Ca{sub x}Ti{sub (1−y)}Zr{sub y}O{sub 3} ferroelectric thin films

    Energy Technology Data Exchange (ETDEWEB)

    Daumont, C. J. M., E-mail: christophe.daumont@univ-tours.fr; Le Mouellic, E.; Negulescu, B.; Wolfman, J. [Laboratoire GREMAN, UMR7347 CNRS, Faculté de Sciences et Techniques, Université François Rabelais, 37200 Tours (France); Simon, Q.; Payan, S.; Maglione, M. [Institute of Condensed Matter Chemistry of Bordeaux, ICMCB-CNRS, Université de Bordeaux, 33608 Pessac Cedex (France); Gardes, P.; Poveda, P. [STMicroelectronics, 10 rue Thalès de Milet, 37071 Tours Cedex (France)

    2016-03-07

    Tunable ferroelectric capacitors, which exhibit a decrease of the dielectric permittivity (ϵ) under electric field, are widely used in electronics for RF tunable applications (e.g., antenna impedance matching). Current devices use barium strontium titanate as the tunable dielectric, and the need for performance enhancement of the tunable element is the key for device improvement. We report here on libraries of Ba{sub 0.97}Ca{sub 0.03}Ti{sub 1−x}Zr{sub x}O{sub 3} thin films (0 ≤ x ≤ 27%) with a thickness of about 130 nm deposited on IrO{sub 2}/SiO{sub 2}/Si substrates using combinatorial pulsed laser deposition allowing for gradients of composition on one sample. A total of 600 capacitors on a single sample were characterized in order to statistically investigate the dielectric properties. We show that the tunabilty is maximum at intermediate compositions, reaching values up to 60% for an electric field of about 400 kV cm{sup −1}. We attribute the high tunability in the intermediate compositions to the paraelectric-ferroelectric phase transition, which is brought down to room temperature by the addition of Zr. In addition, the piezoelectric coefficient is found to be decreasing with increasing Zr content.

  20. Improvement of the performance of microwave X band absorbers based on pure and doped Ba-hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Seyyed Afghahi, Seyyed Salman [Department of Materials Science and Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of); Jafarian, Mojtaba, E-mail: m.jafarian@srbiau.ac.ir [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Salehi, Mohsen [Young Researchers and Elite Club, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Atassi, Yomen [Department of Applied Physics, Higher Institute for Applied Sciences and Technology, Damascus (Syrian Arab Republic)

    2017-01-01

    Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite prepared via mechanical activation. X-ray diffractometer (XRD), scanning electron microscope (SEM), vibrating sample magnetometer (VSM) and vector network analyzer are used to analyze phases, structures, electromagnetic and microwave absorption properties. The mole ratio of Fe/Ba=10 is detected to be optimum for doping and synthesizing the Ba-hexaferrite. In order to achieve high absorption in X band the ions of Zr{sup 4+}–Sn{sup 4+}–Ti{sup 4+}–M{sup 2+} (M=Mg{sup 2+}, Zn{sup 2+}, Cu{sup 2+}, Co{sup 2+}) are used as dopants. The results indicate the formation of single phase Ba-hexaferrite in either pure or doped compounds without any non-magnetic intermediate phases and with spherical and hexagonal morphologies respectively for the pure and doped ferrite. It is found out that BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19} compound has the maximum saturation magnetization (49.80 emu/g). Also the composite of BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19} 50 wt% in epoxy resin exhibits a minimum reflection loss of −29 dB at 12.2 GHz with 2.6 GHz bandwidth. - Highlights: • Optimum Fe/Ba mole ratio is determined in doped Ba-hexaferrite. • Formation of a single phase M-hexaferrite, pure or doped when Fe/Ba=10. • Preparation of microwave absorber of BaCo{sub 2}Zr(SnTi){sub 0.5}Fe{sub 8}O{sub 19}/epoxy resin, 50 wt%. • The absorber exhibits a minimum RL of −29 dB at 12.2 GHz with 2.6 GHz bandwidth.

  1. Over 15 MA/cm2 of critical current density in 4.8 µm thick, Zr-doped (Gd,Y)Ba2Cu3Ox superconductor at 30 K, 3T.

    Science.gov (United States)

    Majkic, Goran; Pratap, Rudra; Xu, Aixia; Galstyan, Eduard; Selvamanickam, Venkat

    2018-05-03

    An Advanced MOCVD (A-MOCVD) reactor was used to deposit 4.8 µm thick (Gd,Y)BaCuO tapes with 15 mol% Zr addition in a single pass. A record-high critical current density (J c ) of 15.11 MA/cm 2 has been measured over a bridge at 30 K, 3T, corresponding to an equivalent (I c ) value of 8705 A/12 mm width. This corresponds to a lift factor in critical current of ~11 which is the highest ever reported to the best of author's knowledge. The measured critical current densities at 3T (B||c) and 30, 40 and 50 K, respectively, are 15.11, 9.70 and 6.26 MA/cm 2 , corresponding to equivalent Ic values of 8705, 5586 and 3606 A/12 mm and engineering current densities (J e ) of 7068, 4535 and 2928 A/mm 2 . The engineering current density (J e ) at 40 K, 3T is 7 times higher than that of the commercial HTS tapes available with 7.5 mol% Zr addition. Such record-high performance in thick films (>1 µm) is a clear demonstration that growing thick REBCO films with high critical current density (J c ) is possible, contrary to the usual findings of strong J c degradation with film thickness. This achievement was possible due to a combination of strong temperature control and uniform laminar flow achieved in the A-MOCVD system, coupled with optimization of BaZrO 3 nanorod growth parameters.

  2. The part of soluble and insoluble forms of Pb, Be, Ba, Ca, Mg, Sr in particulate matter and in the pharyngeal tonsils

    Directory of Open Access Journals (Sweden)

    Maria Gerycka

    2014-09-01

    Full Text Available Introduction. Previous studies have confirmed that the pharyngeal tonsil is a good biomarker of exposure due to its position relative to inhaled air so that multiple elements can be accumulated in this organ. The aim of the study is to determine the share of soluble and insoluble compounds of individual elements in suspended particles in the accumulation of Pb, Be, Ba, Sr, Ca,Mg by the pharyngeal tonsils. Material and methods. The content of the analyzed elements is defined in 86 samples of pharyngeal tonsils from children living in Tychy and in 76 samples of pharyngeal tonsils from children living in Chorzów, as well as in the suspended particles in the air occurring in soluble and insoluble form. The specified coefficients k1, k2 present in the equation division allow the indication the greater importance of soluble and insoluble fraction of an element present in the inhaled air. Results. The value of the coefficients in the equation division based on gender confirmed its importance. Conclusions. The values detect area variation in relation to passive smoking in the extent of accumulation of Pb, Be, Ba, Sr, Mg, Ca in pharyngeal tonsils.

  3. Fabrication and studies of microstructure and mechanical properties of Ba2MgNbO5,5 ceramics for application in the petroleum industry

    International Nuclear Information System (INIS)

    Oliveira, J.C. da S.; Ferreira, R.A.S.; Yadava, Y.P.

    2011-01-01

    The present work aims at the elaboration of a ceramic complex perovskite ceramic components for temperature sensors for oil wells, as well as the study of microstructural characteristics and mechanical properties of ceramics Ba 2 MgNbO 5,5 . The manufacture of pottery Ba 2 MgNbO 5,5 was performed using a thermo-mechanical and solid-state sintering. The pellets of compressed green were calcined for 24 hours at a temperature of 1200°C and then crushed with the help of a set pistil / agate mortar. The resulting powder was compacted and new pellets were sintered at a temperature of 1250°C. Basic studies of stability of ceramics sintered in the environment of crude oil, from onshore wells and the sea, the state of Sergipe in northeastern Brazil. The test results showed that the ceramic is inert to crude oil and can be used to produce ceramic components for the oil industry. (author)

  4. Structural, morphological and optical investigations on BaMgAl10O17:Eu2+ elaborated by a microwave induced solution combustion synthesis

    International Nuclear Information System (INIS)

    Pradal, Nathalie; Potdevin, Audrey; Chadeyron, Genevieve; Mahiou, Rachid

    2011-01-01

    Graphical abstract: Graphical abstract (with Research highlights). This is a paragraph for graphical abstract. Research highlights: → Synthesis of BAM:Eu 2+ by MISCS using different fuel to oxidizer molar ratios. → Both blue and red phosphors were obtained. → Majority of blue phosphors was obtained for fuel-rich synthesis. → A specific morphology was observed for each contribution. -- Abstract: Blue-emitting Eu 2+ -doped barium magnesium aluminate (BaMgAl 10 O 17 :Eu 2+ ) for advanced displays and lighting devices was prepared by a microwave induced solution combustion synthesis using urea as combustion fuel and nitrates as oxidizer. Purity control of as-synthesized blue phosphor particles was undertaken by modifying the fuel to oxidizer molar ratio. X-ray diffraction, scanning electron microscopy and photoluminescence were used to investigate powders crystallinity, particles size, morphology and luminescent properties, respectively. Fuel-rich urea reactions preferentially lead to pure phases compared to the powders synthesized with a stoichiometric fuel to oxidizer ratio. In both cases, we produce a nearly pure well-crystallized and nanostructured BaMgAl 10 O 17 :Eu 2+ . Photoluminescence measurements exhibit the characteristic blue emission of Eu 2+ under UV light excitation however a weak red emission associated to Eu 3+ is also detected.

  5. New intermetallic MIrP (M=Ti, Zr, Nb, Mo) and MgRuP compounds related with MoM'P (M'=Ni and Ru) superconductor

    Science.gov (United States)

    Kito, Hijiri; Iyo, Akira; Wada, Toshimi

    2011-01-01

    Using a cubic-anvil high-pressure apparatus, ternary iridium phosphides MIrP (M=Ti, Zr, Nb, Mo) and MgRuP have been prepared by reaction of stoichiometric amounts of each metal and phosphide powders at around 2 Gpa and above 1523 K for the first time. The structure of these compounds prepared at high-pressure has been characterized by X-ray powder diffraction. Diffraction lines of these compounds are assigned by the index of the Co2Si-type structure. The electrical resistivity and the d.c magnetic susceptibility of MIrP (M=Ti, Zr, Nb, Mo) have measured at low temperatures. Unfortunately, no superconducting transition for MIrP (M=Ti, Zr, Nb, Mo) and MgRuP are observed down to 2 K.

  6. New intermetallic MIrP (M=Ti, Zr, Nb, Mo) and MgRuP compounds related with MoM'P (M'=Ni and Ru) superconductor

    International Nuclear Information System (INIS)

    Kito, Hijiri; Iyo, Akira; Wada, Toshimi

    2011-01-01

    Using a cubic-anvil high-pressure apparatus, ternary iridium phosphides MIrP (M=Ti, Zr, Nb, Mo) and MgRuP have been prepared by reaction of stoichiometric amounts of each metal and phosphide powders at around 2 Gpa and above 1523 K for the first time. The structure of these compounds prepared at high-pressure has been characterized by X-ray powder diffraction. Diffraction lines of these compounds are assigned by the index of the Co 2 Si-type structure. The electrical resistivity and the d.c magnetic susceptibility of MIrP (M=Ti, Zr, Nb, Mo) have measured at low temperatures. Unfortunately, no superconducting transition for MIrP (M=Ti, Zr, Nb, Mo) and MgRuP are observed down to 2 K.

  7. Efeito da segregação e solubilização do MgO na morfologia de pós de ZrO2 durante a síntese pelo método Pechini Effect of MgO segregation and solubilization on the morphology of ZrO2 powders during synthesis by the Pechini's method

    Directory of Open Access Journals (Sweden)

    P. J. B. Marcos

    2004-03-01

    Full Text Available Trabalhos realizados em vários sistemas de óxidos cerâmicos têm demonstrado que a segregação dos íons durante a síntese de materiais cerâmicos pelo método Pechini tem conseqüências muito importantes tanto para a morfologia dos pós como para a sinterização. Este trabalho tem como objetivo estabelecer a influência da segregação/solubilização do MgO na morfologia e na sinterização de pós à base de ZrO2. O estudo foi realizado em pós preparados por síntese química derivada do método Pechini a 500 °C por 15 h. Observa-se que para concentrações de MgO até o limite de solubilidade no ZrO2 ocorre o crescimento de partículas e uma diminuição da área de superfície específica por causa da solubilização e do aumento do coeficiente de difusão pela geração de vacâncias de oxigênio. Contudo, após o limite de solubilidade, ocorre um aumento gradual da área de superfície específica devido à segregação dos íons na superfície dos pós e à diminuição da energia de superfície. Concentrações de MgO até 60 % molar foram utilizadas e áreas de superfície específica tão elevadas quanto 120 m²/g foram obtidas, mas as fases cristalinas formadas foram exclusivamente da zircônia solução sólida sem a presença de fases cristalinas de MgO.Studies carried out in several ceramic oxide systems have shown that segregation of ions during synthesis of ceramic materials by the Pechini's method has important morphology consequences for the powder. The aim of this paper is to establish the influence of the MgO segregation/solubilization on the morphology of ZrO2 powders. The study was performed in powders prepared by chemical synthesis derived from the Pechini's method at 500 ºC for 15 h. It is observed that MgO concentrations up to the solubility limit promote ZrO2 particle coarsening and a reduction of specific surface area by increasing the diffusion coefficient. However, MgO amounts higher than the solubility

  8. A-axis oriented superconductive YBCO thin films. Growth mechanism on MgO substrate. [Y-Ba-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Hamet, J F; Mercey, B; Hervieu, M; Poullain, G; Raveau, B [Centre de Materiaux Supraconducteurs, CRISMAT-ISMRa, 14 - Caen (France)

    1992-08-01

    The growth mechanism of a-axis oriented YBCO thin films has been studied by TEM. At 650degC, a disordered cubic perovskite is first formed with a[sub p]parallela[sub MgO], then a strained tetragonal a-axis oriented perovskite is observed, with c=3a[sub p], slightly misoriented with respect to MgO and showing a marquetry-like contrast. At 750degC, a [1anti 10] axis oriented perovskite is formed whose lattice exhibits a rotation with respect to MgO lattice, but also a tilting of the [CuO[sub 2

  9. Kampelite, Ba3Mg1.5Sc4(PO4)6(OH)3·4H2O, a new very complex Ba-Sc phosphate mineral from the Kovdor phoscorite-carbonatite complex (Kola Peninsula, Russia)

    Science.gov (United States)

    Yakovenchuk, Victor N.; Ivanyuk, Gregory Yu.; Pakhomovsky, Yakov A.; Panikorovskii, Taras L.; Britvin, Sergei N.; Krivovichev, Sergey V.; Shilovskikh, Vladimir V.; Bocharov, Vladimir N.

    2018-02-01

    Kampelite, Ba3Mg1.5Sc4(PO4)6(OH)3·4H2O, is a new Ba-Sc phosphate from the Kovdor phoscorite-carbonatite complex (Kola Peninsula, Russia). It is orthorhombic, Pnma, a = 11.256(1), b = 8.512(1), c = 27.707(4) Å, V = 2654.6(3) Å3 and Z = 4 (from powder diffraction data) or a = 11.2261(9), b = 8.5039(6), c = 27.699(2) Å, V = 2644.3(3) Å3 (from single-crystal diffraction data). The mineral was found in a void within the calcite-magnetite phoscorite (enriched in hydroxylapatite and Sc-rich baddeleyite) inside the axial zone of the Kovdor phoscorite-carbonatite pipe. Kampelite forms radiated aggregates (up to 1.5 mm in diameter) of platy crystals grown on the surfaces of crystals of quintinite-2 H in close association with pyrite, bobierrite and quintinite-3 R. Kampelite is colourless, with a pearly lustre and a white streak. The cleavage is perfect on {001}, the fracture is smooth. Mohs hardness is about 1. In transmitted light, the mineral is colourless without pleochroism or dispersion. Kampelite is biaxial + (pseudouniaxial), α ≈ β = 1.607(2), γ = 1.612(2) (589 nm), and 2 V calc = 0°. The calculated and measured densities are 3.28 and 3.07(3) g·cm-3, respectively. The mean chemical composition determined by electron microprobe is: MgO 4.79, Al2O3 0.45, P2O5 31.66, K2O 0.34, Sc2O3 16.17, Mn2O3 1.62, Fe2O3 1.38, SrO 3.44, and BaO 29.81 wt%. The H2O content estimated from the crystal-structure refinement is 7.12 wt%, giving a total of 96.51 wt%. The empirical formula calculated on the basis of P = 6 apfu (atoms per formula unit) is (Ba2.62Sr0.45K0.10Ca0.06)Σ3.23Mg1.60Mn0.28(Sc3.15Fe3+ 0.23Al0.12)Σ3.50(PO4)6(OH)2.61·4.01H2O. The simplified formula is Ba3Mg1.5Sc4(PO4)6(OH)3·4H2O. The mineral easily dissolves in 10% cold HCl. The strongest X-ray powder-diffraction lines [listed as d in Å ( I) ( hkl)] are as follows: 15.80(100)(001), 13.86(45)(002), 3.184(18)(223), 3.129(19)(026), 2.756(16)(402), 2.688(24)(10 10). The crystal structure of kampelite was

  10. Fast reactor irradiation effects on fracture toughness of Si_3N_4 in comparison with MgAl_2O_4 and yttria stabilized ZrO_2

    International Nuclear Information System (INIS)

    Tada, K.; Watanabe, M.; Tachi, Y.; Kurishita, H.; Nagata, S.; Shikama, T.

    2016-01-01

    Fracture toughness of silicon nitride (Si_3N_4), magnesia-alumina spinel (MgAl_2O_4) and yttria stabilized zirconia (8 mol%Y_2O_3–ZrO_2) was evaluated by the Vickers-indentation technique after the fast reactor irradiation up to 55 dpa (displacement per atom) at about 700 °C in the Joyo. The change of the fracture toughness by the irradiation was correlated with nanostructural evolution by the irradiation, which was examined by transmission electron microscopy. The observed degradation of fracture toughness in Si_3N_4 is thought to be due to the relatively high density of small-sized of the irradiation induced defects, which should be resulted from a large amount of transmutation gases of hydrogen and helium. Observed improvement of fracture toughness in MgAl_2O_4 was due to the blocking of crack propagation by the antiphase boundaries. The radiation effects affected the fracture toughness of yttria stabilized zirconia at 55 dpa, suggesting that the generated high density voids would affect the propagation of cracks. - Highlights: • Si_3N_4, MgAl_2O_4 and YSZ were neutron irradiated up to 55dpa around 700 °C in the Joyo. • They are candidate ceramics for the inert matrices of nuclear fuels in the fast reactors. • The irradiation enhanced the fracture toughness of MgAl_2O_4 and YSZ, while degraded that of Si_3N_4. • The toughness changes were correlated with radiation induced defects and transmutation gases.

  11. Growth and microstructure of columnar Y-doped SrZrO{sub 3} films deposited on Pt-coated MgO by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Sijun, E-mail: sluo1@tulane.edu; Riggs, Brian C.; Shipman, Joshua T.; Adireddy, Shiva; Sklare, Samuel C.; Chrisey, Douglas B., E-mail: dchrisey@tulane.edu [Department of Physics and Engineering Physics, Tulane University, New Orleans, Louisiana 70118 (United States); Zhang, Xiaodong; Koplitz, Brent [Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States)

    2015-07-21

    Direct integration of proton conductor films on Pt-coated substrates opens the way to film-based proton transport devices. Columnar SrZr{sub 0.95}Y{sub 0.05}O{sub 3−δ} (SZY) films with dense microstructure were deposited on Pt-coated MgO(100) substrates at 830 °C by pulsed laser deposition. The optimal window of ambient O{sub 2} pressure for good crystallinity of SZY films is from 400 to 600 mTorr. The ambient O{sub 2} compresses the plasma plume of SZY and increases the deposition rate. The 10 nm thick Ti adhesion layer on MgO(100) greatly affects the orientation of the sputtered Pt layers. Pt deposited directly on MgO shows a highly (111)-preferred orientation and leads to preferentially oriented SZY films while the addition of a Ti adhesion layer makes Pt show a less preferential orientation that leads to randomly oriented SZY films. The RMS surface roughness of preferentially oriented SZY films is larger than that of randomly oriented SZY films deposited under the same ambient O{sub 2} pressure. As the O{sub 2} pressure increased, the RMS surface roughness of preferentially oriented SZY films increased, reaching 45.7 nm (2.61% of film thickness) at 600 mTorr. This study revealed the ambient O{sub 2} pressure and orientation dependent surface roughness of SZY films grown on Pt-coated MgO substrates, which provides the potential to control the surface microstructure of SZY films for electrochemical applications in film-based hydrogen devices.

  12. Characterizing the residual glass in a MgO/Al2O3/SiO2/ZrO2/Y2O3 glass-ceramic

    Science.gov (United States)

    Seidel, Sabrina; Patzig, Christian; Wisniewski, Wolfgang; Gawronski, Antje; Hu, Yongfeng; Höche, Thomas; Rüssel, Christian

    2016-01-01

    The non-isochemical crystallization of glasses leads to glass-ceramics in which the chemical composition of the amorphous matrix differs from that of the parent glass. It is challenging to solely analyse the properties of these residual glassy phases because they frequently contain finely dispersed crystals. In this study, the composition of the residual glass matrix after the crystallization of a glass with the mol% composition 50.6 SiO2 · 20.7 MgO · 20.7 Al2O3 · 5.6 ZrO2 · 2.4 Y2O3 is analysed by scanning transmission electron microscopy (STEM) including energy dispersive X-ray analysis (EDXS). A batch of the residual glass with the determined composition is subsequently melted and selected properties are analysed. Furthermore, the crystallization behaviour of this residual glass is studied by X-ray diffraction, scanning electron microscopy including electron backscatter diffraction and STEM-EDXS analyses. The residual glass shows sole surface crystallization of indialite and multiple yttrium silicates while bulk nucleation does not occur. This is in contrast to the crystallization behaviour of the parent glass, in which a predominant bulk nucleation of spinel and ZrO2 is observed. The crystallization of the residual glass probably leads to different crystalline phases when it is in contact to air, rather than when it is enclosed within the microstructure of the parent glass-ceramics. PMID:27734918

  13. Solution Treatment Effect on Tensile, Impact and Fracture Behaviour of Trace Zr Added Al-12Si-1Mg-1Cu Piston Alloy

    Science.gov (United States)

    Kaiser, Md. Salim

    2018-04-01

    The effects of T6 solution treatment on tensile, impact and fracture properties of cast Al-12Si-1Mg-1Cu piston alloys with trace of zirconium were investigated. Cast alloys were given precipitation strengthening treatment having a sequence of homogenizing, solutionizing, quenching and ageing. Both cast and solutionized samples are isochronally aged for 90 min at different temperatures up to 300 °C. Tensile and impact properties of the differently processed alloys have been studied to understand the precipitation strengthening of the alloys. Fractograpy of the alloys were observed to understand the mode of fracture. It is observed that the improvement in tensile properties in the aged alloys through heat treatment is mainly attributed to the formation of the Al2Cu and Mg2Si precipitates within the Al matrix. Solution treatment improves the tensile strength for the reason that during solution treatment some alloying elements are re-dissolved to produce a solute-rich solid solution. Impact energy decreases with ageing temperature due to formation of GP zones, β' and β precipitates. The fractography shows large and small dimple structure and broken or cracked primary Si, particles. Microstructure study of alloys revealed that the solution treatment improved distribution of silicon grains. The addition of Zr produces an improvement in the tensile properties as a result of its grain refining action and grain coarsening resistance in the matrix at a higher temperature.

  14. Radiation processes in glass of Ba(PO/sub 3/)/sub 2/-MgF/sub 2/-LiF system. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bocharova, T.V.; Karapetyan, G.O.; Khalilev, V.D.

    1984-11-01

    Optical spectra of additional absorption of glasses of Ba(PO/sub 3/)/sub 2/-MgF/sub 2/-LiF system ..gamma..-irradiated up to 10/sup 6/ R dose are presented. It was established that introduction of up to 70 mol% of fluorides into phosphate glass doesn't result in occurrence of AAB (additional absorption band) in spectra, related to color centers similar to F-centers in MgF/sub 2/ and LiF crystals. It was shown that occurring color centers in phosphate matrix form nonelementary AAB in approximately 20,000 cm/sup -1/ spectrum region. The contribution to the total spectrum of additional absorption in visible region is made, besides (PO)/sub 4/-centers, by radiation color centers related with the presence of Mg/sup +2/ ions near PO/sub 4/ tetrahedrons. It was assumed that change of AAB position and intensity with ..gamma..sub(max) approximately 20,000 cm/sup -1/ in fluorophosphate glass with regularly changed composition reflects structural rebuilding of glass network taking place simultaneously with fluoride introduction. The obtained results support the conclusion, that MgF/sub 2/ takes part in formation of structural glass network whereas LiF acts as a component which breaks phosphate chains.

  15. SYNGAS PRODUCTION FROM CO2-REFORMING OF CH4 OVER SOL-GEL SYNTHESIZED Ni-Co/Al2O3-MgO-ZrO2 NANOCATALYST: EFFECT OF ZrO2 PRECURSOR ON CATALYST PROPERTIES AND PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Seyed Mehdi Sajjadi

    2015-05-01

    Full Text Available Ni-Co/Al2O3-MgO-ZrO2 nanocatalyst with utilization of two different zirconia precursors, namely, zirconyl nitrate hydrate (ZNH and zirconyl nitrate solution (ZNS, was synthesized via the sol-gel method. The physiochemical properties of nanocatalysts were characterized by XRD, FESEM, EDX, BET and FTIR analyses and employed for syngas production from CO2-reforming of CH4. XRD patterns, exhibiting proper crystalline structure and homogeneous dispersion of active phase for the nanocatalyst ZNS precursor employed (NCAMZ-ZNS. FESEM and BET results of NCAMZ-ZNS presented more uniform morphology and smaller particle size and consequently higher surface areas. In addition, average particle size of NCAMZ-ZNS was 15.7 nm, which is close to the critical size for Ni-Co catalysts to avoid carbon formation. Moreover, FESEM analysis indicated both prepared samples were nanoscale. EDX analysis confirmed the existence of various elements used and also supported the statements made in the XRD and FESEM analyses regarding dispersion. Based on the excellent physiochemical properties, NCAMZ-ZNS exhibited the best reactant conversion across all of the evaluated temperatures, e.g. CH4 and CO2 conversions were 97.2 and 99% at 850 ºC, respectively. Furthermore, NCAMZ-ZNS demonstrated a stable yield with H2/CO close to unit value during the 1440 min stability test.

  16. Dielectric properties of BaMg1/3Nb2/3O3 doped Ba0.45Sr0.55Tio3 thin films for tunable microwave applications

    Science.gov (United States)

    Alema, Fikadu; Pokhodnya, Konstantin

    2015-11-01

    Ba(Mg1/3Nb2/3)O3 (BMN) doped and undoped Ba0.45Sr0.55TiO3 (BST) thin films were deposited via radio frequency magnetron sputtering on Pt/TiO2/SiO2/Al2O3 substrates. The surface morphology and chemical state analyses of the films have shown that the BMN doped BST film has a smoother surface with reduced oxygen vacancy, resulting in an improved insulating properties of the BST film. Dielectric tunability, loss, and leakage current (LC) of the undoped and BMN doped BST thin films were studied. The BMN dopant has remarkably reduced the dielectric loss (˜38%) with no significant effect on the tunability of the BST film, leading to an increase in figure of merit (FOM). This is attributed to the opposing behavior of large Mg2+ whose detrimental effect on tunability is partially compensated by small Nb5+ as the two substitute Ti4+ in the BST. The coupling between MgTi″ and VO•• charged defects suppresses the dielectric loss in the film by cutting electrons from hopping between Ti ions. The LC of the films was investigated in the temperature range of 300-450K. A reduced LC measured for the BMN doped BST film was correlated to the formation of defect dipoles from MgTi″, VO•• and NbTi• charged defects. The carrier transport properties of the films were analyzed in light of Schottky thermionic emission (SE) and Poole-Frenkel (PF) emission mechanisms. The result indicated that while the carrier transport mechanism in the undoped film is interface limited (SE), the conduction in the BMN doped film was dominated by bulk processes (PF). The change of the conduction mechanism from SE to PF as a result of BMN doping is attributed to the presence of uncoupled NbTi• sitting as a positive trap center at the shallow donor level of the BST.

  17. Investigation of conduction and relaxation phenomena in BaZr{sub x}Ti{sub 1−x}O{sub 3} (x=0.05) by impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mahajan, Sandeep, E-mail: sandeepmahajan02@yahoo.com [Centre for Materials for Electronics Technology (C-MET), IDA Phase-III, Cherlapally, HCl (PO), Hyderabad-500051 (India); Department of Physics and Astrophysics, University of Delhi, Delhi-110054 (India); Haridas, Divya [Keshav Mahavidyalaya, H-4-5 Zone, Sainik Vihar Pitampura, Delhi-110034 (India); Ali, S.T.; Munirathnam, N.R. [Centre for Materials for Electronics Technology (C-MET), IDA Phase-III, Cherlapally, HCl (PO), Hyderabad-500051 (India); Sreenivas, K. [Department of Physics and Astrophysics, University of Delhi, Delhi-110054 (India); Thakur, O.P.; Prakash, Chandra [Solid State Physics Laboratory, Lucknow Road, Delhi-110054 (India)

    2014-10-15

    In present study we have prepared ferroelectric BaZr{sub x}Ti{sub 1−x}O{sub 3} (x=0.05) ceramic by conventional solid state reaction route and studied its electrical properties as a function of temperature and frequency. X-ray diffraction (XRD) analysis shows single-phase formation of the compound with orthorhombic crystal structure at room temperature. Impedance and electric modulus spectroscopy analysis in the frequency range of 40 Hz–1 MHz at high temperature (200–600 °C) suggests two relaxation processes with different time constant are involved which are attributed to bulk and grain boundary effects. Frequency dependent dielectric plot at different temperature shows normal variation with frequency while dielectric loss (tanδ) peak was found to obey an Arrhenius law with activation energy of 1.02 eV. The frequency-dependent AC conductivity data were also analyzed in a wide temperature range. - Graphical abstract: The electrical properties which give electrical microstructure that correlates to its ceramic microstructure are less studied for BZT. Various parameters such as grain, grain boundary and electrode/interface that affect the electrical properties in ceramics. The charge transport can be attributed to the charge displacement, dipole reorientation and space charge formation. In present work we have studied the role of grain and grain boundaries on the electrical behaviour of Zr-doped BaTiO{sub 3} and their dependence on temperature and frequency by complex impedance and modulus spectroscopy (CIS) technique in a wide frequency (40 Hz–1 MHz) and high temperature range. - Highlights: • BaZr{sub x}Ti{sub 1−x}O{sub 3} (x=0.05) ceramic by conventional solid state reaction route. • CIS used to study the material behaviour in wide range of frequency and temperature. • tanδ peak was found to obey an Arrhenius law with activation energy of 1.02 eV. • A parallel combination of RC circuit found for grain and grain boundaries.

  18. Microstructural and Mechanical Characterization of Al-0.80Mg-0.85Si-0.3Zr Alloy

    Directory of Open Access Journals (Sweden)

    Kahrıman F.

    2017-12-01

    Full Text Available In this study, Al-0.80Mg-0.85Si alloy was modified with the addition of 0.3 wt.-% zirconium and the variation of microstructural features and mechanical properties were investigated. In order to produce the billets, vertical direct chill casting method was used and billets were homogenized at 580 °C for 6 h. Homogenized billets were subjected to aging practice following three stages: (i solution annealing at 550 °C for 3 h, (ii quenching in water, (iii aging at 180 °C between 0 and 20 h. The hardness measurements were performed for the alloys following the aging process. It was observed that peak hardness value of Al-0.80Mg-0.85Si alloy increased with the addition of zirconium. This finding was very useful to obtain aging parameters for the extruded hollow profiles which are commonly used in automotive industry. Standard tensile tests were applied to aged profiles at room temperature and the results showed that modified alloy had higher mechanical properties compared to the non-modified alloy.

  19. CALPHAD simulation of the Mg–(Mn, Zr)–Fe system and experimental comparison with as-cast alloy microstructures as relevant to impurity driven corrosion of Mg-alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gandel, D.S., E-mail: darren.gandel@monash.edu [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia); Easton, M.A. [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia); Gibson, M.A. [CAST Cooperative Research Centre (Australia); CSIRO Process Science and Engineering, Clayton, VIC 3168 (Australia); Birbilis, N. [CAST Cooperative Research Centre (Australia); Department of Materials Engineering, Monash University, Clayton, VIC 3800 (Australia)

    2014-02-14

    Four Mg alloys with variations in the ratio of Mn, Zr and Fe additions were cast and their microstructures analysed via electron microscopy. Thermodynamic calculations of the expected phases using PANDAT were evaluated with actual as-cast microstructures. Some of the as-cast alloys did appear to form phases similar to those anticipated from the PANDAT calculations. Furthermore, there was a new Mn–Fe particle interaction observed that was not predicted, but which is posited to be responsible for the increase in corrosion resistance among Mn containing Mg alloys with Fe impurities. The experimental work herein has been shown to be invaluable in the understanding of this practically important system with sparingly soluble Fe and its potential influence on the corrosion of Mg alloys. - Highlights: • Alloy microstructure of the Mg-(Mn,Zr, Fe) system was analysed and reported. • CALPHAD analysis was used in conjunction with traditional SEM analysis techniques in this study. • A proposed Mn–Fe interaction within Mg has been observed for the first time. • Experimental validation of calculated phases is required to understand the effect of Mn and Zr on Mg.

  20. Superlattice structure of Ce{sup 3+}-doped BaMgF{sub 4} fluoride crystals - x-ray diffraction, electron spin-resonance, and optical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Yamaga, M.; Hattori, K. [Department of Electrical and Electronic Engineering, Faculty of Engineering, Gifu University, Gifu (Japan); Kodama, N. [Department of Materials Science and Engineering, Faculty of Engineering and Resource Science, Akita University, Akita (Japan); Ishizawa, N. [Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama (Japan); Honda, M. [Faculty of Science, Naruto University of Education, Naruto (Japan); Shimamura, K.; Fukuda, T. [Institute for Materials Research, Tohoku University, Sendai (Japan)

    2001-09-14

    The x-ray diffraction patterns for Ce{sup 3+}-doped BaMgF{sub 4} (BMF) crystals suggest the existence of superlattice structure. The superlattice model is consistent with the characterization of the 4f{sup 1} ground state of Ce{sup 3+} as a probe ion using the electron spin-resonance (ESR) technique. The distinct Ce{sup 3+} luminescence spectra with different peak energies and lifetimes also support the superlattice model. Although the detailed superlattice structure could not be analysed using the diffraction spots, a model has been proposed, taking into account the eight Ce{sup 3+} polyhedra with different anion coordinations in the unit cell of the BMF crystal obtained from the ESR experiments. (author)

  1. Electric conductivity of solid solutions the Cs3-2xMxPO4 (M=Ba, Sr, Ca, Mg) systems

    International Nuclear Information System (INIS)

    Burmakin, E.I.; Stroev, S.S.; Shekhtman, G.Sh.; Antonov, B.D.

    2003-01-01

    The solid solutions in the Cs 3-2x M x PO 4 (M=Ba, Sr, Ca, Mg) system are synthesized and their thermal behavior and electric conductivity are studied. The introduction of the alkaline earth metal cations into cesium orthophosphates is accompanied by the shift of the phase transition occurring in the pure Cs 3 PO 4 at 450-620 Deg C into the low-temperature area as well as by increase in the cesium-cation conductivity at low temperatures. The electric conductivity in the area of existence of the Cs 3 PO 4 high-temperature modification slightly depends on the availability and concentration of the modifying additions, which make it possible to suppose the calcium sublattice structural disordering [ru

  2. Structural and superconducting properties of (Y,Gd)Ba2Cu3O7-δ grown by MOCVD on samarium zirconate buffered IBAD-MgO

    International Nuclear Information System (INIS)

    Stan, L; Holesinger, T G; Maiorov, B; Feldmann, D M; Usov, I O; DePaula, R F; Civale, L; Foltyn, S R; Jia, Q X; Chen, Y; Selvamanickam, V

    2008-01-01

    Textured samarium zirconate (SZO) films have been grown by reactive cosputtering directly on an ion beam assisted deposited (IBAD) MgO template, without an intermediate homoepitaxial MgO layer. The subsequent growth of 0.9 μm thick (Y,Gd)Ba 2 Cu 3 O 7-δ ((Y, Gd)BCO) films by metal organic chemical vapor deposition (MOCVD) yielded well textured films with a full width at half maximum of 1.9 0 and 3.4 0 for the out-of-plane and in-plane texture, respectively. Microstructural characterizations of the SZO buffered samples revealed clean interfaces. This indicates that the SZO not only provides a diffusion barrier, but also functions as a buffer for (Y, Gd)BCO grown by MOCVD. The achievement of self-field critical current densities (J c ) of over 2 MA cm -2 at 75.5 K is another proof of the effectiveness of SZO as a buffer on the IBAD-MgO template. The in-field measurements revealed an asymmetric angular dependence of J c and a shift of the ab-plane maxima due to the tilted nature of the template and (Y,Gd) 2 O 3 particles existing in the (Y, Gd)BCO matrix. The present results are especially important because they demonstrate that high temperature superconducting coated conductors with simpler architecture can be fabricated using commercially viable processes

  3. Electrical transport in low-lead (1-x)BaTiO3–xPbMg1/3Nb2/3O3 ceramics

    Institute of Scientific and Technical Information of China (English)

    J. SUCHANICZ; K. KONIECZNY; K. ŚWIERCZEK; M. LIPIŃSKI; M. KARPIERZ; D. SITKO; H. CZTERNASTEK; K. KLUCZEWSKA

    2017-01-01

    Low-lead (1-x)BaTiO3–xPbMg1/3Nb2/3O3 ceramics (x = 0, 0.025, 0.05, 0.075, 0.1, and 0.15) were prepared by the conventional oxide mixed sintering process, and their optical band gap, Seebeck coefficient, ac ( σac ) and dc ( σdc ) conductivities as a function of temperature were investigated for the first time. It was found that all samples have p-type conductivity. The low-frequency (20 Hz–2 MHz) ac conductivity obeys a power law σac ~ ωs , which is characteristic for disordered materials. The frequency exponent s is a decreasing function of temperature and tends to zero at high temperature. σac is proportional to ω0.07 – ω0.31 in the low-frequency region and to ω0.51 – ω0.98 in the high-temperature region. The temperature dependence of the dc conductivity showed a change in slope around the temperature at which the phase transition appeared. Both ac and dc conductivities showed a thermally activated character and possessed linear parts with different activation energies and some irregular changes. It was found that the hopping charge carriers dominate at low temperature and small polarons and oxygen vacancies dominate at higher temperature. (1-x)BaTiO3–xPbMg1/3Nb2/3O3 ceramics are expected to be promising new candidate for low-lead electronic materials.

  4. Magnetodielectric effect in (1 - x)(Ba0.88Ca0.12)(Ti0.88Zr0.12)O3 - xCoFe2O4

    Science.gov (United States)

    Pan, Pengfei; Tao, Jin; Ma, Fusheng; Zhang, Ning

    2018-05-01

    Magnetodielectric (MD) materials have attracted considerable attention due to their intriguing physics and potential future applications. In this work, polycrystalline (1 - x)(Ba0.88Ca0.12)(Ti0.88Zr0.12)O3 - xCoFe2O4 (x = 0.10, 0.20, 0.30, 0.40) ceramic have been prepared via sol-gel method. The room temperature magnetic and ferroelectric behaviors of the synthesized composites were investigated. For the composite with x = 0.40, a MD ratio of 5.37% was achieved under a magnetic field of 1.5 T at f = 1 kHz. The measured "butterfly hysteresis" MD curves exhibit an obvious dielectric anomaly. Theoretical analysis suggests that the observed magnetodielectric effect is attributed to the magnetoresistance effect and magnetoelectric coupling.

  5. Large Electrocaloric Effect in Lead-Free (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 Ceramics Prepared via Citrate Route

    Science.gov (United States)

    Shi, Jing; Zhu, Rongfeng; Liu, Xing; Yuan, Ningyi; Ding, Jianning; Luo, Haosu

    2017-01-01

    The 1 wt % Li-doped (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 (BCZT-Li) ceramics prepared by the citrate method exhibit improved phase purity, densification and electrical properties, which provide prospective possibility to develop high-performance electrocaloric materials. The electrocaloric effect was evaluated by phenomenological method, and the BCZT-Li ceramics present large electrocaloric temperature change ∆T, especially large electrocaloric responsibility ξ = ∆Tmax/∆Emax, which can be comparable to the largest values reported in the lead-free piezoelectric ceramics. The excellent electrocaloric effect is considered as correlating with the coexistence of polymorphic ferroelectric phases, which are detected by the Raman spectroscopy. The large ξ value accompanied by decreased Curie temperature (around 73 °C) of the BCZT-Li ceramics prepared by the citrate method presents potential applications as the next-generation solid-state cooling devices. PMID:28927004

  6. Fibras de vidro a base de Li20 - Zr02 - BaO - Si02 recobertas com Nb205 para utilização em micro-extração em fase sólida

    OpenAIRE

    Silveira, Cristian Berto da

    2005-01-01

    Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-graduação em Química Neste trabalho são descritas as metodologias para obtenção e modificações da superfície de fibras de vidro de composição Li2O-ZrO2-BaO-SiO2. Apresenta-se também as aplicações destas fibras na determinação, por SPME, de fenol e de uma mistura de álcoois. Para obtenção das fibras de vidro construiu-se um equipamento, o qual baseia-se na técnica de estiram...

  7. Large Electrocaloric Effect in Lead-Free (Ba0.85Ca0.15(Zr0.1Ti0.9O3 Ceramics Prepared via Citrate Route

    Directory of Open Access Journals (Sweden)

    Jing Shi

    2017-09-01

    Full Text Available The 1 wt % Li-doped (Ba0.85Ca0.15(Zr0.1Ti0.9O3 (BCZT-Li ceramics prepared by the citrate method exhibit improved phase purity, densification and electrical properties, which provide prospective possibility to develop high-performance electrocaloric materials. The electrocaloric effect was evaluated by phenomenological method, and the BCZT-Li ceramics present large electrocaloric temperature change ∆T, especially large electrocaloric responsibility ξ = ∆Tmax/∆Emax, which can be comparable to the largest values reported in the lead-free piezoelectric ceramics. The excellent electrocaloric effect is considered as correlating with the coexistence of polymorphic ferroelectric phases, which are detected by the Raman spectroscopy. The large ξ value accompanied by decreased Curie temperature (around 73 °C of the BCZT-Li ceramics prepared by the citrate method presents potential applications as the next-generation solid-state cooling devices.

  8. Temperature dependent polarization reversal mechanism in 0.94(Bi1/2Na1/2) TiO3-0.06Ba(Zr0.02Ti0.98)O3 relaxor ceramics

    DEFF Research Database (Denmark)

    Glaum, Julia; Simons, Hugh; Hudspeth, Jessica

    2015-01-01

    and structural investigation of the polarization reversal process in the prototypical lead-free relaxor 0.94(Bi1/2Na1/2)TiO3-0.06Ba(Zr0.02Ti0.98)O3 reveals that an applied electric field can trigger depolarization and onset of relaxor-like behavior well below TF-R. The polarization reversal process can...... as such be described as a combination of (1) ferroelectric domain switching and (2) a reversible phase transition between two polar ferroelectric states mediated by a non-polar relaxor state. Furthermore, the threshold fields of the second, mediated polarization reversal mechanism depend strongly on temperature....... These results are concomitant with a continuous ferroelectric to relaxortransition occurring over a broad temperature range, during which mixed behavior is observed. The nature of polarization reversal can be illustrated in electric-field-temperature (E-T) diagrams showing the electric field amplitudes...

  9. Correlation between in-field critical currents in Zr-added (Gd, Y)Ba2Cu3Ox superconducting tapes at 30 and 77 K

    International Nuclear Information System (INIS)

    Selvamanickam, V; Xu, A; Liu, Y; Khatri, N D; Galstyan, E; Majkic, G; Lei, C; Chen, Y

    2014-01-01

    Critical current (I c ) values of 1384 A/12 mm, corresponding to a critical current density of 12.47 MA cm −2 and a pinning force of 374 GN m −3 , have been achieved at 30 K, 3 T in the orientation of field parallel to the c axis (B ∥ c) in (Gd, Y)BaCuO tapes with 15 mol% Zr addition made by metal organic chemical vapor deposition (MOCVD). These tapes show pinning force levels as high as 453 GN m −3 at 30 K. An analysis of the properties of 24–28 (Gd, Y)BaCuO tapes with 15 mol% Zr addition showed a lack of correlation between their critical currents at 30 K, 3 T (B ∥ c) and I c values both at 77 K, zero field and at 77 K, 1 T (B ∥ c). However, a strong correlation was found between the critical currents at 30 K, 3 T and at 77 K, 3 T (B ∥ c). It has also been discovered that the minimum critical current (I c, min ) value at 77 K, 3 T has no influence on the I c, min value at 30 K, 3 T, and it in turn depends on the ratio of the I c values in the orientations of field parallel and perpendicular to the c axis at 77 K, 3 T. (paper)

  10. High performance fuel electrodes fabricated by electroless plating of copper on BaZr0.8Ce0.1Y0.1O3-δ proton-conducting ceramic

    Science.gov (United States)

    Patki, Neil S.; Way, J. Douglas; Ricote, Sandrine

    2017-10-01

    The stability of copper at high temperatures in reducing and hydrocarbon-containing atmospheres makes it a good candidate for fabricating fuel electrodes on proton-conducting ceramics, such as BaZr0.9-xCexY0.1O3-δ (BZCY). In this work, the electrochemical performance of Cu-based electrodes fabricated by electroless plating (ELP) on BaZr0.8Ce0.1Y0.1O3-δ is studied with impedance spectroscopy. Three activation catalysts (Pd, Ru, and Cu) are investigated and ELP is compared to a commercial Cu paste (ESL 2312-G) for electrode fabrication. The area specific resistances (ASR) for Pd, Ru, and Cu activations at 700 °C in moist 5% H2 in Ar are 2.1, 3.2, and 13.4 Ω cm2, respectively. That is a 1-2 orders of magnitude improvement over the commercial Cu paste (192 Ω cm2). Furthermore, the ASR has contributions from electrode processes and charge transfer at the electrode/electrolyte interface. Additionally, the morphology of the as-fabricated electrode is unaffected by the activation catalyst. However, heat treatment at 750 °C in H2 for 24 h leads to sintering and large reorganization of the electrode fabricated with Cu activation (micron sized pores seen in the tested sample), while Pd and Ru activations are immune to such reorganization. Thus, Pd and Ru are identified as candidates for future work with improvements to charge transfer required for the former, and better electrode processes required for the latter.

  11. Evolution of phase transformation behavior and dielectric temperature stability of BaTiO3–Bi(Zn0.5Zr0.5)O3 ceramics system

    International Nuclear Information System (INIS)

    Wang, Yiliang; Chen, Xiuli; Zhou, Huanfu; Fang, Liang; Liu, Laijun; Zhang, Hui

    2013-01-01

    Highlights: ► (1 − x)BaTiO 3 –xBi(Zn 0.5 Zr 0.5 )O 3 ceramics were synthesized. ► A systematic structural change was observed near x = 0.07 and x = 0.4. ► A change from a normal ferroelectric behavior to diffusive and dispersive relaxor-like characteristic was also observed. ► (1 − x)BT–xBZZ ceramics show good dielectric temperature stability over a wide temperature range. - Abstract: (1 − x)BaTiO 3 –xBi(Zn 0.5 Zr 0.5 )O 3 [(1 − x)BT–xBZZ, 0.01 ⩽ x ⩽ 0.6] ceramics were synthesized by solid-state reaction technique. Based on the X-ray diffraction data analysis, a systematic structure change from the ferroelectric tetragonal phase to pseudocubic phase and the pseudocubic phase to orthorhombic phase was observed near x = 0.07 and x = 0.4 at room temperature, respectively. Dielectric measurements show a dielectric anomaly, over the temperature range from 50 to 200 °C for the compositions with 0.03 ⩽ x ⩽ 0.09. A change from a normal ferroelectric behavior to diffusive and dispersive relaxor-like characteristic was also observed. Moreover, (1 − x)BT–xBZZ ceramics show good dielectric temperature stability over a wide temperature range, which indicates that these ceramics can be applied in the temperature stability devices.

  12. Magnetocapacitance of BaZr0.2Ti0.8O3 and La0.67Sr0.33MnO3 thin film heterostructures

    International Nuclear Information System (INIS)

    Tarale, A.N.; Padal, N.T.; Salunkhe, D.J.; Joshi, P.B.; Kulkarni, S.B.; Reddy, V.R.

    2012-01-01

    The present paper reports MD properties of BaZr 0.2 Ti 0.8 O 3 and La 0.67 Sr 0.33 MnO 3 (LSMO) thin film multilayer composite. The BZT is known to be relaxer possessing Curie temperature in vicinity of room temperature while LSMO is a CMR material possessing T c at room temperature. The Magnetoresistance of LSMO is known to cause change in intragrain interfacial polarization as function of applied magnetic field and dielectric constant ε H changes with applied magnetic field. From the literature survey it is observed that the MD properties based on CMR phenomena are not well investigated and efforts towards further exploration of these phenomena are required. Recent reports also indicate that that the magneto capacitance posses the contribution due giant magnetostriction of LMSO. The BZT as well as LSMO gels are synthesized using modified Pechini method. Initially hydroxide precipitates of Ba, Zr, Ti and La, Sr, Mn are dissolved in citric acid to form citrates of cations individually. The citrate solution is polymerized by addition of ethylene glycol and used as a coating solution. The alternate layers of thin films of BZT and LSMO are deposited on SiO 2 /nSi(100) substrate. The nanoparticles heterostructure are formed by sintering the thin films at 800 deg C. The thin films are investigated for crystal structure, morphology, dielectric constant, and complex impedance as a function of frequency f up to 1 MHz and magnetic field up to 5 kOe respectively. It is observed that the thin film composites exhibits magnetocapacitance of 8.3% for 1 KHz and possess a finite value even at 1MHz. The observed variation of impedance spectra in terms of Maxwell-Wagner model and in the light of the recent observation by Xiaodong Tang, et al. 2011. (author)

  13. Effect of the substrate temperature on the microstructure and texture of Mg{sub 90}Zr{sub 10} (at.%) films deposited by sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Garces, Gerardo [Department of Physical Metallurgy, CENIM, CSIC, Av. De Gregorio del Amo 8, 28040 Madrid (Spain)]. E-mail: ggarces@cenim.csic.es; Landais, Stephan [Office National dEtudes et de Recherches Aerospatiales, ONERA, BP72-29 Avenue de la Division Leclerc F-92322 Chatillon, Paris (France); Adeva, Paloma [Department of Physical Metallurgy, CENIM, CSIC, Av. De Gregorio del Amo 8, 28040 Madrid (Spain)

    2006-11-30

    The microstructure of Mg{sub 90}Zr{sub 10} (at.%) films obtained by sputtering onto copper substrate at three different temperatures (180, 320 and 350 deg. C) has been studied. Films exhibited an intense (0 0 0 1) basal plane fibre texture with the fibre axis parallel to the growth direction. Their microstructure consisted of columnar grains growing from the copper substrate to the free surface which is typical of the zone II of the Movchan and Demchishin zone model developed for PVD materials. Nevertheless, the microstructure of films was dependent on the substrate temperature. The grain diameter increased as the substrate temperature was increased. Moreover, the dislocation density inside the grains as well as that piled-up forming sub-grain boundaries decreased as the deposition temperature increased. Although the film growth in zone II is controlled by surface diffusion the larger surface mobility of the atoms as the substrate temperature increased led to changes in the solubility of zirconium. At low substrate temperatures all zirconium was in solid solution. However, at 350 deg. C the formation of small zirconium particles occurred at grain boundaries.

  14. Effects of extrusion and heat treatment on the mechanical properties and biocorrosion behaviors of a Mg-Nd-Zn-Zr alloy.

    Science.gov (United States)

    Zhang, Xiaobo; Yuan, Guangyin; Mao, Lin; Niu, Jialin; Fu, Penghuai; Ding, Wenjiang

    2012-03-01

    Mechanical properties at room temperature and biocorrosion behaviors in simulated body fluid (SBF) at 37 °C of a new type of patented Mg-3Nd-0.2Zn-0.4Zr (hereafter, denoted as JDBM) alloy prepared at different extrusion temperatures, as well as heat treatment, were studied. The mechanical properties of this magnesium alloy at room temperature were improved significantly after extrusion and heat treatment compared to an as-cast alloy. The results of mechanical properties show that the yield strength (YS) decreases with increasing extrusion temperature. The tensile elongation decreases a little while the ultimate tensile strength (UTS) has no obvious difference. The yield strength and ultimate tensile strength were improved clearly after heat treatment at 200 °C for 10 h compared with that at the extrusion state, which can be mainly contributed to the precipitation strengthening. The biocorrosion behaviors of the JDBM alloy were studied using immersion tests and electrochemical tests. The results reveal that the extruded JDBM alloy and the aging treatment on the extruded alloy show much better biocorrosion resistance than that at solid solution state (T4 treatment), and the JDBM exhibited favorable uniform corrosion mode in SBF. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Corrosion Behaviour of New Zr Alloys

    DEFF Research Database (Denmark)

    Tolksdorf, E.

    1974-01-01

    Corrosion studies have indicated that the most promising replacements for Zicaloy-2 are ZrCrFe, ZrVFe and probably ZrNbTa, provided they are in their optimized condition. These alloys are conventionally manufactured alloys. An internally oxidized ZrMgO alloy is even superior, from the corrosion...

  16. Effect of precipitates on microstructures and properties of forged Mg-10Gd-2Y-0.5Zn-0.3Zr alloy during ageing process

    International Nuclear Information System (INIS)

    Han, X.Z.; Xu, W.C.; Shan, D.B.

    2011-01-01

    Highlights: · The effect of forging process on microstructure evolution and mechanical properties of Magnesium alloy with rare earth was investigated. · The optimal mechanical properties of the alloy with high strength and enough elongation were obtained after forging and ageing process. · The strength improvement of the alloy after forging and ageing process mainly results from the precipitation of 14H-type LPSO phase. · Strengthening mechanism of the alloy is controlled by the precipitation of β' and 14H-type LPSO phases which can inhibit sliding of dislocations and growth of grain boundaries. - Abstract: The precipitate behavior during forging and ageing process of Mg-10Gd-2Y-0.5Zn-0.3Zr alloy has been investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The mechanical properties of the alloy after forging and ageing process have been evaluated using Vickers hardness and room-temperature tensile tests. The results show that precipitation of 14H-type long period stacking order (LPSO) phase is the main strengthening phase in the as-forged alloy. The LPSO phase and refinement of grains contribute to the strength improvement of the alloy after forging process. The optimal mechanical properties of the alloy are obtained when it is aged at 200 deg. C for 60 h, which mainly owes to the precipitation of large amounts of β' and 14H-type LPSO phases on the α-Mg matrix. The growth of secondary phases, widening of soft precipitate free zones and coarsening of grains during subsequent ageing process at higher temperature lead to the decrease of mechanical properties of the alloy.

  17. Water-gas shift. An examination of Pt promoted MgO and tetragonal and monoclinic ZrO2 by in situ drifts

    International Nuclear Information System (INIS)

    Chenu, Emilie; Jacobs, Gary; Crawford, Adam C.; Keogh, Robert A.; Patterson, Patricia M.; Sparks, Dennis E.; Davis, Burtron H.

    2005-01-01

    In situ DRIFTS measurements on unpromoted and Pt promoted MgO and ZrO 2 (both tetragonal and monoclinic) indicate that at high H 2 O/CO ratios, where the reaction rate has been reported to be zero order in H 2 O and first order in CO, the mechanism involved in the catalysis of water-gas shift is likely a surface formate mechanism, in agreement with Shido and Iwasawa. Pt was found to catalyze the removal of surface carbonates and to facilitate the generation of active OH groups relative to the unpromoted catalyst. Comparison with Pt/ceria revealed that the OH groups involved in the catalysis of magnesia and zirconia may be those of the bridging variety which occur at defect sites. That is, water dissociated over vacancies to produce bridging OH groups, as observed by infrared spectroscopy. The existence of such an adsorbed species is implied in the zero reaction order for water, where kinetics suggests that the surface should be saturated by an adsorbed water species. The lower extent of vacancy formation for magnesia and zirconia-based materials in comparison with ceria could explain a lower surface population of active bridging OH groups. CO was used as a probe molecule of the reduced centers, as it reacts with bridging OH groups to generate surface formates, a proposed WGS intermediate, and the decomposition of which is proposed to be the rate-limiting step. The trends in formate intensity by CO adsorption and CO conversion in WGS catalytic testing both followed the order: Pt/ceria>Pt/m-zirconia>Pt/t-zirconia>Pt/magnesia. In all cases, a normal kinetic isotope effect was observed in switching from H 2 O to D 2 O, consistent with a link between the rate-limiting step and the decomposition of surface formates, as noted previously by Shido and Iwasawa for Rh/ceria, MgO, and ZnO

  18. Investigation of (Y,Gd)Ba2Cu3O7-x grown by MOCVD on a simplified IBAD MgO template

    International Nuclear Information System (INIS)

    Stan, L; Holesinger, T G; Maiorov, B; Civale, L; DePaula, R F; Jia, Q X; Chen, Y; Xiong, X; Selvamanickam, V

    2010-01-01

    We have used an ion beam sputtered Y 2 O 3 -Al 2 O 3 (YALO) composite to simplify the architecture of high temperature superconducting (HTS) coated conductors (CCs) based on a IBAD MgO template. By implementing YALO, we have reduced the total non-superconducting layers between the polycrystalline metal substrate and the superconducting film from five (the standard architecture) to four. Well textured (Y,Gd)Ba 2 Cu 3 O 7-x ((Y, Gd)BCO) films have been successfully grown by MOCVD on this simplified template. The microstructural characterization revealed that all layers are continuous and uniform with sharp and clean interfaces. Additionally, the YALO maintained its amorphous nature after the deposition of the superconductive layer, which is a plus in terms of its efficiency as a diffusion barrier. The achievement of a self-field critical current of 230 A cm -1 at 75.5 K is another proof of the effectiveness of YALO as a diffusion barrier and nucleation seed for the MgO. The transport properties under an applied magnetic field of MOCVD grown (Y, Gd)BCO on LMO buffered MgO/YALO/Ni-alloy are comparable with those of (Y, Gd)BCO on a standard architecture, thus demonstrating good compatibility between the simplified template with the MOCVD grown (Y, Gd)BCO. The use of a single composite YALO layer instead of individual layers of Y 2 O 3 and Al 2 O 3 for the large scale fabrication of HTS CCs based on IBAD MgO provides advantages such as potentially reduced cost due to the reduced number of fabrication steps.

  19. Investigation of (Y,Gd)Ba{sub 2}Cu{sub 3}O{sub 7-x} grown by MOCVD on a simplified IBAD MgO template

    Energy Technology Data Exchange (ETDEWEB)

    Stan, L; Holesinger, T G; Maiorov, B; Civale, L; DePaula, R F; Jia, Q X [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States); Chen, Y [SuperPower, Incorporated, 450 Duane Avenue, Schenectady, NY 12304 (United States); Xiong, X; Selvamanickam, V [Mechanical Engineering Department, University of Houston, Houston, TX 77204-4006 (United States)

    2010-01-15

    We have used an ion beam sputtered Y{sub 2}O{sub 3}-Al{sub 2}O{sub 3} (YALO) composite to simplify the architecture of high temperature superconducting (HTS) coated conductors (CCs) based on a IBAD MgO template. By implementing YALO, we have reduced the total non-superconducting layers between the polycrystalline metal substrate and the superconducting film from five (the standard architecture) to four. Well textured (Y,Gd)Ba{sub 2}Cu{sub 3}O{sub 7-x} ((Y, Gd)BCO) films have been successfully grown by MOCVD on this simplified template. The microstructural characterization revealed that all layers are continuous and uniform with sharp and clean interfaces. Additionally, the YALO maintained its amorphous nature after the deposition of the superconductive layer, which is a plus in terms of its efficiency as a diffusion barrier. The achievement of a self-field critical current of 230 A cm{sup -1} at 75.5 K is another proof of the effectiveness of YALO as a diffusion barrier and nucleation seed for the MgO. The transport properties under an applied magnetic field of MOCVD grown (Y, Gd)BCO on LMO buffered MgO/YALO/Ni-alloy are comparable with those of (Y, Gd)BCO on a standard architecture, thus demonstrating good compatibility between the simplified template with the MOCVD grown (Y, Gd)BCO. The use of a single composite YALO layer instead of individual layers of Y{sub 2}O{sub 3} and Al{sub 2}O{sub 3} for the large scale fabrication of HTS CCs based on IBAD MgO provides advantages such as potentially reduced cost due to the reduced number of fabrication steps.

  20. High dielectric constant observed in (1 − x)Ba(Zr{sub 0.07}Ti{sub 0.93})O{sub 3}–xBa(Fe{sub 0.5}Nb{sub 0.5})O{sub 3} binary solid-solution

    Energy Technology Data Exchange (ETDEWEB)

    Kruea-In, Chatchai [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Eitssayeam, Sukum; Pengpat, Kamonpan [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); Rujijanagul, Gobwute, E-mail: rujijanagul@yahoo.com [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)

    2012-10-15

    Binary solid-solutions of the (1 − x)Ba(Zr{sub 0.07}Ti{sub 0.93})O{sub 3}–xBa(Fe{sub 0.5}Nb{sub 0.5}O{sub 3}) system, with 0.1 ≤ x ≤ 0.9,were fabricated via a solid-state processing technique. X-ray diffraction analysis revealed that all samples exhibited a single perovskite phase. The BaFe{sub 0.5}Nb{sub 0.5}O{sub 3} also promoted densification and grain growth of the system. Dielectric measurements showed that all samples displayed a relaxor like behavior. The x = 0.1 sample presented a dielectric-frequency and temperature with low loss tangent (<0.07 at 10 kHz). For x > 0.2 samples, the dielectric data showed a broad dielectric constant–temperature curve with a giant dielectric characteristic. In addition, a high dielectric constant > 50,000 (at 10 kHz and temperature > 150 °C) was observed for the x = 0.9 sample.

  1. Energy storage properties and relaxor behavior of lead-free Ba1-xSm2x/3Zr0.15Ti0.85O3 ceramics.

    Science.gov (United States)

    Sun, Zheng; Li, Lingxia; Yu, Shihui; Kang, Xinyu; Chen, Siliang

    2017-10-24

    Lead-free Ba 1-x Sm 2x/3 Zr 0.15 Ti 0.85 O 3 (BSZT) ceramics were synthesized by a solid state reaction route. The microstructure, dielectric relaxor behavior and energy storage properties of BSZT ceramics were studied. The growth of grain size was suppressed with the increase of Sm addition and kept in the submicrometer scale. Successive substitution of Sm 3+ for Ba 2+ disrupted the long-range dipole and promoted the increase of polar nano-region (PNR) size, resulting in the enhanced degree of relaxor behavior. The increasing PNR size also lead to the slimmer hysteresis loops and improved the energy storage efficiency. Furthermore, high saturated polarization (P max ) and low remnant polarization (P r ) were obtained due to the formation of defect dipoles, which facilitated the switch of PNRs and contributed to the enhancement of energy storage density. The x = 0.003 sample was found to exhibit a higher energy storage density of 1.15 J cm -3 and an energy storage efficiency of 92%. The result revealed that the BSZT ceramics may be a good candidate for energy storage application.

  2. Structural and pinning properties of Y2Ba4CuMOy (M = Nb,Zr)/YBa2Cu3O7-δ quasi-multilayers fabricated by off-axis pulsed laser deposition

    International Nuclear Information System (INIS)

    Reich, E; Thersleff, T; Huehne, R; Iida, K; Schultz, L; Holzapfel, B

    2009-01-01

    Power applications based on YBa 2 Cu 3 O 7-δ coated conductors demand an enhancement of the critical current density J c in magnetic fields to be achieved using artificial pinning centres. A well-known approach to studying pinning by second phase nanoparticles is based on quasi-multilayer deposition of YBa 2 Cu 3 O 7-δ (Y123) and a dopant material. In this study we use the Y 2 Ba 4 CuMO y (M = Nb, Zr; M2411) phase as a dopant material, which proved to be very successful in increasing J c for bulk samples. Although stability of the M2411 phase in bulk Y123 has been reported, experimental evidence of its stability in thin films is still lacking. We found that during the quasi-multilayer deposition, yttrium doped Ba(M 1-x Y x )O 3 forms instead of the M2411 secondary phase, and this causes an increase of J c at high magnetic fields as well as an increase in the irreversibility field below 80 K as compared against pure Y123 thin films.

  3. Ba{sub 2.2}Ca{sub 0.8}Mg{sub 4}F{sub 14}, a new ''solid solution stabilized'' matrix for an intense blue phosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kubel, F.; Pantazi, M. [TU Vienna, Inst. of Chemical Technologies and Analytics, Getreidemarkt 9, 164-SC, 1060 Vienna (Austria); Hagemann, H. [Departement de Chimie Physique, Universite de Geneve, 30, quai E.Ansermet, 1211 Geneva 4 (Switzerland)

    2011-09-15

    Barium calcium magnesium fluoride (Ba{sub 2}(Ba{sub x}Ca{sub 1-x})Mg{sub 4}F{sub 14}, x=0.19-0.26) has been synthesized at 850 C from precursors prepared by the solution precipitation method. Single crystals with composition of Ba{sub 2.200(2)}Ca{sub 0.800(2)}Mg{sub 4}F{sub 14}were obtained after prolonged heating. Lattice parameters from single crystal data are a = 12.4203(8) and c = 7.4365(5) A [tetragonal, space group P4{sub 2}/mnm (No. 136)]. They increase with increasing barium concentration within a given stability window. The structure is built of a network of MgF{sub 6} octahedra forming a pyrochlore related channel system and isolated fluorine ions. Within the channels, heavy alkaline earth ions are located. The wide channel is filled with off-center positioned barium ions. The channel with a narrow cross section hosts both ions, Ca{sup 2+}and Ba{sup 2+}. The structure is isotypic with Pb{sub 3}Nb{sub 4}O{sub 12}F{sub 2} but has a different coordination around Ba/Ca and Pb, respectively. Doped with {proportional_to}1% Eu(II), the compound shows intense blue luminescence under UV activation. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. CHARACTERIZATION OF COMMERCIALLY AVAILABLE ALKALI RESISTANT GLASS FIBER FOR CONCRETE REINFORCEMENT AND CHEMICAL DURABILITY COMPARISON WITH SrO-Mn2O3-Fe2O3-MgO-ZrO2-SiO2 (SMFMZS SYSTEM GLASSES

    Directory of Open Access Journals (Sweden)

    Göktuğ GÜNKAYA

    2012-12-01

    Full Text Available According to the relevant literature, the utilization of different kind of glass fibers in concrete introduces positive effect on the mechanical behavior, especially toughness. There are many glassfibers available to reinforce concretes. Glass fiber composition is so important because it may change the properties such as strength, elastic modulus and alkali resistance. Its most important property to be used in concrete is the alkali resistance. Some glasses of SrO–MgO–ZrO2–SiO2 (SMZS quaternary system, such as 26SrO, 20MgO, 14ZrO2, 40SiO2 (Zrn glass, have been found to be highly alkali resistant thanks to their high ZrO2 and MgO contents. Previous researches on these glasses with MnO and/or Fe2O3 partially replacing SrO have been made with the aim of improving the chemical resistance and decreasing the production cost.The main target of the present study, first of all, was to characterize commercially available alkali resistant glass fiber for concrete reinforcement and then to compare its alkali durability with those of the SrO-Mn2O3-Fe2O3-MgO-ZrO2-SiO2 (SMFMZS system glasses. For such purposes, XRF, Tg-DTA, alkali resistance tests and SEM analysis conducted with EDX were employed. According tothe alkali endurance test results it was revealed that some of the SMFMZS system glass powders are 10 times resistant to alkali environments than the commercial glass fibers used in this study.Therefore, they can be considered as alternative filling materials on the evolution of chemically resistant concrete structures.

  5. Microstructure, electrical and optical characteristics of Mg(Zr{sub 0.05}Ti{sub 0.95})O{sub 3} thin films grown on Si substrate by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Ching-Fang, E-mail: cftseng@nuu.edu.tw; Chen, Wen-Shiush; Lee, Chih-Wen

    2011-05-31

    Optical properties and microstructures of Mg(Zr{sub 0.05}Ti{sub 0.95})O{sub 3} thin films prepared by sol-gel method on n-type Si(100) substrates at different annealing temperatures have been investigated. The surface structural and morphological characteristics analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscope (AFM) were found to be sensitive to the deposition conditions, such as annealing temperature (600-800 deg. C). The optical transmittance spectra of the Mg(Zr{sub 0.05}Ti{sub 0.95})O{sub 3} thin films were measured by using UV-visible recording spectro-photometer. The diffraction pattern showed that the deposited films exhibited a polycrystalline microstructure. All films exhibited Mg(Zr{sub 0.05}Ti{sub 0.95})O{sub 3} peaks orientation perpendicular to the substrate surface and the grain size with the increase in the annealing temperature. The dependence of the microstructure and dielectric characteristics on annealing temperature was also investigated.

  6. Precipitation behaviors, texture and tensile properties of an extruded Mg-7Y-1Nd-0.5Zr (wt%) alloy bar with large cross-section

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Guoliang, E-mail: shigl@grinm.com; Zhang, Kui; Li, Xinggang; Li, Yongjun; Ma, Minglong; Yuan, Jiawei

    2017-02-08

    Precipitation behaviors, texture and tensile properties of an extruded Mg-7Y-1Nd-0.5Zr (wt%) (WE71) alloy bar with large cross-section of 230 mm×140 mm were investigated by hardness test, tensile test, optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD) macro-texture measurement. The bar was manufactured industrially through a procedure of “multi-direction forging (MDF)+extrusion+on-line quenching+T5 aging”. Totally different age-hardening behaviors are shown during T5 aging at 200 and 235 °C. In the first 100 h, T5 aging at 235 °C brings about 13% increases in hardness, while T5 aging at 200 °C results in 47% increase. During T5 aging at 200 °C, β′ precipitates homogeneously nucleate within the matrix with high number density; however, during T5 aging at 235 °C, β′ precipitates heterogeneously nucleate on discrete and sparse dislocations, resulting in chain-like arrangement of β′ precipitates with broad precipitate free zones in matrix. XRD macro-texture measurement illustrates that basal texture intensity of WE71 bar is much weaker than Mg-8Al-0.5Zn-0.15Mn (wt%) (AZ80) bar; the maximum basal texture intensities in the outer (O) and center (C) of WE71 bar are all about 3, while those of AZ80 bar are 17 and 14, respectively. EBSD micro-texture measurement demonstrates that the maximum texture intensities of C and O are 5.3 and 3.5, respectively. O has higher tensile properties than C because there are more un-dynamic-recrystallization (un-DRX) grains and thus larger average grain size in C. While stretching at room temperature (RT), extrusion direction (ED) in O has the best tensile properties, i.e. ultimate tensile strength (R{sub m})=368 MPa, elongation (A)=5%, and normal direction (ND) in C has the lowest tensile properties, i.e. R{sub m}=255 MPa, A=2%. While stretching at 200 °C, strength does not degrade much; ED in O still has

  7. Effect of ZrO(2) additions on the crystallization, mechanical and biological properties of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics.

    Science.gov (United States)

    Li, H C; Wang, D G; Meng, X G; Chen, C Z

    2014-06-01

    A series of ZrO(2) doped MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics were obtained by sintering method. The crystallization behavior, phase composition, morphology and structure of glass-ceramics were characterized. The bending strength, elastic modulus, fracture toughness, micro-hardness and thermal expansion coefficient (TEC) of glass-ceramics were investigated. The in vitro bioactivity and cytotoxicity tests were used to evaluate the bioactivity and biocompatibility of glass-ceramics. The sedimentation mechanism and growth process of apatites on sample surface were discussed. The results showed that the mainly crystalline phases of glass-ceramics were Ca(5)(PO4)3F (fluorapatite) and β-CaSiO(3). (β-wollastonite). m-ZrO(2) (monoclinic zirconia) declined the crystallization temperatures of glasses. t-ZrO(2) (tetragonal zirconia) increased the crystallization temperature of Ca(5)(PO4)(3)F and declined the crystallization temperature of β-CaSiO(3). t-ZrO(2) greatly increased the fracture toughness, bending strength and micro-hardness of glass-ceramics. The nanometer apatites were induced on the surface of glass-ceramic after soaking 28 days in SBF (simulated body fluid), indicating the glass-ceramic has good bioactivity. The in vitro cytotoxicity test demonstrated the glass-ceramic has no toxicity to cell. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Buffer-layer enhanced crystal growth of BaB6 (1 0 0) thin films on MgO (1 0 0) substrates by laser molecular beam epitaxy

    International Nuclear Information System (INIS)

    Kato, Yushi; Yamauchi, Ryosuke; Arai, Hideki; Tan, Geng; Tsuchimine, Nobuo; Kobayashi, Susumu; Saeki, Kazuhiko; Takezawa, Nobutaka; Mitsuhashi, Masahiko; Kaneko, Satoru; Yoshimoto, Mamoru

    2012-01-01

    Crystalline BaB 6 (1 0 0) thin films can be fabricated on MgO (1 0 0) substrates by inserting a 2-3 nm-thick epitaxial SrB 6 (1 0 0) buffer layer by pulsed laser deposition (PLD) in ultra-high vacuum (i.e., laser molecular beam epitaxy). Reflection high-energy electron diffraction and X-ray diffraction measurements indicated the heteroepitaxial structure of BaB 6 (1 0 0)/SrB 6 (1 0 0)/MgO (1 0 0) with the single domain of the epitaxial relationship. Conversely, BaB 6 thin films without the buffer layer were not epitaxial instead they developed as polycrystalline films with a random in-plane configuration and some impurity phases. As a result, the buffer layer is considered to greatly affect the initial growth of epitaxial BaB 6 thin films; therefore, in this study, buffering effects have been discussed. From the conventional four-probe measurement, it was observed that BaB 6 epitaxial thin films exhibit n-type semiconducting behavior with a resistivity of 2.90 × 10 -1 Ω cm at room temperature.

  9. Differences in photoluminescence properties and thermal degradation between nanoparticle and bulk particle BaMgAl10O17:Eu2+ phosphors under UV?VUV irradiation.

    Science.gov (United States)

    Liu, Bitao; Xin, Shuangyu; Li, Fenghua; Zhang, Jiachi; Wang, Yuhua

    2014-05-01

    BaMgAl10O17:Eu2+ (BAM) phosphors used for plasma display panels and three-band fluorescence lamps are exposed to an oxidizing environment at about 500 degrees C, which is currently unavoidable in actual applications. We investigated the mechanism of the luminance degradation of BAM caused by annealing at 500 degrees C based on the difference in luminance degradation of bulk particle and nanoparticle samples under various excitation source irradiations. When the samples were excited by the different light sources, more than 30% degradation of luminance occurred under 147 nm while less than 10% degradation occurred under 254 nm both for nanoparticle and bulk particle samples. In addition, the luminescence degradation of nanophosphors shows a different tendency compared to the bulk phosphors. With a model based on the particle size and excitation light penetration depth, we demonstrate that the degradation is still mainly ascribed to the oxidized of divalent Eu. The differences in luminescence properties between nanophosphors and bulk phosphors are also illustrated by this model. As a result, the potential industrial applications of nanophosphors are evaluated.

  10. Effects of Nb and Sr doping on crystal structure of epitaxial BaTiO3 thin films on MgO substrates

    International Nuclear Information System (INIS)

    Kim, Yongsam; Chen, Chunhua; Saiki, Atsushi; Wakiya, Naoki; Shinozaki, Kazuo; Mizutani, Nobuyasu

    2002-01-01

    Niobium (Nb) and strontium (Sr) doped barium titanate (BT) films were deposited by radio frequency (RF) magnetron sputtering with Nb and Sr doped BT ceramic targets, respectively. The effect of Nb and Sr doping on the crystal structure of epitaxial BaTiO 3 thin films on MgO substrates was investigated. The crystal structure of the films was examined using the reciprocal space mapping measurement. All the films exhibit a cube-on-cube relation with respect to the substrates. As the amount of doped Sr increased, both of the in-plane and out-of-plane lattice constants of Sr doped BT films slowly approached the BT bulk values. On the other hand, the lattice constants of Nb doped BT films were rapidly coming close to the bulk values. These indicated that the lattices of doped BT films were relaxed as the amount of doped elements increased. In addition, Nb doping had greater influence on the relaxation of the films than Sr doping for the same content of dopant. (author)

  11. Surface exchange kinetics and chemical diffusivities of BaZr{sub 0.2}Ce{sub 0.65}Y{sub 0.15}O{sub 3−δ} by electrical conductivity relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Dae-Kwang; Jeon, Sang-Yun; Singh, Bhupendra [Ionics Lab, School of Materials Science and Engineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwang-Ju 500-757 (Korea, Republic of); Park, Jun-Young [Department of Advanced Materials Engineering, Sejong University, Seoul 143-747 (Korea, Republic of); Song, Sun-Ju, E-mail: song@chonnam.ac.kr [Ionics Lab, School of Materials Science and Engineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwang-Ju 500-757 (Korea, Republic of)

    2014-10-15

    Highlights: • Electrical conductivity relaxation in BaCe{sub 0.65}Zr{sub 0.2}Y{sub 0.15}O{sub 3−δ} was monitored. • Monotonic relaxation behavior was observed during oxidation/reduction. • Nonmonotonic twofold relaxation behavior was observed during hydration/dehydration. • Surface exchange coefficients and diffusivities of O and H were calculated. - Abstract: Perovskite-type oxide BaCe{sub 0.65}Zr{sub 0.2}Y{sub 0.15}O{sub 3−δ} (BCZY2015) was synthesized by a solid state reaction method. BCZY2015 samples were characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The time dependent variation in electrical conductivity of BCZY2015 was monitored during the oxidation/reduction in oxygen partial pressure (pO{sub 2}) range of −2.28 ⩽ log (pO{sub 2}/atm) ⩽ −0.68 at a fixed water vapor pressure (pH{sub 2}O), and during the hydration/dehydration in −3.15 ⩽ log (pH{sub 2}O/atm) ⩽ −2.35 range in air. The electrical conductivity showed a monotonic relaxation behavior by the ambipolar diffusion of V{sub o}{sup ··} and OH{sub o}{sup ·} during the oxidation/reduction and the relaxation process was governed by the diffusivity of oxygen (D-tilde{sub vO}). On the other hand, during the hydration/dehydration process, a non-monotonic twofold relaxation behavior was observed due to the decoupled diffusion of H and O components with the mediation of holes, and the conductivity relaxation process was governed by the diffusivities of both H (D-tilde{sub iH}) and O (D-tlde{sub vH}). The values of surface exchange coefficients and diffusivities of oxygen and hydrogen were calculated from Fick’s second law by the nonlinear least squares fitting of the conductivity data, as proposed by Yoo et al. (2008)

  12. Polymorphic phase transition and morphotropic phase boundary in Ba{sub 1-x}Ca{sub x}Ti{sub 1-y}Zr{sub y}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Abdessalem, M. Ben; Aydi, S.; Aydi, A.; Abdelmoula, N.; Khemakhem, H. [Universite de Sfax, Faculte des Sciences de Sfax (FSS), Laboratoire des Materiaux Multifonctionnels et Applications (LaMMA) LR16ES18, B.P.1171, Sfax (Tunisia); Sassi, Z. [Laboratoire de Genie Electrique et Ferroelectricite (LGEF) de L' INSA de Lyon, Lyon (France)

    2017-09-15

    This paper deals with Ca and Zr co-doped BaTiO{sub 3} (BCTZ{sub (x,} {sub y)}) (x = 0.1, 0.13, 0.2 and y = 0.05, 0.1, 0.15). These ceramics were prepared using the conventional solid state method. The symmetry, dielectric properties, Raman spectroscopy, ferroelectric behavior and piezoelectric effect were examined. X-ray diffraction (XRD) results display that morphotropic boundary occurs from tetragonal to orthorhombic region of BCZT{sub (x=0.1,} {sub 0.2,} {sub y=0.05,} {sub 0.1)} and polymorphic phase transitions from tetragonal to orthorhombic, orthorhombic to rhombohedral regions of BCZT{sub (x=0.13,} {sub y=0.1)}. The evolution of the Raman spectra was investigated as a function of compositions at room temperature, in correlation with XRD analysis and dielectric measurements. We note that the substitution of Ca in Ba site and Zr ions in Ti site slightly decreased the cubic-tetragonal temperature transition (T{sub C}) and increased the orthorhombic-tetragonal (T{sub 1}) and rhombohedral-orthorhombic (T{sub 2}) temperatures transitions. The ferroelectric properties were examined by a P-E hysteresis loop. The two parameters ΔT{sub 1} and ΔT{sub 2} are defined as ΔT{sub 1} = T{sub C} - T{sub 1} and ΔT{sub 2} = T{sub C} - T{sub 2}, they come close to T{sub C} for x = 0.13, y = 0.1, which reveals that this composition is around the polymorphic phase. The excellent piezoelectric coefficient of d{sub 33} = 288 pC N{sup -1}, the electromechanical coupling factor k{sub p} = 40%, high constant dielectric 9105, coercive field E{sub c} = 0.32 (KV mm{sup -1}) and remanent polarization P{sub r} = 0.1 (μc mm{sup -2}) were obtained for composition x = 0.13, y = 0.1. (orig.)

  13. Bias polarization study of steam electrolysis by composite oxygen electrode Ba0.5Sr0.5Co0.8Fe0.2O3-δ/BaCe0.4Zr0.4Y0.2O3-δ

    Science.gov (United States)

    Yang, Tao; Shaula, Aliaksandr; Pukazhselvan, D.; Ramasamy, Devaraj; Deng, Jiguang; da Silva, E. L.; Duarte, Ricardo; Saraiva, Jorge A.

    2017-12-01

    The polarization behavior of Ba0.5Sr0.5Co0.8Fe0.2O3-δ-BaCe0.4Zr0.4Y0.2O3-δ (BSCF-BCZY) electrode under steam electrolysis conditions was studied in detail. The composite oxygen electrode supported by BCZY electrolyzer has been assessed as a function of temperature (T), water vapor partial pressures (pH2O), and bias polarization voltage for electrodes of comparable microstructure. The Electrochemical impedance spectra show two depressed arcs in general without bias polarization. And the electrode resistance became smaller with the increase of the bias polarization under the same water vapor partial pressures. The total resistance of the electrode was shown to be significantly affected by temperature, with the same level of pH2O and bias polarization voltage. This result highlights BSCF-BCZY as an effective oxygen electrode under moderate polarization and pH2O conditions.

  14. Mechanisms Responsible for the Large Piezoelectricity at the Tetragonal-Orthorhombic Phase Boundary of (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 System.

    Science.gov (United States)

    Yang, Tao; Ke, Xiaoqin; Wang, Yunzhi

    2016-09-16

    Recently it was found that in the lead-free (1-x)BaZr0.2Ti0.8O3-xBa0.7Ca0.3TiO3 (BZT-xBCT) system, the highest piezoelectric d33 coefficient appears at the tetragonal (T) - orthorhombic (O) phase boundary rather than the O - rhombohedral (R) phase boundary, but the physical origin of it is still unclear. In this work we construct the phase diagram of the BZT-xBCT system using a generic sixth-order Landau free energy polynomial and calculate the energy barrier (EB) for direct domain switching between two variants of the stable low-symmetry ferroelectric phase. We find that the EB at the T-O phase boundary is lower than that at the O-R phase boundary and EB may serve as a rigorous quantitative measure of the degree of polarization anisotropy through Landau potential. The calculations may shed some light on the physical origin of the highest piezoelectric coefficients as well as the softest elastic compliance at the T-O phase boundary observed in experiments.

  15. Symmetry determination on Pb-free piezoceramic 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 using convergent beam electron diffraction method

    International Nuclear Information System (INIS)

    Gao, Jinghui; Zhong, Lisheng; Zhang, Lixue; Xue, Dezhen; Kimoto, Takayoshi; Song, Minghui; Ren, Xiaobing

    2014-01-01

    (1−x)(Ba(Zr 0.2 Ti 0.8 )O 3 -x(Ba 0.7 Ca 0.3 )TiO 3 (BZT-xBCT) Pb-free piezoceramic has been reported showing ultrahigh piezoelectric performance in its morphotropic phase boundary (MPB) region. However, the crystal structure characteristic for the MPB composition of BZT-xBCT is still under debate—between single orthorhombic phase and tetragonal + rhombohedral two phase mixture. In the present study, we perform the local symmetry determination on the MPB composition x = 0.5 using convergent beam electron diffraction analysis (CBED). Our CBED results from multiple zone axes suggest that there are two coexisting phases with the point group symmetries of 4 mm (tetragonal) and 3 m (rhombohedral) respectively, which agree with two phase mixture model. The strong piezoelectricity can thus be understood by considering the polarization rotation between tetragonal and rhombohedral phases by external field

  16. In situ transmission electron microscopy studies of microstructure evolution in Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} piezoceramic

    Energy Technology Data Exchange (ETDEWEB)

    Zakhozheva, Marina

    2016-10-21

    The purpose of this work is to understand the microstructural features which contribute to the strong electromechanical properties of the lead-free Ba (Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} (BZT-xBCT) piezoelectric ceramic. Detailed conventional transmission electron microscopy (TEM) studies on a broad variety of BZT - xBCT were performed in order to demonstrate the composition dependent structural changes. Moreover, several in situ TEM techniques, including in situ hot- and cold-stage, in situ electric field and in situ electric field with simultaneous cooling, were successfully applied in order to monitor the domain morphology evolution in real time. By means of in situ temperature dependent TEM experiments it was shown that during rhombohedral → orthorhombic → tetragonal phase transition the domain morphology changed according to the crystal structure present. During in situ electric field investigations the displacement of the domain walls and changes in the domain configuration during electrical poling were observed, which indicates a high extrinsic contribution to the piezoelectric response in all BZT - xBCT compositions studied. From the results of in situ electric field TEM experiments with simultaneous cooling, we obtained experimental evidence that the further the composition deviates from the polymorphic phase boundary, the higher the electric field required to fully pole the material.

  17. BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.1}Yb{sub 0.1}O{sub 3-{delta}} electrolyte-based solid oxide fuel cells with cobalt-free PrBaFe{sub 2}O{sub 5+{delta}} layered perovskite cathode

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Hanping; Xue, Xingjian [Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2010-10-15

    A new anode-supported SOFC material system Ni-BZCYYb vertical stroke BZCYYb vertical stroke PBFO is investigated, in which a cobalt-free layered perovskite oxide, PrBaFe{sub 2}O{sub 5+{delta}} (PBFO), is synthesized and employed as a novel cathode while the synthesized BZCYYb is used as an electrolyte. The cell is fabricated by a simple dry-pressing/co-sintering process. The cell is tested and characterized under intermediate temperature range from 600 to 700 C with humified H{sub 2} ({proportional_to}3% H{sub 2}O) as fuel, ambient air as oxidant. The results show that the open-circuit potential of 1.006 V and maximal power density of 452 mW cm{sup -2} are achieved at 700 C. The polarization resistance of the electrodes is 0.18 {omega} cm{sup 2} at 700 C. Compared to BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.1}O{sub 3-{delta}}, the conductivity of co-doped barium zirconate-cerate BZCYYb is significantly improved. The ohmic resistance of single cell is 0.37 {omega} cm{sup 2} at 700 C. The results indicate that the developed Ni-BZCYYb vertical stroke BZCYYb vertical stroke PBFO cell is a promising functional material system for SOFCs. (author)

  18. Electric-field control of electronic transport properties and enhanced magnetoresistance in La0.7Sr0.3MnO3/0.5BaZr0.2Ti0.8O3-0.5Ba0.7Ca0.3TiO3 lead-free multiferroic structures

    Science.gov (United States)

    Yan, Jian-Min; Gao, Guan-Yin; Liu, Yu-Kuai; Wang, Fei-Fei; Zheng, Ren-Kui

    2017-10-01

    We report the fabrication of lead-free multiferroic structures by depositing ferromagnetic La0.7Sr0.3MnO3 (LSMO) polycrystalline films on polished 0.5BaZr0.2Ti0.8O3-0.5Ba0.7Ca0.3TiO3 (BZT-BCT) piezoelectric ceramic substrates. By applying electric fields to the BZT-BCT along the thickness direction, the resistivity of LSMO films can be effectively manipulated via the piezoelectric strain of the BZT-BCT. Moreover, the LSMO polycrystalline films exhibit almost temperature independent and significantly enhanced magnetoresistance (MR) below TC. At T = 2 K and H = 8 T, the MR of polycrystalline films is approximately two orders of magnitude higher than that of LSMO epitaxial films grown on (LaAlO3)0.3(SrAl1/2Ta1/2O3)0.7 single-crystal substrates. The enhanced MR mainly results from the spin-polarized tunneling of charge carriers across grain boundaries. The LSMO/BZT-BCT structures with electric-field controllable modulation of resistivity and enhanced MR effect may have potential applications in low-energy consumption and environmentally friendly electronic devices.

  19. A comparative study of SrO and BaO doping to CeO2-ZrO2: Characteristic and its catalytic performance for three-way catalysts

    International Nuclear Information System (INIS)

    Guo, Jiaxiu; Shi, Zhonghua; Wu, Dongdong; Yin, Huaqiang; Gong, Maochu; Chen, Yaoqiang

    2013-01-01

    Graphical abstract: Display Omitted Highlights: ► The prepared materials have a face-centered cubic structure and nanosize particles. ►Comparing to CZB, aged CZS has 494 μmol/g of OSC and 30 m 2 /g of surface area. ► CZS and CZB have similar NO sorption and reductive properties and different H 2 uptake. ► T 50 of Pt-Rh/CZS/LA is as low as 199 °C for CO, 228 °C for NO, and 252 °C for C 3 H 8 . ► Pt-Rh/CZS/LA has wider working-window at 320 °C under different λ value. -- Abstract: Ceria-zirconia-strontia (Ce 0.35 Zr 0.55 Sr 0.10 O 1.9 ) and ceria-zirconia-baria (Ce 0.35 Zr 0.55 Ba 0.10 O 1.9 ) were synthesized using an oxidation-co-precipitation method with hydrogen peroxide (H 2 O 2 ) as oxidant. The physical and chemical properties of the prepared materials were investigated using Brunauer–Emmett–Teller surface area characterization, transmission electron microscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, and oxygen pulse reaction. The prepared materials were used in preparing three-way catalysts with low Pt and Rh content. Moreover, catalytic activities were evaluated at a fixed bed under a simulated gaseous mixture. The results are as follows: (1) the prepared materials have a face-centered cubic structure and are nano-sized; (2) aged Ce 0.35 Zr 0.55 Sr 0.10 O 1.9 has higher oxygen storage capacity (494 μmol/g), better thermal stability (30 m 2 /g), good low-temperature reducibility, and high hydrogen uptake after TPR-redox cycles; (3) the light-off temperature (T 50 ) of Pt-Rh/CZS/LA can be as low as 199 °C for CO, 228 °C for NO, and 252 °C for C 3 H 8 ; and (4) Pt-Rh/CZS/LA has a fairly wide working-window.

  20. Assessment of stability of ceramics type perovskite, Ba{sub 2}MgWO{sub 6}, submerged in crude oil taken from oil wells of Sergipe - Brazil; Avaliacao da estabilidade de ceramicas tipo perovskita, Ba{sub 2}MgWO{sub 6}, submersas em petroleo cru retirado de pocos do estado de Sergipe - Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Yadava, Y.P.; Sales, D.G.; Lima, M.M.; Ferreira, R.A.S. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)], e-mail: daniella_guedes@yahoo.com.br

    2008-07-01

    Oil wells are harsh environments, thus, it is necessary to find materials that are able to resist the weather imposed by these sites. Many of the new technology incorporating ceramic components because their chemical properties, electrical, mechanical, thermal and structural. The ceramics exhibit high hardness and therefore resistant to high pressure, have high melting point, resisting the high temperatures, and make inert nature in hostile environments. The ceramics, type Perovskite Ba{sub 2}MgWO{sub 6}, were submerged in crude oil for thirty days and then examined by X-ray diffraction, optical microscopy and Vickers microhardness to see if there were changes in structural characteristics, microstructural and mechanical properties. This work was evaluated and discussed by these results, the stability of these ceramics when subject to attack by crude oil taken from oil wells of land and sea state of Sergipe, Brazil. (author)

  1. Grain-size dependence of the deterioration of oxygen transport for pure and 3 mol% Zr-doped Ba0.5Sr0.5Co0.8Fe0.2O3-δ induced by thermal annealing

    NARCIS (Netherlands)

    Saher, S.; Meffert, M.; Störmer, H.; Gerthsen, D.; Bouwmeester, Henricus J.M.

    2017-01-01

    In this study, the influence of long-term annealing at intermediate temperatures on oxygen transport of Ba0.5Sr0.5Co0.8Fe0.2O3 d (BSCF) and 3 mol% Zr-doped BSCF (BSCF-Z3) ceramics with different grain sizes was studied by means of in situ electrical conductivity relaxation (ECR) measurements.

  2. Electrical properties and phase transition of Ba(Zr{sub 0.05}Ti{sub 0.95}){sub 1−x}(Fe{sub 0.5}Ta{sub 0.5}){sub x}O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Kruea-In, C. [Faculty of Science and Technology, Chiang Mai Rajabhat University (Thailand); Rujijanagul, G., E-mail: rujijanagul@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University (Thailand)

    2015-09-15

    Highlights: • Properties of of Ba(Zr{sub 0.05}Ti{sub 0.95}){sub 1−x}(Fe{sub 0.5}Ta{sub 0.5}){sub x}O{sub 3} ceramics were investigated. • Small amount of dopant produced a large change in dielectric and phase transition. • A phase diagram of Ba(Zr{sub 0.05}Ti{sub 0.95}){sub 1−x}(Fe{sub 0.5}Ta{sub 0.5}){sub x}O{sub 3} ceramics was proposed. • Dielectric tunability increased with increasing x concentration. - Abstract: In this work, properties of Ba(Zr{sub 0.05}Ti{sub 0.95}){sub 1−x}(Fe{sub 0.5}Ta{sub 0.5}){sub x}O{sub 3} ceramics with 0.00≤ x ≤0.07 were investigated. The ceramics were fabricated by a solid state reaction technique. X-ray diffraction analysis indicated that all samples exhibited single phase perovskite. Examination of the dielectric spectra revealed that the Fe and Ta additives promoted a diffuse phase transition, and the two phase transition temperatures, as observed in the dielectric curve of pure Ba(Zr{sub 0.05}Ti{sub 0.95})O{sub 3}, merged into a single phase transition temperature for higher x concentrations. The transformation was confirmed by ferroelectric measurements. In addition, the doped ceramics exhibited high relative dielectric tunability, especially for higher x concentration samples.

  3. Intermediate-to-low temperature protonic ceramic membrane fuel cells with Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}}-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} composite cathode

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Bin; Ding, Hanping; Dong, Yingchao; Wang, Songlin; Zhang, Xiaozhen; Fang, Daru; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China)

    2009-01-01

    The perovskite-type Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}}-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BSCF-BZCY) composite oxides were synthesized by a modified Pechini method and examined as a novel composite cathode for intermediate-to-low temperature protonic ceramic membrane fuel cells (ILT-PCMFCs). Thin proton-conducting BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (BZCY) electrolyte and NiO-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} (NiO-BZCY) anode functional layer were prepared over porous anode substrates composed of NiO-BaZr{sub 0.1}Ce{sub 0.7}Y{sub 0.2}O{sub 3-{delta}} by a one-step dry-pressing/co-firing process. A laboratory-sized quad-layer cell of NiO-BZCY/NiO-BZCY({proportional_to}50 {mu}m)/BZCY({proportional_to}20 {mu}m)/BSCF-BZCY({proportional_to}50 {mu}m) was operated from 550 to 700 C with humidified hydrogen ({proportional_to}3% H{sub 2}O) as fuel and the static air as oxidant. A high open-circuit potential of 1.009 V, a maximum power density of 418 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.10 {omega} cm{sup 2} was achieved at 700 C. These investigations have indicated that proton-conducting BZCY electrolyte with BSCF perovskite cathode is a promising material system for the next generation solid oxide fuel cells (SOFCs). (author)

  4. Electrochemical Behavior Assessment of As-Cast Mg-Y-RE-Zr Alloy in Phosphate Buffer Solutions (X Na3PO4 + Y Na2HPO4) Using Electrochemical Impedance Spectroscopy and Mott-Schottky Techniques

    Science.gov (United States)

    Fattah-alhosseini, Arash; Asgari, Hamed

    2018-05-01

    In the present study, electrochemical behavior of as-cast Mg-Y-RE-Zr alloy (RE: rare-earth alloying elements) was investigated using electrochemical tests in phosphate buffer solutions (X Na3PO4 + Y Na2HPO4). X-ray diffraction techniques and Scanning electron microscopy equipped with energy dispersive x-ray spectroscopy were used to investigate the microstructure and phases of the experimental alloy. Different electrochemical tests such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis were carried out in order to study the electrochemical behavior of the experimental alloy in phosphate buffer solutions. The PDP curves and EIS measurements indicated that the passive behavior of the as-cast Mg-Y-RE-Zr alloy in phosphate buffer solutions was weakened by an increase in the pH, which is related to formation of an imperfect and less protective passive layer on the alloy surface. The presence of the insoluble zirconium particles along with high number of intermetallic phases of RE elements mainly Mg24Y5 in the magnesium matrix can deteriorate the corrosion performance of the alloy by disrupting the protective passive layer that is formed at pH values over 11. These insoluble zirconium particles embedded in the matrix can detrimentally influence the passivation. The M-S analysis revealed that the formed passive layers on Mg-Y-RE-Zr alloy behaved as an n-type semiconductor. An increase in donor concentration accompanying solutions of higher alkalinity is thought to result in the formation of a less resistive passive layer.

  5. Raman spectroscopy of DNA-metal complexes. I. Interactions and conformational effects of the divalent cations: Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd.

    Science.gov (United States)

    Duguid, J; Bloomfield, V A; Benevides, J; Thomas, G J

    1993-11-01

    Interactions of divalent metal cations (Mg2+, Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) with DNA have been investigated by laser Raman spectroscopy. Both genomic calf-thymus DNA (> 23 kilobase pairs) and mononucleosomal fragments (160 base pairs) were employed as targets of metal interaction in solutions containing 5 weight-% DNA and metal:phosphate molar ratios of 0.6:1. Raman difference spectra reveal that transition metal cations (Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) induce the greatest structural changes in B-DNA. The Raman (vibrational) band differences are extensive and indicate partial disordering of the B-form backbone, reduction in base stacking, reduction in base pairing, and specific metal interaction with acceptor sites on the purine (N7) and pyrimidine (N3) rings. Many of the observed spectral changes parallel those accompanying thermal denaturation of B-DNA and suggest that the metals link the bases of denatured DNA. While exocyclic carbonyls of dT, dG, and dC may stabilize metal ligation, correlation plots show that perturbations of the carbonyls are mainly a consequence of metal-induced denaturation of the double helix. Transition metal interactions with the DNA phosphates are weak in comparison to interactions with the bases, except in the case of Cu2+, which strongly perturbs both base and phosphate group vibrations. On the other hand, the Raman signature of B-DNA is largely unperturbed by Mg2+, Ca2+, Sr2+, and Ba2+, suggesting much weaker interactions of the alkaline earth metals with both base and phosphate sites. A notable exception is a moderate perturbation by alkaline earths of purine N7 sites in 160-base pair DNA, with Ca2+ causing the greatest effect. Correlation plots demonstrate a strong interrelationship between perturbations of Raman bands assigned to ring vibrations of the bases and those of bands assigned to exocyclic carbonyls and backbone phosphodiester groups. However, strong correlations do not occur between

  6. Spectroscopic study and enhanced thermostability of combustion-derived BaMgAl10O17:Eu2+ blue phosphors for solid-state lighting

    Science.gov (United States)

    Pradal, Nathalie; Potdevin, Audrey; Chadeyron, Geneviève; Bonville, Pierre; Caillier, Bruno; Mahiou, Rachid

    2017-02-01

    Blue-emitting BaMgAl10O17:Eu2+ (BAM:Eu), suitable for applications in a next generation of Hg-free lamps based on UV LEDs, was prepared by a microwave induced solution combustion synthesis, using urea as combustion fuel and nitrates as oxidizers. Purity control of the as-synthesized blue phosphor was undertaken by a washing step followed by a reduction one. Structural and morphological properties of the outcoming phosphors have been considered. Synthesis process allows producing a well-crystallized and nanostructured BAM phase within only few minutes. The influence of reduction treatment on the relative amounts of Eu2+/Eu3+ in our samples has been investigated through an original study by magnetization and Mössbauer spectroscopy. Furthermore, a complete optical study has been carried out and allowed us to determine the europium localization in the three possible sites in BAM matrix. The percentage of Eu2+ increased twofold after the reduction treatment, entailing an increase in the luminescence efficiency upon UV excitation. Finally, temperature-dependent luminescence of combustion-derived powders has been studied till 170 °C and compared to that of commercial BAM:Eu. MISCS-derived phosphors present a higher thermal stability than commercial one: whereas the emission efficiency of this last was reduced by 64%, the one of combustion-derived BAM:Eu experienced an only 12% decline. Furthermore, while commercial BAM suffered from a severe blue-shift with increasing temperature, our phosphors keep its color quality with a good stability of the photometric parameters.

  7. Cubic Re6+ (5d1) Double Perovskites, Ba2MgReO6, Ba2ZnReO6, and Ba2Y2/3ReO6: Magnetism, Heat Capacity, μSR, and Neutron Scattering Studies and Comparison with Theory.

    Science.gov (United States)

    Marjerrison, Casey A; Thompson, Corey M; Sala, Gabrielle; Maharaj, Dalini D; Kermarrec, Edwin; Cai, Yipeng; Hallas, Alannah M; Wilson, Murray N; Munsie, Timothy J S; Granroth, Garrett E; Flacau, Roxana; Greedan, John E; Gaulin, Bruce D; Luke, Graeme M

    2016-10-04

    Double perovskites (DP) of the general formula Ba 2 MReO 6 , where M = Mg, Zn, and Y 2/3 , all based on Re 6+ (5d 1 , t 2g 1 ), were synthesized and studied using magnetization, heat capacity, muon spin relaxation, and neutron-scattering techniques. All are cubic, Fm3̅m, at ambient temperature to within the resolution of the X-ray and neutron diffraction data, although the muon data suggest the possibility of a local distortion for M = Mg. The M = Mg DP is a ferromagnet, T c = 18 K, with a saturation moment ∼0.3 bohr magnetons at 3 K. There are two anomalies in the heat capacity: a sharp feature at 18 K and a broad maximum centered near 33 K. The total entropy loss below 45 K is 9.68 e.u., which approaches R ln 4 (11.52 e.u.) supporting a j = 3/2 ground state. The unit cell constants of Ba 2 MgReO 6 and the isostructural, isoelectronic analogue, Ba 2 LiOsO 6 , differ by only 0.1%, yet the latter is an anti-ferromagnet. The M = Zn DP also appears to be a ferromagnet, T c = 11 K, μ sat (Re) = 0.1 μ B . In this case the heat capacity shows a somewhat broad peak near 10 K and a broader maximum at ∼33 K, behavior that can be traced to a smaller particle size, ∼30 nm, for this sample. For both M = Mg and Zn, the low-temperature magnetic heat capacity follows a T 3/2 behavior, consistent with a ferromagnetic spin wave. An attempt to attribute the broad 33 K heat capacity anomalies to a splitting of the j = 3/2 state by a crystal distortion is not supported by inelastic neutron scattering, which shows no transition at the expected energy of ∼7 meV nor any transition up to 100 meV. However, the results for the two ferromagnets are compared to the theory of Chen, Pereira, and Balents, and the computed heat capacity predicts the two maxima observed experimentally. The M = Y 2/3 DP, with a significantly larger cell constant (3%) than the ferromagnets, shows predominantly anti-ferromagnetic correlations, and the ground state is complex with a spin frozen component T

  8. Ferroelectric and impedance response of lead-free (B/sub o.5/N/sub 0.5/)TiO/sub 3/-BaZrO/sub 3/ piezoelectric ceramics

    International Nuclear Information System (INIS)

    Rehman, J. U.; Hussain, A.; Maqbool, A.; Kim, J. S.; Song, T. K.; Lee, J. H.; Kim, W. J.; Kim, M. H.

    2013-01-01

    Lead-free piezoelectric (0.96B/sub 0.5/N/sub 0.5/TiO/sub 3/)-0.04BaZrO/sub 3/ (BNT-BZ4) was synthesized by using a solid-state reaction method. SEM micrograph shows dense microstructure. X-ray diffraction (XRD) indicated the formation of a BNB-BZ4 single phase having pseudocubic symmetry. A maximum value of remnant polarization (30 meuC/cm2) and piezoelectric constant (112 pC/N) was observed for BNT-BZ4 ceramic. The temperature dependences of the dielectric properties of BNT-BZ4 were investigated in the temperature range of 25-600 degree C at various frequencies (0.1 Hz-1 MHz). The maximum dielectric constant value (epsilonr) reaches a highest value of 4046 (at 10 kHz). The electrical properties were investigated by using complex impedance spectroscopy and provided better understanding of relaxation process. (author)

  9. Ferroelectric and dielectric properties of BaTi0.9Zr0.1O3 doped with Li0.5Fe2.5O4 ceramics

    Science.gov (United States)

    Gajula, Ganapathi Rao; Buddiga, Lakshmi Rekha; Chidambara Kumar, K. N.; Ch, Arun Kumar; Samatha, K.; Kokkiragadda, Sreeramachandra Murthy; Dasari, Madhava Prasad

    2018-06-01

    We have prepared a composite BaTi0.9Zr0.1O3 (BTZr) doped with Li0.5Fe2.5O4 (LF) having chemical formulae (1- x) BTZr + (x) LF (x=0, 0.05, 0.1 and 0.15) conventional solid state reaction technique. We have sintered the grown composites at 1150 °C for 3 h. We have characterized the grown composites using XRD, FESEM, P-E loop tracer and LCR meter. The XRD measurements reveal the tetragonal nature of the composites. The morphological studies reveal that the composite exhibits dense microstructure with small pores. The P-E loops confirm that the composites exhibit remnant polarization and the coercive field increases with increasing concentration of Lithium Ferrite (LF). We have studied dielectric property of the composites by varying the temperature of the sample from 30 °C to 500 °C at 1 kHz, 10 kHz and also by varying the frequency from 1 Hz to 10 MHz at 30 °C. The dielectric property of BTZr has increased after doping LF in BTZr which reveals the enhancement of electrical properties of the grown composite.

  10. Temperature dependent polarization reversal mechanism in 0.94(Bi1/2Na1/2)TiO3-0.06Ba(Zr0.02Ti0.98)O3 relaxor ceramics

    Science.gov (United States)

    Glaum, Julia; Simons, Hugh; Hudspeth, Jessica; Acosta, Matias; Daniels, John E.

    2015-12-01

    The temperature at which the electric field induced long-range ordered ferroelectric state undergoes transition into the short-range ordered relaxor state, TF-R, is commonly defined by the onset of strong dispersion of the dielectric permittivity. However, this combined macroscopic property and structural investigation of the polarization reversal process in the prototypical lead-free relaxor 0.94(Bi1/2Na1/2)TiO3-0.06Ba(Zr0.02Ti0.98)O3 reveals that an applied electric field can trigger depolarization and onset of relaxor-like behavior well below TF-R. The polarization reversal process can as such be described as a combination of (1) ferroelectric domain switching and (2) a reversible phase transition between two polar ferroelectric states mediated by a non-polar relaxor state. Furthermore, the threshold fields of the second, mediated polarization reversal mechanism depend strongly on temperature. These results are concomitant with a continuous ferroelectric to relaxor transition occurring over a broad temperature range, during which mixed behavior is observed. The nature of polarization reversal can be illustrated in electric-field-temperature (E-T) diagrams showing the electric field amplitudes associated with different polarization reversal processes. Such diagrams are useful tools for identifying the best operational temperature regimes for a given composition in actuator applications.

  11. Synthesis of ceramic BaCe_0_._7Zr_0_,_1Y_0_._2O_3_-_δ electrolyte containing ZnO through the method hidrogel

    International Nuclear Information System (INIS)

    Vieira, J.H.A.; Fagury Neto, E.; Rabelo, A.A.

    2014-01-01

    The solid oxide fuel cells are promising sources of sustainable energy, once they produce electricity from an electrochemical reaction only with steam water as the product of this reaction. In this paper the synthesis of ceramic electrolyte BaCe_0_._7Zr_0_._1Y_0_._2O_3_-_δ using the hydrogel method which involves using an organic gelatin inexpensive and nontoxic modifying the conventional route of polymeric precursor was performed. It was used different amounts of the sintering additive ZnO to decrease the sintering temperature, typically around 1600 °C, towards a minimum relative density of 95%. The polymeric resin was pyrolyzed at 300 °C, subjected to calcination at 600 °C and sintering at temperatures of 1350, 1400 and 1450 °C for 2 hours. Characterizations were carried out by determination of relative density and apparent porosity and using the techniques of differential thermal analysis and simultaneous thermogravimetric, X-ray diffraction and scanning electron microscopy.(author)

  12. Contributions of intrinsic and extrinsic polarization species to energy storage properties of Ba0.95Ca0.05Zr0.2Ti0.8O3 ceramics

    Science.gov (United States)

    Zhan, Di; Xu, Qing; Huang, Duan-Ping; Liu, Han-Xing; Chen, Wen; Zhang, Feng

    2018-03-01

    Ba0.95Ca0.05Zr0.2Ti0.8O3 ceramics were prepared at different sintering temperatures by citrate precursor and solid-state reaction methods, respectively. The crystal structure and microstructure of the specimens were characterized. In view of energy storage capacitor utilizations, the dielectric properties of the specimens were investigated at room temperature as a function of frequency and applied electric field. Moreover, the nature of mobile charge carriers in the specimens was diagnosed by complex impedance spectroscopy at elevated temperatures. While the dielectric constants of the specimens prepared by different methods are quite different (4.4 × 103-2.2 × 104 at 10 kHz) at zero electric field, the energy storage densities at an identical strong electric field are similar (e.g. 0.32-0.41 J/cm3 at 120 kV/cm). The dielectric constants under bias electric field were fitted to a multipolarization mechanism model to resolve the contributions of intrinsic and extrinsic polarization mechanisms. It turned out that the extrinsic contributions fade out within low electric field range (dielectric responses at higher fields. Based on the fitting result, the energy storage properties of the specimens were interpreted.

  13. Structural analysis, optical and dielectric function of [Ba{sub 0.9}Ca{sub 0.1}](Ti{sub 0.9}Zr{sub 0.1})O{sub 3} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Herrera-Pérez, G., E-mail: guillermo.herrera@cimav.edu.mx, E-mail: damasio.morales@cimav.edu.mx [Centro de Investigación en Materiales Avanzados (CIMAV), S. C. Miguel de Cervantes 120, Chihuahua 31136, Chihuahua (Mexico); Physics of Materials Department, Centro de Investigación en Materiales Avanzados (CIMAV), S. C. Miguel de Cervantes 120, Chihuahua 31136, Chihuahua (Mexico); Morales, D., E-mail: guillermo.herrera@cimav.edu.mx, E-mail: damasio.morales@cimav.edu.mx; Paraguay-Delgado, F.; Reyes-Rojas, A.; Fuentes-Cobas, L. E. [Physics of Materials Department, Centro de Investigación en Materiales Avanzados (CIMAV), S. C. Miguel de Cervantes 120, Chihuahua 31136, Chihuahua (Mexico); Borja-Urby, R. [Centro de Nanociencias Micro y Nanotecnologías, Instituto Politécnico Nacional, 07300 México City (Mexico)

    2016-09-07

    This work presents the identification of inter-band transitions in the imaginary part of the dielectric function (ε{sub 2}) derived from the Kramers–Kronig analysis for [Ba{sub 0.9}Ca{sub 0.1}](Ti{sub 0.9}Zr{sub 0.1})O{sub 3} (BCZT) nanocrystals synthesized by the modified Pechini method. The analysis started with the chemical identification of the atoms that conform BCZT in the valence loss energy region of a high energy-resolution of electron energy loss spectroscopy. The indirect band energy (E{sub g}) was determined in the dielectric response function. This result is in agreement with the UV-Vis technique, and it obtained an optical band gap of 3.16 eV. The surface and volume plasmon peaks were observed at 13.1 eV and 26.2 eV, respectively. The X-ray diffraction pattern and the Rietveld refinement data of powders heat treated at 700 °C for 1 h suggest a tetragonal structure with a space group (P4 mm) with the average crystal size of 35 nm. The average particle size was determined by transmission electron microscopy.

  14. Effect of Pulse Laser Welding Parameters and Filler Metal on Microstructure and Mechanical Properties of Al-4.7Mg-0.32Mn-0.21Sc-0.1Zr Alloy

    Directory of Open Access Journals (Sweden)

    Irina Loginova

    2017-12-01

    Full Text Available The effect of pulse laser welding parameters and filler metal on microstructure and mechanical properties of the new heat-treatable, wieldable, cryogenic Al-4.7Mg-0.32Mn-0.21Sc-0.1Zr alloy were investigated. The optimum parameters of pulsed laser welding were found. They were 330–340 V in voltage, 0.2–0.25 mm in pulse overlap with 12 ms duration, and 2 mm/s speed and ramp-down pulse shape. Pulsed laser welding without and with Al-5Mg filler metal led to the formation of duplex (columnar and fine grains as-cast structures with hot cracks and gas porosity as defects in the weld zone. Using Al-5Ti-1B filler metal for welding led to the formation of the fine grain structure with an average grain size of 4 ± 0.2 µm and without any weld defects. The average concentration of Mg is 2.8%; Mn, 0.2%; Zr, 0.1%; Sc, 0.15%; and Ti, 2.1% were formed in the weld. The ultimate tensile strength (UTS of the welded alloy with AlTiB was 260 MPa, which was equal to the base metal in the as-cast condition. The UTS was increased by 60 MPa after annealing at 370 °C for 6 h that was 85% of UTS of the base alloy.

  15. Solubility of uranovanadates of the series A2+(VUO6)2 · nH2O (A2+ = Mg, Ca, Sr, Ba, Co, Ni, Cu, Pb) in water or aqueous solutions

    International Nuclear Information System (INIS)

    Chernorukov, N.G.; Sulejmanov, E.V.; Nipruk, O.V.; Lizunova, G.M.

    2001-01-01

    Solubility of uranovanadates of the series A 2+ (VUO 6 ) 2 · nH 2 O (A 2+ - Mg, Ca, Sr, Ba, Co, Ni, Cu, Pb) in water and aqueous solutions of inorganic acids at 25 deg C and different pH values was determined experimentally. The data obtained permitted calculation the Gibbs standard functions of formation and consideration of their state under conditions that were not studied experimentally, in the presence of carbon dioxide, in particular [ru

  16. Electrical properties of Sb and Cr-doped PbZrO3-PbTiO3-PbMg1/3Nb2/3O3 ceramics

    OpenAIRE

    Whatmore, Roger W.; Molter, O.; Shaw, Christopher P.

    2003-01-01

    The pyroelectric, dielectric and DC resistive properties of Sb and Cr-doped ceramics with a base composition of Pb(Mg1/3Nb2/3)0.025(Zr0.825Ti0.175)0.975O3 have been studied. Sb doping has been shown to produce a linear reduction in Curie temperature (TC=−22z+294 °C) with concentration (z) and to give an increase in pyroelectric coefficient from 250 to 310 μCm−2 K−1 for z increasing from 0 to 3 at.%. It also produces first a reduction and then an increase in both dielectric constant and loss, ...

  17. Microwave dielectric properties of La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yih-Chien; Chen, Kuei-Chien; Hsu, Wei-Yu [Department of Electrical Engineering, Lunghwa University of Science and Technology, Gueishan Shiang, Taoyuan County (China)

    2010-11-15

    This study examined the potential applications of microwave dielectric properties of La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics in rectenna. The La{sub (1-2x/3)}Ba{sub x}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics were prepared by the conventional solid-state method with various sintering temperatures. An apparent density of 6.62 g/cm{sup 3}, a dielectric constant of 20.3, a quality factor of 51,700 GHz, and a temperature coefficient of resonant frequency of -78.2 ppm/K were obtained for La{sub 2.98/3}Ba{sub 0.01}(Mg{sub 0.5}Sn{sub 0.5})O{sub 3} ceramics that were sintered at 1550 C for 4 h. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  18. VUV-UV–vis photoluminescence of Ce{sup 3+} and Ce{sup 3+}-Eu{sup 2+} energy transfer in Ba{sub 2}MgSi{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jing; Liu, Chunmeng; Zhou, Weijie [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275 (China); Huang, Yan; Tao, Ye [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China); Liang, Hongbin, E-mail: cesbin@mail.sysu.edu.cn [MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, KLGHEI of Environment and Energy Chemistry, School of Chemistry, Sun Yat-sen University, Guangzhou 510275 (China)

    2017-05-15

    A series of Ce{sup 3+} doped and Ce{sup 3+}-Eu{sup 2+} co-doped Ba{sub 2}MgSi{sub 2}O{sub 7} phosphors was prepared via a high-temperature solid-state reaction technique. The photoluminescence properties, which include synchrotron radiation VUV-UV excitation spectra, emission spectra and concentration effect, thermal stability of Ce{sup 3+} are investigated. Hence the energies of the crystal field split 5d excited states of Ce{sup 3+} are determined. Due to spectral overlap, the energy transfer from sensitizer Ce{sup 3+} to activator Eu{sup 2+} in Ba{sub 2}MgSi{sub 2}O{sub 7}:Ce{sup 3+}, Eu{sup 2+} occurs, and the mechanism is demonstrated to be an electric dipole−dipole interaction. - Highlights: •The energies of five crystal field split 5d states of Ce{sup 3+} in Ba{sub 2}MgSi{sub 2}O{sub 7} were determined by synchrotron radiation VUV-UV excitation spectrum. •The concentration effect, thermal stability of Ce{sup 3+} were investigated. •The energy transfer from Ce{sup 3+} to Eu{sup 2+} and its influence on luminescence decays of Ce{sup 3+} and Eu{sup 2+} were studied.

  19. Relationship between ferroelectric properties and local structure of Pb{sub 1−x}Ba{sub x}Zr{sub 0.40}Ti{sub 0.60}O{sub 3} ceramic materials studied by X-ray absorption and Raman spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Alexandre, E-mail: mesquita@rc.unesp.br [Instituto de Geociências e Ciências Exatas, UNESP – Univ Estadual Paulista, Departamento de Física, Av. 24-a, 1515, Rio Claro, SP 13506-900 (Brazil); Institut de Chimie et des Materiaux Paris Est, CNRS and Université Paris Est Créteil, 2 Rue Henri Dunant, 94320 Thiais (France); Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São-Carlense, 400, São Carlos, SP (Brazil); Michalowicz, Alain, E-mail: michalov@u-pec.fr [Institut de Chimie et des Materiaux Paris Est, CNRS and Université Paris Est Créteil, 2 Rue Henri Dunant, 94320 Thiais (France); Moscovici, Jacques, E-mail: moscovic@u-pec.fr [Institut de Chimie et des Materiaux Paris Est, CNRS and Université Paris Est Créteil, 2 Rue Henri Dunant, 94320 Thiais (France); Pizani, Paulo Sergio, E-mail: pizani@df.ufscar.br [Departamento de Física, Universidade Federal de São Carlos, Rodovia Washington Luís, s/n, São Carlos, SP, 13565-905 (Brazil); Mastelaro, Valmor Roberto, E-mail: valmor@ifsc.usp.br [Instituto de Física de São Carlos, Universidade de São Paulo, Av. Trabalhador São-Carlense, 400, São Carlos, SP (Brazil)

    2016-08-15

    This paper reports on the structural characterization of Pb{sub 1−x}Ba{sub x}Zr{sub 0.40}Ti{sub 0.60}O{sub 3} (PBZT) ferroelectric ceramic compositions prepared by the conventional solid state reaction method. X-ray absorption spectroscopy (XAS) and Raman spectroscopy were used in the probing of the local structure of PBZT samples that exhibit a normal or relaxor ferroelectric behavior. They showed a considerable local disorder around Zr and Pb atoms in the samples of tetragonal or cubic long-range order symmetry. The intensity of the E(TO{sub 3}) mode in the Raman spectra of PBZT relaxor samples remains constant at temperatures lower than T{sub m}, which has proven the stabilization of the correlation process between nanodomains. - Graphical abstract: X-ray absorption measurements showed considerable local disorder around Zr and Pb atoms in the samples of tetragonal or cubic long-range order symmetry. The intensity of the E(TO{sub 3}) mode in the Raman spectra of PBZT relaxor samples remains constant at temperatures lower than T{sub m}, which has proven the stabilization of the correlation process between nanodomains. Display Omitted - Highlights: • Structural characterization of Pb{sub 1−x}Ba{sub x}Zr{sub 0.40}Ti{sub 0.60}O{sub 3} (PBZT) ferroelectric ceramic. • X-ray absorption and Raman spectroscopies were used to probe the structure of PBZT. • Dissymmetry of Zr and Pb sites was observed in samples long-range cubic symmetry. • Local disorder in all PBZT samples through the observation of Raman active modes.

  20. Surface properties of Co-doped BaFe{sub 2}As{sub 2} thin films deposited on MgO with Fe buffer layer and CaF{sub 2} substrates

    Energy Technology Data Exchange (ETDEWEB)

    Sobota, R. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Plecenik, T., E-mail: tomas.plecenik@fmph.uniba.sk [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Gregor, M.; Truchly, M.; Satrapinskyy, L.; Vidis, M.; Secianska, K. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia); Kurth, F.; Holzapfel, B.; Iida, K. [Institute for Metallic Materials, IFW Dresden, PO Box 270116, D-01171 Dresden (Germany); Kus, P.; Plecenik, A. [Department of Experimental Physics, FMPI, Comenius University, 842 48 Bratislava (Slovakia)

    2014-09-01

    Highlights: • Surfaces of Co-doped Ba-122 films on various substrates were studied. • Substrate influences topography and surface conductivity distribution of the films. • Surface conductivity of Co-doped Ba-122 is highly inhomogeneous. • Point contact spectroscopy results can be affected by the surface differences. - Abstract: Surface properties of Co-doped BaFe{sub 2}As{sub 2} (Ba-122) thin films prepared by pulsed laser deposition on MgO with Fe buffer layer and CaF{sub 2} substrates were inspected by atomic force microscopy, scanning spreading resistance microscopy, scanning tunneling microscopy, X-ray photoelectron spectroscopy, auger electron spectroscopy/microscopy and point contact spectroscopy (PCS). Selected PCS spectra were fitted by extended 1D BTK model. The measurements were done on as-received as well as ion beam etched surfaces. Our results show that the substrate is considerably influencing the surface properties of the films, particularly the topography and surface conductivity distribution, what can affect results obtained by surface-sensitive techniques like PCS.

  1. Synthesis, crystal structure and spectroscopy properties of Na 3AZr(PO 4) 3 ( A=Mg, Ni) and Li 2.6Na 0.4NiZr(PO 4) 3 phosphates

    Science.gov (United States)

    Chakir, M.; El Jazouli, A.; de Waal, D.

    2006-06-01

    Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates were prepared at 750 °C by coprecipitation route. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Li 2.6Na 0.4NiZr(PO 4) 3 was synthesized through ion exchange from the sodium analog. These materials belong to the Nasicon-type structure. Raman spectra of Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates present broad peaks in favor of the statistical distribution in the sites around PO 4 tetrahedra. Diffuse reflectance spectra indicate the presence of octahedrally coordinated Ni 2+ ions.

  2. Evaluation of BaZr0.1Ce0.7Y0.2O3-δ-based proton-conducting solid oxide fuel cells fabricated by a one-step co-firing process

    International Nuclear Information System (INIS)

    Sun Wenping; Wang Yanfei; Fang Shumin; Zhu Zhiwen; Yan Litao; Liu Wei

    2011-01-01

    Proton-conducting solid oxide fuel cells, incorporating BaZr 0.1 Ce 0.7 Y 0.2 O 3-δ (BZCY) electrolyte, NiO-BZCY anode, and Sm 0.5 Sr 0.5 CoO 3-δ -Ce 0.8 Sm 0.2 O 2-δ (SSC-SDC) cathode, were successfully fabricated by a combined co-pressing and printing technique after a one-step co-firing process at 1100, 1150, or 1200 o C. Scanning electron microscope (SEM) results revealed that the co-firing temperature significantly affected not only the density of the electrolyte membrane but the grain size and porosity of the electrodes. Influences of the co-firing temperature on the electrochemical performances of the single cells were also studied in detail. Using wet hydrogen (2% H 2 O) as the fuel and static air as the oxidant, the cell co-fired at 1150 o C showed the highest maximum power density (PD max ) of 552 and 370 mW cm -2 at 700 and 650 o C, respectively, while the one co-fired at 1100 o C showed the highest PD max of 276 and 170 mWcm -2 at 600 and 550 o C, respectively. The Arrhenius equation was proposed to analyze the dependence of the PD max on the operating temperature, and revealed that PD max of the cell co-fired at a lower temperature was less dependent on operating temperature. The influences of the co-firing temperature on the resistances of the single cells, which were estimated from the electrochemical impedance spectroscopy measured under open circuit conditions, were also investigated.

  3. Structural, multiferroic, dielectric and magnetoelectric properties of (1-x)Ba0.85Ca0.15Ti0.90Zr0.10O3-(x)CoFe2O4 lead-free composites

    Science.gov (United States)

    Negi, N. S.; Kumar, Rakesh; Sharma, Hakikat; Shah, J.; Kotnala, R. K.

    2018-06-01

    High performance lead-free multiferroic composites with strong magnetoelectric coupling effect are desired to replace lead-based ceramics in multifunctional device applications due to increasing environmental issues. We report crystal structure, ferroelectric, magnetic, dielectric and magnetoelectric properties of (1-x)Ba0.85Ca0.15Ti0.90Zr0.10O3-(x)CoFe2O4 (BCTZ-CFO) lead-free composites with x = 0.1, 0.3, 0.5, 0.7 and 0.9 synthesized by chemical solution method. BCTZ power was synthesized by sol-gel method while CFO was prepared by metallo-organic decomposition (MOD) method. The XRD results confirm successful formation of the BCTZ-CFO composites without presence of any impurity phase. At room temperature, the BCTZ-CFO composites show multiferroic behavior characterized by ferroelectric and ferromagnetic hysteresis curves. The composite having 10 wt% of CFO exhibited maximum polarization, remnant polarization and coercive field of Ps ∼ 5.1 μC/cm2, Pr ∼ 1.4 μC/cm2 and Ec ∼ 11.6 kV/cm respectively. The BCTZ-CFO composite with 90 wt% of CFO incorporation exhibits improved ferromagnetic properties with Ms ∼ 32 emu/g, Mr ∼ 11.7 emu/g and Hc ∼ 504 Oe. Mӧssbauer spectra analysis show two sets of six-line hyperfine patterns for BCTZ-CFO composites, indicating the presence of Fe3+ ions in both A and B sites. Increasing BCTZ content was found to decrease the hyperfine field strength at both sites and is consistent with the decreasing magnetic moment observed for the samples. The maximum dielectric constant value ε‧ ∼ 678 is obtained at 1 MHz for composite with 10 wt% of CFO phase. The results indicate that the BCTZ-CFO composites are potential lead-free room temperature multiferroic systems.

  4. Investigation of the structural, electronic and optical properties of the cubic RbMF{sub 3} perovskites (M = Be, Mg, Ca, Sr and Ba) using modified Becke-Johnson exchange potential

    Energy Technology Data Exchange (ETDEWEB)

    Sandeep, E-mail: sndp.chettri@gmail.com [Department of Physics, Mizoram University, Aizawl, 796004 (India); Rai, D.P. [Department of Physics, Pachhunga University College, Mizoram University, 796001 (India); Shankar, A. [Department of Physics, University of North Bengal, Darjeeling, 734013 (India); Ghimire, M.P. [Condensed Matter Physics Research Center, Butwal-13, Rupandehi, Lumbini (Nepal); IFW-Dresden, Helmholtzstraße 20, D-01069, Dresden (Germany); Khenata, R. [Laboratoire de Physique Quantique de la Mati´ere et de Modélisation Mathématique LPQ3M, Université de Mascara, Mascara, 29000 (Algeria); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P. O. Box 2455, Riyadh, 11451 (Saudi Arabia); Syrotyuk, S.V. [Semiconductor Electronics Department, Lviv Polytechnic National University, Lviv, 79013 (Ukraine); Thapa, R.K. [Department of Physics, Mizoram University, Aizawl, 796004 (India)

    2017-05-01

    The structural, electronic and optical properties of the cubic RbMF{sub 3} perovskites (M = Be, Mg, Ca, Sr, Ba) have been investigated using the full-potential linearized augmented plane wave (FP-LAPW) method. The exchange and correlation potential was applied using the generalized gradient approximation for calculating the structural properties In addition, the modified Becke-Johnson (TB-mBJ) potential was used for calculating the electronic and optical properties. It was found that the lattice constant increases while the bulk modulus decreases with the change of cation (M) in going from Be to Ba in the RbMF{sub 3} perovskites (M = Be, Mg, Ca, Sr, Ba). The reflectivity and absorption properties were also studied using the mBJ method to understand the inter-band transitions and their possible applications in absorption devices in the UV-region. - Highlights: • Closer estimate of the band-gaps of RbMF{sub 3} with experimental results using GGA and mBJ results predicting them to be absorption devices and substrates for thin film growth. • The RbMF{sub 3} were also found to be potential candidate for in absorption devices in UV-region which were correlated to their calculated optical properties. • The materials are transparent, so may be used as substrates for thin film growth, for the optoelectric applications.

  5. Excitation-dependent local symmetry reversal in single host lattice Ba2A(BO3)2:Eu3+ [A = Mg and Ca] phosphors with tunable emission colours.

    Science.gov (United States)

    Jayakiruba, S; Chandrasekaran, S Selva; Murugan, P; Lakshminarasimhan, N

    2017-07-05

    Eu 3+ activated phosphors are widely used as red emitters in various display devices and light emitting diodes (LEDs). The emission characteristics of Eu 3+ depend on the local site symmetry. The present study demonstrates the role of excitation-dependent local symmetry changes due to the structural reorganization on the emission colour tuning of Eu 3+ from orange-red to orange in single host lattices, Ba 2 Mg(BO 3 ) 2 and Ba 2 Ca(BO 3 ) 2 . The choice of these lattices was based on the difference in the extent of strain experienced by the oxygen atoms. The samples with Eu 3+ at Ba or Mg (Ca) sites were synthesized using the conventional high-temperature solid-state reaction method. The samples were characterized using powder XRD, 11 B MAS-NMR, FT-IR, and diffuse reflectance UV-Vis spectroscopic techniques. The room temperature photoluminescence (PL) recorded using different excitation wavelengths revealed a clear difference in the PL emission features due to symmetry reversal from non-inversion to inversion symmetry around Eu 3+ . The reorganization of highly strained oxygen atoms leads to such symmetry reversal. First-principles calculations were used to deduce the optimized structures of the two borate host lattices, and local geometries and their distortions upon Eu 3+ substitution. The outcomes of these calculations support the experimental findings.

  6. Metaheuristics-Assisted Combinatorial Screening of Eu2+-Doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N Compositional Space in Search of a Narrow-Band Green Emitting Phosphor and Density Functional Theory Calculations.

    Science.gov (United States)

    Lee, Jin-Woong; Singh, Satendra Pal; Kim, Minseuk; Hong, Sung Un; Park, Woon Bae; Sohn, Kee-Sun

    2017-08-21

    A metaheuristics-based design would be of great help in relieving the enormous experimental burdens faced during the combinatorial screening of a huge, multidimensional search space, while providing the same effect as total enumeration. In order to tackle the high-throughput powder processing complications and to secure practical phosphors, metaheuristics, an elitism-reinforced nondominated sorting genetic algorithm (NSGA-II), was employed in this study. The NSGA-II iteration targeted two objective functions. The first was to search for a higher emission efficacy. The second was to search for narrow-band green color emissions. The NSGA-II iteration finally converged on BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphors in the Eu 2+ -doped Ca-Sr-Ba-Li-Mg-Al-Si-Ge-N compositional search space. The BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphor, which was synthesized with no human intervention via the assistance of NSGA-II, was a clear single phase and gave an acceptable luminescence. The BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphor as well as all other phosphors that appeared during the NSGA-II iterations were examined in detail by employing powder X-ray diffraction-based Rietveld refinement, X-ray absorption near edge structure, density functional theory calculation, and time-resolved photoluminescence. The thermodynamic stability and the band structure plausibility were confirmed, and more importantly a novel approach to the energy transfer analysis was also introduced for BaLi 2 Al 2 Si 2 N 6 :Eu 2+ phosphors.

  7. Hexagonal perovskites with cationic vacancies. 23. Rhombohedral 12 L stacking polytypes of type Ba/sub 3/LaBsup(II)Resup(VII)Wsup(VI)vacantO/sub 12/ with Bsup(II) = Mg, Co, Ni, Cu, Zn

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, M; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

    1980-11-01

    The rhombohedral 12 L pervoskites with cationic vacancies of type Ba/sub 3/LaBsup(II)ReWvacantO/sub 12/ with Bsup(II) = Mg, Co, Ni, Cu, Zn are isotypic. According to intensity calculations on powder patterns of Ba/sub 3/LaZnReWvacantO/sub 12/ the series crystallize in the space group R-3m with the sequence (hhcc)/sub 3/; the refined, intensity related R' value is 5.7%. The octahedral net consists of blocks of three face connected octahedra with central void (ReWvacantO/sub 12/ units), which are linked via common corners through single octahedra, occupied by zinc.

  8. Highly efficient red-emitting BaMgBO3F:Eu3+,R+ (R: Li, Na, K, Rb) phosphor for near-UV excitation synthesized via glass precursor solid-state reaction

    Science.gov (United States)

    Shinozaki, Kenji; Akai, Tomoko

    2017-09-01

    Eu3+-doped fluoroborate crystals of BaMgBO3F were synthesized by a solid-state reaction using a glassy precursor material, and their photoluminescence (PL) was investigated. To compensate for the incorporation of Eu3+ into Ba2+ sites, samples codoped with alkali ions (Li+, Na+, K+, Rb+) were also prepared. The Eu3+-doped sample showed red PL with a quantum yield (QY) of 65% caused by near-UV excitation (λ = 393 nm), and PL intensity and QY increased with the codoping of Eu3+ and alkali ions. It was found that the Eu3+,Li+-codoped sample showed the highest PL intensity and a QY of 83%.

  9. Lattice mismatch and energy transfer of Eu- and Dy-codoped MO–Al2O3–SrO (M=Mg, Ca, Ba) ternary compounds affecting luminescence behavior

    International Nuclear Information System (INIS)

    Liang, Chen-Jui; Huang, Kuan-Yu

    2017-01-01

    A systematic investigation of energy transfers and luminescence behaviors for M x Sr 0.94−x Al 2 O 4 :Eu 0.02 , Dy 0.04 (M=Mg, Ca, Ba; x=0, 0.235, 0.47, 0.705, 0.94) ternary compounds was accomplished. The results demonstrated that six phenomena must be fitted into the energy-transfer mechanisms of the ternary compounds: (1) the optical band-gap energy of Mg 0.94 Al 2 O 4 :Eu 0.02 Dy 0.04 is extremely low and does not allow photoemission; (2) Ca 2+ and Ba 2+ ions are the main hosts when x≥0.47 in Ca x Sr 1−x Al 2 O 4 :Eu 0.02 Dy 0.04 and Ba x Sr 1−x Al 2 O 4 :Eu 0.02 Dy 0.04 , respectively; (3) Eu 3+ ions are the main activator ions in Ca x Sr 1−x Al 2 O 4 :Eu 0.02 Dy 0.04 with x=0.47 and in Ba x Sr 1−x Al 2 O 4 :Eu 0.02 Dy 0.04 with x=0.353−0.705; (4) Sr 2+ and Eu 2+ ions are the main host and activator ions, respectively, when x<0.353 in each ternary compound; (5) energy transfers from the MO phases to the SrO phase because the conduction band energy of SrO is the lowest; and (6) mutual substitution between alkaline-earth ions does not alter the resultant structures’ crystal field and nephelauxetic effects, as determined by measuring their luminescence. Two energy transfer paths were discovered to be possible in CaO–Al 2 O 3 –SrO and BaO–Al 2 O 3 –SrO ternary compounds, and the boundaries determining which path was chosen were the atomic ratios Ca:Sr and Ba:Sr, both approximately 1.6:1 (x=0.353). Because second path increased the energy transferred from the MO band gap to the SrO band gap, the corresponding structure's spectrum emission intensity was approximately 4.3 times higher than that of the SrO−Al 2 O 3 binary compound, and their photoluminescence was thus substantially higher.

  10. Solid electrolytes based on {1 − (x + y}ZrO2-(xMgO-(yCaO ternary system: Preparation, characterization, ionic conductivity, and dielectric properties

    Directory of Open Access Journals (Sweden)

    Nazli Zeeshan

    2018-01-01

    Full Text Available Different composition of composite material of zirconium dioxide co-doped with magnesium oxide [MgO(x] and calcium oxide [CaO(y] according to the general molecular formula {1 − (x + y}ZrO2-(xMgO-(yCaO were prepared by co-precipitation method and characterized by different techniques, such as XRD, FTIR, TG-DTA, and SEM. Co-doping was conducted to enhance the ionic conductivity, as mixed system show higher conductivity than the single doped one. Arrhenius plots of the conductance revealed that the co-doped composition “6Mg3Ca” has a higher conductivity with a minimum activation energy of 0.003 eV in temperature range of 50–190 °C. With increasing temperature, dielectric constant value increased; however, with increasing frequency it shows opposite trend. Co-doped composition C2 exhibit higher conductivity compared to C3, owing to the concentration of Mg content (0–6%; the conductivity decreases thereafter. Zirconium oxide was firstly used for medical purpose in orthopaedics, but currently different type of zirconia-ceramic materials has been successfully introduced into the clinic to fix the dental prostheses.

  11. Infrared emissions in MgSrAl{sub 10}O{sub 17}:Er{sup 3+} phosphor co-doped with Yb{sup 3+}/Ba{sup 2+}/Ca{sup 2+} obtained by solution combustion route

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Vijay, E-mail: vijayjiin2006@yahoo.com [Physical Chemistry, Institute for Pure and Applied Chemistry and Center of Interface Science, University of Oldenburg, 26129 Oldenburg (Germany); Kumar Rai, Vineet [Department of Applied Physics, Indian School of Mines, Dhanbad 826 004 (India); Venkatramu, V. [Department of Physics, Yogi Vemana University, Kadapa 516 003 (India); Chakradhar, R.P.S. [CSIR-National Aerospace, Bangalore 560 017 (India); Hwan Kim, Sang [Department of Chemical Engineering, Konkuk University, Seoul 143-701 (Korea, Republic of)

    2013-02-15

    An intense infrared emitting MgSrAl{sub 10}O{sub 17}:Er{sup 3+} phosphor co-doped with Yb{sup 3+}, Ba{sup 2+} and Ca{sup 2+} ions have been prepared by a solution combustion method. Phase purity of the derived compounds was confirmed by X-ray diffraction technique. The vibrational properties of MgSrAl{sub 10}O{sub 17} phosphor was studied by Fourier transform infrared spectroscopy. The broad and strong infrared emission of Er{sup 3+} ions at around 1.53 {mu}m was observed upon excitation at 980 nm. Effect of co-doping with the Yb{sup 3+}{sub ,} Ba{sup 2+} and Ca{sup 2+} ions on the infrared luminescence intensity of Er{sup 3+} ions and the mechanism responsible for the variation in the infrared intensity have been discussed. The results indicate that these materials may be suitable for the optical telecommunication window and wavelength division multiplexing applications. - Highlights: Black-Right-Pointing-Pointer The hexagonal phase of MgSrAl{sub 10}O{sub 17} could be obtained by the low temperature combustion method. Black-Right-Pointing-Pointer The broad and strong infrared emission of Er{sup 3+} ions at around 1.53 {mu}m was observed. Black-Right-Pointing-Pointer Effect of co-doping with the Yb{sup 3+}{sub ,} Ba{sup 2+} and Ca{sup 2+} ions on the infrared luminescence intensity of Er{sup 3+} were reported.

  12. Mixed ligand complexes of alkaline earth metals: Part XII. Mg(II, Ca(II, Sr(II and Ba(II complexes with 5-chlorosalicylaldehyde and salicylaldehyde or hydroxyaromatic ketones

    Directory of Open Access Journals (Sweden)

    MITHLESH AGRAWAL

    2002-04-01

    Full Text Available The reactions of alkaline earth metal chlorides with 5-chlorosalicylaldehyde and salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been carried out in 1 : 1 : 1 mole ratio and the mixed ligand complexes of the type MLL’(H2O2 (where M = Mg(II, Ca(II, Sr(II and Ba(II, HL = 5-chlorosalicylaldehyde and HL’ = salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been isolated. These complexes were characterized by TLC, conductance measurements, IR and 1H-NMR spectra.

  13. Proton-oxygen conductivity in substituted perovskites ATi0.95Mo0.05O3-α (A = Ca, Sr, Ba; M = Sc, Mg) in the reducing hydrogen-containing atmospheres

    International Nuclear Information System (INIS)

    Gorelov, V.P.; Balakireva, V.B.; Sharova, N.V.

    1999-01-01

    Electric conductivity depending on temperature, oxygen partial pressure, as well as the number of t i ion transfer and transfer hydrogen numbers in the perovskites ATi 0.95 Mo 0.05 O 3-α (A = Ca, Sr, Ba; M = Sc, Mg) in reducing hydrogen-containing atmospheres in the temperature range of 450-850 deg C have been measured. With the temperature decrease t i increases reaching 1.0 at a temperature of 550 deg C for all compositions. Proton conductivity under conditions of assumed concomitant transfer of either O 2- or OH - has been ascertained [ru

  14. Raman spectroscopy of DNA-metal complexes. II. The thermal denaturation of DNA in the presence of Sr2+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+.

    OpenAIRE

    Duguid, J G; Bloomfield, V A; Benevides, J M; Thomas, G J

    1995-01-01

    Differential scanning calorimetry, laser Raman spectroscopy, optical densitometry, and pH potentiometry have been used to investigate DNA melting profiles in the presence of the chloride salts of Ba2+, Sr2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+. Metal-DNA interactions have been observed for the molar ratio [M2+]/[PO2-] = 0.6 in aqueous solutions containing 5% by weight of 160 bp mononucleosomal calf thymus DNA. All of the alkaline earth metals, plus Mn2+, elevate the melting temperature of ...

  15. Unraveling the resistive switching effect in ZnO/0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Silva, J.P.B., E-mail: josesilva@fisica.uminho.pt [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Vorokhta, M.; Dvořák, F. [Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Sekhar, K.C. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Department of Physics, School of Basic and Applied Science, Central University of Tamil Nadu, Thiruvarur 610 101 (India); Matolín, V. [Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000 Prague 8 (Czech Republic); Moreira, J. Agostinho [IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal); Pereira, M.; Gomes, M.J.M. [Centre of Physics, University of Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2017-04-01

    Highlights: • ZnO/0.5BZT-0.5BCT heterostructures exhibited resistive switching (RS) ratio ≥ 10 4. • Effect of oxygen pressure used in the deposition of ZnO on RS ratio is highlighted. • Determination of the Band alignment in ZnO/0.5BZT-0.5BCT heterojunctions from XPS. • Resistive Switching is explained based on charge coupling effect. - Abstract: This work reports the effect of partial oxygen pressure, used in the deposition of the ZnO layer, on the band alignment at ZnO – 0.5Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}-0.5(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} (0.5BZT-0.5BCT) interface and on the resistive switching (RS) behavior of pulsed laser deposited ZnO/0.5BZT-0.5BCT heterostructures. X-ray photoelectron spectroscopy (XPS) has been employed to measure the valence band offset and the conduction band offset of the ZnO/0.5BZT-0.5BCT heterojunctions. The valence and conduction band offsets of the ZnO/0.5BZT-0.5BCT heterostucture with ZnO deposited at 10{sup −2} mbar of partial oxygen pressure were found to be 0.27 and 0.80 eV, respectively. The RS effect in heterostructures is explained on the base of the charge coupling between the switchable polarization of ferroelectric layer and the non-switchable polarization of semiconductor layer. The heterostructure with ZnO deposited at 10{sup −2} mbar of partial oxygen pressure displays optimum RS characteristics, with a switching ratio ≥ 10{sup 4} and excellent retention and endurance characteristics. The optimum RS characteristics are attributed to a good interface quality with enough carrier concentration in ZnO, as evidenced by XPS.

  16. The stored energy in processed Cu-0.4 wt.%Cr-0.12 wt.%Zr-0.02 wt.%Si-0.05 wt.%Mg

    International Nuclear Information System (INIS)

    Li, X.F.; Dong, A.P.; Wang, L.T.; Yu, Z.; Meng, L.

    2011-01-01

    Research highlights: → The crystal orientation in processed Cu-0.4 wt.%Cr-0.12 wt.%Zr-0.02 wt.%Si-0.05 wt.%Mg is deviating from the as-cast specimens and microstrain of the alloy is gradually increasing as the draw ratio rising before η ≤ 6.7. → The dynamic recovery has taken place as 6.7 texture is formed with the draw ratio rising. Meanwhile, the stored energy also increases with the draw ratio rising and a peak is reached with draw ratio of 6.7. The release of stored energy is primarily due to the decrease of dislocation density. The flow stress estimated from the stored energy has a similar variation trend with the measured data with a stress difference ∼20 to 120 MPa. The main strengthening effect is attributed to dislocation mechanism.

  17. Strong piezoelectric anisotropy d15/d33 in ⟨111⟩ textured Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3 ceramics

    Science.gov (United States)

    Yan, Yongke; Priya, Shashank

    2015-08-01

    The shear mode piezoelectric properties of Pb(Mg1/3Nb2/3)O3-Pb(Zr,Ti)O3 (PMN-PZT) ceramic with 72% ⟨111⟩ texture were investigated. The piezoelectric anisotropic factor d15/d33 was as high as 8.5 in ⟨111⟩ textured ceramic as compared to 2.0 in random counterpart. The high d15/d33 indicates the "rotator" ferroelectric characteristics of PMN-PZT system and suggests that the large shear piezoelectric response contributes towards the high longitudinal piezoelectric response (d33) in non-polar direction (d33 = 1100 pC/N in ⟨001⟩ textured ceramic vs. d33 = 112 pC/N in ⟨111⟩ textured ceramic).

  18. Stable and easily sintered BaCe0.5Zr0.3Y0.2O3−δ electrolytes using ZnO and Na2CO3 additives for protonic oxide fuel cells

    International Nuclear Information System (INIS)

    Li, Yong; Guo, Ruisong; Wang, Chao; Liu, Yu; Shao, Zongping; An, Jing; Liu, Chongwei

    2013-01-01

    Highlights: ► Sintering temperature of BCZY-Z pellets was reduced by adding ZnO and Na 2 CO 3 . ► Chemical stability of BCZY-Z towards CO 2 was improved with Na 2 CO 3 addition. ► Good chemical stability against boiling water was observed for BCZY-Z-C2 sample. ► The electrical conductivity is 7.68 × 10 −3 S cm −1 for BCZY-Z-C2 sample at 700 °C. ► An anode-supported POFC delivered a peak output 302 mW cm 2 at 700 °C. -- Abstract: BaCe 0.5 Zr 0.3 Y 0.2 O 3−δ (BCZY) based composite electrolyte materials were fabricated with ZnO sintering aid (BCZY-Z). The effects of Na 2 CO 3 modification on sintering behavior, chemical stability and electrochemical performance were systematically investigated. The X-ray diffraction patterns indicate that the specimens with Na 2 CO 3 addition possessed a single perovskite structure after sintering at 1320 °C for 2 h. The linear shrinkage of 0.5 mol% Na 2 CO 3 -modified BCZY-Z sample (BCZY-Z-C2) was about 17.5%, higher than that without Na 2 CO 3 addition (14.9%). Energy dispersive spectrometer shows that Na and C elements still existed and mainly distributed along the grain boundaries. Reactivities with carbon dioxide and boiling water of BCZY-Z and Na 2 CO 3 -modified BCZY-Z samples were also evaluated and good chemical stability was observed for Na 2 CO 3 -modified BCZY-Z samples. A conductivity of 7.68 × 10 −3 S cm −1 for BCZY-Z-C2 was obtained at 700 °C in 3% wet hydrogen atmosphere. An anode-supported fuel cell with thin-film BCZY-Z-C2 as electrolyte was fabricated. The fuel cell delivered a peak power density of 302 mW cm 2 and interface resistance value of 0.08 Ω cm 2 at 700 °C

  19. Effect of Ca{sup 2+} substitution on impedance and electrical conduction mechanism of Ba{sub 1−x}Ca{sub x}Zr{sub 0.1}Ti{sub 0.9}O{sub 3} (0.00≤x≤0.20) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Tanusree [Functional Ceramics Laboratory, Department of Applied Physics, Indian Institute of Technology (ISM), Dhanbad 826004 (India); Das, Sayantani [Department of Physics, University of Calcutta, 92, Acharya Prafulla Chandra Road, Kolkata 700009 (India); Badapanda, T. [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar, Odisha 7520544 (India); Sinha, T.P. [Department of Physics, Bose Institute, 93/1, Acharya Prafulla Chandra Road, Kolkata 700009 (India); Sarun, P.M., E-mail: sarun.res@gmail.com [Functional Ceramics Laboratory, Department of Applied Physics, Indian Institute of Technology (ISM), Dhanbad 826004 (India)

    2017-03-01

    The Ca modified Ba{sub 1−x}Ca{sub x}Zr{sub 0.1}Ti{sub 0.9}O{sub 3} (BCZT) system for x=0.00–0.20 is synthesized by the high-temperature conventional solid state reaction method. The morphotropic phase boundary (MPB) between the tetragonal and cubic structure is obtained at room temperature for the composition x=0.15. The doping of Ca facilitates the enhancement of the homogeneity of microstructure and growth of the grain size. The phase transition is also confirmed by Raman spectroscopy. In order to explore the effect of Ca concentration variation on the conduction mechanism of BaZr{sub 0.1}Ti{sub 0.9}O{sub 3} (BZT) ceramic, the frequency dependent ac impedance spectroscopy technique is used at various temperatures. The effect of Ca doping on the electrical properties of BZT is clearly noticeable. The resistance of the grain (bulk) and the grain boundary is increased as a consequence of the increase in the activation energy of Ca substituted BZT samples. The enhanced resistivity of the Ca substituted BZT ceramics is explained in terms of the decrease in the mobility of the charge carriers associated with the lattice distortion. The electric modulus analysis reveals the enhanced capacitance of BCZT ceramics which is in good agreement with the results obtained from complex impedance analysis.

  20. Stable, easily sintered BaCe0.5Zr0.3Y0.16Zn0.04O3-δ electrolyte-based proton-conducting solid oxide fuel cells by gel-casting and suspension spray

    International Nuclear Information System (INIS)

    Lin Bin; Dong Yingchao; Wang Songlin; Fang Daru; Ding Hanping; Zhang Xiaozhen; Liu Xingqin; Meng Guangyao

    2009-01-01

    Protonic ceramic membrane fuel cells (PCMFCs) based on oxide proton conductors exhibit more advantages than traditional solid oxide fuel cells (SOFCs) based on oxygen-ion conducting electrolytes, such as low activation energy and high energy efficiency. In order to develop a simple and cost-effective route to fabricate PCMFCs with SrCo 0.9 Sb 0.1 O 3-δ (SCS) cubic perovskite cathode, a dense BaCe 0.5 Zr 0.3 Y 0.16 Zn 0.04 O 3-δ (BCZYZn) electrolyte was fabricated in situ metal oxide on a porous anode support by gel-casting and suspension spray, which is cost-effective, easy to realize, and suitable for mass-production. The key part of this process is to directly spray well-mixed suspension of BaCO 3 , CeO 2 , ZrO 2 , Y 2 O 3 and ZnO instead of pre-synthesized BCZYZn ceramic powder on the anode substrate. With SCS cubic perovskite cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H 2 as fuel and the static air as oxidant. An open-circuit potential of 0.987 V, a maximum power density of 364 mW cm -2 , and a low polarization resistance of the electrodes of 0.07 Ω cm 2 was achieved at 700 deg. C.

  1. Structure, solvation, and dynamics of Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, and Ba{sup 2+} complexes with 3-hydroxyflavone and perchlorate anion in acetonitrile medium: A molecular dynamics simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Agieienko, Vira N.; Kolesnik, Yaroslav V.; Kalugin, Oleg N., E-mail: onkalugin@gmail.com [Department of Inorganic Chemistry, V. N. Karazin Kharkiv National University, Kharkiv 61022 (Ukraine)

    2014-05-21

    Molecular dynamics simulations of complexes of Mg{sup 2+}, Ca{sup 2+}, Sr{sup 2+}, and Ba{sup 2+} with 3-hydroxyflavone (flavonol, 3HF) and ClO {sub 4}{sup −} in acetonitrile were performed. The united atoms force field model was proposed for the 3HF molecule using the results of DFT quantum chemical calculations. 3HF was interpreted as a rigid molecule with two internal degrees of freedom, i.e., rotation of the phenyl ring and of the OH group with respect to the chromone moiety. The interatomic radial distribution functions showed that interaction of the cations with flavonol occurs via the carbonyl group of 3HF and it is accompanied with substitution of one of the acetonitrile molecules in the cations’ first solvation shells. Formation of the cation–3HF complexes does not have significant impact on the rotation of the phenyl ring with respect to the chromone moiety. However, the orientation of the flavonol's OH-group is more sensitive to the interaction with doubly charged cations. When complex with Mg{sup 2+} is formed, the OH-group turns out of the plane of the chromone moiety that leads to rupture of intramolecular H-bond in the ligand molecule. Complexation of Ca{sup 2+}, Sr{sup 2+}, and BaClO {sub 4}{sup +} with 3HF produces two structures with different OH-positions, as in the free flavonol with the intramolecular H-bond and as in the complex with Mg{sup 2+} with disrupted H-bonding. It was shown that additional stabilization of the [MgClO{sub 4}(3HF)]{sup +} and [BaClO{sub 4}(3HF)]{sup +} complexes is determined by strong affinity of perchlorate anion to interact with flavonol via intracomplex hydrogen bond between an oxygen atom of the anion and the hydrogen atom of the 3-hydroxyl group. Noticeable difference in the values of the self-diffusion coefficients for Kt{sup 2+} from one side and ClO {sub 4}{sup −}, 3HF, and AN in the cations’ coordination shell from another side implies quite weak interaction between cation, anion, and ligands in

  2. Lattice mismatch and energy transfer of Eu- and Dy-codoped MO–Al{sub 2}O{sub 3}–SrO (M=Mg, Ca, Ba) ternary compounds affecting luminescence behavior

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Chen-Jui, E-mail: cjliang@fcu.edu.tw; Huang, Kuan-Yu

    2017-05-15

    A systematic investigation of energy transfers and luminescence behaviors for M{sub x}Sr{sub 0.94−x}Al{sub 2}O{sub 4}:Eu{sub 0.02}, Dy{sub 0.04} (M=Mg, Ca, Ba; x=0, 0.235, 0.47, 0.705, 0.94) ternary compounds was accomplished. The results demonstrated that six phenomena must be fitted into the energy-transfer mechanisms of the ternary compounds: (1) the optical band-gap energy of Mg{sub 0.94}Al{sub 2}O{sub 4}:Eu{sub 0.02}Dy{sub 0.04} is extremely low and does not allow photoemission; (2) Ca{sup 2+} and Ba{sup 2+} ions are the main hosts when x≥0.47 in Ca{sub x}Sr{sub 1−x}Al{sub 2}O{sub 4}:Eu{sub 0.02}Dy{sub 0.04} and Ba{sub x}Sr{sub 1−x}Al{sub 2}O{sub 4}:Eu{sub 0.02}Dy{sub 0.04}, respectively; (3) Eu{sup 3+} ions are the main activator ions in Ca{sub x}Sr{sub 1−x}Al{sub 2}O{sub 4}:Eu{sub 0.02}Dy{sub 0.04} with x=0.47 and in Ba{sub x}Sr{sub 1−x}Al{sub 2}O{sub 4}:Eu{sub 0.02}Dy{sub 0.04} with x=0.353−0.705; (4) Sr{sup 2+} and Eu{sup 2+} ions are the main host and activator ions, respectively, when x<0.353 in each ternary compound; (5) energy transfers from the MO phases to the SrO phase because the conduction band energy of SrO is the lowest; and (6) mutual substitution between alkaline-earth ions does not alter the resultant structures’ crystal field and nephelauxetic effects, as determined by measuring their luminescence. Two energy transfer paths were discovered to be possible in CaO–Al{sub 2}O{sub 3}–SrO and BaO–Al{sub 2}O{sub 3}–SrO ternary compounds, and the boundaries determining which path was chosen were the atomic ratios Ca:Sr and Ba:Sr, both approximately 1.6:1 (x=0.353). Because second path increased the energy transferred from the MO band gap to the SrO band gap, the corresponding structure's spectrum emission intensity was approximately 4.3 times higher than that of the SrO−Al{sub 2}O{sub 3} binary compound, and their photoluminescence was thus substantially higher.

  3. Conductivity study of dense BaCex Zr(0.9-x)Y0.1O(3 − δ) prepared by solid state reactive sintering at 1500 deg. C

    DEFF Research Database (Denmark)

    Ricote, Sandrine; Bonanos, Nikolaos; Manerbino, A.

    2012-01-01

    with the cerium content. Some samples have also been prepared using barium sulfate (BaSO4) as barium precursor (instead of barium carbonate BaCO3) due to its non toxicity. The corresponding samples (prepared at 1575 °C) showed similar properties as the ones prepared with barium carbonate. Furthermore, different...

  4. Fragilidade ambiental e uso do solo da bacia hidrográfica do Córrego Pindaíba, Uberlândia, MG, Brasil

    Directory of Open Access Journals (Sweden)

    Silvio Carlos Rodrigues

    2008-04-01

    Full Text Available This paper presents an environmental analysis of the fragility of Pindaíba Creek Hydrographic Basin using the analysis of natural and anthropic components interactions in the study area. The main objective of this research was to identify and map the environmental fragility of this basin. The specific objectives consisted in the physical characterization of land use and land cover. To accomplish this research, several field campaigns were conducted throughout the basin. The cartographic base was compiled using the Taboca and Pau Furado charts at 1:25.000 scale that were digitized using the software Cartalinx. The thematic maps of geology, geomorphology, and land use were compiled using the software Arcview 3.2. The fragility map was also derived based on the software Arcview 3.2 using the tool Geoprocessing Wizard. The methodology developed by Ross (1990, 1994 was used for the evaluation of the landscape fragility. This methodology attributes values to environment variables according to their potentialities. Results allowed the identification of major natural and anthropic actions in the study area represented in a map of fragility potential. These results indicate that land use has to be changed in order to adjust to the landscape morphology, considering not only natural resources, but also the needs of the people who live in the study area.

  5. Stable, easily sintered BaCe{sub 0.5}Zr{sub 0.3}Y{sub 0.16}Zn{sub 0.04}O{sub 3-{delta}} electrolyte-based protonic ceramic membrane fuel cells with Ba{sub 0.5}Sr{sub 0.5}Zn{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} perovskite cathode

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Bin; Hu, Mingjun; Ma, Jianjun; Meng, Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), 96 Jinzhai Road, Hefei, Anhui 230026 (China); Jiang, Yinzhu [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), 96 Jinzhai Road, Hefei, Anhui 230026 (China); Department of Chemistry, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Tao, Shanwen [Department of Chemistry, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom)

    2008-09-01

    A stable, easily sintered perovskite oxide BaCe{sub 0.5}Zr{sub 0.3}Y{sub 0.16}Zn{sub 0.04}O{sub 3-{delta}} (BCZYZn) as an electrolyte for protonic ceramic membrane fuel cells (PCMFCs) with Ba{sub 0.5}Sr{sub 0.5}Zn{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} (BSZF) perovskite cathode was investigated. The BCZYZn perovskite electrolyte synthesized by a modified Pechini method exhibited higher sinterability and reached 97.4% relative density at 1200 C for 5 h in air, which is about 200 C lower than that without Zn dopant. By fabricating thin membrane BCZYZn electrolyte (about 30 {mu}m in thickness) on NiO-BCZYZn anode support, PCMFCs were assembled and tested by selecting stable BSZF perovskite cathode. An open-circuit potential of 1.00 V, a maximum power density of 236 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.17 {omega} cm{sup 2} were achieved at 700 C. This investigation indicated that proton conducting electrolyte BCZYZn with BSZF perovskite cathode is a promising material system for the next generation solid oxide fuel cells. (author)

  6. Domain wall motion and electromechanical strain in lead-free piezoelectrics: Insight from the model system (1 − x)Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} using in situ high-energy X-ray diffraction during application of electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Tutuncu, Goknur [Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611 (United States); Li, Binzhi [Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, California 95616 (United States); Bowman, Keith [Illinois Institute of Technology, Armour College of Engineering, Chicago, Illinois 60616 (United States); School of Materials Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Jones, Jacob L., E-mail: JacobJones@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-04-14

    The piezoelectric compositions (1 − x)Ba(Zr{sub 0.2}Ti{sub 0.8})O{sub 3}–x(Ba{sub 0.7}Ca{sub 0.3})TiO{sub 3} (BZT-xBCT) span a model lead-free morphotropic phase boundary (MPB) between room temperature rhombohedral and tetragonal phases at approximately x = 0.5. In the present work, in situ X-ray diffraction measurements during electric field application are used to elucidate the origin of electromechanical strain in several compositions spanning the tetragonal compositional range 0.6 ≤ x ≤ 0.9. As BCT concentration decreases towards the MPB, the tetragonal distortion (given by c/a-1) decreases concomitantly with an increase in 90° domain wall motion. The increase in observed macroscopic strain is predominantly attributed to the increased contribution from 90° domain wall motion. The results demonstrate that domain wall motion is a significant factor in achieving high strain and piezoelectric coefficients in lead-free polycrystalline piezoelectrics.

  7. Structure and composition of Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} films deposited on (001) MgO substrates and the influence of sputtering pressure

    Energy Technology Data Exchange (ETDEWEB)

    Twigg, M.E.; Alldredge, L.M.B.; Chang, W.; Podpirka, A.; Kirchoefer, S.W.; Pond, J.M.

    2013-12-02

    The structure and composition of Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films, sputter deposited on (001) MgO substrates, have been characterized by transmission electron microscopy. Deviations in film stoichiometry are seen to strongly correlate with the structural and dielectric properties of these films, with the films deposited at the lower sputtering pressures either Ti-deficient or capped with a titanium oxide layer similar to the rutile TiO{sub 2} phase. Preferential sputtering of cations is found to be an important factor governing film stoichiometry. The Ti-deficient films deposited at a lower sputtering pressure contain Ruddlesden–Popper faults that increase the average lattice constant of the film and result in compressive strain and low dielectric tunability. - Highlights: • Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) film deposited at very low pressure is capped with TiO{sub 2} layer. • TiO{sub 2} capped film is under only slight compressive strain, but has poor tunability. • BST films deposited at low pressure contain Ruddlesden–Popper Faults (RPFs). • RPF-containing films have high compressive strains and poor dielectric tunability. • High-pressure films have no RPFs, little compression strain, and high tunability.

  8. Caracterización microestructural y estabilidad térmica de la aleación Mg-23 %wt Zr sintetizada mediante Deposición Física en Fase Vapor (PVDW

    Directory of Open Access Journals (Sweden)

    Garcés, G.

    2003-02-01

    Full Text Available The objective of this work has been the study of the microstructure and the thermal stability of the alloy Mg-2.3 %Zr grown by Physical Vapour Deposition. This study has been carried out by Differential Scanning Calorimetry and Transmission Electron Microscopy. The alloy in the "as-deposited" condition consists of a solid solution of zirconium atoms in the magnesium matrix. The microstructure of the alloy is characterised by elongated grains oriented in the growth direction. These grains grow with the [0001] direction parallel to the deposit growth direction. During a continuous heating, the deposit shows three exothermal transformations which have been associated with a recovery process, the zirconium precipitation in the magnesium matrix and oxidation at high temperatures. The activation energy for the precipitation reaction calculated from Kissinger analysis is 139 kjmol-1.

    El objetivo del trabajo es estudiar la microestructura y estabilidad térmica de la aleación Mg-2,3 %wt Zr, crecida mediante deposición física en fase vapor. Las principales técnicas experimentales empleadas en este estudio son la calorimetría diferencial de barrido y la microscopía electrónica de transmisión. La aleación, en la condición estado de depósito (as-depositedy es una solución sólida de átomos de circonio en magnesio. La microestructura de la aleación está caracterizada por granos alargados en la dirección de crecimiento. Los granos crecen con la dirección [0001] paralela a la dirección de crecimiento del depósito. Durante un calentamiento continuo del depósito, se observan tres transformaciones exotérmicas que se han asociado a restauración, precipitación del circonio en la matriz de magnesio y oxidación. Se calculó, mediante el análisis de Kissinger, que la energía de activación para el proceso de precipitación es de 138 kjmol-1.

  9. Specific heat and thermodynamic functions of uranovanadates of the M2+(VUO6)2 · nH2O series (M2+ = Mg, Ca, Sr, Ba, Pb)

    International Nuclear Information System (INIS)

    Karyakin, N.V.; Chernorukov, N.G.; Sulejmanov, E.V.; Trostin, V.L.; Alimzhanov, M.I.; Razuvaeva, E.A.

    1999-01-01

    Isobaric specific heat of crystal uranovanadates Ca(VUO 6 ) 2 · 8H 2 O, Ba(VUO 6 ) 2 · 4H 2 O in the temperature range of 10 - 300 K and of M 1 (VUO 6 ) 2 · 5H 2 O, (M 1 = Mg, Ca, Sr, Pb) at 80 -300 K are measured by the method of adiabatic vacuum calorimetry. The functions H 0 (T) - H 0 (0), S 0 (T), G 0 (T) - H 0 (T) for all the above-mentioned compounds in the range of 0 - 300 K have been calculated, the standard entropies and Gibbs functions of uranovanadates formation at 298.15 K being calculated as well [ru

  10. Degradation mechanisms of the blue-emitting phosphor BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} under baking and VUV-irradiating treatments

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Shuxiu E-mail: shuxiu_zhang@dyden.co.jp; Kono, Toshihiko; Ito, Akira; Yasaka, Taketo; Uchiike, Heiju

    2004-01-01

    The luminescent properties of an Eu{sup 2+}-activated hexagonal aluminate, BaMgAl{sub 10}O{sub 17} (BAM), were studied under 147- and 254-nm excitations. The BAM samples were thermally treated by baking and then irradiated in vacuum ultraviolet (VUV) rays. The results show that the emission efficiency of Eu{sup 2+} in BAM under 147-nm excitation degraded seriously after baking or VUV-irradiating treatments, while no significant degradation was observed under 254-nm excitation. The degree of degradation depended on the excitation wavelength, and the absorption edge of the BAM host was suggested to be close to 175 nm (7.2 eV). The differences between the thermal-induced and the VUV-irradiation-induced degradations, and their mechanisms are discussed for the color plasma display applications.

  11. Electric field induced lattice strain in pseudocubic Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-modified BaTiO{sub 3}-BiFeO{sub 3} piezoelectric ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Ichiro, E-mail: ifujii@rins.ryukoku.ac.jp [Department of Materials Chemistry, Ryukoku University, Otsu, Shiga 520-2194 (Japan); Iizuka, Ryo; Ueno, Shintaro; Nakashima, Kouichi; Wada, Satoshi [Interdisciplinary Graduate School of Medical and Engineering, University of Yamanashi, Kofu, Yamanashi 400-8510 (Japan); Nakahira, Yuki; Sunada, Yuya; Magome, Eisuke; Moriyoshi, Chikako; Kuroiwa, Yoshihiro [Department of Physical Science, Hiroshima University, Higashihiroshima, Hiroshima 739-8526 (Japan)

    2016-04-25

    Contributions to the piezoelectric response in pseudocubic 0.3BaTiO{sub 3}-0.1Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-0.6BiFeO{sub 3} ceramics were investigated by synchrotron X-ray diffraction under electric fields. All of the lattice strain determined from the 110, 111, and 200 pseudocubic diffraction peaks showed similar lattice strain hysteresis that was comparable to the bulk butterfly-like strain curve. It was suggested that the hysteresis of the lattice strain and the lack of anisotropy were related to the complex domain structure and the phase boundary composition.

  12. Electro-optic properties of epitaxial Sr0.6Ba0.4Nb2O6 films grown on MgO substrates using LixNi2-xO buffer layer

    Science.gov (United States)

    Li, X. T.; Du, P. Y.; Ye, H.; Mak, C. L.; Wong, K. H.

    2008-08-01

    Textured LixNi2-xO (LNO) thin films have been fabricated on (001)MgO substrates by pulsed laser deposition technique. The as-deposited LNO films shows a conductivity of 2.5×10-3 Ω m and possess a transmittance of about 35% in the visible region. Subsequent deposition of Sr0.6Ba0.4Nb2O6 (SBN60) thin film on these LNO-coated MgO substrates resulted in a textured SBN layer with a orientation perpendicular to the substrate plane. Phi scans on the (221) plane of the SBN layer indicated that the films have two in-plane orientations with respect to the substrate. The SBN unit cells were rotated in the plane of the film by ± 8.2° as well as ± 45° with respect to the LNO/MgO substrate. Besides the highly (00l)-orientation, the SBN films also exhibited a dense microstructure as shown by scanning electron microscopy. The electro-optic coefficient (r33) of the SBN film was measured to be 186 pm/V. On the basis of our results, we have demonstrated that the LNO film can be used as a buffer layer as well as a transparent bottom electrode for waveguide applications. The SBN/LNO heterostructure is also a suitable candidate for integrated electro-optics devices.

  13. Properties of the ZrO2MgO/MgZrO3NiCr/NiCr triple-layer thermal barrier coating deposited by the atmospheric plasma spray process / Характеристики трехслойных термобарьерных покрытий ZrO2MgO/ MgZrO3NiCr/ NiCr, нанесенных воздушно-плазменным напылением / Svojstva troslojne termo barijerne prevlake ZrO2MgO/ MgZrO3NiCr/ NiCr deponovane atmosferskim plazma sprej procesom

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2016-04-01

    Full Text Available This paper presents the results of the examinations of TBC - ZrO2MgO / MgZrO3NiCr / NiCr thermal barrier layers deposited by the plasma spray process at the atmospheric pressure on substrates of Al alloys. In order to obtain the structural and mechanical properties of layers, which will provide a good heat and abrasion protection of the tail elevators of aircraft J-22 when firing '.Lightning' and 'Thunder' rockets, the deposition of three powder types was performed on 0.6 mm thick Al alloy substrates. This study describes a procedure of using triple-layer TBC coatings as a good combination among many available ones, which gives a good compromise between thermal protection and resistance to abrasion for protecting aircraft tail elevators. The study is mainly based on the experimental approach. The evaluation of the mechanical properties of layers was done by the examination of microhardness by method HV0.3 and bond strength on the tensile machine. The structure of layers was examined by the method of light microscopy while the surface of ZrO2MgO ceramic layers was examined by the method of scanning electron microscopy (SEM.The thermal protection of TBC layers and resistance to abrasion were tested in the tunnel of the Military Technical Institute, Zarkovo. The obtained characteristics of the surface layers and the rocket firing simulations have proven the triple-layer system of TBC coatings reliable. / В данной статье представлены результаты испытаний термобарьерных покрытий ТБС ZrO2MgO/MgZrO3NiCr/NiCr, нанесенных воздушно-плазменным напылением при атмосферном давлении на субстраты сплавов Al. Испытания проводились с целью получения структурных и механических характеристик слоев, обеспечивающих ка

  14. Determination and analysis of non-linear index profiles in electron-beam-deposited MgOAl2O3ZrO2 ternary composite thin-film optical coatings

    International Nuclear Information System (INIS)

    Sahoo, N.K.; Thakur, S.; Senthilkumar, M.; Das, N.C.

    2005-01-01

    Thickness-dependent index non-linearity in thin films has been a thought provoking as well as intriguing topic in the field of optical coatings. The characterization and analysis of such inhomogeneous index profiles pose several degrees of challenges to thin-film researchers depending upon the availability of relevant experimental and process-monitoring-related information. In the present work, a variety of novel experimental non-linear index profiles have been observed in thin films of MgOAl 2 O 3 ZrO 2 ternary composites in solid solution under various electron-beam deposition parameters. Analysis and derivation of these non-linear spectral index profiles have been carried out by an inverse-synthesis approach using a real-time optical monitoring signal and post-deposition transmittance and reflection spectra. Most of the non-linear index functions are observed to fit polynomial equations of order seven or eight very well. In this paper, the application of such a non-linear index function has also been demonstrated in designing electric-field-optimized high-damage-threshold multilayer coatings such as normal- and oblique-incidence edge filters and a broadband beam splitter for p-polarized light. Such designs can also advantageously maintain the microstructural stability of the multilayer structure due to the low stress factor of the non-linear ternary composite layers. (orig.)

  15. In-situ analysis of the slip activity during tensile deformation of cast and extruded Mg-10Gd-3Y-0.5Zr (wt.%) at 250 °C

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H. [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); The State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824 (United States); Boehlert, C.J., E-mail: boehlert@egr.msu.edu [Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824 (United States); Wang, Q.D., E-mail: wangqudong@sjtu.edu.cn [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); The State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Yin, D.D. [Key Laboratory of Advanced Materials Technology under Ministry of Education, School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Ding, W.J. [National Engineering Research Center of Light Alloy Net Forming, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); The State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2016-06-15

    The slip activity and slip interaction in tensile deformation of peak-aged cast and extruded Mg-10Gd-3Y-0.5Zr (wt.%) at 250 °C was investigated using in-situ scanning electron microscopy. Basal slip was the most likely system to be activated during the tensile deformation, while prismatic < a > and pyramidal < c + a > slip also contributed to the deformation. No twinning was observed. The number of non-basal slip systems accounted for ~ 36% of the total active slip systems for the cast alloy, while non-basal slip accounted for 12–17% of the total deformation observations in the extruded alloy. Multiple-slip was observed within grains, and the basal/prismatic pairing type dominated the multiple-slip observations. Slip transfer occurred across grain boundaries and most of the slip transfer observations showed basal-basal type. The involved slip systems of slip transfer pairs were always associated with the same < a > direction. The slip transfer occurred more easily at low angle boundaries (LABs) and boundaries with misorientations greater than 75°. - Highlights: • Slip deformation of a Mg-RE alloy at 250 °C was investigated using in-situ SEM. • The extruded-T5 GW103 alloy did not exhibit a high anisotropic behavior. • Multiple-slip was observed within grains, and basal/prismatic type dominated. • Slip transfer occurred and most of the observations showed basal-basal type. • Slip transfer occurred more easily at LABs and boundaries with misorientations > 75°.

  16. The Effect of Barium Non-Stoichiometry on the Phase Structure, Sintering and Electrical Conductivity of BaZr0.7Pr0.1Y0.2O3

    KAUST Repository

    Mohamed Shibly, Kaamil

    2015-01-01

    This thesis attempts to test the effects of barium non stoichiometry and varying calcination temperatures on the microstructure and electrical conductivity of BaxZr0.7Pr0.1Y0.2O3- δ (x = 0.9, 1.0, 1.1). BZPY powders were fabricated using a

  17. Stable, easily sintered BaCe{sub 0.5}Zr{sub 0.3}Y{sub 0.16}Zn{sub 0.04}O{sub 3-{delta}} electrolyte-based proton-conducting solid oxide fuel cells by gel-casting and suspension spray

    Energy Technology Data Exchange (ETDEWEB)

    Lin Bin; Dong Yingchao; Wang Songlin; Fang Daru; Ding Hanping; Zhang Xiaozhen; Liu Xingqin [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China); Meng Guangyao [Department of Materials Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China)], E-mail: bin@mail.ustc.edu.cn

    2009-06-10

    Protonic ceramic membrane fuel cells (PCMFCs) based on oxide proton conductors exhibit more advantages than traditional solid oxide fuel cells (SOFCs) based on oxygen-ion conducting electrolytes, such as low activation energy and high energy efficiency. In order to develop a simple and cost-effective route to fabricate PCMFCs with SrCo{sub 0.9}Sb{sub 0.1}O{sub 3-{delta}} (SCS) cubic perovskite cathode, a dense BaCe{sub 0.5}Zr{sub 0.3}Y{sub 0.16}Zn{sub 0.04}O{sub 3-{delta}} (BCZYZn) electrolyte was fabricated in situ metal oxide on a porous anode support by gel-casting and suspension spray, which is cost-effective, easy to realize, and suitable for mass-production. The key part of this process is to directly spray well-mixed suspension of BaCO{sub 3}, CeO{sub 2}, ZrO{sub 2}, Y{sub 2}O{sub 3} and ZnO instead of pre-synthesized BCZYZn ceramic powder on the anode substrate. With SCS cubic perovskite cathode synthesized by gel-casting on the bi-layer, single cells were assembled and tested with H{sub 2} as fuel and the static air as oxidant. An open-circuit potential of 0.987 V, a maximum power density of 364 mW cm{sup -2}, and a low polarization resistance of the electrodes of 0.07 {omega} cm{sup 2} was achieved at 700 deg. C.

  18. Effect of Sb{sub 2}O{sub 3} on the electrical properties of Ba{sub 0.9}Ca{sub 0.1}Zr{sub 0.1}Ti{sub 0.9}O{sub 3} ceramics fabricated using nanocrystals seed

    Energy Technology Data Exchange (ETDEWEB)

    Parjansri, P. [Rajamangala University of Technology Krungthep, Physics Division, Faculty of Science and Technology, Bangkok (Thailand); Intatha, U. [Mae Fah Luang University, School of Science, Chiang Rai (Thailand); Guo, R.; Bhalla, A.S. [University of Texas at San Antonio, Department of Electrical and Computer Engineering, Faculty of Engineering, San Antonio, TX (United States); Eitssayeam, S. [Chiang Mai University, Department of Physics and Materials Science, Faculty of Science, Chiang Mai (Thailand); Chiang Mai University, Materials Science Research Center, Faculty of Science, Chiang Mai (Thailand)

    2016-09-15

    This work was to investigate the effects of antimony oxide (Sb{sub 2}O{sub 3}) on the electrical properties of Ba{sub 0.9}Ca{sub 0.1}Zr{sub 0.1}Ti{sub 0.9}O{sub 3} (BCZT) ceramics and was prepared by adding 1 mol% of BCZT nanocrystals. The seed is nanocrystals of BCZT which was synthesized by the molten salt method. The ceramics powders were prepared by the mixed oxide method using BaCO{sub 3}, CaCO{sub 3}, ZrO{sub 2}, TiO{sub 2} as starting materials, and the BCZT seed was added as nanocrystal for induce phase transition. They were doped with x mol% Sb{sub 2}O{sub 3} (x = 0.0-0.5). Results indicated that all samples show pure perovskite phase. The Sb{sub 2}O{sub 3} enhanced the electrical properties of the ceramic systems. Excellent values of a dielectric constant (ε {sub r}) at room temperature (T{sub r}) were 4086 with sample of x = 0.5, and at Curie temperature (T{sub c}) was 15,485 for samples with x = 0.1. The highest remnant polarization (P{sub r}), piezoelectric charge coefficient (d{sub 33}), piezoelectric voltage coefficient (g{sub 33}), electromechanical coefficient for planar mode (k{sub p}) and thickness mode (k{sub t}) values were 6.3 μC/cm{sup 2}, 346 pC/N, 15.6 x 10{sup -3} Vm/N, 42 and 41 %, respectively, which were obtained for the sample of x = 0.2 mol% Sb. (orig.)

  19. O USO DO BIOFERTILIZANTE EM SOLOS AGRÍCOLAS DO CERRADO DA REGIÃO DO ALTO PARANAÍBA (MG

    Directory of Open Access Journals (Sweden)

    Rodrigo Cavalcanti do Nascimento

    2010-12-01

    Full Text Available Since the implementation of the integrated project in pork meat production, the region of Alto Paranaiba (MGfaced a new sector restructuring, which resulted in the installation of several agribusiness companies. However,the region is experiencing a strong environmental impact caused by the accumulation of pig slurry and themisuse of technological mechanisms that attempt to correct and fertilize soils without proper accountability.Aware of the various environmental concerns on a global scale that have been highlighted in international environmentalconferences (e.g., Kyoto Protocol, transnational companies, in partnership with pork meat producersfrom the region, began to invest in anaerobic biodigesters, which allow to reduce the organic load by 96%, providingelectrical energy (biogas and producing biofertilizer. From the results of research done by Embrapa, theapplication of biofertilizer on the coffee and corn plantation has brought gains in productivity and plague elimination.Analyzing the soil after application, has found harmful high chemical concentrations to the environment.Therefore, this article aims to analyze the positive and negative aspects. This article aims to analyze the use ofbiofertilizers in agricultural areas of the Alto Paranaiba (MG region, specifically in the municipalities of Patosde Minas and Patrocinio.

  20. Formation of qualified BaHfO3 doped Y0.5Gd0.5Ba2Cu3O7-δ film on CeO2 buffered IBAD-MgO tape by self-seeding pulsed laser deposition

    Science.gov (United States)

    Liu, Linfei; Wang, Wei; Yao, Yanjie; Wu, Xiang; Lu, Saidan; Li, Yijie

    2018-05-01

    Improvement in the in-filed transport properties of REBa2Cu3O7-δ (RE = rare earth elements, REBCO) coated conductor is needed to meet the performance requirements for various practical applications, which can be accomplished by introducing artificial pinning centers (APCs), such as second phase dopant. However, with increasing dopant level the critical current density Jc at 77 K in zero applied magnetic field decreases. In this paper, in order to improve Jc we propose a seed layer technique. 5 mol% BaHfO3 (BHO) doped Y0.5Gd0.5Ba2Cu3O7-δ (YGBCO) epilayer with an inserted seed layer was grown on CeO2 buffered ion beam assisted deposition MgO (IBAD-MgO) tape by pulsed laser deposition. The effect of the conditions employed to prepare the seed layer, including tape moving speed and chemical composition, on the quality of 5 mol% BHO doped YGBCO epilayer was systematically investigated by X-ray diffraction (XRD) measurements and scanning electron microscopy (SEM) observations. It was found that all the samples with seed layer have higher Jc (77 K, self-field) than the 5 mol% BHO doped YGBCO film without seed layer. The seed layer could inhibit deterioration of the Jc at 77 K and self-filed. Especially, the self-seed layer (5 mol% BHO doped YGBCO seed layer) was more effective in improving the crystal quality, surface morphology and superconducting performance. At 4.2 K, the 5 mol% BHO doped YGBCO film with 4 nm thick self-seed layer had a very high flux pinning force density Fp of 860 GN/m3 for B//c under a 9 T field, and more importantly, the peak of the Fp curve was not observed.

  1. Valence electron structure and properties of stabilized ZrO2

    Institute of Scientific and Technical Information of China (English)

    LI JinPing; HAN JieOai; MENG SongHe; ZHANG XingHong

    2008-01-01

    To reveal the properties of stabilizers in ZrO2 on nanoscopic levels,the valence elec-tron structures of four stable ZrO2 phases and c-ZrO2 were analyzed on the basis of the empirical electron theory of solids and molecules.The results showed that the hybridization levels of Zr atoms in c-ZrO2 doped with Ca and Mg dropped from B17 to B13,the hybridization levels of Zr atoms in c-ZrO2 doped with Y and Ce dropped from B17 to B15,and that the four stabilizing atoms all made the hybridization levels of O atoms drop from level 4 to level 2.The numbers of covalent electrons in the strongest covalent bond in the descending order are c-ZrO2>ZrCeO2>ZrYOZrMgO>ZrCaO.The bond energies of the strongest covalent bond and the melting points of the solid solutions in the descending order are ZrCeO2>c-ZrO2>ZrYO>ZrMgO>ZrCaO.The percent-ages of the total number of covalent electrons in the descending order arec-ZrO2>ZrYO> ZrCeO2>ZrMgO> ZrCaO.From the above analysis,it can be concluded that the stabilizing degrees of the four stabilizers in the descending order are CaO> MgO>Y2O3>CeO2.

  2. Structural and superconducting properties of (Y,Gd)Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} grown by MOCVD on samarium zirconate buffered IBAD-MgO

    Energy Technology Data Exchange (ETDEWEB)

    Stan, L; Holesinger, T G; Maiorov, B; Feldmann, D M; Usov, I O; DePaula, R F; Civale, L; Foltyn, S R; Jia, Q X [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM 87545 (United States); Chen, Y; Selvamanickam, V [SuperPower, Incorporated, 450 Duane Avenue, Schenectady, NY 12304 (United States)

    2008-10-01

    Textured samarium zirconate (SZO) films have been grown by reactive cosputtering directly on an ion beam assisted deposited (IBAD) MgO template, without an intermediate homoepitaxial MgO layer. The subsequent growth of 0.9 {mu}m thick (Y,Gd)Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} ((Y, Gd)BCO) films by metal organic chemical vapor deposition (MOCVD) yielded well textured films with a full width at half maximum of 1.9{sup 0} and 3.4{sup 0} for the out-of-plane and in-plane texture, respectively. Microstructural characterizations of the SZO buffered samples revealed clean interfaces. This indicates that the SZO not only provides a diffusion barrier, but also functions as a buffer for (Y, Gd)BCO grown by MOCVD. The achievement of self-field critical current densities (J{sub c}) of over 2 MA cm{sup -2} at 75.5 K is another proof of the effectiveness of SZO as a buffer on the IBAD-MgO template. The in-field measurements revealed an asymmetric angular dependence of J{sub c} and a shift of the ab-plane maxima due to the tilted nature of the template and (Y,Gd){sub 2}O{sub 3} particles existing in the (Y, Gd)BCO matrix. The present results are especially important because they demonstrate that high temperature superconducting coated conductors with simpler architecture can be fabricated using commercially viable processes.

  3. Revisiting isoreticular MOFs of alkaline earth metals: a comprehensive study on phase stability, electronic structure, chemical bonding, and optical properties of A-IRMOF-1 (A = Be, Mg, Ca, Sr, Ba).

    Science.gov (United States)

    Yang, Li-Ming; Vajeeston, Ponniah; Ravindran, Ponniah; Fjellvåg, Helmer; Tilset, Mats

    2011-06-07

    Formation energies, chemical bonding, electronic structure, and optical properties of metal-organic frameworks of alkaline earth metals, A-IRMOF-1 (where A = Be, Mg, Ca, Sr, or Ba), have been systemically investigated with DFT methods. The unit cell volumes and atomic positions were fully optimized with the Perdew-Burke-Ernzerhof functional. By fitting the E-V data into the Murnaghan, Birch and Universal equation of states (UEOS), the bulk modulus and its pressure derivative were estimated and provided almost identical results. The data indicate that the A-IRMOF-1 series are soft materials. The estimated bandgap values are all ca. 3.5 eV, indicating a nonmetallic behavior which is essentially metal independent within this A-IRMOF-1 series. The calculated formation energies for the A-IRMOF-1 series are -61.69 (Be), -62.53 (Mg), -66.56 (Ca), -65.34 (Sr), and -64.12 (Ba) kJ mol(-1) and are substantially more negative than that of Zn-based IRMOF-1 (MOF-5) at -46.02 kJ mol(-1). From the thermodynamic point of view, the A-IRMOF-1 compounds are therefore even more stable than the well-known MOF-5. The linear optical properties of the A-IRMOF-1 series were systematically investigated. The detailed analysis of chemical bonding in the A-IRMOF-1 series reveals the nature of the A-O, O-C, H-C, and C-C bonds, i.e., A-O is a mainly ionic interaction with a metal dependent degree of covalency. The O-C, H-C, and C-C bonding interactions are as anticipated mainly covalent in character. Furthermore it is found that the geometry and electronic structures of the presently considered MOFs are not very sensitive to the k-point mesh involved in the calculations. Importantly, this suggests that sampling with Γ-point only will give reliable structural properties for MOFs. Thus, computational simulations should be readily extended to even more complicated MOF systems.

  4. Electrical tuning of magnetization rotation and microwave properties in FeCoZr/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32(011) multiferroic heterostructure

    International Nuclear Information System (INIS)

    Phuoc, Nguyen N; Ong, C K

    2015-01-01

    The permeability spectra of a multiferroic heterostructure composed of a FeCoZr thin film grown onto a [Pb(Mg 1/3 Nb 2/3 )O 3 ] 0.68 -[PbTiO 3 ] 0.32 (011) (PMN-PT) substrate are characterized as a function of an electrical field applied through the thickness of the substrate. When the sample is in an unpoled state and the applied electrical field is increased from 0 kV cm −1 to 2 kV cm −1 , the resonance frequency remains relatively the same. However, as the electrical field is increased beyond 2 kV cm −1 , the resonance frequency is drastically increased from 2.17 GHz to 3.28 GHz and the peak of the permeability spectra becomes much broader. When the electrical field is further increased from 2 kV cm −1 to 6 kV cm −1 , the resonance frequency is gradually increased and finally reaches 4 GHz. As the electrical field is reduced from 6 kV cm −1 back to 2 kV cm −1 , the resonance frequency is reduced in the same manner, and the peak disappears when the electrical field is reduced to less than 2 kV cm −1 . These behaviors are discussed in terms of the magnetization rotation and magnetic anisotropy dispersion based on the stress distribution of the piezoelectric substrate as a function of the applied electrical field. This argument is consistent with the hysteresis loops measured before and after poling. The result suggests that the electrical tunability of the magnetization rotation in multiferroic heterostructures can be employed to electrically turn on and off the microwave operation of the materials, which is promising for applications. (paper)

  5. Raman spectroscopy of DNA-metal complexes. II. The thermal denaturation of DNA in the presence of Sr2+, Ba2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+.

    Science.gov (United States)

    Duguid, J G; Bloomfield, V A; Benevides, J M; Thomas, G J

    1995-12-01

    Differential scanning calorimetry, laser Raman spectroscopy, optical densitometry, and pH potentiometry have been used to investigate DNA melting profiles in the presence of the chloride salts of Ba2+, Sr2+, Mg2+, Ca2+, Mn2+, Co2+, Ni2+, and Cd2+. Metal-DNA interactions have been observed for the molar ratio [M2+]/[PO2-] = 0.6 in aqueous solutions containing 5% by weight of 160 bp mononucleosomal calf thymus DNA. All of the alkaline earth metals, plus Mn2+, elevate the melting temperature of DNA (Tm > 75.5 degrees C), whereas the transition metals Co2+, Ni2+, and Cd2+ lower Tm. Calorimetric (delta Hcal) and van't Hoff (delta HVH) enthalpies of melting range from 6.2-8.7 kcal/mol bp and 75.6-188.6 kcal/mol cooperative unit, respectively, and entropies from 17.5 to 24.7 cal/K mol bp. The average number of base pairs in a cooperative melting unit () varied from 11.3 to 28.1. No dichotomy was observed between alkaline earth and transition DNA-metal complexes for any of the thermodynamic parameters other than their effects on Tm. These results complement Raman difference spectra, which reveal decreases in backbone order, base unstacking, distortion of glycosyl torsion angles, and rupture of hydrogen bonds, which occur after thermal denaturation. Raman difference spectroscopy shows that transition metals interact with the N7 atom of guanine in duplex DNA. A broader range of interaction sites with single-stranded DNA includes ionic phosphates, the N1 and N7 atoms of purines, and the N3 atom of pyrimidines. For alkaline earth metals, very little interaction was observed with duplex DNA, whereas spectra of single-stranded complexes are very similar to those of melted DNA without metal. However, difference spectra reveal some metal-specific perturbations at 1092 cm-1 (nPO2-), 1258 cm-1 (dC, dA), and 1668 cm-1 (nC==O, dNH2 dT, dG, dC). Increased spectral intensity could also be observed near 1335 cm-1 (dA, dG) for CaDNA. Optical densitometry, employed to detect DNA

  6. Quaternary equilibrium diagrams ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}). A powerful tool for the development of new materials by reaction sintering; Diagramas de equilibrio cuaternarios ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}- (CaO, MgO, TiO{sub 2}). Una poderosa herramienta para el desarrollo de nuevos materiales por sinterizacion reactiva

    Energy Technology Data Exchange (ETDEWEB)

    Moya, J. S.; Bartolome, J. F.; Pena, P.

    2011-07-01

    In this paper we set out, discuss and evaluate the work on Mullite-zirconia composites obtained by reaction sintering led and inspired by Salvador de Aza on the basis of ZrO{sub 2}-Al{sub 2}O{sub 3}-SiO{sub 2}-(CaO, MgO, TiO{sub 2}) multicomponent phase equilibrium diagrams. We analyze their impact on different areas of ceramic science and technology such as refractory grogs, aluminum industry, etc. The possible fields of future applications such as dental prosthesis replacing partially stabilized zirconia materials with rare earths are also reported. (Author) 42 refs.

  7. Synthesis of ceramic BaCe{sub 0.7}Zr{sub 0,1}Y{sub 0.2}O{sub 3-δ} electrolyte containing ZnO through the method hidrogel; Sintese do eletrolito ceramico BaCe{sub 0,7}Z{sub 0,1}Y{sub 0,2}O{sub 3-}δ com adicao de ZnO atraves do metodo hidrogel

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, J.H.A.; Fagury Neto, E.; Rabelo, A.A., E-mail: adriano@unifesspa.edu.br [Universidade Federal do Sul e Sudeste do Para (FEMAT/UNIFESSPA), Maraba, PA (Brazil)

    2014-07-01

    The solid oxide fuel cells are promising sources of sustainable energy, once they produce electricity from an electrochemical reaction only with steam water as the product of this reaction. In this paper the synthesis of ceramic electrolyte BaCe{sub 0.7}Zr{sub 0.1}Y{sub 0.2}O{sub 3-δ} using the hydrogel method which involves using an organic gelatin inexpensive and nontoxic modifying the conventional route of polymeric precursor was performed. It was used different amounts of the sintering additive ZnO to decrease the sintering temperature, typically around 1600 °C, towards a minimum relative density of 95%. The polymeric resin was pyrolyzed at 300 °C, subjected to calcination at 600 °C and sintering at temperatures of 1350, 1400 and 1450 °C for 2 hours. Characterizations were carried out by determination of relative density and apparent porosity and using the techniques of differential thermal analysis and simultaneous thermogravimetric, X-ray diffraction and scanning electron microscopy.(author)

  8. Superconducting transition temperature in the Y(1-x)M(x)Ba2Cu3O(y) system

    Science.gov (United States)

    Suzuki, Takeyuki; Yamazaki, Tsutomu; Sekine, Ryuuta; Koukitsu, Akinori; Seki, Hisashi

    1989-04-01

    Experimental results are presented for the inclusion of compositional additives, M, to the sintered high-temperature superconductor Y(1-x)M(x)Ba2Cu3O(y); M can be the oxides of Mg, Ce, Gd, Yb, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, and Te, as well as Li, Na, K, Ca, Sr, and La carbonates. Temperature dependence of the electrical resistance was measured down to about 80 K. Attention is given to the influence of ionic radius and the valence of the M species.

  9. Magnetic field orientation dependence of flux pinning in (Gd,Y)Ba2Cu3O7-x coated conductor with tilted lattice and nanostructures

    International Nuclear Information System (INIS)

    Zhang, Y.; Specht, E.D.; Cantoni, C.; Christen, D.K.; Thompson, J.R.; Sinclair, J.W.; Goyal, A.; Zuev, Y.L.; Aytug, T.; Paranthaman, M.P.; Chen, Y.; Selvamanickam, V.

    2009-01-01

    The dependence of the critical current density (J c ) on the orientation of an applied magnetic field was studied for a prototype (Gd,Y)Ba 2 Cu 3 O 7-x (GdYBCO) coated conductor fabricated by MOCVD on an IBAD-MgO template. Additional rare-earth cations (Y and Gd) and Zr were incorporated into the superconducting film to form (Y,Gd) 2 O 3 and BaZrO 3 nanoparticles extended nearly parallel to the a-b planes and to the c-axis, respectively, to enhance the flux pinning. In-field measurement of J c was carried out with electrical current flowing either along or perpendicular to the longitudinal axis of the tape, while a maximum Lorentz force configuration was always maintained. Details in the angular dependence of J c were related to the unique structure of the film, specifically the tilt in the GdYBCO lattice and the tilts in the extended (Y,Gd) 2 O 3 and BaZrO3 nanoparticles. XRD and TEM were used to study the structure of the coated conductor. The effect of the misalignment between the external field H and the internal field B on the angular dependence of J c is discussed.

  10. Magnetic field orientation dependence of flux pinning in (Gd,Y)Ba2Cu3O7-x coated conductor with tilted lattice and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yifei [ORNL; Specht, Eliot D [ORNL; Cantoni, Claudia [ORNL; Christen, David K [ORNL; Zuev, Yuri L [ORNL; Goyal, Amit [ORNL; Sinclair, J. [University of Tennessee, Knoxville (UTK); Thompson, James R [ORNL; Aytug, Tolga [ORNL; Paranthaman, Mariappan Parans [ORNL; Chen, Y [SuperPower Incorporated, Schenectady, New York; Selvamanickam, V. [SuperPower Incorporated, Schenectady, New York

    2009-01-01

    The dependence of the critical current density (J{sub c}) on the orientation of an applied magnetic field was studied for a prototype (Gd,Y)Ba{sub 2}Cu{sub 3}O{sub 7?x} (GdYBCO) coated conductor fabricated by MOCVD on an IBAD-MgO template. Additional rare-earth cations (Y and Gd) and Zr were incorporated into the superconducting film to form (Y,Gd){sub 2}O{sub 3} and BaZrO{sub 3} nanoparticles extended nearly parallel to the a-b planes and to the c-axis, respectively, to enhance the flux pinning. In-field measurement of J{sub c} was carried out with electrical current flowing either along or perpendicular to the longitudinal axis of the tape, while a maximum Lorentz force configuration was always maintained. Details in the angular dependence of J{sub c} were related to the unique structure of the film, specifically the tilt in the GdYBCO lattice and the tilts in the extended (Y,Gd){sub 2}O{sub 3} and BaZrO{sub 3} nanoparticles. XRD and TEM were used to study the structure of the coated conductor. The effect of the misalignment between the external field H and the internal field B on the angular dependence of J{sub c} is discussed.

  11. Physicochemical impact studies of gamma rays on "aspirin" analgesics drug and its metal complexes in solid form: Synthesis, spectroscopic and biological assessment of Ca(II), Mg(II), Sr(II) and Ba(II) aspirinate complexes

    Science.gov (United States)

    Refat, Moamen S.; Sharshar, T.; Elsabawy, Khaled M.; Heiba, Zein K.

    2013-09-01

    Metal aspirinate complexes, M2(Asp)4, where M is Mg(II), Ca(II), Sr(II) or Ba(II) are formed by refluxed of aspirin (Asp) with divalent non-transition metal ions of group (II) and characterized by elemental analysis and spectroscopic measurements (infrared, electronic, 1H NMR, Raman, X-ray powder diffraction and scanning electron microscopy). Elemental analysis of the chelates suggests the stoichiometry is 1:2 (metal:ligand). Infrared spectra of the complexes agree with the coordination to the central metal atom through three donation sites of two oxygen atoms of bridge bidentate carboxylate group and oxygen atom of sbnd Cdbnd O of acetyl group. Infrared spectra coupled with the results of elemental analyzes suggested a distorted octahedral structure for the M(II) aspirinate complexes. Gamma irradiation was tested as a method for stabilization of aspirin as well as their complexes. The effect of gamma irradiation, with dose of 80 Gy, on the properties of aspirinate complexes was studied. The aspirinate chelates have been screened for their in vitro antibacterial activity against four bacteria, gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two strains of fungus (Aspergillus flavus and Candida albicans). The metal chelates were shown to possess more antibacterial activity than the free aspirin chelate.

  12. Absence of low temperature phase transitions and enhancement of ferroelectric transition temperature in highly strained BaTiO{sub 3} epitaxial films grown on MgO Substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Satish; Kumar, Dhirendra; Sathe, V. G., E-mail: vasant@csr.res.in [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452001 (India); Kumar, Ravi; Sharma, T. K. [Semiconductor Physics and Devices Lab, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2015-04-07

    Recently, a large enhancement in the ferroelectric transition temperature of several oxides is reported by growing the respective thin films on appropriate substrates. This phenomenon is correlated with high residual strain in thin films often leading to large increase in the tetragonality of their crystal structure. However, such an enhancement of transition temperature is usually limited to very thin films of ∼10 nm thickness. Here, we report growth of fully strained epitaxial thin films of BaTiO{sub 3} of 400 nm thickness, which are coherently grown on MgO substrates by pulsed laser deposition technique. Conventional high resolution x-ray diffraction and also the reciprocal space map measurements confirm that the film is fully strained with in-plane tensile strain of 5.5% that dramatically increases the tetragonality to 1.05. Raman measurements reveal that the tetragonal to cubic structural phase transition is observed at 583 K, which results in an enhancement of ∼200 K. Furthermore, temperature dependent Raman studies on these films corroborate absence of all the low temperature phase transitions. Numerical calculations based on thermodynamical model predict a value of the transition temperature that is greater than 1500 °C. Our experimental results are therefore in clear deviation from the existing strain dependent phase diagrams.

  13. Strongly enhanced vortex pinning from 4 to 77 K in magnetic fields up to 31 T in 15 mol.% Zr-added (Gd, Y)-Ba-Cu-O superconducting tapes

    OpenAIRE

    A. Xu; L. Delgado; N. Khatri; Y. Liu; V. Selvamanickam; D. Abraimov; J. Jaroszynski; F. Kametani; D. C. Larbalestier

    2014-01-01

    Applications of REBCO coated conductors are now being developed for a very wide range of temperatures and magnetic fields and it is not yet clear whether vortex pinning strategies aimed for high temperature, low field operation are equally valid at lower temperatures and higher fields. A detailed characterization of the superconducting properties of a 15 mol. % Zr-added REBCO thin film made by metal organic chemical vapor deposition, from 4.2 to 77 K under magnetic fields up to 31 T is presen...

  14. Photoluminescence