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Sample records for high-k titanate la2ti2o7

  1. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, Jean-Claude

    2009-01-01

    The electronic structure of binary titanate La2Ti2O7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La2Ti2O7 are determined as alpha(Ti) = 872...

  2. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.

    2009-02-01

    The electronic structure of binary titanate La2Ti2O7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La2Ti2O7 are determined as αTi = 872.4 and αO = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences ΔTi = (BE O 1s - BE Ti 2p3/2) = 71.6 eV and ΔLa = (BE La 3d5/2 - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  3. Electronic structure of layered ferroelectric high-k titanate La2Ti2O7

    International Nuclear Information System (INIS)

    Atuchin, V V; Gavrilova, T A; Grivel, J-C; Kesler, V G

    2009-01-01

    The electronic structure of binary titanate La 2 Ti 2 O 7 has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La 2 Ti 2 O 7 are determined as α Ti = 872.4 and α O = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences Δ Ti = (BE O 1s - BE Ti 2p 3/2 ) = 71.6 eV and Δ La = (BE La 3d 5/2 - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  4. Electronic structure of layered ferroelectric high-k titanate La{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V V [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Gavrilova, T A [Laboratory of Electron Microscopy and Submicron Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Grivel, J-C [Materials Research Department, National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde (Denmark); Kesler, V G, E-mail: atuchin@thermo.isp.nsc.r [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2009-02-07

    The electronic structure of binary titanate La{sub 2}Ti{sub 2}O{sub 7} has been studied by x-ray photoelectron spectroscopy. Spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in La{sub 2}Ti{sub 2}O{sub 7} are determined as alpha{sub Ti} = 872.4 and alpha{sub O} = 1042.3 eV. Chemical bonding effects have been discussed with binding energy (BE) differences DELTA{sub Ti} = (BE O 1s - BE Ti 2p{sub 3/2}) = 71.6 eV and DELTA{sub La} = (BE La 3d{sub 5/2} - BE O 1s) = 304.7 eV as key parameters in comparison with those in several titanium- and lanthanum-bearing oxides.

  5. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    International Nuclear Information System (INIS)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, J.-C.; Kesler, V.G.; Troitskaia, I.B.

    2012-01-01

    The spectroscopic parameters and electronic structure of binary titanate Pr 2 Ti 2 O 7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr 2 Ti 2 O 7 have been determined as α Ti =872.8 and α O =1042.3 eV. Variations of cation–anion bond ionicity have been discussed using binding energy differences Δ Ti =(BE O 1s–BE Ti 2p 3/2 )=71.6 eV and Δ Pr =BE(Pr 3d 5/2 )−BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides. Highlights: ► Solid state synthesis of polar titanate Pr 2 Ti 2 O 7 . ► Structural and spectroscopic properties and electronic structure determination. ► Ti–O and Pr–O bonding analysis using Ti 2p 3/2 , Pr 3d 5/2 and O 1s core levels.

  6. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.; Troitskaia, I. B.

    2012-11-01

    The spectroscopic parameters and electronic structure of binary titanate Pr2Ti2O7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr2Ti2O7 have been determined as αTi=872.8 and αO=1042.3 eV. Variations of cation-anion bond ionicity have been discussed using binding energy differences ΔTi=(BE O 1s-BE Ti 2p3/2)=71.6 eV and ΔPr=BE(Pr 3d5/2)-BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides.

  7. Electronic structure of layered ferroelectric high-k titanate Pr{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Gavrilova, T.A. [Laboratory of Nanodiagnostics and Nanolithography, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Grivel, J.-C. [Materials Research Division, National Laboratory for Sustainable Energy, Technical University of Denmark, Frederiksborgvej 399, DK-4000, Roskilde (Denmark); Kesler, V.G. [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Troitskaia, I.B. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2012-11-15

    The spectroscopic parameters and electronic structure of binary titanate Pr{sub 2}Ti{sub 2}O{sub 7} have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Pr{sub 2}Ti{sub 2}O{sub 7} have been determined as {alpha}{sub Ti}=872.8 and {alpha}{sub O}=1042.3 eV. Variations of cation-anion bond ionicity have been discussed using binding energy differences {Delta}{sub Ti}=(BE O 1s-BE Ti 2p{sub 3/2})=71.6 eV and {Delta}{sub Pr}=BE(Pr 3d{sub 5/2})-BE(O 1s)=403.8 eV as key parameters in comparison with those of other titanium- and praseodymium-bearing oxides. Highlights: Black-Right-Pointing-Pointer Solid state synthesis of polar titanate Pr{sub 2}Ti{sub 2}O{sub 7}. Black-Right-Pointing-Pointer Structural and spectroscopic properties and electronic structure determination. Black-Right-Pointing-Pointer Ti-O and Pr-O bonding analysis using Ti 2p{sub 3/2}, Pr 3d{sub 5/2} and O 1s core levels.

  8. Electronic structure of layered ferroelectric high-k titanate Pr2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, Jean-Claude

    2012-01-01

    The spectroscopic parameters and electronic structure of binary titanate Pr2Ti2O7 have been studied by IR-, Raman and X-ray photoelectron spectroscopy (XPS) for the powder sample prepared by solid state synthesis. The spectral features of valence band and all constituent element core levels have...

  9. Response of Gd 2 Ti 2 O 7 and La 2 Ti 2 O 7 to swift-heavy ion irradiation and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sulgiye; Lang, Maik; Tracy, Cameron L.; Zhang, Jiaming; Zhang, Fuxiang; Trautmann, Christina; Rodriguez, Matias D.; Kluth, Patrick; Ewing, Rodney C.

    2015-07-01

    Swift heavy ion (2 GeV 181Ta) irradiation-induced amorphization and temperature-induced recrystallization of cubic pyrochlore Gd2Ti2O7 (Fd3¯m) are compared with the response of a compositionally-similar material with a monoclinic-layered perovskite-type structure, La2Ti2O7 (P21). The averaged electronic energy loss, dE/dx, was 37 keV/nm and 35 keV/nm in Gd2Ti2O7 and La2Ti2O7, respectively. Systematic analysis of the structural modifications was completed using transmission electron microscopy, synchrotron X-ray diffraction, Raman spectroscopy, and small-angle X-ray scattering. Increasing ion-induced amorphization with increasing ion fluence was evident in the X-ray diffraction patterns of both compositions by a reduction in the intensity of the diffraction maxima concurrent with the growth in intensity of a broad diffuse scattering halo. Transmission electron microscopy analysis showed complete amorphization within ion tracks (diameter: ~10 nm) for the perovskite-type material; whereas a concentric, core–shell morphology was evident in the ion tracks of the pyrochlore, with an outer shell of disordered yet still crystalline material with the fluorite structure surrounding an amorphous track core (diameter: ~9 nm). The radiation response of both titanate oxides with the same stoichiometry can be understood in terms of differences in their structures and compositions. While the radiation damage susceptibility of pyrochlore A2B2O7 materials decreases as a function of the cation radius ratio rA/rB, the current study correlates this behavior with the stability field of monoclinic structures, where rLa/rTi > rGd/rTi. Isochronal annealing experiments of the irradiated materials showed complete recrystallization of La2Ti2O7 at 775 °C and of Gd2Ti2O7 at 850 °C. The annealing behavior is discussed in terms of enhanced damage recovery in La2Ti2O7, compared to the pyrochlore compounds Gd2Ti2O7. The difference in the recrystallization behavior may be related to structural

  10. Electronic structure of layered titanate Nd2Ti2O7

    DEFF Research Database (Denmark)

    Atuchin, V.V.; Gavrilova, T.A.; Grivel, Jean-Claude

    2008-01-01

    The electronic structure of the binary titanate Nd2Ti2O7 has been studied by X-ray photoelectron spectroscopy (XPS). Spectral features of the valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Nd2Ti2O7 are determined as alpha...

  11. Electronic structure of layered titanate Nd 2Ti 2O 7

    Science.gov (United States)

    Atuchin, V. V.; Gavrilova, T. A.; Grivel, J.-C.; Kesler, V. G.

    2008-10-01

    The electronic structure of the binary titanate Nd 2Ti 2O 7 has been studied by X-ray photoelectron spectroscopy (XPS). Spectral features of the valence band and all constituent element core levels have been considered. The Auger parameters of titanium and oxygen in Nd 2Ti 2O 7 are determined as αTi = 873.5 and αO = 1042.2 eV. Chemical bonding effects have been discussed with the binding energies differences ΔTi = (BE O 1s - BE Ti 2p 3/2) = 71.5 eV and ΔNd = (BE Nd 3d 5/2 - BE O 1s) = 452.5 eV as key parameters in comparison with those in other titanium- and neodymium-bearing oxides.

  12. The production of grain oriented lanthanum titanate (La2Ti2O7) ceramics by uniaxial hot-forging process for improved fracture toughness

    International Nuclear Information System (INIS)

    Ceylan, Ali

    2008-01-01

    The layered-structural ceramics, such as lanthanum titanate (La 2 Ti 2 O 7 ), have been known for their good electrical and optical properties at high frequencies and temperatures. However, few studies have been conducted on the mechanical properties of these ceramics. The interest in ceramic hot-forging (HF) has been greatly increased recently due to the enhancement in fracture toughness via bridging effect of oriented grains. In this study, grain oriented lanthanum titanate was produced by the hot-forging process. The characterizations of the samples were achieved by density measurement, scanning electron microscopy (SEM), optical microscopy, X-ray diffraction (XRD), Vickers indentation and three-point bending test. According to X-ray diffraction patterns, the orientation factor (f) was found to be 0.73 for certain hot-forging conditions resulting an improved fracture toughness. The improved fracture toughness of La 2 Ti 2 O 7 (3.2 MPa m 1/2 ) reached to the value of monolithic alumina (Al 2 O 3 ) between 3 and 4 MPa m 1/2

  13. Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics for capacitor applications

    Directory of Open Access Journals (Sweden)

    Zhang Chen

    2018-03-01

    Full Text Available Microstructure and dielectric properties of La2O3 doped Ti-rich barium strontium titanate ceramics, prepared by solid state method, were investigated with non-stoichiometric level and various La2O3 content, using XRD, SEM and LCR measuring system. With an increase of non-stoichiometric level, the unit cell volumes of perovskite lattices for the single phase Ti-rich barium strontium titanate ceramics increased due to the decreasing A site vacancy concentration V″A. The unit cell volume increased and then decreased slightly with the increasing La2O3 content. Relatively high non-stoichiometric level and high La2O3 content in Ti-rich barium strontium titanate ceramics contributed to the decreased average grain size as well as fine grain size distribution, which correspondingly improved the temperature stability of the relative dielectric constant. The relative dielectric constant єrRT, dielectric loss tanδRT and the maximum relative dielectric constant єrmax decreased and then increased with the increasing non-stoichiometric level. With the increase of La2O3 doping content, the relative dielectric constant єrRT increased initially and then decreased. The maximum relative dielectric constant єrmax can be increased by applying low doping content of La2O3 in Ti-rich barium strontium titanate ceramics due to the increased spontaneous polarization.

  14. Hydrothermal crystallization of Na2Ti6O13, Na2Ti3O7, and Na16Ti10O28 in the NaOH-TiO2-H2O system at a temperature of 500 deg. C and a pressure of 0.1 GPa: The structural mechanism of self-assembly of titanates from suprapolyhedral clusters

    International Nuclear Information System (INIS)

    Hyushin, G. D.

    2006-01-01

    An increase in the NaOH concentration in the NaOH-TiO 2 (rutile)-H 2 O system at a temperature of 500 deg. C and a pressure of 0.1 GPa leads to the crystallization R-TiO 2 + Na 2 Ti 6 O 13 → Na 2 Ti 3 O 7 → Na 16 Ti 10 O 28 . Crystals of the Na 2 Ti 6 O 13 titanate (space group C2/m) have the three-dimensional framework structure Ti 6 O 13 . The structure of the Na 2 Ti 3 O 7 titanate (space group P2 1 /m) contains the two-dimensional layers Ti 3 O 7 . The structure of the Na 16 Ti 10 O 28 titanate (space group P-1) is composed of the isolated ten-polyhedron cluster precursors Ti 10 O 28 . In all the structures, the titanium atoms have an octahedral coordination (MTiO 6 ). The matrix self-assembly of the Na 2 Ti 6 O 13 and Na 2 Ti 3 O 7 (Na 4 Ti 6 O 14 ) crystal structures from Na 4 M 12 invariant precursors is modeled. These precursors are clusters consisting of twelve M polyhedra linked through the edges. It is demonstrated that the structurally rigid precursors Na 4 M 12 control all processes of the subsequent evolution of the crystal-forming titanate clusters. The specific features of the self-assembly of the Na 2 Ti 3 O 7 structure that result from the additional incorporation of twice the number of sodium atoms into the composition of the high-level clusters are considered

  15. Synthesis of titanate, TiO2 (B), and anatase TiO2 nanofibers from natural rutile sand

    International Nuclear Information System (INIS)

    Pavasupree, Sorapong; Suzuki, Yoshikazu; Yoshikawa, Susumu; Kawahata, Ryoji

    2005-01-01

    Titanate nanofibers were synthesized by hydrothermal method (150 deg. C for 72 h) using natural rutile sand as the starting materials. TiO 2 (B) and anatase TiO 2 (high crystallinity) nanofibers with the diameters of 20-100 nm and the lengths of 10-100 μm were obtained by calcined titanate nanofibers for 4 h at 400 and 700 deg. C (in air), respectively. The samples characterized by XRD, SEM, TEM, SAED, HRTEM, and BET surface area. This synthesis method provides a simple route to fabricate one-dimensional nanostructured TiO 2 from low cost material. -- Graphical abstract: Titanate nanofibers (b) were synthesized by hydrothermal method (150 deg. C for 72 h) using natural rutile sand (a) as the starting materials. TiO 2 (B) (c) and anatase TiO 2 (d) nanofibers with the diameters of 20-50 nm and the lengths of 10-100 μm were obtained by calcined titanate nanofibers for 4 h at 400 deg. C and 700 deg. C (in air), respectively

  16. Defect Chemistry of a Zinc-Doped Lepidocrocite Titanate CsxTi2−x/2Znx/2O4 (x = 0.7) and its Protonic Form

    DEFF Research Database (Denmark)

    Gao, Tao; Fjellvåg, Helmer; Norby, Poul

    2009-01-01

    A zinc-doped layered titanate CsxTi2−x/2Znx/2O4 (x = 0.7) with lepidocrocite (γ-FeOOH)-type layered structure was prepared via solid-state calcination. A complete extraction of both lattice Zn atoms and interlayer Cs ions was observed upon acid exchange, producing a protonic form H2xTi2−x/2x/2O4·H2....... The protonic titanate H2xTi2−x/2x/2O4·H2O readily underwent delamination to produce its molecular single sheets Ti1−δδO24δ− (δ = 0.175) with distinctive two-dimensional morphology and small thickness (1 nm), suggesting promising applications in the assembly of functional nanostructures....

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-15

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

  18. Adsorption of carbon dioxide on TEPA-modified TiO_2/titanate composite nano-rods

    International Nuclear Information System (INIS)

    Kapica-Kozar, Joanna; Michalkiewicz, Beata; Wrobel, Rafal J.; Mozia, Sylwia; Pirog, Ewa; Usiak-Nejman, Ewelina K.; Serafin, Jaroslaw; Morawski, Antoni W.; Narkiewicz, Urszula

    2017-01-01

    A titanate-TiO_2 composite was obtained through hydrothermal treatment of TiO_2 in KOH solution. The presence of a titanate phase was confirmed by X-ray diffraction (XRD), whereas scanning electron microscopy (SEM) measurements showed the porous nano-rod structure of the material. The obtained nano-rods were treated with tetra-ethylene-pentamine (TEPA). Such synthesized sorbents were applied for CO_2 removal. The CO_2 capacity under a pressure of 1 bar and at 80 C was 0.47, 0.34, and 3.11 mmol.g"-"1 for the starting TiO_2, the titanate-TiO_2 composite and the TEPA-titanate-TiO_2 composite (27.4 wt% of TEPA), respectively. The experimental isotherms of CO_2 were analysed using the Langmuir, Freundlich, Sips, Toth, Unilan, Redlich-Peterson, Radke-Prausnitz, Dubinin-Radushkevich, Temkin and Pyzhev, and Jovanovich models. The error sums of squares (SSR) function was used to test the fit of the models. The analysis revealed that the Sips isotherm is the best-fitting model for the CO_2 adsorption on the starting TiO_2, whereas the Freundlich equation should be used to describe the CO_2 adsorption isotherm on the titanate-TiO_2 composite. The CO_2 adsorption on the TEPA-modified sorbents was proposed to be described using the Sips isotherm for physical sorption and the modified Sips model for chemical sorption. The calculated isosteric heat of adsorption was found to be E46 kJ mol"-"1, which is about two times higher than the heat of CO_2 absorption in liquid TEPA reported in the literature (i.e. E85 kJ.mol"-"1). Therefore, it was concluded that the TEPA-titanate-TiO_2 composite is an attractive alternative for liquid amines due to the lower energy of regeneration in the sorption-desorption process. The material was proved to be stable during multiple sorption-desorption cycles. Moreover, its thermal stability up to 150 C was confirmed by thermogravimetric analysis (TGA). All these features make it a promising alternative for sorbents based on liquid amines. (authors)

  19. Glass forming in La2O3-TiO2-ZrO2 ternary system by containerless processing

    Science.gov (United States)

    Kaneko, Masashi; Kentei Yu, Yu; Kumar, Vijaya; Masuno, Atsunobu; Inoue, Hiroyuki; Odawara, Osamu; Yoda, Shinichi

    The containerless processing is an appropriate method to create new glasses, because it sup-presses nucleation at the boundary between liquid and crucible during solidification and it enables molten samples to be solidified without crystallization. Recently, we have succeeded in forming BaTi2 O5 glass in the bulk state by using an aerodynamic levitation furnace. BaTi2 O5 glass includes no traditional glass network former and it possesses high electric permittivity [1, 2]. From the point of view of optical application, BaTi2 O5 glass has high refractive indices over 2.1. BaTi2 O5 glass, however, vitrify only in a small sphere, and it crystallize when its diameter exceed 1.5 mm. In order to synthesize new titanate oxide glasses which possess higher refractive indices and larger diameter than BaTi2 O5 , La and Zr can be used as substitutive components. When Ba is replaced with La, refractive indices are expected to increase because of the heavier element. The addition of a third element is thought to be effective for enhance-ment of glass formation ability and Zr can be a candidate because Ti and Zr are homologous. In this research, we have succeeded in forming new bulk glass in La2 O3 -TiO2 -ZrO2 ternary system by means of the aerodynamic levitation furnace. We investigated the glass forming region, thermal properties and optical properties of La2 O3 -TiO2 -ZrO2 glass. Glass transition temperature, crystallization temperature, density, refractive indices and transmittance spectra were varied depending on the chemical composition. Reference [1] J. Yu et al, "Fabrication of BaTi2O5 Glass-Ceramics with Unusual Dielectric Properties during Crystallization", Chem-istry of Materials, 18 (2006) 2169-2173. [2] J. Yu et al., "Comprehensive Structural Study of Glassy and Metastable Crystalline BaTi2O5", Chemistry of Materials, 21 (2009) 259-263.

  20. Thermal expansion studies on europium titanate (Eu2TiO5)

    International Nuclear Information System (INIS)

    Panneerselvam, G.; Subramanian, G.G.S.; Antony, M.P.

    2008-01-01

    The lattice thermal expansion characteristics of europium titanate (Eu 2 TiO 5 ) have been studied by measuring the lattice parameter by high temperature X-ray diffraction technique (HT-XRD) in the temperature range 298-1573K. Percentage linear thermal expansion and mean linear thermal expansion coefficients were computed from the lattice parameter data. The percentage linear thermal expansion in the temperature range 298-1573 K along a, b and c axes are 1.05, 1.15 and 0.95 respectively. (author)

  1. Theoretical study of disorder in Ti-substituted La2Zr2O7

    International Nuclear Information System (INIS)

    Chartier, Alain; Meis, Constantin; Weber, William J.; Corrales, L. Rene

    2002-01-01

    Pyrochlores have the striking feature that their radiation resistance is highly dependent on their composition. In this work, the propensity of a pyrochlore to transform to a cation-disordered structure and the influence of titanium ions is ascertained from the mechanisms of defect formation. A detailed study of defect formation and migration activation energies in Ti-substituted La 2 Zr 2 O 7 is carried out by modern theoretical computational methods that include the use of a classical interatomic potential with a modified shell model to capture the effects of local charge transfer. The results show that La 2 Zr 2 O 7 has a tendency towards cation disorder, whereas, substitution of Zr with Ti makes this tendency energetically less favorable

  2. Controllable solvothermal synthesis and photocatalytic properties of complex (oxy)fluorides K{sub 2}TiOF{sub 4}, K{sub 3}TiOF{sub 5}, K{sub 7}Ti{sub 4}O{sub 4}F{sub 7} and K{sub 2}TiF{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Sheng Jie [Division of Nanomaterials and Nanochemistry, Hefei National Laboratory for Physical Sciences at Microscale, Hefei, Anhui 230026 (China); Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tang Kaibin, E-mail: kbtang@ustc.edu.cn [Division of Nanomaterials and Nanochemistry, Hefei National Laboratory for Physical Sciences at Microscale, Hefei, Anhui 230026 (China); Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China); Cheng Wei; Wang Junli; Nie Yanxiang; Yang Qing [Division of Nanomaterials and Nanochemistry, Hefei National Laboratory for Physical Sciences at Microscale, Hefei, Anhui 230026 (China); Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2009-11-15

    Complex (oxy)fluorides K{sub 2}TiF{sub 6}, K{sub 2}TiOF{sub 4}, K{sub 3}TiOF{sub 5} and K{sub 7}Ti{sub 4}O{sub 4}F{sub 7} have been successfully synthesized for the first time through a controllable solvothermal route involving different solvents, for example, methanol, methanol-H{sub 2}O and methanol-H{sub 2}O{sub 2}. The as-prepared products were characterized by X-ray powder diffraction, N{sub 2} surface area adsorption, scanning electron microscope, Fourier transform infrared spectroscopy, UV-vis absorption spectra and X-ray fluorescence. The influences of reaction conditions such as the ratio of methanol to H{sub 2}O{sub 2} or methanol to H{sub 2}O, reaction temperature on the phase, crystallizability and purity of the (oxy)fluorides products were discussed in detail. Meanwhile, the photocatalytic behaviors of the as-prepared K{sub 2}TiF{sub 6}, K{sub 2}TiOF{sub 4}, K{sub 3}TiOF{sub 5} and K{sub 7}Ti{sub 4}O{sub 4}F{sub 7} were evaluated by degradation of rhodamine B molecules, and the results showed that all of the products possessed photocatalytic activities in the order of K{sub 2}TiOF{sub 4} > K{sub 2}TiF{sub 6} > K{sub 7}Ti{sub 4}O{sub 4}F{sub 7} > K{sub 3}TiOF{sub 5} at room temperature under the UV light.

  3. Comparison of the Supercooled Spin Liquid States in the Pyrochlore Magnets Dy2Ti2O7 and Ho2Ti2O7

    Science.gov (United States)

    Eyal, Anna; Eyvazov, Azar B.; Dusad, Ritika; Munsie, Timothy J. S.; Luke, Graeme M.; Davis, J. C. Séamus

    Despite a well-ordered crystal structure and strong magnetic interactions between the Dy or Ho ions, no long-range magnetic order has been detected in the pyrochlore titanates Ho2Ti2O7 and Dy2Ti2O7. The low temperature state in these materials is governed by spin-ice rules. These constrain the Ising like spins in the materials, yet does not result in a global broken symmetry state. To explore the actual magnetic phases, we simultaneously measure the time- and frequency-dependent magnetization dynamics of Dy2Ti2O7 and Ho2Ti2O7 using toroidal, boundary-free magnetization transport techniques. We demonstrate a distinctive behavior of the magnetic susceptibility of both compounds, that is indistinguishable in form from the permittivity of supercooled dipolar liquids. Moreover, we show that the microscopic magnetic relaxation times for both materials increase along a super-Arrhenius trajectory also characteristic of supercooled glass-forming liquids. Both materials therefore exhibit characteristics of a supercooled spin liquid. Strongly-correlated dynamics of loops of spins is suggested as a possible mechanism which could account for these findings. Potential connections to many-body spin localization will also be discussed.

  4. Tuning piezoelectric properties through epitaxy of La2Ti2O7 and related thin films.

    Science.gov (United States)

    Kaspar, Tiffany C; Hong, Seungbum; Bowden, Mark E; Varga, Tamas; Yan, Pengfei; Wang, Chongmin; Spurgeon, Steven R; Comes, Ryan B; Ramuhalli, Pradeep; Henager, Charles H

    2018-02-14

    Current piezoelectric sensors and actuators are limited to operating temperatures less than ~200 °C due to the low Curie temperature of the piezoelectric material. Strengthening the piezoelectric coupling of high-temperature piezoelectric materials, such as La 2 Ti 2 O 7 (LTO), would allow sensors to operate across a broad temperature range. The crystalline orientation and piezoelectric coupling direction of LTO thin films can be controlled by epitaxial matching to SrTiO 3 (001), SrTiO 3 (110), and rutile TiO 2 (110) substrates via pulsed laser deposition. The structure and phase purity of the films are investigated by x-ray diffraction and scanning transmission electron microscopy. Piezoresponse force microscopy is used to measure the in-plane and out-of-plane piezoelectric coupling in the films. The strength of the out-of-plane piezoelectric coupling can be increased when the piezoelectric direction is rotated partially out-of-plane via epitaxy. The strongest out-of-plane coupling is observed for LTO/STO(001). Deposition on TiO 2 (110) results in epitaxial La 2/3 TiO 3 , an orthorhombic perovskite of interest as a microwave dielectric material and an ion conductor. La 2/3 TiO 3 can be difficult to stabilize in bulk form, and epitaxial stabilization on TiO 2 (110) is a promising route to realize La 2/3 TiO 3 for both fundamental studies and device applications. Overall, these results confirm that control of the crystalline orientation of epitaxial LTO-based materials can govern the resulting functional properties.

  5. Photocatalytic oxidation of propylene on La and N codoped TiO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinfeng; Li, Haiyan; Zong, Lanlan; Li, Qiuye, E-mail: lqybys@163.com; Wang, Xiaodong; Zhang, Min; Yang, Jianjun, E-mail: yangjianjun@henu.edu.cn [Henan University, Key Laboratory for Special Functional Materials (China)

    2015-02-15

    Lanthanum- and nitrogen-codoped TiO{sub 2} photocatalysts was synthesized using orthorhombic nanotubes titanic acid as the precursor by a simple impregnation and subsequent calcination method. The morphology, phase structure, and properties of La- and N-codoped TiO{sub 2} were well characterized by transmission electron microscopy, X-ray diffraction, Raman spectra, X-ray photoelectron spectroscopy, and UV–Vis diffuse reflectance spectra. The La-/N-codoped TiO{sub 2} showed excellent photoactivity of propylene oxidation compared with the single-doped TiO{sub 2} and La-/N-codoped P25 TiO{sub 2} nanoparticles under visible light irradiation. The origin of the enhancement of the visible light-responsive photocatalytic activity was discussed in detail.

  6. High temperature phase transition of Tm2Ti2O7

    International Nuclear Information System (INIS)

    Shlyakhtina, A.V.; Shcherbakova, L.G.; Knot'ko, A.V.; Larina, L.L.; Borichev, S.A.

    2004-01-01

    A high temperature phase transition type order-disorder is investigated in Tm 2 Ti 2 O 7 at t>1600 Deg C. It is shown that this transformation is irreversible. Ion conductivity of synthesized at 1670 Deg C nanocrystalline Tm 2 Ti 2 O 7 constitutes 2x10 -3 S/cm at 740 Deg C and remains constant after heat treatment at 860 Deg C for 240 h in the air. It is revealed that the conductivity of specimens (grain size of 20-30 nm) on the basis of Tm 2 Ti 2 O 7 high temperature modification with a structure of disordered pyrochlore is independent of grain size [ru

  7. Tuning piezoelectric properties through epitaxy of La2Ti2O7 and related thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kaspar, Tiffany C.; Hong, Seungbum; Bowden, Mark E.; Varga, Tamas; Yan, Pengfei; Wang, Chongmin; Spurgeon, Steven R.; Comes, Ryan B.; Ramuhalli, Pradeep; Henager, Charles H.

    2018-02-14

    Current piezoelectric sensors and actuators are limited to operating temperatures less than ~200°C due to the low Curie temperature of the piezoelectric material. High temperature piezoelectric materials such as La2Ti2O7 (LTO) would facilitate the development of high-temperature sensors if the piezoelectric coupling coefficient could be maximized. We have deposited epitaxial LTO films on SrTiO3(001), SrTiO3(110), and rutile TiO2(110) substrates by pulsed laser deposition, and show that the crystalline orientation of the LTO film, and thus its piezoelectric coupling direction, can be controlled by epitaxial matching to the substrate. The structure and phase purity of the films were investigated by x-ray diffraction and scanning transmission electron microscopy. To characterize the piezoelectric properties, piezoresponse force microscopy was used to measure the in-plane and out-of-plane piezoelectric coupling in the films. We find that the strength of the out-of-plane piezoelectric coupling can be increased when the piezoelectric crystalline direction is rotated partially out-of-plane via epitaxy. The strongest out-of-plane coupling is observed for LTO/STO(001). Deposition on TiO2(110) results in epitaxial La2/3TiO3, an orthorhombic perovskite of interest as a microwave dielectric material. La2/3TiO3 can be difficult to stabilize in bulk form, and epitaxial deposition has not been previously reported. These results confirm that control of the crystalline orientation of LTO-based materials can increase the out-of-plane strength of its piezoelectric coupling, which can be exploited in piezoelectric devices.

  8. Efecto de la estequiometría y de la temperatura de cocción en el desarrollo de la fase Al2TiO5

    Directory of Open Access Journals (Sweden)

    Baptista, J.

    2003-04-01

    Full Text Available Aluminum Titanate (Al2TiO5 due to its low termal expansion coefficient, low wettability and high refractoriness is a promissing refractory ceramic to be in contact with non ferrous metals, specially molten aluminum. Controlled amounts of CaO, SiO2, MgO and ZrO2 are normally added in order to avoid expontaneous decomposition, lower than 1300°C, into its constituint oxides. In this work through the adoption of a new approach, it was investigated the Al2TiO5 phase development and stabilization with respect to stoichiometry and firing temperature. It was found that an excess of Titania (TiO2 helps the development of a stable and purer Aluminum Titanate phase.El Titanato de Aluminio (Al2TiO5 debido a su bajo coeficiente de expansión térmica, elevada refractariedad y baja mojabilidad por metales no ferrosos fundidos, es un material prometedor en la industria del Aluminio para aplicaciones donde se exige contacto con el baño metálico. Aditivos como CaO, SiO2, MgO y ZrO2 son necesarios para evitar la descomposición espontánea del Al2TiO5 en sus óxidos constituyentes a temperaturas inferiores a 1300°C. En este trabajo, se ha investigado el efecto de la estequiometría y de la temperatura de sinterización en el desarrollo y estabilidad de la fase Al2TiO5. Se ha encontrado que un exceso de Óxido de Titanio (TiO2 es beneficioso en la producción de Al2TiO5 puro y estable.

  9. Hydrothermal crystallization in the KOH-TiO2-GeO2-H2O system at 500 deg C and 0.1 GPa

    International Nuclear Information System (INIS)

    Ilyushin, G.D.

    2003-01-01

    The identification of structural phases and crystallochemical analysis of phases in a KOH-TiO 2 -GeO 2 -H 2 O system under conditions of high temperatures and pressures are performed. A comparison is made with earlier obtained results for a system of KOH-GeO 2 (quartz-like structure)-H 2 O. It is established that K 2 Ti 6 O 13 skeleton potassium titanate is a basic phase in the system of KOH-TiO 2 -GeO 2 -H 2 O at 500 deg C and 0.1 GPa within a wide range of varying TiO 2 :GeO 2 and KOH concentrations [ru

  10. Effect of Ti doping on magnetic properties and magnetoresistance in LaSr2Mn2O7

    International Nuclear Information System (INIS)

    Feng, J.; Che, P.; Wang, J.P.; Lu, M.F.; Liu, J.F.; Cao, X.Q.; Meng, J.

    2005-01-01

    The effect of Ti substitution for Mn on magnetic and transport properties has been investigated for layered manganese oxides LaSr 2 Mn 2-x Ti x O 7 . Titanium doping hampered the canted antiferromagnetic (AFM) exchange at low temperature and their Neel temperature (T N ) decreased from 138 K (x = 0) to 106 K (x = 0.1). Meanwhile, spin glass, charge ordering and metal-insulator transition are suppressed by Ti addition. This can be attributed to Mn-site disorder caused by random substitution of Ti 4+ . The suppression of charge ordering leads to magntetoresistance (MR) ratio increase and MR reaches maximum at x = 0.3. The resistivity increases obviously with x increasing because of double exchange interaction channel broken by Ti 4+ addition. The resistivity of all samples in low temperature range fits to the Mott's variable range hopping (VRH) model, while it fits to nearest neighbor hopping of small polarons model in high temperature range. We also found that both disorder and distortion in A-site and B-site will induce the similar effect to electrical and magnetic properties

  11. Synthesis and photocatalytic activity of hydrated layered perovskite K2-xLa2Ti3-xNb xO10 (0 ≤ x ≤ 1) and protonated derivatives

    International Nuclear Information System (INIS)

    Huang Yunfang; Wu Jihuai; Wei Yuelin; Hao Sancun; Huang Miaoliang; Lin Jianming

    2007-01-01

    A series of photocatalytic intercalated materials K 2-x La 2 Ti 3-x Nb x O 10 (0 ≤ x ≤ 1) and a series of its protonated derivatives H 2-x La 2 Ti 3-x Nb x O 10 were prepared by solid-state reaction and ion-exchange reaction. The photocatalytic activities of samples were evaluated using methanol as electron donor under UV irradiation. All H 2-x La 2 Ti 3-x Nb x O 10 samples possessed approximately twofold higher photocatalytic activity than the corresponding K 2-x La 2 Ti 3-x Nb x O 10 . This difference was most pronounced for the photocatalyst H 1.9 La 2 Ti 2.9 Nb 0.1 O 10 which showed the highest activity: 22 μmol H 2 /catalyst (g) for 5 h, more than three times the activity of K 1.9 La 2 Ti 2.9 Nb 0.1 O 10

  12. The influence of Ti doping and annealing on Ce_2Ti_2O_7 flash memory devices

    International Nuclear Information System (INIS)

    Kao, Chyuan Haur; Chen, Su Zhien; Luo, Yang; Chiu, Wang Ting; Chiu, Shih Wei; Chen, I Chien; Lin, Chan-Yu; Chen, Hsiang

    2017-01-01

    Highlights: • Ce_2Ti_2O_7 flash memories have been fabricated. • Material quality can be improved by annealing. • The memory performance can be enhanced by Ti doping. • Ti doping and annealing can reinforce crystallization. - Abstract: In this research, a CeO_2 film with Ti doping was used as a trapping layer in metal oxide high-K-oxide-Si (MOHOS)-type memory devices. Since incorporation of Ti atoms into the film could fix dangling bonds and defects, the Ce_2Ti_2O_7 trapping layer with annealing treatment could have a larger memory window and a faster programming/erasing speed. To confirm the origin, multiple material analyses indicate that annealing at an appropriate temperature and Ti doping could enhance crystallization. The Ce_2Ti_2O_7-based memory device is promising for future industrial flash memory applications.

  13. Al2TiO5-ZrTiO4-ZrO2 composites

    International Nuclear Information System (INIS)

    Parker, F.J.

    1990-01-01

    The characterization and properties of ceramic composites containing the phases Al 2 TiO 5 , ZrTiO 4 , and ZrO 2 are described. The low thermal expansions are apparently due to a combination of microcracking by the titanate phases and a contractive phase transformation by the ZrO 2 . The crystal chemistry and microstructure of the product are processing dependent. Although the composites represent a complex microcracking system, the low thermal expansions and high-temperature stability make them potential candidates for commercial application requiring thermal shock resistance

  14. Visible-light photochemical activity of heterostructured core-shell materials composed of selected ternary titanates and ferrites coated by tiO2.

    Science.gov (United States)

    Li, Li; Liu, Xuan; Zhang, Yiling; Nuhfer, Noel T; Barmak, Katayun; Salvador, Paul A; Rohrer, Gregory S

    2013-06-12

    Heterostructured photocatalysts comprised of microcrystalline (mc-) cores and nanostructured (ns-) shells were prepared by the sol-gel method. The ability of titania-coated ATiO3 (A = Fe, Pb) and AFeO3 (A = Bi, La, Y) catalysts to degrade methylene blue in visible light (λ > 420 nm) was compared. The catalysts with the titanate cores had enhanced photocatalytic activities for methylene blue degradation compared to their components alone, whereas the catalysts with ferrite cores did not. The temperature at which the ns-titania shell is crystallized influences the photocatalytic dye degradation. mc-FeTiO3/ns-TiO2 annealed at 500 °C shows the highest reaction rate. Fe-doped TiO2, which absorbs visible light, did not show enhanced photocatalytic activity for methylene blue degradation. This result indicates that iron contamination is not a decisive factor in the reduced reactivity of the titania coated ferrite catalysts. The higher reactivity of materials with the titanate cores suggests that photogenerated charge carriers are more easily transported across the titanate-titanate interface than the ferrite-titanate interface and this provides guidance for materials selection in composite catalyst design.

  15. Fabrication and characterization of laminated Ti-(TiB+La2O3/Ti composite

    Directory of Open Access Journals (Sweden)

    Yuanfei Han

    2015-10-01

    Full Text Available The incorporation of ceramic particulate reinforcements into titanium alloys can improve the specific strength and specific stiffness, while inevitably reduce the plasticity and ductility. In this study, in situ synthesized multilayer Ti-(TiB+La2O3/Ti composite was designed by learning from the microstructure of nature biological materials with excellent mechanical properties. The Ti-(TiB+La2O3/Ti composite with unique characteristic of laminated structure was prepared by combined powder metallurgy and hot rolling. The method has the synthesize advantages with in-situ reaction of Ti and LaB6 at high temperature and controllability of reinforcements size and constituent phases in composites. The result shows that the pores in the as sintered laminated structure composite completely disappeared after hot rolling at 1050 °C. The agglomerated reinforcement particles were well dispersed and distributed uniformly along the rolling direction. The thickness of pure Ti layer and (TiB+La2O3/Ti composite layer decreased from 1 mm to about 200 μm. Meanwhile, the grains size was refined obviously after rolling deformation. The room temperature tensile test indicates that the elongation of the laminated Ti-(TiB+La2O3/Ti composite improved from 13% to 17% in comparison with the uniform (TiB+La2O3/Ti composite, while the tensile strength had little change. It provides theoretical and experimental basis for fabricating the novel high performance laminated Ti-(TiB+La2O3/Ti composites.

  16. Thermal expansion of lanthanum silicate oxyapatite (La9.33+2x(SiO4)6O2+3x), lanthanum oxyorthosilicate (La2SiO5) and lanthanum sorosilicate (La2Si2O7)

    International Nuclear Information System (INIS)

    Fukuda, Koichiro; Asaka, Toru; Uchida, Tomohiro

    2012-01-01

    Four types of powder specimens of La 9.33 (SiO 4 ) 6 O 2 (space group P6 3 /m and Z=1), La 9.33+2x (SiO 4 ) 6 O 2+3x with 0.06≤x≤0.13 (P6 3 /m and Z=1), La 2 SiO 5 (P2 1 /c and Z=4) and La 2 Si 2 O 7 (P2 1 /c and Z=4) were examined by high-temperature X-ray powder diffractometry to determine the changes in unit-cell dimensions up to 1473 K. The anisotropy of thermal expansion was demonstrated for the former two crystals to clarify the thermal behaviors of the highly c-axis-oriented polycrystals. With La 9.33 (SiO 4 ) 6 O 2 , the linear expansion coefficient of the a-axis (α a ) was 4.8×10 −6 K −1 and that of the c-axis (α c ) was 1.8×10 −6 K −1 in the temperature range from 298 to 1473 K. The α a - and α c -values of La 9.33+2x (SiO 4 ) 6 O 2+3x (0.06≤x≤0.13) were, respectively, 5.9×10 −6 K −1 and 2.3×10 −6 K −1 . The coefficients of mean linear thermal expansion were 4.9×10 −6 K −1 for La 2 SiO 5 and 6.0×10 −6 K −1 for La 2 Si 2 O 7 , which describe the thermal expansion behaviors of the randomly grain-oriented polycrystalline materials. - Graphical abstarct: Temperature dependence of the coefficients of thermal expansion (CTE). The linear CTE along the a-axes for La 9.33 (SiO 4 ) 6 O 2 and La 9.33+2x (SiO 4 ) 6 O 2+3x with 0.06≤x≤0.13. The mean linear CTE for La 2 SiO 5 and La 2 Si 2 O 7 . Highlights: ► We examined the thermal expansion of La 9.33+2x (SiO 4 ) 6 O 2+3x (x=0 and 0.06≤x≤0.13), La 2 SiO 5 and La 2 Si 2 O 7 ► Unit-cell dimensions were determined up to 1473 K by high-temperature X-ray diffraction ► Anisotropic expansion was clarified for La 9.33+2x (SiO 4 ) 6 O 2+3x (x=0 and 0.06≤x≤0.13) ► Mean linear thermal expansion was determined for La 2 SiO 5 and La 2 Si 2 O 7.

  17. Magnetic properties of Aurivillius lanthanide-bismuth (LnFeO3nBi4Ti3O12 (n = 1,2 layered titanates

    Directory of Open Access Journals (Sweden)

    Tartaj, J.

    2008-06-01

    Full Text Available Bismuth titanates of Aurivillius layer-structure (BiFeO3nBi4Ti3O12, are of great technological interest because of their applications as non-volatile ferroelectric memories and high-temperature piezoelectric materials. The synthesis and crystallographic characterization of a new family of compounds (LnFeO3nBi4Ti3O12 was recently reported, in which the layers consist of LnFeO3 perovskites with a lanthanide Ln3+ substituting diamagnetic Bi3+. We report herein the magnetic properties of bulk samples, with Ln = Nd, Eu, Gd and Tb, and n = 1 and 2. Single-layer materials are paramagnetic, similar to non-substituted bismuth titanate Bi5FeTi3O15, and show crystal field effects due to the crystallographic environment of Eu3+ and Tb3+. Several anomalies are detected in the magnetization M(T of double-layer (LnFeO32Bi4Ti3O12 compounds, related to the strong magnetism of Tb and Gd, since they weakly appear for Nd and they are absent in the VanVleck Eu3+ ion and in the parent Bi6Fe2Ti3O18 compound.Los titanatos de hierro y bismuto con estructura laminar tipo Aurivillius, (BiFeO3nBi4Ti3O12, tienen un gran interés tecnológico debido a sus aplicaciones como memorias ferroeléctricas no volátiles y como piezoeléctrico cerámico de alta temperatura. La síntesis y la caracterización cristalina de una nueva familia de compuestos (LnFeO3nBi4Ti3O12 han sido recientemente reportadas, en la que el catión diamagnético Bi3+ ha sido sustituido por los paramagnéticos Ln3+ en los bloques de perovskita. Se estudian las propiedades magnéticas de muestras cerámicas en volumen con Ln = Nd, Eu, Gd y Tb, y n = 1 y 2. Los materiales con n=1 son paramagnéticos y similares al no sustituido Bi5FeTi3O15, y muestran efectos de campo cristalino debido al entorno cristalino de Eu3+ y Tb3+. Se han detectado algunas anomalías en la magnetización M(T de los compuestos n=2 (LnFeO32Bi4Ti3O12 que están relacionadas con el fuerte magnetismo de Tb y Gd, que aparecen d

  18. Sol–gel preparation of well-adhered films and long range ordered inverse opal films of BaTiO{sub 3} and Bi{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Al-Arjan, Wafa S. [Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); King Faisal University, PO Box 380, Al Hofuf (Saudi Arabia); Algaradah, Mohammed M.F. [Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); King Khalid College, Riyadh (Saudi Arabia); Brewer, Jack [Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Hector, Andrew L., E-mail: a.l.hector@soton.ac.uk [Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom)

    2016-02-15

    Highlights: • Highly adaptable sols are presented for processing of the electroceramic materials BaTiO{sub 3} and Bi{sub 2}Ti{sub 2}O{sub 7}. • High quality thin films are produced by dip coating with good phase control. • Infiltration of cross-linked polystyrene templates led to high quality inverse opals. - Abstract: Barium and bismuth titanate thin films and well-ordered inverse opal films are produced by dip coating from sols containing titanium alkoxides with acetic acid, acetylacetone, methoxyethanol and water. The inverse opal preparations used crosslinked polystyrene opal templates. Heat treatment in air produced tetragonal BaTiO{sub 3} or mixtures of the hexagonal and tetragonal phases, or phase pure Bi{sub 2}Ti{sub 2}O{sub 7}. Good quality films were obtained with a thickness of 5 μm from a single dipping, and the thickness could be increased by dipping multiple times. Inverse opals were well ordered and exhibited opalescence and photonic stop band effects.

  19. First-principles calculation of structural and energetic properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La)

    International Nuclear Information System (INIS)

    Zhang, Z.L.; Xiao, H.Y.; Zu, Xiaotao T.; Gao, Fei; Weber, William J.

    2009-01-01

    A first-principles method has been employed to investigate the structural and energetic properties for A2Ti2O7 (A = Lu, Er, Y, Gd, Sm, Nd, La), including the formation energies of the cation antisite-pair, the anion Frenkel pair that defines anion-disorder, and the coupled cation antisite-pair/anion-Frenkel. It is proposed that the interaction may have more significant influence on the radiation resistance behavior of titanate pyrochlores, although the interactions are relatively much stronger than the interactions. It is found that the defect formation energies are not simple functions of the A-site cation radii. The formation energy of the cation antisite-pair increases continuously as the A-site cation varies from Lu to Gd, and then decreases continuously with the variation of the A-site cation from Gd to La, in excellent agreement with the radiation-resistance trend of the titanate pyrochlores. The band gaps in these pyrochlores were also measured, and the band gap widths changed continuously with cation radius.

  20. Perovskite-type La2Ti2O7 mesoporous photocatalyst

    Science.gov (United States)

    Onozuka, K.; Kawakami, Y.; Imai, H.; Yokoi, T.; Tatsumi, T.; Kondo, J. N.

    2012-08-01

    Crystalline particles of mesoporous La2Ti2O7, a perovskite-type material, were prepared by hydrothermal synthesis at 210 °C in the presence of structure directing agent. Crystallization and simultaneous sintering occurred in the time course of the hydrothermal treatment, resulting in the improvement in crystallinity with a sacrifice of the decrease in surface area. The photocatalytic property was evaluated by hydrogen evolution from water with methanol sacrificial agent. The increase and the decrease of the material in crystallinity and surface area were responsible for the photocatalytic activity: the activity was improved by crystallization but the concurrent decrease in surface area (increase in size) of crystalline particles was disadvantageous.

  1. Hydrothermal transformation of titanate nanotubes into single-crystalline TiO2 nanomaterials with controlled phase composition and morphology

    International Nuclear Information System (INIS)

    Xu, Yuanmei; Fang, Xiaoming; Xiong, Jian; Zhang, Zhengguo

    2010-01-01

    Single-crystalline TiO 2 nanomaterials were synthesized by hydrothermally treating suspensions of H-titanate nanotubes and characterized by XRD, TEM, and HRTEM. The effects of the pH values of the suspensions and the hydrothermal temperatures on the phase composition and morphology of the obtained TiO 2 nanomaterials were systematically investigated. The H-titanate nanotubes were predominately transformed into anatase nanoparticle with rhombic shape when the pH value was greater than or equal to 1.0, whereas primarily turned into rutile nanorod with two pyramidal ends at the pH value less than or equal to 0.5. We propose a possible mechanism for hydrothermal transformation of H-titanate nanotubes into single-crystalline TiO 2 nanomaterials. While the H-titanate nanotubes transform into tiny anatase nanocrystallites of ca. 3 nm in size, the formed nanocrystallites as an intermediate grow into the TiO 2 nanomaterials with controlled phase composition and morphology. This growth process involves the steps of protonation, oriented attachment, and Ostwald ripening.

  2. The influence of Ti doping and annealing on Ce{sub 2}Ti{sub 2}O{sub 7} flash memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Chyuan Haur [Department of Electronic Engineering, Chang Gung University, No. 259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC (China); Kidney Research Center, Department of Nephrology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan, ROC (China); Department of Electronic Engineering, Ming Chi University of Technology, Taiwan, ROC (China); Chen, Su Zhien [Department of Electronic Engineering, Chang Gung University, No. 259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC (China); Kidney Research Center, Department of Nephrology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan, ROC (China); Luo, Yang; Chiu, Wang Ting; Chiu, Shih Wei; Chen, I Chien [Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, No. 1, University Rd., Puli, Nantou Country 54561, Taiwan, ROC (China); Lin, Chan-Yu [Kidney Research Center, Department of Nephrology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan, ROC (China); Chen, Hsiang, E-mail: hchen@ncnu.edu.tw [Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, No. 1, University Rd., Puli, Nantou Country 54561, Taiwan, ROC (China)

    2017-02-28

    Highlights: • Ce{sub 2}Ti{sub 2}O{sub 7} flash memories have been fabricated. • Material quality can be improved by annealing. • The memory performance can be enhanced by Ti doping. • Ti doping and annealing can reinforce crystallization. - Abstract: In this research, a CeO{sub 2} film with Ti doping was used as a trapping layer in metal oxide high-K-oxide-Si (MOHOS)-type memory devices. Since incorporation of Ti atoms into the film could fix dangling bonds and defects, the Ce{sub 2}Ti{sub 2}O{sub 7} trapping layer with annealing treatment could have a larger memory window and a faster programming/erasing speed. To confirm the origin, multiple material analyses indicate that annealing at an appropriate temperature and Ti doping could enhance crystallization. The Ce{sub 2}Ti{sub 2}O{sub 7}-based memory device is promising for future industrial flash memory applications.

  3. The system K2NbF7-K2TiF6-KCl

    International Nuclear Information System (INIS)

    Kamenskaya, L.A.; Matveev, A.M.

    1984-01-01

    Using visual-polythermal and thermographical methods the ternary system K 2 NbF 7 -K 2 TiE 6 -KCl has been studied. Crystallization fields of initial components and the field of solid solutions of double compounds K 3 NbClF 7 and K 3 TiClF 6 are outlined. Ternary eutectics at 654 deg C, having the composition K 2 NbF 6 -41, K 2 TiP 6 -41, KCl-18 mol.%, is determined. Potassium fluoroniobate and fluorotitanate form continuous solid solutions unstable in the presence of the third component, potassium chloride

  4. Nanocomposites of TiO2/cyanoethylated cellulose with ultra high dielectric constants

    International Nuclear Information System (INIS)

    Madusanka, Nadeesh; Shivareddy, Sai G; Hiralal, Pritesh; Choi, Youngjin; Amaratunga, Gehan A J; Eddleston, Mark D; Oliver, Rachel A

    2016-01-01

    A novel dielectric nanocomposite containing a high permittivity polymer, cyanoethylated cellulose (CRS) and TiO 2 nanoparticles was successfully prepared with different weight percentages (10%, 20% and 30%) of TiO 2 . The intermolecular interactions and morphology within the polymer nanocomposites were analysed. TiO 2 /CRS nanofilms on SiO 2 /Si wafers were used to form metal–insulator–metal type capacitors. Capacitances and loss factors in the frequency range of 1 kHz–1 MHz were measured. At 1 kHz CRS-TiO 2 nanocomposites exhibited ultra high dielectric constants of 118, 176 and 207 for nanocomposites with 10%, 20% and 30% weight of TiO 2 respectively, significantly higher than reported values of pure CRS (21), TiO 2 (41) and other dielectric polymer-TiO 2 nanocomposite films. Furthermore, all three CRS-TiO 2 nanocomposites show a loss factor <0.3 at 1 kHz and low leakage current densities (10 −6 –10 −7 A cm −2 ). Leakage was studied using conductive atomic force microscopy and it was observed that the leakage is associated with TiO 2 nanoparticles embedded in the CRS polymer matrix. A new class of ultra high dielectric constant hybrids using nanoscale inorganic dielectrics dispersed in a high permittivity polymer suitable for energy management applications is reported. (paper)

  5. Structural properties of the geometrically frustrated pyrochlore Tb2Ti2O7

    International Nuclear Information System (INIS)

    Han, Sang-Wook; Gardner, Jason S.; Booth, Corwin H.

    2004-01-01

    Although materials that exhibit nearest-neighbor-only antiferromagnetic interactions and geometrical frustration theoretically should not magnetically order in the absence of disorder, few such systems have been observed experimentally. One such system appears to be the pyrochlore Tb 2 Ti 2 O 7 . However, previous structural studies indicated that Tb 2 Ti 2 O 7 is an imperfect pyrochlore. To clarify the situation, we performed neutron powder diffraction (NPD) and x-ray absorption fine structure (XAFS) measurements on samples that were prepared identically to those that show no magnetic order. The NPD measurements show that the long-range structure of Tb 2 Ti 2 O 7 is well ordered with no structural transitions between 4.5 and 600 K. In particular, mean-squared displacements (u 2 's) for each site follow a Debye model with no offsets. No evidence for Tb/Ti site interchange was observed within an upper limit of 2%. Likewise, no excess or deficiency in the oxygen stoichiometry was observed, within an upper limit of 2% of the nominal pyrochlore value. Tb L III and Ti K-edge XAFS measurements from 20-300 K similarly indicate a well-ordered local structure. Other aspects of the structure are considered. We conclude that Tb 2 Ti 2 O 7 has, within experimental error, an ideal, disorder-free pyrochlore lattice, thereby allowing the system to remain in a dynamic, frustrated spin state to the lowest observed temperatures

  6. Structure and Properties of La2O3-TiO2 Nanocomposite Films for Biomedical Applications

    Science.gov (United States)

    Zhang, Lin; Sun, Zhi-Hua; Yu, Feng-Mei; Chen, Hong-Bin

    2011-01-01

    The hemocompatibility of La2O3-doped TiO2 films with different concentration prepared by radio frequency (RF) sputtering was studied. The microstructures and blood compatibility of TiO2 films were investigated by scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-visible optical absorption spectroscopy, respectively. With the increasing of the La2O3 concentrations, the TiO2 films become smooth, and the grain size becomes smaller. Meanwhile, the band gap of the samples increases from 2.85 to 3.3 eV with increasing of the La2O3 content in TiO2 films from 0 to 3.64%. La2O3-doped TiO2 films exhibit n-type semiconductor properties due to the existence of Ti2+ and Ti3+. The mechanism of hemocompatibility of TiO2 film doped with La2O3 was analyzed and discussed. PMID:22162671

  7. Deposition barium titanate (BaTiO3) doped lanthanum with chemical solution deposition

    International Nuclear Information System (INIS)

    Iriani, Y.; Nurhadi, N.; Jamaludin, A.

    2016-01-01

    Deposition of Barium Titanate (BaTiO 3 ) thin films used Chemical Solution Deposition (CSD) method and prepared with spin coater. BaTiO 3 is doped with lanthanum, 1%, 2%, and 3%. The thermal process use annealing temperature 900°C and holding time for 3 hours. The result of characterization with x-ray diffraction (XRD) equipment show that the addition of La 3+ doped on Barium Titanate caused the change of angle diffraction.The result of refine with GSAS software shows that lanthanum have been included in the structure of BaTiO 3 . Increasing mol dopant La 3+ cause lattice parameter and crystal volume become smaller. Characterization result using Scanning Electron Microscopy (SEM) equipment show that grain size (grain size) become smaller with increasing mole dopant (x) La 3+ . The result of characterization using Sawyer Tower methods show that all the samples (Barium Titanante and Barium Titanate doped lanthanum) are ferroelectric material. Increasing of mole dopant La 3+ cause smaller coercive field and remanent polarization increases. (paper)

  8. Structural and sensing characteristics of Gd2Ti2O7, Er2TiO5 and Lu2Ti2O7 sensing membrane electrolyte–insulator–semiconductor for bio-sensing applications

    International Nuclear Information System (INIS)

    Pan, Tung-Ming; Liao, Pei-You; Chang, Kung-Yuan; Chi, Lifeng

    2013-01-01

    Highlights: ► The structural and sensing properties of Gd 2 Ti 2 O 7 , Er 2 TiO 5 and Lu 2 Ti 2 O 7 sensing films grown on Si substrates by reactive co-sputtering. ► The EIS device incorporating a Lu 2 Ti 2 O 7 sensing film exhibited a higher sensitivity, a larger drift rate, a higher hysteresis voltage, and a larger hysteresis gap than other sensing films. ► The impedance effect of EIS sensors has been investigated using C–V method. -- Abstract: This paper describes the structural and sensing characteristics of Gd 2 Ti 2 O 7 , Er 2 TiO 5 , and Lu 2 Ti 2 O 7 sensing membranes deposited on Si substrates through reactive co-sputtering for electrolyte–insulator–semiconductor (EIS) pH sensors. In this work, the structural properties of Gd 2 Ti 2 O 7 , Er 2 TiO 5 , and Lu 2 Ti 2 O 7 membranes were investigated by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. The observed structural properties were then correlated with the resulting pH sensing performances. The EIS device incorporating a Lu 2 Ti 2 O 7 sensing film exhibited a higher sensitivity (59.32 mV pH −1 ), a larger drift rate (0.55 mV h −1 ), a higher hysteresis voltage (5 mV), and a larger hysteresis gap (∼70 mV) compared to those of the other sensing films. This result is attributed to the higher surface roughness and the formation of a thicker interfacial layer at the oxide–Si interface. Furthermore, the impedance effect of EIS sensors has been investigated using capacitance–voltage (C–V) method (frequency-dependent C–V curves). From the impedance spectroscopy analysis, we find that the diameter of a semicircle of an EIS sensor becomes smaller due to a gradual decrease in the bulk resistance of the device with degree of pH value

  9. Synthesis of Nano-Ilmenite (FeTiO3) doped TiO2/Ti Electrode for Photoelectrocatalytic System

    Science.gov (United States)

    Hikmawati; Watoni, A. H.; Wibowo, D.; Maulidiyah; Nurdin, M.

    2017-11-01

    Ilmenite (FeTiO3) doped on Ti and TiO2/Ti electrodes were successfully prepared by using the sol-gel method. The structure, morphology, and optical properties of FeTiO3 are characterized by XRD, UV-Vis DRS, and SEM. The FeTiO3 and TiO2 greatly affect the photoelectrocatalysis performance characterized by Linear Sweep Voltammetry (LSV) and Cyclic Voltammetry (CV). The characterization result shows a band gap of FeTiO3 is 2.94 eV. XRD data showed that FeTiO3 formed at 2θ were 35.1° (110), 49.9° (024), and 61.2° (214). The morphology of FeTiO3/Ti and FeTiO3.TiO2/Ti using SEM shows that the formation of FeTiO3 thin layer signifies the Liquid Phase Deposition method effectively in the coating process. Photoelectrochemical (PEC) test showed that FeTiO3.TiO2/Ti electrode was highly oxidation responsive under visible light compared to the FeTiO3/Ti electrodes i.e. 7.87×10-4 A and 9.87×10-5 A. Degradation test of FeTiO3/Ti and FeTiO3.TiO2/Ti electrodes on titan yellow showed that the percentages of degradation with photoelectrocatalysis at 0.5 mg/L were 41% and 43%, respectively.

  10. Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO_3) ceramics

    International Nuclear Information System (INIS)

    Billah, Masum; Ahmed, A.; Rahman, Md. Miftaur; Mahbub, Rubbayat; Gafur, M. A.; Bashar, M. Shahriar

    2016-01-01

    In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La_2O_3) doped Barium Titanate (BaTiO_3) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO_3 with 0.3, 0.5 and 0.7 mole% La_2O_3 under different sintering parameters. The raw materials used were La_2O_3 nano powder of ~80 nm grain size and 99.995% purity and BaTiO_3 nano powder of 100 nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanning Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO_3 ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La_2O_3) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La_2O_3 with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La"3"+ concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO_3 ceramics.

  11. Structural properties of the geometrically frustrated pyrochlore Tb2Ti2O7

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sang-Wook; Gardner, Jason S.; Booth, Corwin H.

    2004-06-14

    Although materials that exhibit nearest-neighbor-only antiferromagnetic interactions and geometrical frustration theoretically should not magnetically order in the absence of disorder, few such systems have been observed experimentally. One such system appears to be the pyrochlore Tb{sub 2}Ti{sub 2}O{sub 7}. However, previous structural studies indicated that Tb{sub 2}Ti{sub 2}O{sub 7} is an imperfect pyrochlore. To clarify the situation, we performed neutron powder diffraction (NPD) and x-ray absorption fine structure (XAFS) measurements on samples that were prepared identically to those that show no magnetic order. The NPD measurements show that the long-range structure of Tb{sub 2}Ti{sub 2}O{sub 7} is well ordered with no structural transitions between 4.5 and 600 K. In particular, mean-squared displacements (u{sup 2}'s) for each site follow a Debye model with no offsets. No evidence for Tb/Ti site interchange was observed within an upper limit of 2%. Likewise, no excess or deficiency in the oxygen stoichiometry was observed, within an upper limit of 2% of the nominal pyrochlore value. Tb L{sub III} and Ti K-edge XAFS measurements from 20-300 K similarly indicate a well-ordered local structure. Other aspects of the structure are considered. We conclude that Tb{sub 2}Ti{sub 2}O{sub 7} has, within experimental error, an ideal, disorder-free pyrochlore lattice, thereby allowing the system to remain in a dynamic, frustrated spin state to the lowest observed temperatures.

  12. Pulsed laser deposition of {CeO_2} and {Ce_{1-x}M_xO_2} (M = La, Zr): Application to insulating barrier in cuprate heterostructures

    Science.gov (United States)

    Berger, S.; Contour, J.-P.; Drouet, M.; Durand, O.; Khodan, A.; Michel, D.; Régi, F.-X.

    1998-03-01

    SrTiO_3 had been often tentatively used as an insulating barrier for HT superconductor/insulator heterostructures. Unfortunately, the deposition of SrTiO_3 on the YBa_2Cu_3O_7 inverse interface results in a poor epitaxial regrowth producing a high roughness dislocated titanate layer. Taking into account the good matching with YBa_2Cu_3O_7 and LaAlO_3, CeO_2 and Ce_{1-x}M_xO_2 (M = La, Zr), epitaxial layers were grown by pulsed laser deposition on LaAlO_3 substrates and introduced into YBa_2Cu_3O_7 based heterostructures as insulating barrier. After adjusting the growth parameters from RHEED oscillations, epitaxial growth is achieved, the oxide crystal axes being rotated by 45^circ from those of the substrate. The surface roughness of 250 nm thick films is very low with a rms value lower than 0.5 nm over 1;μ m^2. The YBa_2Cu_3O_7 layers of a YBa_2Cu_3O_7/CeO_2 /YBa_2Cu_3O_7 heterostructures grown using these optimized parameters show an independent resistive transition, when the thickness is larger than 25 nm, respectively at T_c_1 = 89.6;K and T_c_2 = 91.4;{K}. SrTiO3 est souvent utilisé comme barrière isolante dans des hétérostructures SIS de cuprates supraconducteurs, cependant les défauts générés lors de la croissance de ce titanate sur l'interface inverse de YBa2Cu3O7 conduisent à un matériau dont la qualité cristalline et les propriétés physiques sont médiocres. L'oxyde de cérium CeO2 est également une barrière isolante potentielle intéressante pour ces structures SIS basées sur YBa2Cu3O7 car cet oxyde cubique (a = 0,5411 nm, asqrt{2}/2 = 0,3825 nm) qui est peu désaccordé par rapport au plan ab du cuprate (Δ a/a = - 0,18 %, Δ b/a = 1,6 %) présente de plus un coefficient de dilatation thermique (10,6 × 10^{-6 circ}C^{-1}) très voisin de celui de YBa2Cu3O7 (13 × 10^{-6 circ}C^{-1}). Nous avons donc étudié l'épitaxie de CeO2 et des oxydes de type Ce{1-x}MxO2 (M = La, Zr) en ablation laser pulsée afin de définir des conditions de

  13. Preparation of Pd-loaded La-doped TiO{sub 2} nanotubes and investigation of their photocatalytic activity under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Zong, Lanlan; Li, Qiuye, E-mail: qiuyeli@henu.edu.cn; Zhang, Jiwei; Wang, Xiaodong; Yang, Jianjun [Henan University, Key Laboratory for Special Functional Materials (China)

    2013-11-15

    Orthorhombic titanic acid nanotubes (TAN) have large BET surface area and small-diameter one-dimensional nanotubular morphology, so they can work as a good supporter and a precursor of TiO{sub 2}. However, in our former research, we found that calcination of TAN to anatase TiO{sub 2} would destroy the nanotubular structure and decrease the BET surface area sharply. In this work, we utilized the pillar effect of the foreign nanoparticles (La{sub 2}O{sub 3}) to keep the nanotubular morphology of TiO{sub 2}, and obtained the anatase TiO{sub 2} nanotubes with large BET surface area. For improving the photocatalytic activity, Pd nanoparticles were loaded as the electron traps on the surface of La-doped TiO{sub 2} by photo-deposition method. The photocatalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, diffuse reflectance spectra, and N{sub 2} adsorption–desorption isotherms measurement. Their photocatalytic activities were evaluated by the removal of propylene under visible light irradiation (λ ≥ 420 nm). The results showed that the photocatalytic activity of Pd-loaded La-doped TiO{sub 2} nanotubes improved effectively compared with that of La-doped TiO{sub 2} and pure TiO{sub 2}.

  14. Properties of phases in HfO2-TiO2 system

    International Nuclear Information System (INIS)

    Red'ko, V.P.; Terekhovskij, P.B.; Majster, I.M.; Shevchenko, A.V.; Lopato, L.M.; Dvernyakova, A.A.

    1990-01-01

    A study was made on axial and linear coefficients of thermal expansion (CTE) of HfO 2 -TiO 2 system samples in concentration range of 25-50 mol% TiO 2 . Samples, containing 35 and 37 mol% TiO 2 , are characterized by the lowest values of linear CTE. Dispersion of the basic substances doesn't affect CTE value. Correlation with axial and linear CTE of samples in ZrO 2 -TiO 2 system was conducted. Presence of anisotropy of change of lattice parameters was supported for samples, containing 37.5 and 40 mol% TiO 2 . Polymorphous transformations for hafnium titanate were not revealed

  15. High Tc screen-printed YBa2Cu3O(7-x) films - Effect of the substrate material

    Science.gov (United States)

    Bansal, Narottam P.; Simons, Rainee N.; Farrell, D. E.

    1988-08-01

    Thick films of YBa2Cu3O(7-x) have been deposited on highly polished alumina, magnesia spinel, nickel aluminum titanate (Ni-Al-Ti), and barium tetratitanate (Ba-Ti) substrates by the screen printing technique. Properties of the films were found to be highly sensitive to the choice of the substrate material. The film on Ba-Ti turned green after firing, due to a reaction with the substrate and were insulating. A film on Ni-Al-Ti had a Tc (onset) of about 95 K and lost 90 percent of its resistance by about 75 K. However, even at 4 K it was not fully superconducting, possibly due to a reaction between the film and the substrate and interdiffusion of the reaction products. The film on alumina had Tc (onset) of about 96 K, Tc (zero) of about 66 K, and Delta Tc of about 10 K. The best film was obtained on spinel and had Tc (onset) of about 94 K, zero resistance at 81 K, and a transition width of about 7 K.

  16. Synthesis and characterization of La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} and the visible light photocatalytic oxidation of 4-chlorophenol

    Energy Technology Data Exchange (ETDEWEB)

    Cao Guangxiu [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Department of Chemistry, Shangqiu Normal University, Shangqiu 476000 (China); Li Yaogang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Zhang Qinghong, E-mail: zhangqh@dhu.edu.cn [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Donghua University, Shanghai 201620 (China); Wang Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China)

    2010-06-15

    In this work, we investigated the synergetic effect of La and F on the visible light photocatalytic activity of TiO{sub 2} catalysts. La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} photocatalysts were prepared by a simple sol-gel process using tetrabutyl titanate (TBT), La(NO{sub 3}){sub 3} and NH{sub 4}F as precursors. XPS results revealed that La{sub 2}O{sub 3} accumulated on the surface of TiO{sub 2}, which enhanced the surface area of TiO{sub 2} and inhibited the recombination of electron-hole pairs. It also showed that two kinds of fluorine species were formed and these increased the acid active sites and enhanced the oxidation potential of the photogenerated holes in the valance band. UV-vis diffuse reflection spectra of La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} showed that intraband gap states were present and these are probably responsible for its absorption of visible light while the intrinsic absorption band was shifted slightly to a longer wavelength. At molar ratios of La and F to Ti of 1.5:100 and 5:100 and after calcination at 500 deg. C, the degradation rate of 4-chlorophenol (4-CP) over the sample was about 1.2-3.0 times higher than that of the other doped samples and undoped TiO{sub 2}. The total organic carbon (TOC) removal rates of 4-CP showed that 4-CP was mineralized efficiently in the presence of the sample under visible light illumination.

  17. Thermodynamic investigation of the phase equilibrium boundary between TiO2 rutile and its α-PbO2-type high-pressure polymorph

    Science.gov (United States)

    Kojitani, Hiroshi; Yamazaki, Monami; Kojima, Meiko; Inaguma, Yoshiyuki; Mori, Daisuke; Akaogi, Masaki

    2018-06-01

    Heat capacity (C P) of rutile and α-PbO2 type TiO2 (TiO2-II) were measured by the differential scanning calorimetry and thermal relaxation method. Using the results, standard entropies at 1 atm and 298.15 K of rutile and TiO2-II were determined to be 50.04(4) and 46.54(2) J/mol K, respectively. Furthermore, thermal expansivity (α) determined by high-temperature X-ray diffraction measurement and mode Grüneisen parameters obtained by high-pressure Raman spectroscopy suggested the thermal Grüneisen parameter (γ th) for TiO2-II of 1.7(1). By applying the obtained low-temperature C P and γ th, the measured C P and α data of TiO2-II were extrapolated to higher temperature region using a lattice vibrational model calculation, as well as rutile. Internally consistent thermodynamic data sets of both rutile and TiO2-II assessed in this study were used to thermodynamically calculate the rutile‒TiO2-II phase equilibrium boundary. The most plausible boundary was obtained to be P (GPa) = 0.0074T (K) - 1.7. Our boundary suggests that the crystal growth of TiO2-II observed below 5.5 GPa and 900 K in previous studies advanced in its stability field. The phase boundary calculation also suggested small, exothermic phase transition enthalpy from rutile to TiO2-II at 1 atm and 298.15 K of - 0.5 to - 1.1 kJ/mol. This implies that the thermodynamic stability of rutile at 1 atm above room temperature is due to larger contribution of entropy term.

  18. Magnetic two-dimensional electron gas at the manganite-buffered LaAlO3/SrTiO3 interface

    DEFF Research Database (Denmark)

    R. Zhang, H.; Zhang, Y.; Zhang, H.

    2017-01-01

    Fabrication of highly mobile spin-polarized two-dimensional electron gas (2DEG) is crucially important for both fundamental and applied research. Usually, spin polarization appears below 10 K for the 2DEG of LaAlO3/SrTiO3 interface, stemming from the magnetic ordering of Ti3+ ions with the mediat......Fabrication of highly mobile spin-polarized two-dimensional electron gas (2DEG) is crucially important for both fundamental and applied research. Usually, spin polarization appears below 10 K for the 2DEG of LaAlO3/SrTiO3 interface, stemming from the magnetic ordering of Ti3+ ions...... with the mediation of itinerant electrons. Herein, we report a magnetic 2DEG at a La7/8Sr1/8MnO3-buffered LaAlO3/SrTiO3 interface, which simultaneously shows electrically tunable anomalous Hall effect and high conductivity. The spin-polarized temperature for the 2DEG is promoted to 30 K while the mobility remains...... high. The magnetism likely results from a gradient manganese interdiffusion into SrTiO3. The present work demonstrates the great potential of manganite-buffered LaAlO3/SrTiO3 interfaces for spintronic applications....

  19. Thermal expansion studies on Hafnium titanate (HfTiO4)

    International Nuclear Information System (INIS)

    Panneerselvam, G.; Subramanian, G.G.S.; Antony, M.P.

    2006-01-01

    The lattice thermal expansion characteristics of hafnium titanate (HfTiO 4 ) have been studied by measuring the lattice parameter as a function of temperature by high temperature X-ray diffraction technique (HT-XRD) in the temperature range 298-1973K. Percentage linear thermal expansion and mean linear thermal expansion coefficients were computed from the lattice parameter data. The thermal expansion of HfTiO 4 is highly anisotropic. The expansivity along 'a' axis is large; as compared to the expansivity along 'b' axis which is negative below 1073 K. The percentage linear thermal expansion in the temperature range 298-1973 K along a, b and c axis are 2.74, 0.901 and 1.49 respectively. Thermal expansion values obtained in the present study are in reasonable agreement with the existing thermal expansion data. (author)

  20. Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO{sub 3}) ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Billah, Masum, E-mail: masum.buet09@gmail.com; Ahmed, A., E-mail: jhinukbuetmme@gmail.com; Rahman, Md. Miftaur, E-mail: miftaurrahman@mme.buet.ac.bd [Department of Materials & Metallurgical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000 (Bangladesh); Mahbub, Rubbayat, E-mail: rubayyatm@gce.buet.ac.bd [Department of Glass and Ceramic Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000 (Bangladesh); Gafur, M. A., E-mail: d-r-magafur@bcsir.gov.bd [Bangladesh Council of Scientific & Industrial Research (BCSIR), Dhaka-1205 (Bangladesh); Bashar, M. Shahriar, E-mail: bashar@agni.com [Institute of Fuel Research & Development, Bangladesh Council of Scientific & Industrial Research (BCSIR), Dhaka-1205 (Bangladesh)

    2016-07-12

    In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La{sub 2}O{sub 3}) doped Barium Titanate (BaTiO{sub 3}) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO{sub 3} with 0.3, 0.5 and 0.7 mole% La{sub 2}O{sub 3} under different sintering parameters. The raw materials used were La{sub 2}O{sub 3} nano powder of ~80 nm grain size and 99.995% purity and BaTiO{sub 3} nano powder of 100 nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanning Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO{sub 3} ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La{sub 2}O{sub 3}) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La{sub 2}O{sub 3} with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La{sup 3+} concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO{sub 3} ceramics.

  1. Thermoluminescence response and glow curve structure of Sc2TiO5 ß-irradiated

    International Nuclear Information System (INIS)

    Muñoz, I.C.; Brown, F.; Durán-Muñoz, H.; Cruz-Zaragoza, E.; Durán-Torres, B.; Alvarez-Montaño, V.E.

    2014-01-01

    Discandium titanate (Sc 2 TiO 5 ) powder was synthesized in order to analyze its thermoluminescence (TL) response. The TL glow curve structure shows two peaks: at 453–433 K and at 590–553 K. The TL beta dose–response has a linear behavior over the dose range 50–500 Gy. The T stop preheat method shows five glow peaks that were taken into account to calculate the kinetic parameters using the CGCD procedure. TL results support the possible use of Sc 2 TiO 5 as a new phosphor in high ß-dose dosimetry. - Highlights: • Discandium titanate was synthesized, and its TL properties were analyzed. • The beta dose–response has a linear behavior on the dose range 50–500 Gy. • The kinetic parameters were obtained by the CGCD procedure. • Results support the possible use of Sc 2 TiO 5 as a new phosphor for ß-dose dosimetry

  2. Ln28Ti2O7 (Ln = La, Nd, Sm, Gd): a novel series of defective Ruddlesden–Popper phases formed by topotactic dehydration of HLnTiO4

    OpenAIRE

    Thangadurai, V; Subbanna, GN; Gopalakrishnan, J

    1998-01-01

    Topotactic dehydration of HLnTiO4 (Ln = La, Nd, Sm or Gd) around 480–500 °C yields a new series of metastable layered perovskite oxides, Ln28Ti2O7, that possess a defective Sr3Ti2O7 structure, where the cubooctahedral sites within the double-perovskite layers are most likely vacant.

  3. Highly uniform bipolar resistive switching characteristics in TiO2/BaTiO3/TiO2 multilayer

    International Nuclear Information System (INIS)

    Ma, W. J.; Zhang, X. Y.; Wang, Ying; Zheng, Yue; Lin, S. P.; Luo, J. M.; Wang, B.; Li, Z. X.

    2013-01-01

    Nanoscale multilayer structure TiO 2 /BaTiO 3 /TiO 2 has been fabricated on Pt/Ti/SiO 2 /Si substrate by chemical solution deposition method. Highly uniform bipolar resistive switching (BRS) characteristics have been observed in Pt/TiO 2 /BaTiO 3 /TiO 2 /Pt cells. Analysis of the current-voltage relationship demonstrates that the space-charge-limited current conduction controlled by the localized oxygen vacancies should be important to the resistive switching behavior. X-ray photoelectron spectroscopy results indicated that oxygen vacancies in TiO 2 play a crucial role in the resistive switching phenomenon and the introduced TiO 2 /BaTiO 3 interfaces result in the high uniformity of bipolar resistive switching characteristics

  4. Comparative study of A-site order in the lead-free bismuth titanates M1/2Bi1/2TiO3 (M=Li, Na, K, Rb, Cs, Ag, Tl) from first-principles

    International Nuclear Information System (INIS)

    Gröting, Melanie; Albe, Karsten

    2014-01-01

    We investigate the possibility of enhancing chemical order in the relaxor ferroelectric Na 1/2 Bi 1/2 TiO 3 upon substitution of Na + by other monovalent cations M + using total energy calculations based on density functional theory. All chemically available monovalent cations M + , which are Li, Na, Ag, K, Tl, Rb and Cs, are considered and an analysis of the structurally relaxed structures in terms of symmetry-adapted distortion modes is given in order to quantify the chemically induced structural distortions. We demonstrate that the replacement of Na + by other monovalent cations can hardly alter the tendency of chemical order with respect to Na 1/2 Bi 1/2 TiO 3 . Only Tl 1/2 Bi 1/2 TiO 3 and Ag 1/2 Bi 1/2 TiO 3 show enhanced tendency for chemical ordering. Both heavy metals behave similar to the light alkali metals in terms of structural relaxations and relative stabilities of the ordered configurations. Although a comparison of the Goldschmidt factors of components (M TiO 3 ) − reveals for Tl a value above the upper stability limit for perovskites, the additional lone-pair effect of Tl + stabilizes the ordered structure. - Graphical abstract: Amplitudes of chemically induced distortion modes in different ordered perovskites M 1/2 Bi 1/2 TiO 3 and visualisation of atomic displacements associated with distortion mode X + 1 in the 001-ordered compounds Li 1/2 Bi 1/2 TiO 3 and Cs 1/2 Bi 1/2 TiO 3 . Due to a substantial size mismatch between bismuth (green) and caesium (dark blue), incorporation of the latter leads to enhanced displacements of oxygen atoms (red) and suppresses displacements of titanium (silver) as compared to lithium (light blue) or other smaller monovalent cations. - Highlights: • Lead-free A-site mixed bismuth titanates M 1/2 Bi 1/2 TiO 3 are studied by first-principles calculations. • Investigation of chemical ordering tendency for M=Li, Na, K, Rb, Cs, Ag, and Tl. • Group theoretical analysis of different ordered structures. • Ag and Tl

  5. Microstructures and Dehydrogenation Properties of Ball-milled MgH2-K2Ti6O13-Ni Composite Systems

    Directory of Open Access Journals (Sweden)

    ZHANG Jian

    2016-11-01

    Full Text Available The K2Ti6O13 whisker separate-doped and K2Ti6O13 whisker and Ni powder multi-doped MgH2 hydrogen storage composite systems were prepared by mechanical milling method. The microstructures and dehydrogenation properties of the prepared samples were characterized by some testing methods such as X-ray diffraction (XRD, scanning electron microscope (SEM and differential scanning calorimeter (DSC. The results show that the K2Ti6O13 whisker not only plays the roles in refining the MgH2 crystalline grain, but also inhibit the agglomeration of MgH2 particles in K2Ti6O13 whisker separate-doped system, which results in the decreased dehydrogenation temperature of MgH2 matrix. When the mass ratio of K2Ti6O13 to MgH2 is 3:7, the improvement effect on dehydrogenation properties of MgH2 is the most remarkable. As compared with pure ball-milled MgH2, the dehydrogenation temperature of MgH2 in K2Ti6O13 whisker separate-doped system is decreased by nearly 75℃. For K2Ti6O13 whisker and Ni powder multi-dopedsystem, the dehydrogenation temperature of MgH2 matrix is further decreased compared to K2Ti6O13 whisker separate-doped one due to the dual effects of refined MgH2 crystalline grain by K2Ti6O13 whisker and destabilized MgH2 lattice by Ni solution. As compared with pure ball-milled MgH2, the dehydrogenation temperature of MgH2 in K2Ti6O13 whisker and Ni powder multi-doped system is decreased by nearly 87℃.

  6. Topotactic dehydration of the lamellar oxide HK2Ti5NbO14 x H2O: the oxide K4Ti10Nb2O27

    International Nuclear Information System (INIS)

    Grandin, A.; Borel, M.M.; Hervieu, M.; Raveau, B.

    1987-01-01

    The lamellar oxide HK 2 Ti 5 NbO 14 x H 2 O can be topotactically dehydrated to K 4 Ti 10 Nb 2 O 27 . Electron diffraction and X-ray diffraction studies of this phase lead to a monoclinic cell with the parameters a = 17.005, b = 3.78, c = 9.01 A and β 92.14 0 . Diffusion streaks on the electron diffraction patterns indicate disorder whereas the existence of two sets of lattices on the same crystal give evidence of the topotactic character of the reaction. A structural model is proposed for K 4 Ti 10 Nb 2 O 27 , which corresponds to the intergrowth of K 3 TiNbO 14 layers with the K 2 Ti 6 O 13 tunnel structure. The possibility of formation of various intergrowths such as (KTi 5 NbO 13 )/sub n/ (HK 2 Ti 5 NbO 14 )/sub n/' is suggested

  7. K{sub 2}MnF{sub 5}·H{sub 2}O as reactant for synthesizing highly efficient red emitting K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors by a modified cation exchange approach

    Energy Technology Data Exchange (ETDEWEB)

    Han, Tao, E-mail: danbaiht@126.com; Wang, Jun; Lang, Tianchun; Tu, Mingjing; Peng, Lingling

    2016-11-01

    As reactant for synthesizing K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors, the cross-shaped and cuboid-shaped K{sub 2}MnF{sub 5}·H{sub 2}O powders were prepared by the simple chemical method. Based on the reaction mechanism, oxidizing K{sub 2}MnF{sub 5}·H{sub 2}O (Mn{sup 3+}) to Mn{sup 4+} by KMnO{sub 4} (Mn{sup 7+}), a modified cation exchange approach for synthesizing highly efficient red emitting K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphor was proposed. The obtained K{sub 2}TiF{sub 6}:Mn{sup 4+} (2.7–5.3 at.%) phosphors have the size of 30–80 μm with a rough surface, their emission spectra consist of five narrow bands extending from 580 to 660 nm with the strongest peak at 634.8 nm, whose relative emitting intensity depends on the molar ratio of KMnO{sub 4} to K{sub 2}MnF{sub 5}·H{sub 2}O (the platform value = 3.2), and two broad excitation bands are peaking at ∼365 nm and ∼460 nm. The internal quantum yield of our synthesized K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors is up to 82.5%, which is higher than the commercial CaAlSiN{sub 3}:Eu{sup 2+} value, their excitation bands peak at ∼460 and ∼365 nm are consistent with those of Y{sub 3}A{sub 5}O{sub 12}:Ce{sup 3+} phosphors and their emission bands are more suitable for the sensitivity curve of photopic human vision. In addition, our synthesized phosphors show better thermal quenching properties. These findings show a large potential of the synthesized K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors for commercialization. - Highlights: • We synthesize the cross-shaped and cuboid-shaped K{sub 2}MnF{sub 5}·H{sub 2}O. • K{sub 2}MnF{sub 5}·H{sub 2}O is as a reactant for synthesizing K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors. • K{sub 2}TiF{sub 6}:Mn{sup 4+} will improve the current white LED with high CRI for indoor lighting.

  8. Electrochemically active nanocomposites of Li4Ti5O12 2D nanosheets and SnO2 0D nanocrystals with improved electrode performance

    International Nuclear Information System (INIS)

    Han, Song Yi; Kim, In Young; Lee, Sang-Hyup; Hwang, Seong-Ju

    2012-01-01

    Electrochemically active nanocomposites consisting of Li 4 Ti 5 O 12 2D nanosheets and SnO 2 0D nanocrystals are synthesized by the crystal growth of tin dioxide on the surface of 2D nanostructured lithium titanate. According to powder X-ray diffraction and electron microscopic analyses, the rutile-structured SnO 2 nanocrystals are stabilized on the surface of spinel-structured Li 4 Ti 5 O 12 2D nanosheets. The homogeneous hybridization of tin dioxide with lithium titanate is confirmed by elemental mapping analysis. Ti K-edge X-ray absorption near-edge structure and Sn 3d X-ray photoelectron spectroscopy indicate the stabilization of tetravalent titanium ions in the spinel lattice of Li 4 Ti 5 O 12 and the formation of SnO 2 phase with tetravalent Sn oxidation state. The electrochemical measurements clearly demonstrate the promising functionality of the present nanocomposites as anode for lithium secondary batteries. The Li 4 Ti 5 O 12 –SnO 2 nanocomposites show larger discharge capacity and better cyclability than do the uncomposited Li 4 Ti 5 O 12 and SnO 2 phases, indicating the synergistic effect of nanocomposite formation on the electrode performance of Li 4 Ti 5 O 12 and SnO 2 . The present experimental findings underscore the validity of 2D nanostructured lithium titanate as a useful platform for the stabilization of nanocrystalline electrode materials and also for the improvement of their functionality.

  9. Ferroelectric properties of sandwich structured (Bi, La)4T3O12/Pb(Zr, Ti)O3/ (Bi, La)4Ti3O12 thin films on Pt/Ti/SiO2/Si substrates

    International Nuclear Information System (INIS)

    Bao Dinghua; Wakiya, Naoki; Shinozaki, Kazuo; Mizutani, Nobuyasu

    2002-01-01

    Sandwich structured (Bi, La) 4 Ti 3 O 12 /Pb(Zr, Ti)O 3 /(Bi, La) 4 Ti 3 O 12 thin films were fabricated on Pt/Ti/SiO 2 /Si substrates, with the intention of simultaneously utilizing the advantages of both (Bi, La) 4 Ti 3 O 12 (BLT) and Pb(Zr, Ti)O 3 (PZT) thin films such as non-fatigue behaviours of BLT and good ferroelectric properties of PZT. Both BLT and PZT layers were prepared by a chemical solution deposition technique. The experiments demonstrated that the sandwich structure showed fatigue-free characteristics at least up to 10 10 switching bipolar pulse cycles under 8 V and excellent retention properties. The sandwich structured thin films also exhibited well-defined hysteresis loops with a remanent polarization (2P r ) of 8.8 μC cm -2 and a coercive field (E c ) of 47 kV cm -1 . The room-temperature dielectric constant and dissipation factor were 210 and 0.031, respectively, at a frequency of 100 kHz. These results suggest that this sandwich structure is a promising material combination for ferroelectric memory applications. (author)

  10. Magnetoelastic properties of the quantum-spin-ice candidate Yb{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Stoeter, T.; Wang, Z.S.; Wosnitza, J. [SFB 1143 (Germany); TUD/IFP, Dresden (Germany); HZDR, Dresden (Germany); Doerr, M.; Granovsky, S. [SFB 1143 (Germany); TUD/IFP, Dresden (Germany); Erfanifam, S.; Green, E. [HZDR, Dresden (Germany); Zherlitsyn, S. [SFB 1143 (Germany); HZDR, Dresden (Germany); Maljuk, A.; Wurmehl, S. [SFB 1143 (Germany); IFW, Dresden (Germany)

    2016-07-01

    Intriguing phenomena such as the occurrence of magnetic monopoles and a wide variety of ground states are associated to magnetic frustration. In a number of cases, elastic effects, e.g. lattice distortions, may result in the lifting of degeneracies or the appearance of new magnetic states. The rare-earth titanate Yb{sub 2}Ti{sub 2}O{sub 7}, where the magnetic Yb{sup 3+} ions form a pyrochlore spin network, is a prime example of a geometrically frustrated material, with numerous field-induced phases and strong ferromagnetic correlations below 170 mK. In order to characterize the magneto-elastic coupling in this material, we have investigated the thermal expansion, magnetostriction, and sound propagation in different dilution refrigerators between 60 mK and 1.5 K and large applied magnetic fields. At around 170 mK we find distinct anomalies in the expansion coefficient, acoustic properties, as well as the specific heat. Lattice anomalies in field hint to additional low temperature phases.

  11. Decorating TiO2 Nanowires with BaTiO3 Nanoparticles: A New Approach Leading to Substantially Enhanced Energy Storage Capability of High-k Polymer Nanocomposites.

    Science.gov (United States)

    Kang, Da; Wang, Guanyao; Huang, Yanhui; Jiang, Pingkai; Huang, Xingyi

    2018-01-31

    The urgent demand of high energy density and high power density devices has triggered significant interest in high dielectric constant (high-k) flexible nanocomposites comprising dielectric polymer and high-k inorganic nanofiller. However, the large electrical mismatch between polymer and nanofiller usually leads to earlier electric failure of the nanocomposites, resulting in an undesirable decrease of electrical energy storage capability. A few studies show that the introduction of moderate-k shell onto a high-k nanofiller surface can decrease the dielectric constant mismatch, and thus, the corresponding nanocomposites can withstand high electric field. Unfortunately, the low apparent dielectric enhancement of the nanocomposites and high electrical conductivity mismatch between matrix and nanofiller still result in low energy density and low efficiency. In this study, it is demonstrated that encapsulating moderate-k nanofiller with high-k but low electrical conductivity shell is effective to significantly enhance the energy storage capability of dielectric polymer nanocomposites. Specifically, using BaTiO 3 nanoparticles encapsulated TiO 2 (BaTiO 3 @TiO 2 ) core-shell nanowires as filler, the corresponding poly(vinylidene fluoride-co-hexafluoropylene) nanocomposites exhibit superior energy storage capability in comparison with the nanocomposites filled by either BaTiO 3 or TiO 2 nanowires. The nanocomposite film with 5 wt % BaTiO 3 @TiO 2 nanowires possesses an ultrahigh discharged energy density of 9.95 J cm -3 at 500 MV m -1 , much higher than that of commercial biaxial-oriented polypropylene (BOPP) (3.56 J cm -3 at 600 MV m -1 ). This new strategy and corresponding results presented here provide new insights into the design of dielectric polymer nanocomposites with high electrical energy storage capability.

  12. A 2 TiO 5 (A = Dy, Gd, Er, Yb) at High Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sulgiye [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Rittman, Dylan R. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Tracy, Cameron L. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Chapman, Karena W. [X-ray Science Division, Advanced Photon; Zhang, Fuxiang [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States; Park, Changyong [HPCAT, Carnegie Institution of Washington, Argonne, Illinois 60439, United States; Tkachev, Sergey N. [Center for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637, United States; O’Quinn, Eric [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Shamblin, Jacob [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Lang, Maik [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States; Mao, Wendy L. [Department of Geological Science, Stanford University, Stanford, California 94305, United States; Stanford; amp, Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States; Ewing, Rodney C. [Department of Geological Science, Stanford University, Stanford, California 94305, United States

    2018-02-07

    The structural evolution of lanthanide A2TiO5 (A = Dy, Gd, Yb, and Er) at high pressure is investigated using synchrotron X-ray diffraction. The effects of A-site cation size and of the initial structure are systematically examined by varying the composition of the isostructural lanthanide titanates, and the structure of dysprosium titanate polymorphs (orthorhombic, hexagonal and cubic), respectively. All samples undergo irreversible high pressure phase transformations, but with different onset pressures depending on the initial structure. While individual phase exhibits different phase transformation histories, all samples commonly experience a sluggish transformation to a defect cotunnite-like (Pnma) phase for a certain pressure range. Orthorhombic Dy2TiO5 and Gd2TiO5 form P21am at pressures below 9 GPa and Pnma above 13 GPa. Pyrochlore-type Dy2TiO5 and Er2TiO5 as well as defect-fluorite-type Yb2TiO5 form Pnma at ~ 21 GPa, followed by Im-3m. Hexagonal Dy2TiO5 forms Pnma directly, although a small amount of remnants of hexagonal Dy2TiO5 is observed even at the highest pressure (~ 55 GPa) reached, indicating a kinetic limitations in the hexagonal Dy2TiO5 phase transformations at high pressure. Decompression of these materials leads to different metastable phases. Most interestingly, a high pressure cubic X-type phase (Im-3m) is confirmed using highresolution transmission electron microscopy on recovered pyrochlore-type Er2TiO5. The kinetic constraints on this metastable phase yield a mixture of both the X-type phase and amorphous domains upon pressure release. This is the first observation of an X-type phase for an A2BO5 composition at high pressure.

  13. Hydrothermal synthesis of Ti oxide nanostructures and TiO2:SnO2 heterostructures applied to the photodegradation of rhodamine B

    International Nuclear Information System (INIS)

    Mourão, Henrique A.J.L.; Junior, Waldir Avansi; Ribeiro, Caue

    2012-01-01

    The present study describes the synthesis, characterization and testing of the photocatalytic potential of TiO 2 nanoparticles (NPs), TiO 2 :SnO 2 heterostructures and potassium titanate nanotubes (TNTs) obtained by the alkaline hydrothermal method. The materials were characterized by X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, surface area estimated from the N 2 physisorption isotherm (BET), X-ray absorption near-edge structure (XANES) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and Fourier transform near-infrared (FT-NIR) spectroscopy, among other methods. Photocatalytic potential was assessed by rhodamine B dye photodegradation under UVC radiation. The properties of the materials were shown to depend on the KOH concentration. Potassium TNTs with high surface area were obtained only in 5 mol L −1 KOH. The material composed of TiO 2 anatase phase, which was obtained in KOH solution ranging from 10 −4 to 1 mol L −1 , showed higher photocatalytic activity than the TNTs, despite the lower surface area and lower density of hydroxyl groups on the anatase. In the heterostructure syntheses, SnO 2 NPs were identified attached to TiO 2 when 10 −4 and 10 −2 mol L −1 KOH were used, whereas at [KOH] = 1 and 5 mol L −1 , Sn remained in solution during the synthetic process and only the respective TiO 2 phase was identified. The TiO 2 :SnO 2 heterostructures were more active than the material without SnO 2 prepared at the same KOH concentrations. Highlights: ► The formation of the materials depends on the [KOH] used during syntheses. ► The heterostructures were obtained with the lower [KOH]. ► Photoactivity of the heterostructures was higher than the respective TiO 2 nanostructures. ► Titanate nanotubes showed high concentration of OH groups but low photoactivity.

  14. Epitaxial films of YBa2Cu3O/sub 7-//sub δ/ on NdGaO3, LaGaO3, and SrTiO3 substrates deposited by laser ablation

    International Nuclear Information System (INIS)

    Koren, G.; Gupta, A.; Giess, E.A.; Segmueller, A.; Laibowitz, R.B.

    1989-01-01

    Frequency-doubled Nd:YAG laser (532 nm) pulses of 1.7 J/cm 2 and 10 ns duration were used to deposit thin films of YBa 2 Cu 3 O/sub 7-//sub δ/ by laser ablation on NdGaO 3 , LaGaO 3 , and SrTiO 3 substrates held at 725 +- 5 0 C in 0.2 Torr of O 2 ambient. Electrical resistivities versus temperature of all films show normal metallic behavior and sharp superconducting transitions with T/sub c/ (R = 0) at 92--93 K. Critical current densities in 0.3--0.6 μm thick, 200 μm long, and 10--30 μm wide strips were measured to be 10 6 A/cm 2 at 60, 77, and 80 K in the films on LaGaO 3 , NdGaO 3 , and SrTiO 3 , respectively. X-ray diffraction patterns show that all films grew epitaxially, with domains of only two crystalline orientations rotated 90 0 with respect to each other in the a-b plane (consistent with twins), and the c axis perpendicular to the substrates. The closely matched lattice constants of the film and substrates (0.8--2.1%) result in epitaxial growth of the films

  15. Degradation and Mineralization of Benzohydroxamic Acid by Synthesized Mesoporous La/TiO2

    Directory of Open Access Journals (Sweden)

    Xianping Luo

    2016-10-01

    Full Text Available Rare earth element La-doped TiO2 (La/TiO2 was synthesized by the sol-gel method. Benzohydroxamic acid was used as the objective pollutant to investigate the photocatalytic activity of La/TiO2. The physicochemical properties of the prepared materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, specific surface area and porosity, scanning electron microscopy and transmission electron microscopy. As a result, the doping of La could inhibit the crystal growth of TiO2, increase its specific surface area and expand its response to visible light, thus improving its photocatalytic activity. La/TiO2 with the doping ratio of 0.75% calcined at 500 °C, showing the highest photocatalytic activity to degrade benzohydroxamic acid under the irradiation of 300 W mercury lamp. About 94.1% of benzohydroxamic acid with the original concentration at 30 mg·L−1 was removed after 120 min in a solution of pH 4.4 with an La/TiO2 amount of 0.5 g·L−1. Furthermore, 88.5% of the total organic carbon was eliminated after 120 min irradiation. In addition, after four recycling runs, La/TiO2 still kept high photocatalytic activity on the photodegradation of benzohydroxamic acid. The interfacial charge transfer processes were also hypothesized.

  16. Ratiometric luminescence thermometry with different combinations of emissions from Eu3+ doped Gd2Ti2O7 nanoparticles

    International Nuclear Information System (INIS)

    Lojpur, Vesna; Ćulubrk, Sanja; Dramićanin, Miroslav D.

    2016-01-01

    Herein, Eu 3+ doped Gd 2 Ti 2 O 7 nanoparticles were tested for application in ratiometric luminescence thermometry. It is shown that two combinations of emissions: one that uses two emissions of Eu 3+ ions and one that uses one emission of Eu 3+ ions and trap emission of Gd 2 Ti 2 O 7 provide thermometry over the 303–423 K temperature range with relative sensitivities between 0.14% K −1 and 0.95% K −1 . Thermometry based on two Eu 3+ emissions from 5 D 0 to 5 D 1 levels has a higher relative sensitivity, but lower absolute sensitivity than thermometry based on one Eu 3+ emission and trap emission of Gd 2 Ti 2 O 7 . The tested material is prepared by Pechini-type polymerized complex route and is composed of agglomerated nanoparticles of ~30–50 nm in size with pure-phase cubic structure (space group Fd-3m) as evidenced from electron microscopy and X-ray diffraction measurements. - Highlights: • Eu 3+ doped Gd 2 Ti 2 O 7 nanoparticles can serve as probes for luminescence thermometry. • Gd 2 Ti 2 O 7 trap emission is an excellent internal standard for luminescence thermometry. • Temperature is measured over 303–423 K range with sensitivity ranging 0.14–0.95% K −1 .

  17. A study of photocatalytic graphene–TiO{sub 2} synthesis via peroxo titanic acid refluxed sol

    Energy Technology Data Exchange (ETDEWEB)

    Low, Wasu, E-mail: masterwasulow@hotmail.com [The Joint Graduate School of Energy and Environment, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Boonamnuayvitaya, Virote, E-mail: virote.boo@kmutt.ac.th [Department of Chemical Engineering, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand)

    2013-08-01

    Graphical abstract: - Highlights: • TiO{sub 2} synthesized via PTA as a precursor demonstrates exclusively anatase phase. • The TEM image of GR–TiO{sub 2} (PTA) demonstrates that TiO{sub 2} nanoparticles are successfully loaded onto graphene sheet. • The specific surface area seems to increase with increasing weight ratio of graphene oxide. It was observed that GR–TiO{sub 2} showed higher adsorption compared to bare TiO{sub 2} (PTA). • The GR–TiO{sub 2} (PTA, 1:50) catalyst showed higher photocatalytic activity than any other catalyst. - Abstract: In the present work, graphene–TiO{sub 2} (GR–TiO{sub 2}) photocatalyst with various weight ratios of graphene was synthesized using peroxo titanic acid solution (PTA) as a precursor for TiO{sub 2}. Graphene oxide prepared by Hummer's method was converted to graphene under ultraviolet (UV) irradiation in ethanol–water solvent for 48 h. The as-prepared GR–TiO{sub 2} composites were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV–vis spectrophotometry, and transmission electron microscopy (TEM). The automated potentiostat was applied to measure the photocurrent generations of prepared catalysts. The photocatalytic activities of GR–TiO{sub 2} (PTA) catalysts were determined by measuring the percentage methylene blue (MB) degradation. The results showed that TiO{sub 2} nanoparticles were successfully loaded onto graphene sheet and the surface area of catalysts increased with increasing weight ratio of graphene. In addition, GR–TiO{sub 2} (PTA, 1:50) exhibited the highest photocatalytic activity among the catalysts under UV and visible light irradiation. The adsorption edge of GR–TiO{sub 2} was shifted to a longer wavelength of 400 nm in comparison with that of pure TiO{sub 2} (PTA). The increase in the photocatalytic performance of GR–TiO{sub 2} (PTA) catalyst may be attributed to the increase in surface area, the extension of light absorption

  18. Two-dimensional assembly structure of graphene and TiO2 nanosheets from titanic acid with enhanced visible-light photocatalytic performance

    Science.gov (United States)

    Hao, Rong; Guo, Shien; Wang, Xiuwen; Feng, Tong; Feng, Qingmao; Li, Mingxia; Jiang, Baojiang

    2016-06-01

    The titanic acid sheets were prepared by one-step hydrazine hydrate-assisted hydrothermal process. Then the reduced graphite oxide (rGO)@TiO2 nanosheet composites were finally obtained through ultrasonic exfoliation and following calcination treatment process. rGO@TiO2 nanosheet composites show excellent hydrogen production performance under AM1.5 light source. The highest hydrogen evolution yield (923.23 μmol) is nearly two times higher than that of pure TiO2, mainly due to the special electron structure and more active sites for TiO2 nanosheet. The introduction of graphene could improve the TiO2 nanosheet stability and extend visible-light absorption range.

  19. The influence of excess K2O on the electrical properties of (K,Na)1/2Bi1/2TiO3 ceramics

    Science.gov (United States)

    Li, Linhao; Li, Ming; Sinclair, Derek C.

    2018-04-01

    The solid solution (KxNa0.50-x)Bi0.50TiO3 (KNBT) between Na1/2Bi1/2TiO3 and K1/2Bi1/2TiO3 (KBT) has been extensively researched as a candidate lead-free piezoelectric material because of its relatively high Curie temperature and good piezoelectric properties, especially near the morphotropic phase boundary (MPB) at x ˜ 0.10 (20 mol. % KBT). Here, we show that low levels of excess K2O in the starting compositions, i.e., (Ky+0.03Na0.50-y)Bi0.50TiO3.015 (y-series), can significantly change the conduction mechanism and electrical properties compared to a nominally stoichiometric KNBT series (KxNa0.50-x)Bi0.50TiO3 (x-series). Impedance spectroscopy measurements reveal significantly higher bulk conductivity (σb) values for y ≥ 0.10 samples [activation energy (Ea) ≤ 0.95 eV] compared to the corresponding x-series samples which possess bandgap type electronic conduction (Ea ˜ 1.26-1.85 eV). The largest difference in electrical properties occurs close to the MPB composition (20 mol. % KBT) where y = 0.10 ceramics possess σb (at 300 °C) that is 4 orders of magnitude higher than that of x = 0.10 and the oxide-ion transport number in the former is ˜0.70-0.75 compared to processing. This demonstrates the electrical properties of KNBT to be sensitive to low levels of A-site nonstoichiometry and indicates that excess K2O in KNBT starting compositions to compensate for volatilisation can lead to undesirable high dielectric loss and leakage currents at elevated temperatures.

  20. Formation of aluminum titanate with small additions of MgO and SiO2

    International Nuclear Information System (INIS)

    Guedes-Silva, Cecilia Chaves; Ferreira, Thiago dos Santos; Genova, Luis Antonio; Carvalho, Flavio Machado de Souza

    2016-01-01

    The formation of aluminum titanate was investigated by isothermal treatments of samples obtained from equimolar mixtures of alumina and titania, containing small amounts of silica and magnesia. Results of differential thermal analysis and Rietveld refinements of data collected by X-ray powder diffraction (XRPD) showed that additions of silica in amounts used in this work did not influence the formation of aluminum titanate. However, the presence of magnesia favored the formation of aluminum titanate in two steps, first one by incorporating Mg 2+ into Al 2 TiO 5 lattice during its initial formation, and the second one by accelerating the Al 2 TiO 5 formation, contributing to large quantities of this phase. MgO doped samples have also developed a more suitable microstructure for stabilizing of Al 2 TiO 5 , what make them promising for applications such as thermal barriers, internal combustion engines and support material for catalyst. (author)

  1. Multiferroic magnetoelectric coupling effect of bilayer La1.2Sr1.8Mn2O7/PbZr0.3Ti0.7O3 complex thin film

    Science.gov (United States)

    Liang, K.; Zhou, P.; Ma, Z. J.; Qi, Y. J.; Mei, Z. H.; Zhang, T. J.

    2017-05-01

    Magnetoelectric (ME) coupling effect of 2-2-type ferromagnetic/ferroelectric bi-layer multiferroic epitaxial thin film (La1.2Sr1.8Mn2O7/PbZr0.3Ti0.7O3, LSMO/PZT) on SrRuO3 (SRO) substrate is investigated systematically by using Landau-Ginzburg-Devonshire (LGD) thermodynamic theory and modified constitutive equations. The calculating results clarify the detail relationships between ME coupling response and the residual strain, the volume fraction of constituent phases, the interface coupling coefficients, the magnetic field and the temperature. It also shows that improved ME coupling response can be modulated by these parameters. External magnetic fields (H1) induced ME coupling effect could be enhanced around Curie Temperature (Tc) of ferromagnetic phase and ME voltage coefficient (αE31) approaches a maximum at H1 ∼ 4.5 kOe near Tc. The remarkable variations of ME coupling response can be used to provide useful guidelines on the design of multifunctional devices.

  2. Investigation of the stability of glass-ceramic composites containing CeTi2O6 and CaZrTi2O7 after ion implantation

    Science.gov (United States)

    Paknahad, Elham; Grosvenor, Andrew P.

    2017-12-01

    Glass-ceramic composite materials have been investigated for nuclear waste sequestration applications due to their ability to incorporate large amounts of radioactive waste elements. A key property that needs to be understood when developing nuclear waste sequestration materials is how the structure of the material responds to radioactive decay of nuclear waste elements, which can be simulated by high energy ion implantation. Borosilicate glass-ceramic composites containing brannerite-type (CeTi2O6) or zirconolite-type (CaZrTi2O7) oxides were synthesized at different annealing temperatures and investigated after being implanted with high-energy Au ions to mimic radiation induced structural damage. Backscattered electron (BSE) images were collected to investigate the interaction of the brannerite crystallites with the glass matrix before and after implantation and showed that the morphology of the crystallites in the composite materials were not affected by radiation damage. Surface sensitive Ti K-edge glancing angle XANES spectra collected from the implanted composite materials showed that the structures of the CeTi2O6 and CaZrTi2O7 ceramics were damaged as a result of implantation; however, analysis of Si L2,3-edge XANES spectra indicated that the glass matrix was not affected by ion implantation.

  3. Investigation of the stability of glass-ceramic composites containing CeTi 2 O 6 and CaZrTi 2 O 7 after ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Paknahad, Elham; Grosvenor, Andrew P.

    2017-12-01

    Glass-ceramic composite materials have been investigated for nuclear waste sequestration applications due to their ability to incorporate large amounts of radioactive waste elements. A key property that needs to be understood when developing nuclear waste sequestration materials is how the structure of the material responds to radioactive decay of nuclear waste elements, which can be simulated by high energy ion implantation. Borosilicate glass-ceramic composites containing brannerite-type (CeTi2O6) or zirconolite-type (CaZrTi2O7) oxides were synthesized at different annealing temperatures and investigated after being implanted with high-energy Au ions to mimic radiation induced structural damage. Backscattered electron (BSE) images were collected to investigate the interaction of the brannerite crystallites with the glass matrix before and after implantation and showed that the morphology of the crystallites in the composite materials were not affected by radiation damage. Surface sensitive Ti K-edge glancing angle XANES spectra collected from the implanted composite materials showed that the structures of the CeTi2O6 and CaZrTi2O7 ceramics were damaged as a result of implantation; however, analysis of Si L2,3-edge XANES spectra indicated that the glass matrix was not affected by ion implantation.

  4. Lanthanide stannate pyrochlores (Ln2Sn2O7; Ln = Nd, Gd, Er) at high pressure.

    Science.gov (United States)

    Turner, Katlyn M; Tracy, Cameron L; Mao, Wendy L; Ewing, Rodney C

    2017-11-09

    Lanthanide stannate pyrochlores (Ln2Sn2O7; Ln=Nd, Gd, and Er) were investigated in situ to 50 GPa in order to determine their structural response to compression and compare it to that of lanthanide titanate, zirconate, and hafnate pyrochlores. The cation radius ratio of A3+/B4+ in pyrochlore oxides (A2B2O7) is thought to be the dominant property that influences their compression response. The ionic radius of Sn4+ is intermediate to that of Ti4+, Zr4+, and Hf4+, but the O> bond in stannate pyrochlore is more covalent than the O> bonds in titanates, zirconate, and hafnates. In stannates, the pyrochlore cation and anion sublattices begin to disorder at 0.3 GPa. The extent of sublattice disorder vs. pressure is greater in stannates with a smaller Ln3+ cation. Stannate pyrochlores (Fd-3m) begin a sluggish transformation to a cotunnite-like structure (Pnma) at ~28 GPa; similar transitions have been observed in titanate, zirconate, and hafnate pyrochlore at varying pressures with cation radius ratio. The extent of the phase transition vs. pressure varies directly with the size of the Ln3+ cation. Post-decompression from ~50 GPa, Er2Sn2O7 and Gd2Sn2O7 adopt a pyrochlore structure, rather than the multiscale defect-fluorite + weberite structure adopted by Nd2Sn2O7 that is characteristic of titanate, zirconate, and hafnate pyrochlore treated to similar conditions. Like pyrochlore titanates, zirconates, and hafnates, the bulk modulus, B0, of stannates varies linearly and inversely with cation radius ratio. The trends of bulk moduli in stannates in this study are in excellent agreement with previous experimental studies on stannates, and suggest that the size of the Ln3+ cation is a primary determining factor of B0. Additionally, when normalized to rA/rB, the bulk moduli of stannates are comparable to those of zirconates and hafnates, which vary from titanates. Our results suggest that the cation radius ratio strongly influences the bulk moduli of stannates as well as

  5. Facile synthesis of polyaniline/TiO2/graphene oxide composite for high performance supercapacitors

    Science.gov (United States)

    Su, Haifang; Wang, Teng; Zhang, Shengyi; Song, Jiming; Mao, Changjie; Niu, Helin; Jin, Baokang; Wu, Jieying; Tian, Yupeng

    2012-06-01

    The polyaniline/TiO2/graphene oxide (PANI/TiO2/GO) composite, as a novel supercapacitor material, is synthesized by in situ hydrolyzation of tetrabutyl titanate and polymerization of aniline monomer in the presence of graphene oxide. The morphology, composition and structure of the composites as-obtained are characterized by SEM, TEM, XRD and TGA. The electrochemical property and impedance of the composites are studied by cyclic voltammetry and Nyquist plot, respectively. The results show that the introduction of the GO and TiO2 enhanced the electrode conductivity and stability, and then improved the supercapacitive behavior of PANI/TiO2/GO composite. Significantly, the electrochemical measurement results show that the PANI/TiO2/GO composite has a high specific capacitance (1020 F g-1 at 2 mV s-1, 430 F g-1 at 1 A g-1) and long cycle life (over 1000 times).

  6. One-step synthesis of hierarchically porous hybrid TiO2 hollow spheres with high photocatalytic activity

    Science.gov (United States)

    Liu, Ruiping; Ren, Feng; Yang, Jinlin; Su, Weiming; Sun, Zhiming; Zhang, Lei; Wang, Chang-an

    2016-03-01

    Hierarchically porous hybrid TiO2 hollow spheres were solvothermally synthesized successfully by using tetrabutyl titanate as titanium precursor and hydrated metal sulfates as soft templates. The as-prepared TiO2 spheres with hierarchically pore structures and high specific surface area and pore volume consisted of highly crystallized anatase TiO2 nanocrystals hybridized with a small amount of metal oxide from the hydrated sulfate. The proposed hydrated-sulfate assisted solvothermal (HAS) synthesis strategy was demonstrated to be widely applicable to various systems. Evaluation of the hybrid TiO2 hollow spheres for the photo-decomposition of methyl orange (MO) under visible-light irradiation revealed that they exhibited excellent photocatalytic activity and durability.

  7. HoTbTi2O7, the mixtures of spin ice and spin liquid

    International Nuclear Information System (INIS)

    Chang, L.J.; Terashita, H.; Schweika, W.; Chen, Y.Y.; Gardner, J.S.

    2007-01-01

    Polycrystalline samples of Ho 2- x Tb x Ti 2 O 7 (x=0.5, 1, and 1.5) have been prepared and characterized. No long-range order is observed for HoTbTi 2 O 7 in magnetization and specific heat measurements down to 2 K. The low-energy magnetic excitation measurements suggests that HoTbTi 2 O 7 possesses both characteristics of spin ice and spin liquid in the ground state

  8. Template-free synthesis of two-dimensional titania/titanate nanosheets as electrodes for high-performance supercapacitor applications

    Science.gov (United States)

    Barai, Hasi Rani; Rahman, Md. Mahbubur; Joo, Sang Woo

    2017-12-01

    Template-free two-dimensional (2D) titania/titanate nanosheets on Ti metal foil (TiNS/Ti) is prepared by a hydrothermal method at 150 °C assisted by KOH(aq.),followed by sintering at 500 °C. A single thin layer of TiNS is grown with 2D morphology when using low concentrations of KOH(aq.) (0.25 and 0.5 M). However, the morphology is transformed to 1D when using a high concentration of KOH(aq.). The TiNS is a mixture of rutile TiO2 and K-titanate (K2Ti3O7 and K2Ti2O5) with the formation of Ti3+ interstitials. The optimized TiNS/Ti electrode exhibits quasi-rectangular cyclic voltammograms (CVs) in a wide potential range. The specific capacitance (Cs) are 6.8 × 103 and 4.7 × 103 μF/cm2 according to the CV (scan rate, 5 mV/s) and charge-discharge measurements (CD, current density, 50 μA/cm2), respectively. These values are much higher than those reported for pure 0D and 1D TiO2 nanostructures.The higher Cs for the TiNS/Ti electrode can be ascribed to the increased rate of K+ intercalation and de-intercalation during charging and discharging, as well as enhanced conductivity enable by the K in the crystal lattice (10.30%) and Ti3+ interstitials (5.2%), respectively. The TiNS/Ti electrode shows excellent stability with the Cs retention of 89% even after 5000 CD cycles.

  9. Investigations of the magnetic properties in the pyrochlore Ho{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Schoenemann, Rico; Herrmannsdoerfer, Thomas; Green, Elizabeth Lauren; Wang, Zhaosheng; Wosnitza, Joachim [Dresden High Magnetic Field Laboratory, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Skrotzki, Richard [Dresden High Magnetic Field Laboratory, Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Department of Chemistry and Food Chemistry, TU Dresden, Dresden (Germany); Kaneko, Hiroshi; Suzuki, Haruhiko [Faculty of Mathematics and Physics, Kanazawa University, Kanazawa (Japan)

    2013-07-01

    Pyrochlore compounds such as R{sub 2}Ti{sub 2}O{sub 7} (where R is Ho or Dy) have an highly degenerate ground state where the R{sup 3+} moments obey the ''ice rules''. This provides access to study extraordinary physical phenomena, like the formation of magnetic monopoles. Recent publications evidence monopoles which can be probed using high frequency (adiabatic) susceptibility measurements. We performed ac susceptibility measurements on a single-crystal Ho{sub 2}Ti{sub 2}O{sub 7} sample at low temperatures down to 30 mK and magnetic fields up to 14 T. Based on isothermal frequency sweeps we were able to determine spin relaxation rates. Both the real and imaginary parts of the temperature-dependent magnetic susceptibility measurements show the spins freezing below 1 K and provide insight into the magnetic-monopole density.

  10. Movilidad de oxígeno en conductores iónicos A2Ti2-yZryO7 (A: Y, Gd

    Directory of Open Access Journals (Sweden)

    León, C.

    2004-08-01

    Full Text Available We report a study of ionic conductivity in the series Y2Ti2-yZryO7 and Gd2Ti2-yZryO7 (0≤y≤2 obtained by mechanochemical synthesis. We present a study of oxygen ion dynamics in these materials by Impedance Spectroscopy. The change in dc conductivity and activation energy with Zr content is interpreted in terms of the increase in the number of oxygen vacancies and of structural disorder when increasing Zr content.Presentamos un estudio de la conductividad iónica en las series Y2Ti2-yZryO7 y Gd2Ti2-yZryO7 (0≤y≤2 obtenidas por síntesis mecanoquímica. Se presenta un estudio de la dinámica de iones oxígeno en estos materiales mediante la técnica de Espectroscopia de Admitancias. La variación con el contenido en Zr de la conductividad dc y de su energía de activación se interpreta en términos del aumento tanto del número de vacantes de oxígeno como del desorden en la estructura al aumentar el contenido en Zr.

  11. The Influence of TiO2 Nanoparticles on LaFeO3/TiO2 Nanocomposites for Reduction of Aqueous Organic Dyes

    International Nuclear Information System (INIS)

    Afifah, N.; Saleh, R.

    2016-01-01

    A series of Lanthanum ferrite (LaFeO3) nanoparticles over titanium dioxide (TiO2) were synthesized using sol-gel method at room temperature by varying the loading of LaFeO3 on TiO2. The magnetic properties of samples were measured using vibrating sample magnetometer and photosonocatalytic activity towards the degradation of methylene blue under light (UV or visible) and ultrasound irradiation was also evaluated. The morphology and structure of the samples were characterized by field emission scanning electron microscope, energy dispersive analysis and X-ray diffraction. Furthermore the optical properties were also characterized by UV-visible diffuse reflectance. The experimental results showed that the prepared perovskites had sphere-like shape and strong visible light absorption. LaFeO3 demonstrated ferromagnetic properties and the magnetization decreased with the incorporation of TiO2 in the samples. However, the incorporation of TiO2 increased the photosonocatalytic activity and extended the photoresponding to UV light. (paper)

  12. n/p-Type changeable semiconductor TiO{sub 2} prepared from NTA

    Energy Technology Data Exchange (ETDEWEB)

    Li Qiuye; Wang Xiaodong; Jin Zhensheng, E-mail: zhenshengjin@henu.edu.cn; Yang Dagang; Zhang Shunli; Guo Xinyong; Yang Jianjun; Zhang Zhijun [Henan University, Key Laboratory of Special Functional Materials (China)

    2007-10-15

    A novel kind of nano-sized TiO{sub 2} (anatase) was obtained by high-temperature (400-700 deg. C) dehydration of nanotube titanic acid (H{sub 2}Ti{sub 2}O{sub 4}(OH){sub 2}, NTA). The high-temperature (400-700 deg. C) dehydrated nanotube titanic acids (HD-NTAs) with a unique defect structure exhibited a p-type semiconductor behavior under visible-light irradiation ({lambda}{>=} 420nm, E{sub photon}=2.95 eV), whereas exhibited an n-type semiconductor behavior irradiated with UV light ({lambda}{>=} 365nm, E{sub photon}=3.40 eV)

  13. Photochemical and photocatalytic evaluation of 1D titanate/TiO{sub 2} based nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Conceição, D.S.; Ferreira, D.P. [Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology Instituto Superior Técnico, Universidade de Lisboa Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Graça, C.A.L. [Universidade de São Paulo, Avenida Prof. Luciano Gualberto, tr. 3, 380 São Paulo (Brazil); Júlio, M.F.; Ilharco, L.M. [Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology Instituto Superior Técnico, Universidade de Lisboa Av. Rovisco Pais, 1049-001 Lisboa (Portugal); Velosa, A.C. [Instituto Nacional de Tecnologia, Av. Venezuela 82, Rio de Janeiro (Brazil); Santos, P.F. [Centro de Química, Vila Real Universidade de Trás-os-Montes e Alto Douro, 5001-801 Vila Real (Portugal); Vieira Ferreira, L.F., E-mail: lfvieiraferreira@tecnico.ulisboa.pt [Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology Instituto Superior Técnico, Universidade de Lisboa Av. Rovisco Pais, 1049-001 Lisboa (Portugal)

    2017-01-15

    Highlights: • 1D titanate based nanomaterials were prepared via a hydrothermal approach. • The structural and photochemical evaluation of the nanomaterials was performed. • A fluorescent dye was used as a surface probe in visible excitation conditions. • Amicarbazone was used as the model contaminant for photodegradation studies. - Abstract: One-dimensional (1D) titanate based nanomaterials were synthesized following an alkaline hydrothermal approach of commercial TiO{sub 2} nanopowder. The morphological features of all materials were monitored by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), and also Brunauer-Emmett-Teller (BET) technique. In addition the photochemical behaviour of these nanostructured materials were evaluated with the use of laser induced luminescence (LIL), ground-state diffuse reflectance (GSDR), and laser-flash photolysis in diffuse reflectance mode (DRLFP). The mixed titanate/TiO{sub 2} nanowires presented the least intense fluorescence spectra, suggesting the presence of surficial defects that can extend the lifetime of the excited charge carriers. A fluorescent ‘rhodamine-like’ dye was adsorbed onto different materials and examined via photoexcitation in the visible range to study the self-photosensitization mechanism. The presence of the radical cation of the dye and the degradation kinetics, when compared with a neutral substrate—cellulose, provided significant evidences regarding the photoactivity of the different materials. Regarding all the materials under study, the nanowires exhibited a strong photocatalytic efficiency, for the adsorbed fluorescent probe. The photocatalytic mechanism was also considered by studying the photodegradation capability of the titanate based materials in the presence of an herbicide, Amicarbazone, after ultraviolet (UVA) photoexcitation.

  14. Crystal shape-dependent magnetic susceptibility and Curie law crossover in the spin ices Dy2Ti2O7 and Ho2Ti2O7

    International Nuclear Information System (INIS)

    Bovo, L; Bramwell, S T; Jaubert, L D C; Holdsworth, P C W

    2013-01-01

    We present an experimental determination of the isothermal magnetic susceptibility of the spin ice materials Dy 2 Ti 2 O 7 and Ho 2 Ti 2 O 7 in the temperature range 1.8–300 K. The use of spherical crystals has allowed accurate correction for demagnetizing fields and allowed the true bulk isothermal susceptibility χ T (T) to be estimated. This has been compared against a theoretical expression based on a Husimi tree approximation to the spin ice model. Agreement between experiment and theory is excellent at T > 10 K, but systematic deviations occur below that temperature. Our results largely resolve an apparent disagreement between neutron scattering and bulk measurements that has been previously noted. They also show that the use of non-spherical crystals in magnetization studies of spin ice may introduce very significant systematic errors, although we note some interesting—and possibly new—systematics concerning the demagnetizing factor in cuboidal samples. Finally, our results show how experimental susceptibility measurements on spin ices may be used to extract the characteristic energy scale of the system and the corresponding chemical potential for emergent magnetic monopoles. (paper)

  15. Thermoelectric Properties in the TiO2/SnO2 System

    Science.gov (United States)

    Dynys, F.; Sayir, A.; Sehirlioglu, A.; Berger, M.

    2009-01-01

    Nanotechnology has provided a new interest in thermoelectric technology. A thermodynamically driven process is one approach in achieving nanostructures in bulk materials. TiO2/SnO2 system exhibits a large spinodal region with exceptional stable phase separated microstructures up to 1400 C. Fabricated TiO2/SnO2 nanocomposites exhibit n-type behavior with Seebeck coefficients greater than -300 .V/K. Composites exhibit good thermal conductance in the range of 7 to 1 W/mK. Dopant additions have not achieved high electrical conductivity (<1000 S/m). Formation of oxygen deficient composites, TixSn1-xO2-y, can change the electrical conductivity by four orders of magnitude. Achieving higher thermoelectric ZT by oxygen deficiency is being explored. Seebeck coeffcient, thermal conductivity, electrical conductance and microstructure will be discussed in relation to composition and doping.

  16. Hydrothermal synthesis of Ti oxide nanostructures and TiO{sub 2}:SnO{sub 2} heterostructures applied to the photodegradation of rhodamine B

    Energy Technology Data Exchange (ETDEWEB)

    Mourao, Henrique A.J.L., E-mail: henriquepiau@yahoo.com.br [Universidade Federal de Sao Carlos, Departamento de Quimica, Rod. Washington Luiz, km 235, CEP 13565-905, Sao Carlos, SP (Brazil); EMBRAPA Instrumentacao Agropecuaria, Rua XV de Novembro, 1452, CEP 13560-970, CP 741, Sao Carlos, SP (Brazil); Junior, Waldir Avansi; Ribeiro, Caue [EMBRAPA Instrumentacao Agropecuaria, Rua XV de Novembro, 1452, CEP 13560-970, CP 741, Sao Carlos, SP (Brazil)

    2012-08-15

    The present study describes the synthesis, characterization and testing of the photocatalytic potential of TiO{sub 2} nanoparticles (NPs), TiO{sub 2}:SnO{sub 2} heterostructures and potassium titanate nanotubes (TNTs) obtained by the alkaline hydrothermal method. The materials were characterized by X-ray diffraction (XRD), energy-dispersive X-ray (EDX) spectroscopy, surface area estimated from the N{sub 2} physisorption isotherm (BET), X-ray absorption near-edge structure (XANES) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and Fourier transform near-infrared (FT-NIR) spectroscopy, among other methods. Photocatalytic potential was assessed by rhodamine B dye photodegradation under UVC radiation. The properties of the materials were shown to depend on the KOH concentration. Potassium TNTs with high surface area were obtained only in 5 mol L{sup -1} KOH. The material composed of TiO{sub 2} anatase phase, which was obtained in KOH solution ranging from 10{sup -4} to 1 mol L{sup -1}, showed higher photocatalytic activity than the TNTs, despite the lower surface area and lower density of hydroxyl groups on the anatase. In the heterostructure syntheses, SnO{sub 2} NPs were identified attached to TiO{sub 2} when 10{sup -4} and 10{sup -2} mol L{sup -1} KOH were used, whereas at [KOH] = 1 and 5 mol L{sup -1}, Sn remained in solution during the synthetic process and only the respective TiO{sub 2} phase was identified. The TiO{sub 2}:SnO{sub 2} heterostructures were more active than the material without SnO{sub 2} prepared at the same KOH concentrations. Highlights: Black-Right-Pointing-Pointer The formation of the materials depends on the [KOH] used during syntheses. Black-Right-Pointing-Pointer The heterostructures were obtained with the lower [KOH]. Black-Right-Pointing-Pointer Photoactivity of the heterostructures was higher than the respective TiO{sub 2

  17. Formation of aluminum titanate with small additions of MgO and SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Guedes-Silva, Cecilia Chaves; Ferreira, Thiago dos Santos; Genova, Luis Antonio [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Carvalho, Flavio Machado de Souza, E-mail: cecilia.guedes@ipen.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Geociencias

    2016-03-15

    The formation of aluminum titanate was investigated by isothermal treatments of samples obtained from equimolar mixtures of alumina and titania, containing small amounts of silica and magnesia. Results of differential thermal analysis and Rietveld refinements of data collected by X-ray powder diffraction (XRPD) showed that additions of silica in amounts used in this work did not influence the formation of aluminum titanate. However, the presence of magnesia favored the formation of aluminum titanate in two steps, first one by incorporating Mg{sup 2+} into Al{sub 2}TiO{sub 5} lattice during its initial formation, and the second one by accelerating the Al{sub 2}TiO{sub 5} formation, contributing to large quantities of this phase. MgO doped samples have also developed a more suitable microstructure for stabilizing of Al{sub 2}TiO{sub 5}, what make them promising for applications such as thermal barriers, internal combustion engines and support material for catalyst. (author)

  18. Tm-doped TiO2 and Tm2Ti2O7 pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase.

    Science.gov (United States)

    De Los Santos, Desiré M; Navas, Javier; Aguilar, Teresa; Sánchez-Coronilla, Antonio; Fernández-Lorenzo, Concha; Alcántara, Rodrigo; Piñero, Jose Carlos; Blanco, Ginesa; Martín-Calleja, Joaquín

    2015-01-01

    Tm-doped TiO2 nanoparticles were synthesized using a water-controlled hydrolysis reaction. Analysis was performed in order to determine the influence of the dopant concentration and annealing temperature on the phase, crystallinity, and electronic and optical properties of the resulting material. Various characterization techniques were utilized such as X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy. For the samples annealed at 773 and 973 K, anatase phase TiO2 was obtained, predominantly internally doped with Tm(3+). ICP-AES showed that a doping concentration of up to 5.8 atom % was obtained without reducing the crystallinity of the samples. The presence of Tm(3+) was confirmed by X-ray photoelectron spectroscopy and UV-vis spectroscopy: the incorporation of Tm(3+) was confirmed by the generation of new absorption bands that could be assigned to Tm(3+) transitions. Furthermore, when the samples were annealed at 1173 K, a pyrochlore phase (Tm2Ti2O7) mixed with TiO2 was obtained with a predominant rutile phase. The photodegradation of methylene blue showed that this pyrochlore phase enhanced the photocatalytic activity of the rutile phase.

  19. Synthesis and photocatalytic activity of Ce-doped TiO2 and TiO2 nanotubes

    International Nuclear Information System (INIS)

    Arruda, L.B.; Pereira, E.A.; Paula, F.R.; Lisboa Filho, P.N.

    2016-01-01

    samples with pH 7, XRD measurements showed the coexistence of TiO2 and sodium titanate phase. By decreasing the pH during acid washing the sodium content was eliminated leaving only the main phase. This behavior was observed for samples containing Cerium concentrations up to 0.2%. The obtained nanotubes presented multiple walls, having dimensions of 5 nm of diameter and about 200 nm of length. Energy dispersive X-ray spectroscopy analyzes revealed that nanotubes are mainly composed of titanium and oxygen, with small amounts of sodium when pH is 7 and sodium no was observed for the sample obtained at pH 4. It shows that synthesis conditions are very important in order to obtain single-phase structures. In addition, TiO2 nanotubes showed good photocatalytic activity with degradation around 100 minutes.(author)

  20. Synthesis and photocatalytic activity of Ce-doped TiO2 and TiO2 nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Arruda, L.B.; Pereira, E.A.; Paula, F.R.; Lisboa Filho, P.N. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), SP (Brazil)

    2016-07-01

    samples with pH 7, XRD measurements showed the coexistence of TiO2 and sodium titanate phase. By decreasing the pH during acid washing the sodium content was eliminated leaving only the main phase. This behavior was observed for samples containing Cerium concentrations up to 0.2%. The obtained nanotubes presented multiple walls, having dimensions of 5 nm of diameter and about 200 nm of length. Energy dispersive X-ray spectroscopy analyzes revealed that nanotubes are mainly composed of titanium and oxygen, with small amounts of sodium when pH is 7 and sodium no was observed for the sample obtained at pH 4. It shows that synthesis conditions are very important in order to obtain single-phase structures. In addition, TiO2 nanotubes showed good photocatalytic activity with degradation around 100 minutes.(author)

  1. High rate capacity nanocomposite lanthanum oxide coated lithium zinc titanate anode for rechargeable lithium-ion battery

    International Nuclear Information System (INIS)

    Tang, Haoqing; Zan, Lingxing; Zhu, Jiangtao; Ma, Yiheng; Zhao, Naiqin; Tang, Zhiyuan

    2016-01-01

    Lithium zinc titanate (Li_2ZnTi_3O_8) is an important titanium material of promising candidates for anode materials with superior electrochemical performance and thus has attracted extensive attention. Herein, high capacity, stable Li_2ZnTi_3O_8/La_2O_3 nanocomposite for lithium-ion battery anode is prepared by a facile strategy. Compared to unmodified Li_2ZnTi_3O_8, the Li_2ZnTi_3O_8/La_2O_3 electrode display a high specific capacity of 188.6 mAh g"−"1 and remain as high as 147.7 mAh g"−"1 after 100 cycles at 2.0 A g"−"1. Moreover, a reversible capacity of 76.3 mAh g"−"1 can be obtained after 1000 cycles at 2.0 A g"−"1 and the retention is 42.7% for Li_2ZnTi_3O_8/La_2O_3, which is much higher than un-coated Li_2ZnTi_3O_8. The superior lithium storage performances of the Li_2ZnTi_3O_8/La_2O_3 can be ascribed to the stable layer of protection, small particle size and large surface area. Cyclic voltammograms result reveals that the La_2O_3 coating layer reduces the polarization and improves the electrochemical activity of anode. - Highlights: • Nano layer La_2O_3 coated Li_2ZnTi_3O_8 particles have been prepared via a suspension mixing process followed by heat treatment. • Coated Li_2ZnTi_3O_8 has enhanced high rate capability, cyclic stability and long lifespan performance. • Electrochemical properties were tested in a charge/discharge voltage range of 3.0–0.05 V (vs. Li/Li"+).

  2. Creation of Y2Ti2O7 nanoprecipitates to strengthen the Fe-14Cr-3Al-2W steels by adding Ti hydride and Y2O3 nanoparticles

    International Nuclear Information System (INIS)

    Wang, Linbo; Bai, Zhonglian; Shen, Hailong; Wang, Chenxi; Liu, Tong

    2017-01-01

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

  3. Processing of La(1.8)Sr(0.2)CuO4 and YBa2Cu3O7 superconducting thin films by dual-ion-beam sputtering

    Science.gov (United States)

    Madakson, P.; Cuomo, J. J.; Yee, D. S.; Roy, R. A.; Scilla, G.

    1988-03-01

    High-quality La(1.8)Sr(0.2)CuO4 and YBa2Cu3O7 superconducting thin films, with zero resistance at 88 K, have been made by dual-ion-beam sputtering of metal and oxide targets at elevated temperatures. The films are about 1.0 micron thick and are single phase after annealing. The substrates investigated are Nd-YAP, MgO, SrF2, Si, CaF2, ZrO2-(9 pct)Y2O3, BaF2, Al2O3, and SrTiO3. Characterization of the films was carried out using Rutherford backscattering spectroscopy, resistivity measurements, TEM, X-ray diffraction, and SIMS. Substrate/film interaction was observed in every case. This generally involves diffusion of the substrate into the film, which is accompanied by, for example, the replacement of Ba by Sr in the YBa2Cu2O7 structure, in the case of SrTiO3 substrate. The best substrates were those that did not significantly diffuse into the film and which did not react chemically with the film.

  4. Mesoporous CNT@TiO2-C Nanocable with Extremely Durable High Rate Capability for Lithium-Ion Battery Anodes

    Science.gov (United States)

    Wang, Bin; Xin, Huolin; Li, Xiaodong; Cheng, Jianli; Yang, Guangcheng; Nie, Fude

    2014-01-01

    A well-designed nanostructure CNT@TiO2-C with fine anatase TiO2 particle (glucose in the hydrothermal process not only solves the interfacial incompatibility between CNTs and titanate sol and controls the nucleation and growth of TiO2 particles, but also introduces a uniform, glucose-derived, carbon-layer on the TiO2 particles. The nanosized TiO2 particle, high conducting network, and interconnected nanopores of the CNT@TiO2-C nanocable greatly improve its electrochemical performances, especially rate capability. The CNT@TiO2-C nanocables show remarkable rate capability with reversible charge capacity of 297, 240, 210,178 and 127 mAh g-1 at 1C, 5C, 10C, 20C and 50C, respectively, as well as excellent high rate cycling stability with capacity retention of 87% after 2000 cycles at 50C.

  5. Production of Al-Ti-B grain refining master alloys from Na2B4O7 and K2TiF6

    International Nuclear Information System (INIS)

    Birol, Yuecel

    2008-01-01

    It is very desirable to replace the KBF 4 salt in the popular 'halide salt' process to reduce the volume of fluoride salts to be added to molten aluminium in the production of Al-Ti-B grain refiners. Being over 2 times richer in B, Na 2 B 4 O 7 is a promising replacement for KBF 4 , and is used in the present work to produce Al-Ti-B grain refiner master alloys. A fraction of the aluminide particles were entrapped in the spent salt giving a relatively lower Ti recovery when KBF 4 was replaced by Na 2 B 4 O 7 . The grain refining performance of the Al-Ti-B grain refiner alloy thus produced was nevertheless acceptable. The spent salt became too viscous with the oxides, aluminides and borides to be removed by decanting when Na 2 B 4 O 7 .5H 2 O was used to supply boron. The viscous spent salt, entrained in the grain refiner alloy, did not only impair its performance, but also hurt the fluidity of the molten alloy and made pouring difficult

  6. Electrochemical activity of Li{sub 2}FeTiO{sub 4} and Li{sub 2}MnTiO{sub 4} as potential active materials for Li ion batteries: A comparison with Li{sub 2}NiTiO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Kuezma, Mirjana; Dominko, Robert; Bele, Marjan; Jamnik, Janko [National Institute of Chemistry, Ljubljana (Slovenia); Meden, Anton [Faculty of Chemistry and Chemical Technology, University of Ljubljana (Slovenia); Makovec, Darko [Jozef Stefan Institute, Ljubljana (Slovenia); Gaberscek, Miran [National Institute of Chemistry, Ljubljana (Slovenia); Faculty of Chemistry and Chemical Technology, University of Ljubljana (Slovenia)

    2009-04-01

    We demonstrate, for the first time, a considerable electrochemical activity of two members of lithium transition element titanates: Li{sub 2}FeTiO{sub 4} and Li{sub 2}MnTiO{sub 4}. Both materials consist of 10-20 nm particles embedded in a conductive carbon coating. We show that not the coating but the small particle size is decisive for materials' activity. Li{sub 2}FeTiO{sub 4} shows a stable reversible capacity of up to 123 mA hg{sup -1} at C/20 and 60 C which is 83% of the theoretical value for exchange of 1 electron (148 mA hg{sup -1}). Li{sub 2}MnTiO{sub 4} could only be prepared in a nanosized form that contained about 30% of impurities. The capacity of the whole material (including impurities) is comparable to that of Li{sub 2}FeTiO{sub 4} but the cycling stability is much poorer. In contrast to the Fe and Mn analogues, the third member of the titanate family, Li{sub 2}NiTiO{sub 4}, shows a good electrochemistry even when the particle size is much larger (about 100 nm). During initial cycles at C/10 and 60 C, exchange of more than 1 electron per compound formula has been observed. The cycling stability at high temperatures, however, is poor. (author)

  7. Solvothermal synthesis of TiO2 nanocrystals with {001} facets using titanic acid nanobelts for superior photocatalytic activity

    Science.gov (United States)

    Cao, Yuhui; Zong, Lanlan; Li, Qiuye; Li, Chen; Li, Junli; Yang, Jianjun

    2017-01-01

    Anatase TiO2 nanocrystals exposed with {001} facets were fabricated by solvothermal strategy in HF-C4H9OH mixed solution, using titanic acid nanobelts (TAN) as a precursor. The shape of TAN is a long flat plane with a high aspect ratio, and F- is easily adsorbed on the surface of the nanobelts, inducing a higher exposure of {001} facet of TiO2 nanoparticles during the structure reorganization. The exposed percentage of {001} facets could vary from 40 to 77% by adjusting the amount of HF. The as-prepared samples were characterized by transmission electron microscopy, N2 adsorption-desorption isotherms, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscope. The photocatalytic measurement showed that TiO2 nanocrystals with 77% {001} facets exhibited much superior photocatalytic activity for photodegradation of methyl orange, methylene blue, and rhodamine B. And what's more, the mineralization rate of methyl orange was as high as 96% within 60 min. The photocatalytic enhancement is due to a large amount of the high energetic {001} facets exposing, the special truncated octahedral morphology and a stronger ability for dyes adsorption.

  8. NaLaTi_2O_6 nanosheet as a potential anode material for lithium ion batteries

    International Nuclear Information System (INIS)

    Geng, Qiao; Cao, Liyun; Kong, Xingang; Xu, Zhanwei; Huang, Jianfeng; Li, Jiayin; Cheng, Yayi

    2016-01-01

    Highlights: • NaLaTi_2O_6 nanosheet was achieved by a simple one-step hydrothermal method. • NaLaTi_2O_6 was reported for the first time as an anode material. • NaLaTi_2O_6 shown a high discharge capacity of about 180 mAh/g at 100 mA/g. - Abstract: NaLaTi_2O_6 nanosheet was achieved by one-step hydrothermal method and was reported for the first time as an anode material for lithium ion batteries. The phase structure and morphology analysis reveals that pure pervoskite NaLaTi_2O_6 possesses nanosheet morphology with thickness of about 20 nm and length of several hundred nanometers. The electrochemical performances demonstrate that NaLaTi_2O_6 has a good lithium ion insertion/extraction ability with a discharge capacity of about 180 mAh/g, which is slightly larger than Li_4Ti_5O_1_2 theoretical capacity (175 mAh/g). Even more, after 1000 charge-discharge cycles at 100 mA/g, it still maintains a discharge capacity of 165 mAh/g, suggesting that NaLaTi_2O_6 could be explored as a potential anode material for lithium ion batteries.

  9. Synthesis, Characterization, and NIR Reflectance of Highly Dispersed NiTiO3 and NiTiO3/TiO2 Composite Pigments

    Directory of Open Access Journals (Sweden)

    Yuping Tong

    2016-01-01

    Full Text Available The highly dispersed nanostructured NiTiO3 pigments and NiTiO3/TiO2 composite pigments can be synthesized at relative low temperature. The activation energy of crystal growth of NiTiO3 during calcinations via salt-assistant combustion method is 9.35 kJ/mol. The UV-vis spectra results revealed that the absorbance decreased with the increasing of calcinations temperature due to small size effect of nanometer particles. The optical data of NiTiO3 nanocrystals were analyzed at the near-absorption edge. SEM showed that the obtained NiTiO3 nanocrystals and NiTiO3/TiO2 nanocomposite were composed of highly dispersed spherical-like and spherical particles with uniform size distribution, respectively. The chromatic properties and diffuse reflectance of samples were investigated. The obtained NiTiO3/TiO2 composite samples have higher NIR reflectance than NiTiO3 pigments.

  10. High mobility half-metallicity in the (LaMnO3)2/(SrTiO3)8 superlattice

    KAUST Repository

    Cossu, Fabrizio

    2013-01-28

    First principles calculations have been performed to investigate the LaMnO3/SrTiO3 superlattice. Structural relaxation within the generalized gradient approximation results in no significant tiltings or rotations of oxygen octahedra, but in distinct distortions in the SrTiO3 region. Taking into account the onsite Coulomb interaction, we find that the Mn spins order ferromagnetically, in contrast to the antiferromagnetic state of bulk LaMnO3. Most importantly, the interface strain combined with charge transfer across the interface induces half-metallicity within the MnO2 layers. The superlattice is particulary interesting for spintronics applications because the half-metallic states are characterized by an extraordinary high mobility.

  11. High mobility half-metallicity in the (LaMnO3)2/(SrTiO3)8 superlattice

    KAUST Repository

    Cossu, Fabrizio; Schwingenschlö gl, Udo; Singh, Nirpendra

    2013-01-01

    First principles calculations have been performed to investigate the LaMnO3/SrTiO3 superlattice. Structural relaxation within the generalized gradient approximation results in no significant tiltings or rotations of oxygen octahedra, but in distinct distortions in the SrTiO3 region. Taking into account the onsite Coulomb interaction, we find that the Mn spins order ferromagnetically, in contrast to the antiferromagnetic state of bulk LaMnO3. Most importantly, the interface strain combined with charge transfer across the interface induces half-metallicity within the MnO2 layers. The superlattice is particulary interesting for spintronics applications because the half-metallic states are characterized by an extraordinary high mobility.

  12. Preparation of thermally stable anatase TiO2 photocatalyst from TiOF2 precursor and its photocatalytic activity

    International Nuclear Information System (INIS)

    Lv Kangle; Yu Jiaguo; Cui Longzhe; Chen Shulin; Li Mei

    2011-01-01

    Graphical abstract: The prepared anatase TiO 2 from TiOF 2 shows very high thermal stability (up to 1000 o C) and the 700 o C-calcined sample showed the highest photocatalytic activity. Display Omitted Research highlights: → TiOF 2 was prepared by a simple microwave assisted hydrothermal rout. → Anatase TiO 2 prepared by calcination of TiOF 2 shows high thermal stability. → F - play an important role in the improvement thermal stability of anatase TiO 2 . → The 700 o C-calcined sample shows the highest photocatalytic activity. - Abstract: Preparation of anatase TiO 2 with high themal stability is of great importance for its environmental application. In this work, TiOF 2 was first synthesized by a simple microwave-assisted hydrothermal route using tetrabutyl titanate and hydrofluoric acid as precursors at 200 o C for 20 min. Then the resulted precipitates were calcined at different temperatures (300-1000 o C) for 2 h. The as-prepared samples were characterized by X-ray diffraction, Raman spectrum, scanning electron microscopy, N 2 adsorption-desorption isotherms and X-ray photoelectron spectroscopy. The photocatalytic activity was evaluated using Brilliant Red X3B, an anionic azo dye, as the target organic molecule under UV light irradiation. The results showed that the prepared TiOF 2 exhibited weak or no photocatalytic activity. The phase transformation of TiOF 2 to anatase TiO 2 occurred at about 300 o C. The prepared anatase TiO 2 from TiOF 2 showed very high thermal stability and the anatase-to-rutile phase transformation temperature was up to 1000 o C. Fluoride ions played an important role in the improvement of thermal stability of anatase TiO 2 by strongly adsorbing on the crystal planes of anatase to stabilize the anatase structure. The 700 o C-calcined sample showed the highest photocatalytic activity due to its relative good crystallization and high specific surface areas.

  13. Electrochemical performance of La2O3/Li2O/TiO2 nano-particle coated cathode material LiFePO4.

    Science.gov (United States)

    Wang, Hong; Yang, Chi; Liu, Shu-Xin

    2014-09-01

    Cathode material, LiFePO4 was modified by coating with a thin layer of La2O3/Li2O/TiO2 nano-particles for improving its performance for lithium ion batteries. The morphology and structure of the modified cathode material were characterized by powder X-ray diffraction, scanning electron microcopy and AES. The performance of the battery with the modified cathode material, including cycling stability, C-rate discharge was examined. The results show that the battery composed of the coated cathode materials can discharge at a large current density and show stable cycling performance in the range from 2.5 to 4.0 V. The rate of Li ion diffusion increases in the battery with the La2O3/Li2O/TiO2-coated LiFePO4 as a cathode and the coating layer may acts as a faster ion conductor (La(2/3-x)Li(3x)TiO3).

  14. Rietveld refinement of KLaTiO4 from X-ray powder data

    Directory of Open Access Journals (Sweden)

    Bai-Chuan Zhu

    2011-04-01

    Full Text Available Potassium lanthanum titanate(IV, KLaTiO4, has been synthesized by conventional solid-state reaction. It crystallizes isotypically with the NaLnTiO4 (Ln = La, Pr, Nd, Sm, Eu, Gd, Y and Lu family. Five of the six atoms in the asymmetric unit (one K, one La, one Ti and two O atoms are situated on sites with 4mm symmetry, whereas one O atom has 2mm. site symmetry. The crystal structure can be described as being composed of single layers of distorted corner-sharing TiO6 octahedra extending parallel to (001. The layers are alternately separated by K+ and La3+ cations along [001]. The coordination number of both K+ and La3+ cations is nine, resulting in distorted KO9 and LaO9 polyhedra.

  15. Dirac strings and magnetic monopoles in the spin ice Dy2Ti2O7.

    Science.gov (United States)

    Morris, D J P; Tennant, D A; Grigera, S A; Klemke, B; Castelnovo, C; Moessner, R; Czternasty, C; Meissner, M; Rule, K C; Hoffmann, J-U; Kiefer, K; Gerischer, S; Slobinsky, D; Perry, R S

    2009-10-16

    Sources of magnetic fields-magnetic monopoles-have so far proven elusive as elementary particles. Condensed-matter physicists have recently proposed several scenarios of emergent quasiparticles resembling monopoles. A particularly simple proposition pertains to spin ice on the highly frustrated pyrochlore lattice. The spin-ice state is argued to be well described by networks of aligned dipoles resembling solenoidal tubes-classical, and observable, versions of a Dirac string. Where these tubes end, the resulting defects look like magnetic monopoles. We demonstrated, by diffuse neutron scattering, the presence of such strings in the spin ice dysprosium titanate (Dy2Ti2O7). This is achieved by applying a symmetry-breaking magnetic field with which we can manipulate the density and orientation of the strings. In turn, heat capacity is described by a gas of magnetic monopoles interacting via a magnetic Coulomb interaction.

  16. Recovery and recycling of lithium value from spent lithium titanate (Li{sub 2}TiO{sub 3}) pebbles

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, D., E-mail: dmandal10@gmail.com

    2013-09-15

    Graphical abstract: Effects of various process parameters on the recovery of Li-from spent Li{sub 2}TiO{sub 3} pebbles were investigated. From the experimental results it was observed that the leaching rate increases with speed of stirring till 450 rpm and then above 450 rpm; the increase in speed of stirring does not have any significant effect on the leaching rate as shown in the following figure. Effects of other parameters on the Li-recovery from spent Li{sub 2}TiO{sub 3} pebbles are discussed in this paper. Abstract: In the first generation fusion reactors the fusion of deuterium (D) and tritium (T) is considered to produce energy to meet the future energy demand. Deuterium is available in nature whereas, tritium is not. Lithium-6 (Li{sup 6}) isotope has the ability to produce tritium in the n, α nuclear reaction with neutrons. Thus lithium-based ceramics enriched by Li{sup 6} isotope are considered for the tritium generation for its use in future fusion reactors. Lithium titanate is one such Li-based ceramic material being considered for its some attractive properties viz., high thermal and chemical stability, high thermal conductivity, and low tritium solubility. It is reported in the literature, that the burn up of these pebbles in the fusion reactor will be limited to only 15–17 atomic percentage. At the end of life, the pebbles will contain more than 45% unused Li{sup 6} isotope. Due to the high cost of enriched Li{sup 6} and the waste disposal considerations, it is necessary to recover the unused Li from the spent lithium titanate pebbles. Till date, only the feasibilities of different processes are reported, but no process details are available. Experiments were carried out for the recovery of Li from simulated Li{sub 2}TiO{sub 3} pebbles and to reuse of lithium in lithium titanate pebble fabrication. The details of the experiments and results are discussed in this paper.

  17. Highly efficient enrichment of phosphopeptides from HeLa cells using hollow magnetic macro/mesoporous TiO2 nanoparticles.

    Science.gov (United States)

    Hong, Yayun; Zhan, Qiliang; Pu, Chenlu; Sheng, Qianying; Zhao, Hongli; Lan, Minbo

    2018-09-01

    In this work, hollow magnetic macro/mesoporous TiO 2 nanoparticles (denoted as Fe 3 O 4 @H-fTiO 2 ) were synthesized by a facile "hydrothermal etching assisted crystallization" route to improve the phosphopeptide enrichment efficiency. The porous nanostructure of TiO 2 shell and large hollow space endowed the Fe 3 O 4 @H-fTiO 2 with a high surface area (144.71 m 2 g -1 ) and a large pore volume (0.52 cm 3 g -1 ), which could provide more affinity sites for phosphopeptide enrichment. Besides, the large pore size of TiO 2 nanosheets and large hollow space could effectively prevent the "shadow effect", thereby facilitating the diffusion and release of phosphopeptides. Compared with the hollow magnetic mesoporous TiO 2 with small and deep pores (denoted as Fe 3 O 4 @H-mTiO 2 ) and solid magnetic macro/mesoporous TiO 2 , the Fe 3 O 4 @H-fTiO 2 nanoparticles showed a better selectivity (molar ratio of α-casein/BSA up to 1:10000) and a higher sensitivity (0.2 fmol/μL α-casein) for phosphopeptide enrichment. Furthermore, 1485 unique phosphopeptides derived from 660 phosphoproteins were identified from HeLa cell extracts after enrichment with Fe 3 O 4 @H-fTiO 2 nanoparticles, further demonstrating that the Fe 3 O 4 @H-fTiO 2 nanoparticles had a high-efficiency performance for phosphopeptide enrichment. Taken together, the Fe 3 O 4 @H-fTiO 2 nanoparticles will have unique advantages in phosphoproteomics analysis. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. Comparative study of phase structure and dielectric properties for K0.5Bi0.5TiO3-BiAlO3 and LaAlO3-BiAlO3

    International Nuclear Information System (INIS)

    Hou, Yudong; Zheng, Mupeng; Si, Meiju; Cui, Lei; Zhu, Mankang; Yan, Hui

    2013-01-01

    In this work, two perovskite-type compounds, K 0.5 Bi 0.5 TiO 3 and LaAlO 3 , have been selected as host material to incorporate with BiAlO 3 using a solid-state reaction route. The phase evolution and dielectric properties for both systems have been investigated in detail. For the K 0.5 Bi 0.5 TiO 3 -BiAlO 3 system, it is interesting to find that when using Bi 2 O 3 , Al 2 O 3 , K 2 CO 3 , and TiO 2 as starting materials, the formed compounds are K 0.5 Bi 0.5 TiO 3 -K 0.5 Bi 4.5 Ti 4 O 15 and Al 2 O 3 only plays a dopant role. There are two distinct dielectric peaks appearing in the patterns of temperature dependence of dielectric constant, corresponding to the phase-transition points of perovskite-type K 0.5 Bi 0.5 TiO 3 and Aurivillius-type K 0.5 Bi 4.5 Ti 4 O 15 , independently. In comparison, using Bi 2 O 3 , Al 2 O 3 , and La 2 O 3 as starting materials, the pure perovskite phase LaAlO 3 -BiAlO 3 can be obtained. Compared to the inherent paraelectric behavior in LaAlO 3 , the diffuse phase-transition phenomena can be observed in the LaAlO 3 -BiAlO 3 binary system, which corresponds well to the Vogel-Fulcher (VF) relationship. Moreover, compared to pure LaAlO 3 , the synthesized LaAlO 3 -BiAlO 3 compound shows enhanced dielectric properties, which are promising in application as gate dielectric materials. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. Solvothermal synthesis of TiO{sub 2} nanocrystals with {001} facets using titanic acid nanobelts for superior photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Yuhui; Zong, Lanlan [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Li, Qiuye, E-mail: qiuyeli@henu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China); Li, Chen; Li, Junli [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Yang, Jianjun, E-mail: yangjianjun@henu.edu.cn [National & Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials, Henan University, Kaifeng, 475004 (China); Collaborative Innovation Center of Nano Functional Materials and Applications of Henan Province, Henan University, Kaifeng, 475004 (China)

    2017-01-01

    Highlights: • TiO{sub 2} exposed with {001} facets were firstly prepared using TAN as Ti source. • The mineralization rate of MO on sample with 77% {001} facets was as high as 96%. • The superior photocatalytic activity was greatly due to {001} facets exposing. - Abstract: Anatase TiO{sub 2} nanocrystals exposed with {001} facets were fabricated by solvothermal strategy in HF-C{sub 4}H{sub 9}OH mixed solution, using titanic acid nanobelts (TAN) as a precursor. The shape of TAN is a long flat plane with a high aspect ratio, and F{sup −} is easily adsorbed on the surface of the nanobelts, inducing a higher exposure of {001} facet of TiO{sub 2} nanoparticles during the structure reorganization. The exposed percentage of {001} facets could vary from 40 to 77% by adjusting the amount of HF. The as-prepared samples were characterized by transmission electron microscopy, N{sub 2} adsorption-desorption isotherms, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscope. The photocatalytic measurement showed that TiO{sub 2} nanocrystals with 77% {001} facets exhibited much superior photocatalytic activity for photodegradation of methyl orange, methylene blue, and rhodamine B. And what’s more, the mineralization rate of methyl orange was as high as 96% within 60 min. The photocatalytic enhancement is due to a large amount of the high energetic {001} facets exposing, the special truncated octahedral morphology and a stronger ability for dyes adsorption.

  20. Characterization of Pt catalysts supported in TiO{sub 2} and ZrO{sub 2} stabilized with La{sub 2}O{sub 3} for the nitric oxide elimination; Caracterizacion de catalizadores de Pt soportado en TiO{sub 2} y ZrO{sub 2} estabilizados con La{sub 2}O{sub 3} para la eliminacion de oxido nitrico

    Energy Technology Data Exchange (ETDEWEB)

    Perez H, R.; Arenas, J.; Rodriguez, V.; Aguilar, A.; Gomez C, A.; Diaz, G. [ININ, Carretera Mexico-Toluca, Km. 36.5 Salazar, Estado de Mexico, C.P. 52045 (Mexico)

    2000-07-01

    Simple oxides TiO{sub 2}, ZrO{sub 2}, La{sub 2}O{sub 3} and mixed TiO{sub 2}-La{sub 2}O{sub 3}, ZrO{sub 2}-La{sub 2}O{sub 3} at 10% mol of lanthane were prepared by the precipitation technique. The incorporation of Pt to the supports was by the classical impregnation method. It was characterized the catalytic materials by diverse techniques for determining the lost weight by thermogravimetric analysis (TGA), superficial area (BET), crystallinity of catalytic supports (DR-X) total acidity and for the catalytic activity was realized in the reaction model NO + CH{sub 4}. (Author)

  1. Epitaxial growth of SrTiO3/YBa2Cu3O7 - x heterostructures by plasma-enhanced metalorganic chemical vapor deposition

    Science.gov (United States)

    Liang, S.; Chern, C. S.; Shi, Z. Q.; Lu, P.; Safari, A.; Lu, Y.; Kear, B. H.; Hou, S. Y.

    1994-06-01

    We report heteroepitaxial growth of SrTiO3 on YBa2Cu3O7-x/LaAlO3 substrates by plasma-enhanced metalorganic chemical vapor deposition. X-ray diffraction results indicated that SrTiO3 films were epitaxially grown on a (001) YBa2Cu3O7-x surface with [100] orientation perpendicular to the surface. The film composition, with Sr/Ti molar ratio in the range of 0.9 to 1.1, was determined by Rutherford backscattering spectrometry and energy dispersive spectroscopy. The thickness of the SrTiO3 films is 0.1-0.2 μm. The epitaxial growth was further evidenced by high-resolution transmission electron microscopy and selected area diffraction. Atomically abrupt SrTiO3/YBa2Cu3O7-x interface and epitaxial growth with [100]SrTiO3∥[001]YBa2Cu3O7-x were observed in this study. The superconducting transition temperature of the bottom YBa2Cu3O7-x layer, as measured by ac susceptometer, did not significantly degrade after the growth of overlayer SrTiO3. The capacitance-voltage measurements showed that the dielectric constant of the SrTiO3 films was as high as 315 at a signal frequency of 100 KHz. The leakage current density through the SrTiO3 films is about 1×10-6 A/cm2 at 2-V operation. Data analysis on the current-voltage characteristic indicated that the conduction process is related to bulk-limited Poole-Frenkel emission.

  2. Thermal properties of KUO3(s) and K2U2O7 - by high temperature Calvet calorimeter

    International Nuclear Information System (INIS)

    Jayanthi, K.; Iyer, V.S.; Venugopal, V.

    1998-01-01

    The thermal properties of KUO 3 (s) and K 2 U 2 O 7 (s) were determined using a high temperature Calvet calorimeter by drop method. The enthalpy increments, (H T o - H 298.15 0 ), in kJ/mol for KUO 3 (s) and K 2 U 2 O 7 (s) can be represented by, H T o - H 298.15 0 KUO 3 (s) kJ/mol ± 0.7 = -39.15 + 0.129T + 0.1005x10 -4 T 2 (369-714K) and H T o -H 298.15 0 K 2 U 2 O 7 (s) kJ/mol ± 0.7 = -52.99 + 0.1361T + 0.146x10 -3 T 2 (391 - 683K). (author)

  3. First-principles calculation of the structure and electronic properties of Fe-substituted Bi2Ti2O7

    Science.gov (United States)

    Huang, Jin-Dou; Zhang, Zhenyi; Lin, Feng; Dong, Bin

    2017-12-01

    We performed first-principles calculations to investigate the formation energy, geometry structure, and electronic property of Fe-doped Bi2Ti2O7 systems with different Fe doping content. The calculated formation energies indicate that the substitutional configurations of Fe-doping Bi2Ti2O7 are easy to obtain under O-rich growth condition, but their thermodynamic stability decreases with the increase of Fe content. The calculated spin-resolved density of states and band structures indicate that the introduction of Fe into Bi2Ti2O7 brings high spin polarization. The spin-down impurity levels in Fe x Bi2-x Ti2O7 and spin-up impurity levels in Fe x Bi2Ti2-x O7 systems locate in the bottom of conduction band and narrow the band gap significantly, thus leading to the absorption of visible light. Interestingly, the impurity states in Fe x Bi2-x Ti2O7 are the efficient separation center of photogenerated electron and hole, and less affected by Fe doping content, in comparison, the levels of impurity band in Fe x Bi2Ti2-x O7 systems are largely effected by the Fe doping content, and high Fe doping content is the key factor to improve the separating rate of photogenerated electron and hole.

  4. Ab initio study of a TiO{sub 2}/LaAlO{sub 3} heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Weissmann, M; Ferrari, V, E-mail: weissman@cnea.gov.a, E-mail: ferrari@tandar.cnea.gov.a [Departamento de Fisica, Comision Nacional de EnergIa Atomica, Gral. Paz 1499, 1650 San Martin, Buenos Aires (Argentina)

    2009-05-01

    In this work we explore the origin of the ferromagnetism appearing when a TiO{sub 2} film is grown on another non-magnetic oxide as a substrate such as LaAlO{sub 3} (001), concentrating on the role played by the oxygen vacancies in this phenomenon. Using Density Functional Theory ab-initio methods, we study the free-standing anatase film as well as the interfaces with either the LaO or AlO{sub 2} planes of LaAlO{sub 3}. Our results show that the interface LaO/TiO{sub 2} is favored against the AlO{sub 2}/TiO{sub 2} one if no oxygen vacancies are present in the interface whereas the contrary happens when there are oxygen vacancies. In both cases, the cohesive energy is of the same order of magnitude but only at AlO{sub 2}/TiO{sub 2} we found a magnetic solution.

  5. Characterization of Pt catalysts supported in TiO2 and ZrO2 stabilized with La2O3 for the nitric oxide elimination

    International Nuclear Information System (INIS)

    Perez H, R.; Arenas, J.; Rodriguez, V.; Aguilar, A.; Gomez C, A.; Diaz, G.

    2000-01-01

    Simple oxides TiO 2 , ZrO 2 , La 2 O 3 and mixed TiO 2 -La 2 O 3 , ZrO 2 -La 2 O 3 at 10% mol of lanthane were prepared by the precipitation technique. The incorporation of Pt to the supports was by the classical impregnation method. It was characterized the catalytic materials by diverse techniques for determining the lost weight by thermogravimetric analysis (TGA), superficial area (BET), crystallinity of catalytic supports (DR-X) total acidity and for the catalytic activity was realized in the reaction model NO + CH 4 . (Author)

  6. Effects of La2O3 on microstructure and wear properties of laser clad γ/Cr7C3/TiC composite coatings on TiAl intermatallic alloy

    International Nuclear Information System (INIS)

    Liu Xiubo; Yu Rongli

    2007-01-01

    The effects of La 2 O 3 addition on the microstructure and wear properties of laser clad γ/Cr 7 C 3 /TiC composite coatings on γ-TiAl intermetallic alloy substrates with NiCr-Cr 3 C 2 precursor mixed powders have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive spectrometer (EDS) and block-on-ring wear tests. The responding wear mechanisms are discussed in detail. The results are compared with that for composite coating without La 2 O 3 . The comparison indicates that no evident new crystallographic phases are formed except a rapidly solidified microstructure consisting of the primary hard Cr 7 C 3 and TiC carbides and the γ/Cr 7 C 3 eutectics distributed in the tough γ nickel solid solution matrix. Good finishing coatings can be achieved under a proper amount of La 2 O 3 -addition and a suitable laser processing parameters. The additions of rare-earth oxide La 2 O 3 can refine and purify the microstructure of coatings, relatively decrease the volume fraction of primary blocky Cr 7 C 3 to Cr 7 C 3 /γ eutectics, reduce the dilution of clad material from base alloy and increase the microhardness of the coatings. When the addition of La 2 O 3 is approximately 4 wt.%, the laser clad composite coating possesses the highest hardness and toughness. The composite coating with 4 wt.%La 2 O 3 addition can result the best enhancement of wear resistance of about 30%. However, too less or excessive addition amount of La 2 O 3 have no better influence on wear resistance of the composite coating

  7. Dielectric enhancement of PbZr{sub 0.3}Ti{sub 0.7}O{sub 3}/LaNiO{sub 3} multilayer thick film

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Yasong; Chen, Xiaoyang; Habibul, Arzigul; Zhang, Danyang; Yu, Ping [College of Materials Science and Engineering, Sichuan University, Chengdu, 610064 (China)

    2016-08-15

    Multilayer thick films (∝4 μm) with compositional PbZr{sub 0.3}Ti{sub 0.7}O{sub 3}/LaNiO{sub 3} layers and one-layer PZT thick films were prepared on the silicon substrate by radio-frequency magnetron sputtering. PbZr{sub 0.3}Ti{sub 0.7}O{sub 3}/LaNiO{sub 3} multilayer thick film are characterized by highly preferential (100)-oriented growth and columnar microstructure due to alternately introducing LaNiO{sub 3} seeding layers. The effects of LaNiO{sub 3} layers on microstructure and electrical properties of PbZr{sub 0.3}Ti{sub 0.7}O{sub 3} thick films were investigated in detail. The results show that both PZT and PbZr{sub 0.3}Ti{sub 0.7}O{sub 3}/LaNiO{sub 3} multilayer thick film were pure perovskite crystalline phase. The PbZr{sub 0.3}Ti{sub 0.7}O{sub 3} film texture was dense and well adhered on the LaNiO{sub 3} layer. PbZr{sub 0.3}Ti{sub 0.7}O{sub 3}/LaNiO{sub 3} multilayer thick film possessed obvious enhanced dielectric properties compared with PZT thick film: ε{sub r} ∝2450 (10 kHz) and tanδ ∝0.02 (10 kHz). Rayleigh law was used to analysis the behavior of the enhanced dielectric properties and the pinched-shaped polarization-electric field hysteresis loops. The larger Rayleigh parameter, α ∝51.1408 cm kV{sup -1} (1 kHz) indicates the larger extrinsic contribution to permittivity and strong domain-wall-defect charge interaction. The leakage current behaviors of the multilayer thick film were also investigated in detail. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Systematic study of photoluminescence upon band gap excitation in perovskite-type titanates R 1/2Na1/2TiO3:Pr (R=La, Gd, Lu, and Y)

    International Nuclear Information System (INIS)

    Inaguma, Yoshiyuki; Tsuchiya, Takeshi; Katsumata, Tetsuhiro

    2007-01-01

    Pr 3+ -doped perovskites R 1/2 Na 1/2 TiO 3 :Pr (R=La, Gd, Lu, and Y) were synthesized, and their structures, optical absorption and luminescent properties were investigated, and the relationship between structures and optical properties are discussed. Optical band gap of R 1/2 Na 1/2 TiO 3 increases in the order R=La, Gd, Y, and Lu, which is primarily due to a decrease in band width accompanied by a decrease in Ti-O-Ti bond angle. Intense red emission assigned to f-f transition of Pr 3+ from the excited 1 D 2 level to the ground 3 H 4 state upon the band gap photo-excitation (UV) was observed for all compounds. The wavelength of emission peaks was red-shifted in the order R=La, Gd, Y, and Lu, which originates from the increase in crystal field splitting of Pr 3+ . This is attributed to the decrease in inter-atomic distances of Pr-O together with the inter-atomic distances (R, Na)-O, i.e., increase in covalency between Pr and O. The results indicate that the luminescent properties in R 1/2 Na 1/2 TiO 3 :Pr are governed by the relative energy level between the ground and excited state of 4f 2 for Pr 3+ , and the conduction and valence band, which is primarily dependent on the structure, e.g., the tilt of TiO 6 octahedra and the Pr-Ti inter-atomic distance and the site symmetry of Pr ion. - Graphical abstract: The red intense emission assigned to f-f transition of Pr 3+ from the excited 1 D 2 level to the ground 3 H 4 state upon the band gap photo-excitation (UV) was observed upon the band gap photo-excitation in perovskites R 1/2 Na 1/2 TiO 3 :Pr(R=La, Gd, Lu, and Y). It was found that the systematic changes in their luminescent properties are strongly dependent on the structure

  9. Intermediate magnetization state and competing orders in Dy2Ti2O7 and Ho2Ti2O7

    Science.gov (United States)

    Borzi, R. A.; Gómez Albarracín, F. A.; Rosales, H. D.; Rossini, G. L.; Steppke, A.; Prabhakaran, D.; Mackenzie, A. P.; Cabra, D. C.; Grigera, S. A.

    2016-01-01

    Among the frustrated magnetic materials, spin-ice stands out as a particularly interesting system. Residual entropy, freezing and glassiness, Kasteleyn transitions and fractionalization of excitations in three dimensions all stem from a simple classical Hamiltonian. But is the usual spin-ice Hamiltonian a correct description of the experimental systems? Here we address this issue by measuring magnetic susceptibility in the two most studied spin-ice compounds, Dy2Ti2O7 and Ho2Ti2O7, using a vector magnet. Using these results, and guided by a theoretical analysis of possible distortions to the pyrochlore lattice, we construct an effective Hamiltonian and explore it using Monte Carlo simulations. We show how this Hamiltonian reproduces the experimental results, including the formation of a phase of intermediate polarization, and gives important information about the possible ground state of real spin-ice systems. Our work suggests an unusual situation in which distortions might contribute to the preservation rather than relief of the effects of frustration. PMID:27558021

  10. Combined effects of radiation damage and He accumulation on bubble nucleation in Gd{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Caitlin A., E-mail: ctayl105@vols.utk.edu [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Patel, Maulik K. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Aguiar, Jeffery A. [Fuel Performance and Design Department, Idaho National Laboratory, Idaho Falls, ID 83415-6188 (United States); Material Science Center, National Renewable Energy Laboratory, Golden, CO 80220 (United States); Zhang, Yanwen [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Crespillo, Miguel L. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Wen, Juan [School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu 730000 (China); Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Xue, Haizhou [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Wang, Yongqiang [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Weber, William J. [Department of Materials Science and Engineering, The University of Tennessee, Knoxville, TN 37996 (United States); Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

    2016-10-15

    Pyrochlores have long been considered as host phases for long-term immobilization of radioactive waste nuclides that would undergo α-decay for hundreds of thousands of years. This work utilizes ion-beam irradiations to examine the combined effects of radiation damage and He accumulation on bubble formation in Gd{sub 2}Ti{sub 2}O{sub 7} over relevant waste-form timescales. Helium bubbles are not observed in pre-damaged Gd{sub 2}Ti{sub 2}O{sub 7} implanted with 2 × 10{sup 16} He/cm{sup 2}, even after post-implantation irradiations with 7 MeV Au{sup 3+} at 300, 500, and 700 K. However, He bubbles with average diameters of 1.5 nm and 2.1 nm are observed in pre-damaged (amorphous) Gd{sub 2}Ti{sub 2}O{sub 7} and pristine Gd{sub 2}Ti{sub 2}O{sub 7}, respectively, after implantation of 2 × 10{sup 17} He/cm{sup 2}. The critical He concentration for bubble nucleation in Gd{sub 2}Ti{sub 2}O{sub 7} is estimated to be 6 at.% He. - Highlights: • He bubbles not formed in amorphous Gd{sub 2}Ti{sub 2}O{sub 7} implanted with 2 × 10{sup 16} He/cm{sup 2}, even after additional irradiation at 300 to 700 K. • He bubbles, 1.5 and 2.1 nm diameter, respectively, observed in amorphous and pristine Gd{sub 2}Ti{sub 2}O{sub 7} implanted to 2 × 10{sup 17} He/cm{sup 2}. • The critical He dose for bubble nucleation is estimated to be 6 at.% He.

  11. Photoelectrochemical Properties of FeO Supported on TiO2-Based Thin Films Converted from Self-Assembled Hydrogen Titanate Nanotube Powders

    Directory of Open Access Journals (Sweden)

    Kyung-Jong Noh

    2012-01-01

    Full Text Available A photoanode was fabricated using hematite (α-Fe2O3 nanoparticles which had been held in a thin film of hydrogen titanate nanotubes (H-TiNT, synthesized by repetitive self-assembling method on FTO (fluorine-doped tin oxide glass, which were incorporated via dipping process in aqueous Fe(NO33 solution. Current voltage (I-V electrochemical properties of the photoanode heat-treated at 500°C for 10 min in air were evaluated under ultraviolet-visible light irradiation. Microstructure and crystallinity changes were also investigated. The prepared Fe2O3/H-TiNT/FTO composite thin film exhibited about threefold as much photocurrent as the Fe2O3/FTO film. The improvement in photocurrent was considered to be caused by reduced recombination of electrons and holes, with an appropriate amount of Fe2O3 spherical nanoparticles supported on the H-TiNT/FTO film. Nanosized spherical Fe2O3 particles with about 65 wt% on the H-TiNT/FTO film showed best performance in our study.

  12. Nano-MnO2@TiO2 microspheres: A novel structure and excellent performance as anode of lithium-ion batteries

    Science.gov (United States)

    Cao, Zhiguang; Chen, Xiaoqiao; Xing, Lidang; Liao, Youhao; Xu, Mengqing; Li, Xiaoping; Liu, Xiang; Li, Weishan

    2018-03-01

    A structurally hierarchical MnO2/TiO2 composite (Nano-MnO2@TiO2) is fabricated by calcining MnCO3 microspheres and coating a thin layer of TiO2 through the heat decomposition of tetrabutyl titanate, and evaluated as anode of gravimetrically and volumetrically high energy density lithium ion battery. The characterizations from FESEM, TEM, HRTEM and XRD, indicate that the resulting Nano-MnO2@TiO2 takes a spherical morphology with a core of about 2 μm in diameter, consisting of compact MnO2 nanoparticles, and a shell of 60 nm thick, consisting of smaller TiO2 nanoparticles. The charge/discharge tests demonstrate that Nano-MnO2@TiO2 exhibits excellent performance as anode of lithium ion battery, delivering a capacity of 938 mAh g-1 at 300 mA g-1 after 200 cycles, compared to the 103 mAh g-1 of the uncoated sample. The microsphere consisting of compact nanoparticles provides Nano-MnO2@TiO2 with high specific gravity. The dimensionally and structurally stable TiO2 maintains the integrity of MnO2 microspheres and facilitates lithium insertion/extraction. This unique structure yields the excellent cyclic stability and rate capability of Nano-MnO2@TiO2.

  13. Synthesis and characterisation of the n = 2 Ruddlesden–Popper phases Ln2Sr(Ba)Fe2O7 (Ln = La, Nd, Eu)

    International Nuclear Information System (INIS)

    Gurusinghe, Nicola N.M.; Figuera, Juand de la; Marco, José F.; Thomas, Michael F.; Berry, Frank J.; Greaves, Colin

    2013-01-01

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

  14. Synthesis and photocatalytic properties of visible light responsive La/TiO2-graphene composites

    International Nuclear Information System (INIS)

    Khalid, N.R.; Ahmed, E.; Hong Zhanglian; Ahmad, M.

    2012-01-01

    Highlights: ► Synthesis of La/TiO 2 -graphene composites by two-step hydrothermal method. ► Efficient charge separation due to La doping and graphene incorporation. ► Enhanced photocatalytic activity of composite catalyst for MB degradation under visible-light. - Abstract: La/TiO 2 -graphene composites used as photocatalyst were prepared by two-step hydrothermal method. The as-prepared composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The results of optical properties of La/TiO 2 -graphene composites exhibit extended light absorption in visible-light region and possess better charge separation capability as compared to pure TiO 2 . The photocatalytic activity measurement demonstrate that La/TiO 2 -graphene composites exhibited an enhanced photocatalytic activity for methylene blue (MB) degradation under visible-light irradiation compared to pure TiO 2 , which was attributed to greater adsorptivity of dyes, extended light absorption and increased charge separation efficiency due to excellent electrical properties of graphene and the large surface contact between graphene and La/TiO 2 nanoparticles.

  15. Study on upconversion luminescence and thermal properties of Ho{sup 3+}/Yb{sup 3+} co-doped La{sub 2}O{sub 3}–TiO{sub 2}–ZrO{sub 2} glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Minghui; Wen, Haiqin [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050 (China); Yu, Huimei [Analysis and Testing Center of Inorganic Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050 (China); Ai, Fei [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050 (China); Shao, Hui [School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China); Pan, Xiuhong; Tang, Meibo; Yu, Jianding; Gai, Lijun [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050 (China); Liu, Yan, E-mail: liuyan@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai, 200050 (China)

    2016-07-05

    Bulk Ho{sup 3+}/Yb{sup 3+} co-doped La{sub 2}O{sub 3}–TiO{sub 2}–ZrO{sub 2} glass spheres were fabricated by aerodynamic levitation method. High concentration of Yb{sup 3+} ions was successfully doped in glasses. The effects of Yb{sup 3+} concentration on mechanical properties, Raman, absorption spectra, thermal stability, and glass forming ability were studied systematically. Green, red, and infrared emissions centered at 550, 662, and 758 nm were obtained at 980 nm excitation. Yellow light from glass spheres can be easily observed by naked eyes. As Yb{sup 3+} concentration increases, the upconversion luminescence can be improved obviously. The upconversion luminescence mechanism is a two-photon process of energy transfer, excited state absorption, and energy back transfer. The emission intensity can be enhanced in the samples with high Yb{sup 3+} concentration, since the absorption for the incident laser and the energy transfer efficiency are increased, and the nonradiative relaxation probability is reduced. The light color referring to the ratio for red to green emissions can be tuned by Yb{sup 3+} concentration. Ho{sup 3+}/Yb{sup 3+} co-doped La{sub 2}O{sub 3}–TiO{sub 2}–ZrO{sub 2} glasses show promising comprehensive properties and are helpful to speed the application of upconversion luminescence materials. - Highlights: • Ho{sup 3+}/Yb{sup 3+} doped titanate glasses are prepared by containerless processing. • The effects of Yb{sup 3+} on thermal and mechanical properties have been studied. • High concentration of Yb{sup 3+} is favorable to upconversion luminescence. • The mechanisms are energy transfer, excited state absorption, energy back transfer.

  16. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    Science.gov (United States)

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

  17. Al2O3 doped TiO2 ceramic waste forms

    International Nuclear Information System (INIS)

    Uno, Masayoshi; Kinoshita, Hajime; Sakai, Etsuro; Ikeda, Akira; Matsumoto, Y.; Yamanaka, Shinsuke

    1999-01-01

    Melting of the mixture of Nd 2 O 3 , CeO 2 , SrO, TiO 2 and Al 2 O 3 at 1673 K for 1 hour produced one RE 2 Ti 3 O 9 phase compound. Differential Scanning Calorimetry (DSC) measurement showed that the melting temperature of this compound was 1646 K. Density of the alumina doped oxide was higher than that of the oxide obtained by the pressing and sintering without alumina. Vickers hardness of the oxide obtained by the pressing and sintering was 5.3 GPa and nearly same as that of glass waste. That of the alumina doped oxide was around 7 GPa. 7 days Soxhlet leach test (MCC-5) followed by Inductively Coupled Plasma Spectrometry (ICP) showed that normalized leaching rate of Ti for the oxide obtained by the pressing and sintering was 5.54 x 10 -3 kg/m 2 and that for the alumina doped oxide was 2.24 x 10 -3 kg/m 2 . The value of Sr for the pressed and sintered sample was 0.034 x 10 -3 kg/m 2 but that for alumina doped sample was below the detection limit (0.01 x 10 -3 kg/m 2 ). Al was not detected from the leachate of the alumina doped sample. (author)

  18. Synthesis and Characterization of TiO2(B Nanotubes Prepared by Hydrothermal Method Using [Ti8O12(H2O24]Cl8.HCl.7H2O as Precursor

    Directory of Open Access Journals (Sweden)

    Hari Sutrisno

    2010-04-01

    Full Text Available Low-dimension TiO2-related material has been synthesized by hydrothermal treatment of [Ti8O12(H2O24]Cl8.HCl.7H2O crystal as precursor in a 10 M NaOh aqueous solution at 150 C for 24 h. Characterization of the obtained product was carried out by a range of techniques including X-ray diffraction (XRD, high resolution scanning electron microscopy (HRSEM, high resolution transmission electron microscopy (HRTEM, Raman spectroscopy and nitrogen adsorption-desorption isotherm (Brunauer-Emmett-Teller (BET-Barret-Joyner-Halender (BJH. From HRTEM, XRD and Raman spectra showed that the obtained product has a TiO2(B structure. According to HRTEM observations, it was found that TiO2(B has nanotubular structure with approximately 5-8 nm in outer and 3-6 nm in inner diameter. The BET surface area of TiO2(B nanotubes is quiet large, values of 418.3163 m2/g being obtained. Pore structure analyisis by the BJH method showed that the average pore diameter of TiO2(B nanotubes has 5.5781 nm.

  19. Lithium intercalation in the LiLaNb{sub 2}O{sub 7} perovskite structure; Intercalation du lithium dans la structure perovskite LiLaNb{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Bohnke, C.; Bohnke, O.; Fourquet, J.L. [Universite du Maine, 72 - Le Mans (France). Laboratoire des Fluorures

    1996-12-31

    ABO{sub 3} perovskite-type oxides having vacancies in the A-sites of their structure are interesting candidates for solid electrolytes when their A-sites are occupied by Li{sup +} ions having a high mobility. This is the case with the [Li{sub 3x}La{sub 2/3-x}]TiO{sub 3} solid solution compound which has a 10{sup -3} S cm{sup -1} ionic conductivity at ambient temperature. Electrochemical intercalation in this material is possible thanks to the presence of Ti{sup 4+} but the small amount of vacancies (0.33 maximum) leads to a low intercalation rate. In order to solve this problem, the LiLaNb{sub 2}O{sub 7} material which has a greater amount of vacancies has been studied and the results relative to the electrochemical intercalation of lithium in this perovskite are presented. The thermodynamical and kinetics properties of the lithium intercalation reaction have been studied by intermittent galvano-static discharges and impedance spectroscopy in LiClO{sub 4}-propylene carbonate medium. (J.S.) 7 refs.

  20. Lithium intercalation in the LiLaNb{sub 2}O{sub 7} perovskite structure; Intercalation du lithium dans la structure perovskite LiLaNb{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Bohnke, C; Bohnke, O; Fourquet, J L [Universite du Maine, 72 - Le Mans (France). Laboratoire des Fluorures

    1997-12-31

    ABO{sub 3} perovskite-type oxides having vacancies in the A-sites of their structure are interesting candidates for solid electrolytes when their A-sites are occupied by Li{sup +} ions having a high mobility. This is the case with the [Li{sub 3x}La{sub 2/3-x}]TiO{sub 3} solid solution compound which has a 10{sup -3} S cm{sup -1} ionic conductivity at ambient temperature. Electrochemical intercalation in this material is possible thanks to the presence of Ti{sup 4+} but the small amount of vacancies (0.33 maximum) leads to a low intercalation rate. In order to solve this problem, the LiLaNb{sub 2}O{sub 7} material which has a greater amount of vacancies has been studied and the results relative to the electrochemical intercalation of lithium in this perovskite are presented. The thermodynamical and kinetics properties of the lithium intercalation reaction have been studied by intermittent galvano-static discharges and impedance spectroscopy in LiClO{sub 4}-propylene carbonate medium. (J.S.) 7 refs.

  1. Exposure to TiO2 nanoparticles increases Staphylococcusaureusinfection of HeLa cells

    Science.gov (United States)

    Xu, Yan; Wei, Ming-Tzo; Walker, Stephen. G.; Wang, Hong Zhan; Gondon, Chris; Brink, Peter; Guterman, Shoshana; Zawacki, Emma; Applebaum, Eliana; Rafailovich, Miriam; Ou-Yang, H. Daniel; Mironava, Tatsiana

    TiO2 is one of the most common nanoparticles in industry from food additives to energy generation. Even though TiO2 is also used as an anti-bacterial agent in combination with UV, we found that, in the absence of UV, exposure of HeLa cells to TiO2 nanoparticles largely increased their risk of bacterial invasion. HeLa cells cultured with low dosage rutile and anatase TiO2 nanoparticles (0.1 mg/ml) for 24 hrs prior to exposure to bacteria had 350% and 250% respectively more bacteria infected per cell. The increase was attributed to increased LDH leakage, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO2 particles ingested 40% fewer bacteria, further increasing the risk of infection. In combination, these two factors raise serious concerns regarding the impact of exposure to TiO2 nanoparticles on the ability of organisms to resist bacterial infection.

  2. Hydrogen-permeable TiO{sub 2}/SiO{sub 2} membranes formed by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Heung Yong; Nam, Suk Woo; Yoon, Sung Pil [Korea Institute of Science and Technology, Seoul (Korea, Republic of)] [and others

    1994-12-31

    Thin films of TiO{sub 2}/SiO{sub 2} were deposited on the inner surface of the porous support tubes by the decomposition of tetraisopropyl titanate (TIPT) and tetraethyl orthosilicate (TEOS) at atmospheric pressure. Dense and hydrogen-permeable membranes were formed at 400-600{degrees}C. The permeation rate of H{sub 2} through the membrane at 600{degrees}C was about 0.3 cm{sup 3}(STP)/min-cm{sup 2}-atm and H{sub 2}/N{sub 2} permeation ratio was above 1000. The permeation properties of the membranes were investigated at various deposition temperatures and TIPT/TEOS concentrations. Decomposition of TIPT alone at temperatures above 400{degrees}C produced porous crystalline TiO{sub 2} films which were not H{sub 2}-selective. Decomposition of TEOS, however produced H{sub 2}-permeable SiO{sub 2} films at 400-600{degrees}C but film deposition rate was very low. Addition of TIPT to the TEOS stream significantly accelerated the deposition rate and produced highly H{sub 2}-selective films. Increasing the TEPT/TEOS ratios increased the deposition rate. The TiO{sub 2}/SiO{sub 2} membranes have the permeation properties comparable to those of SiO{sub 2} membranes. The TiO{sub 2}/SiO{sub 2} membranes were stable and did not show significant densification during the treatment at high temperature.

  3. Ion-irradiation resistance of the orthorhombic Ln_2TiO_5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) series

    International Nuclear Information System (INIS)

    Aughterson, Robert D.; Lumpkin, Gregory R.; Ionescu, Mihail; Reyes, Massey de los; Gault, Baptiste; Whittle, Karl R.; Smith, Katherine L.; Cairney, Julie M.

    2015-01-01

    The response of Ln_2TiO_5 (where Ln is a lanthanide) compounds exposed to high-energy ions was used to test their suitability for nuclear-based applications, under two different but complementary conditions. Eight samples with nominal stoichiometry Ln_2TiO_5 (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy), of orthorhombic (Pnma) structure were irradiated, at various temperatures, with 1 MeV Kr"2"+ ions in-situ within a transmission electron microscope. In each case, the fluence was increased until a phase transition from crystalline to amorphous was observed, termed critical dose D_c. At certain elevated temperatures, the crystallinity was maintained irrespective of fluence. The critical temperature for maintaining crystallinity, T_c, varied non-uniformly across the series. The T_c was consistently high for La, Pr, Nd and Sm_2TiO_5 before sequential improvement from Eu to Dy_2TiO_5 with T_c's dropping from 974 K to 712 K. In addition, bulk Dy_2TiO_5 was irradiated with 12 MeV Au"+ ions at 300 K, 723 K and 823 K and monitored via grazing-incidence X-ray diffraction (GIXRD). At 300 K, only amorphisation is observed, with no transition to other structures, whilst at higher temperatures, specimens retained their original structure. The improved radiation tolerance of compounds containing smaller lanthanides has previously been attributed to their ability to form radiation-induced phase transitions. No such transitions were observed here. - Highlights: • First ion-irradiation studies on a number of novel compounds including Pr_2TiO_5, Eu_2TiO_5 and Tb_2TiO_5. • Systematic in-situ ion-irradiation study of almost complete Ln_2TiO_5 series (Ln = lanthanides) with orthorhombic crystal structure type. • The first grazing incidence study of bulk irradiated Dy_2TiO_5 looking for irradiation induced phase transition.

  4. Mechanical Properties of Layered La2Zr2O7 Thermal Barrier Coatings

    Science.gov (United States)

    Guo, Xingye; Li, Li; Park, Hyeon-Myeong; Knapp, James; Jung, Yeon-Gil; Zhang, Jing

    2018-04-01

    Lanthanum zirconate (La2Zr2O7) has been proposed as a promising thermal barrier coating (TBC) material due to its low thermal conductivity and high stability at high temperatures. In this work, both single and double-ceramic-layer (DCL) TBC systems of La2Zr2O7 and 8 wt.% yttria-stabilized zirconia (8YSZ) were prepared using air plasma spray (APS) technique. The thermomechanical properties and microstructure were investigated. Thermal gradient mechanical fatigue (TGMF) tests were applied to investigate the thermal cycling performance. The results showed that DCL La2Zr2O7 + 8YSZ TBC samples lasted fewer cycles compared with single-layered 8YSZ TBC samples in TGMF tests. This is because DCL La2Zr2O7 TBC samples had higher residual stress during the thermal cycling process, and their fracture toughness was lower than that of 8YSZ. Bond strength test results showed that 8YSZ TBC samples had higher bond strength compared with La2Zr2O7. The erosion rate of La2Zr2O7 TBC samples was higher than that of 8YSZ samples, due to the lower critical erodent velocity and fracture toughness of La2Zr2O7. DCL porous 8YSZ + La2Zr2O7 had a lower erosion rate than other SCL and DCL La2Zr2O7 coatings, suggesting that porous 8YSZ serves as a stress-relief buffer layer.

  5. Preparation and characterization of La/sub 2/TiMnO/sub 6/

    Energy Technology Data Exchange (ETDEWEB)

    Ramanujachary, K V; Swamy, C S [Indian Inst. of Tech., Madras. Dept. of Chemistry

    1981-01-01

    The compound La/sub 2/TiMnO/sub 6/ has been prepared by solid state reaction of the component ions in suitable form. X-ray analysis shows it to be orthorhombic and the cell constants are a = 5.506 A, b = 5.950 A and c = 7.636 A. It is found to be essentially a p-type semiconductor with ..cap alpha.. = 150 ..mu..VKsup(-1). Weiss constant has a value -88K and it shows IR bands at 400-450 and 575-600 cmsup(-1) characteristic of ..nu../sub 3/ and ..nu../sub 4/ modes of the Tisup(4+) O/sub 6/ octahedra.

  6. Dielectric measurements of magnetic monopoles on the spin-ice compounds (Ho/Dy){sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Pietsch, Manuel; Grams, Christoph P.; Welter, Jean-Francois; Cho, Victoria; Lorenz, Thomas; Hemberger, Joachim [II. Physikalisches Institut, Universitaet zu Koeln, Cologne (Germany)

    2015-07-01

    In so-called spin-ice compounds a frustrated ground-state with finite zero-point entropy is stabilized via competing interactions and emergent magnetic monopoles excitations. It was postulated that a magnetic monopole holds an electric dipole moment, which allows to investigate their dynamics via the dielectric function ε(ν). In Dy{sub 2}Ti{sub 2}O{sub 7} a critical speeding-up for frequencies up to 100 kHz was reported down to temperatures of 200 mK with a specific focus on the critical endpoint present for a [111] magnetic field. In Ho{sub 2}Ti{sub 2}O{sub 7} both faster relaxation dynamics compared to the sister-compound and an additional relaxation process are suspected. Here we report on broadband dielectric spectroscopy measurements of ε(ν) in Ho{sub 2}Ti{sub 2}O{sub 7}.

  7. 钛酸酯偶联剂对包硅铝钛白粉表面的有机改性%Surface Organic Modification of SiO2 & Al2O3 Coated TiO2 Particles with Titanate Coupling Reagent

    Institute of Scientific and Technical Information of China (English)

    林玉兰; 王亭杰; 覃操; 金涌

    2001-01-01

    The surface organic modification of TiO2 particles with titanate coupling reagent,which was pre-coated with double layers of SiO2 and Al2O3,was studied.Experiments showed that the modified particles exhibited hydrophobic characteristics.The modification state of the particle surface was characterized by IR spectroscopic measurement,pyrolytic gas chromatography,thermogravimetric analysis and X-ray photoelectron spectra.The titanate coupling reagent binding with the hydroxyl on the particle surface was analyzed.The surface characteristics of pre-modification and post-modification particles were compared.

  8. Preparation of Li4Ti5O12 by solution ion-exchange of sodium titanate nanotube and evaluation of electrochemical performance

    International Nuclear Information System (INIS)

    Zhang, Jingwei; Zhang, Fenli; Li, Jiuhe; Cai, Wei; Zhang, Jiwei; Yu, Laigui; Jin, Zhensheng; Zhang, Zhijun

    2013-01-01

    Nano-sized spinel lithium titanate (Li 4 Ti 5 O 12 ) was synthesized using sodium titanate nanotube as precursor via a facile solution ion-exchange method in association with subsequent calcination treatment at relatively low temperature. The influences of precursors, ion-exchange condition, and calcination temperature on the microstructure and electrochemical performance of the products were studied. Results indicate that pure-phase Li 4 Ti 5 O 12 can be harvested from sodium titanate nanotube precursor through an ion-exchanging at room temperature and calcination at 500 °C. The products exhibit a better performance as Li-ion battery anode material than the counterparts prepared from protonic titanate nanotube (H-titanate) precursor. The reason may lie in that sodium titanate nanotube is easier than protonic titanate nanotube to synthesize lithium titanate without TiO 2 impurity, resulting in reduced electron transfer ability and Li-ion transport ability. The capacity of Li 4 Ti 5 O 12 prepared from sodium titanate nanotube is 146 mAh/g at 10 C, and it has only 0.7 % decay after 200 charge/discharge cycles

  9. Multi-modal TiO2-LaFeO3 composite films with high photocatalytic activity and hydrophilicity

    International Nuclear Information System (INIS)

    Gao Kun; Li Shudan

    2012-01-01

    In this paper, a series of multi-modal TiO 2 -LaFeO 3 composite films have been successfully synthesized through a two-step method. The resultant films were characterized in detail by several testing techniques, such as X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectrum (UV-vis DRS), photoluminescence spectrum (PL), surface photovoltage spectroscopy (SPS) and water contact angle measurements. The photocatalytic activity of different films was evaluated for degrading Methylene Blue (MB) aqueous solution. Hydrophilicity of the obtained TiO 2 -LaFeO 3 composite films was also investigated. The results show that TL film and LT film exhibited superior photocatalytic activity and hydrophilicity.

  10. Growth and Dielectric Properties of Ta-Doped La2Ti2O7 Single Crystals

    Directory of Open Access Journals (Sweden)

    Hui Wang

    2018-02-01

    Full Text Available High-quality Ta-doped La2Ti2O7 (Ta-LTO single crystal of about 40 mm in length and 5 mm in diameter was successfully prepared by the optical floating zone method. An X-ray rocking curve reveals that the crystal of LTO has excellent crystalline quality. As-grown crystals were transparent after annealing in air and the transmittance is up to 76% in the visible and near-infrared region. X-ray diffraction showed that this compound possessed a monoclinic structure with P21 space group. The dielectric properties were investigated as functions of temperature (0~300 °C and frequency (102 Hz~105 Hz. Dielectric spectra indicated an increase in the room-temperature dielectric constant accompanied by a drop in the loss tangent as a result of the Ta doping. One relaxation was observed in the spectra of electric modulus, which was ascribed to be related to the oxygen vacancy. The dielectric relaxation with activation energy of 1.16 eV is found to be the polaron hopping caused by the oxygen vacancies.

  11. Ti-catalyzed HfSiO4 formation in HfTiO4 films on SiO2 studied by Z-contrast scanning electron microscopy

    Directory of Open Access Journals (Sweden)

    Elizabeth Ellen Hoppe

    2013-08-01

    Full Text Available Hafnon (HfSiO4 as it is initially formed in a partially demixed film of hafnium titanate (HfTiO4 on fused SiO2 is studied by atomic number (Z contrast high resolution scanning electron microscopy, x-ray diffraction, and Raman spectroscopy and microscopy. The results show exsoluted Ti is the catalyst for hafnon formation by a two-step reaction. Ti first reacts with SiO2 to produce a glassy Ti-silicate. Ti is then replaced by Hf in the silicate to produce HfSiO4. The results suggest this behavior is prototypical of other Ti-bearing ternary or higher order oxide films on SiO2 when film thermal instability involves Ti exsolution.

  12. Surface resistance of YBa2Cu3O7 films deposited on LaGaO3 substrates

    International Nuclear Information System (INIS)

    Cooke, D.W.; Gray, E.R.; Houlton, R.J.; Javadi, H.H.S.; Maez, M.A.; Bennett, B.L.; Rusnak, B.; Meyer, E.A.; Arendt, P.N.; Beery, J.G.; Brown, D.R.; Garzon, F.H.; Raistriek, I.D.; Bolmaro, B.; Elliott, N.E.; Rollett, A.D.; Klein, N.; Muller, G.; Orbach, S.; Piel, H.; Josefowicz, J.Y.; Rensch, O.B.; Drabeck, L.; Gruner, G.

    1989-01-01

    Superconducting films of YBa 2 Cu 3 O 7 deposited onto LaGaO 3 substrates were prepared by e-beam and magnetron sputtering techniques. Surface resistance measurements made at 22 GHz, 86 GHz, and 148 GHz show that these films are superior to those deposited by similar techniques onto SrTiO 3 . Typical surface resistance values measured at 22 GHz and 12 K are ∼2 m(cgom) with the lowest value being 0.2 m(cgom), which is only 2 to 4 times higher than Nb. The surface resistance is proportional to the square of the measuring frequency

  13. Optical Properties and Photoactivity of The Pigmentary TiO2 Doped with P2O5, K2O, Al2O3 and Sb2O3

    International Nuclear Information System (INIS)

    Glen, M; Grzmil, B

    2011-01-01

    The influence of the increasing content of antimony calculated to Sb 2 O 3 (0.08-0.57 mol%) with the constant amount of the other additives (calculated to P 2 O 5 , K 2 O, Al 2 O 3 ) on the optical properties and photostability of doped rutile has been investigated. The properties of the obtained TiO 2 -PKAlSb samples were compared to the commercial TiO 2 -PKAl composition. The starting material was the concentrated suspension of technical-grade hydrated titanium dioxide (HTD). The dopant agents' solutions were introduced to HTD. Prepared samples were calcined with gradually increasing process temperature. The XRD analysis was used to determine the rutile content in the TiO 2 samples. Optical properties of modified titanium dioxide have been determined spectrophotometrically by measuring the colour in the white (brightness, white tone) and grey system (relative lightening power, grey tone). Photostability was characterized by the white lead-glycerin test with UV-Vis light. It was observed that with the increasing content of antimony in rutile TiO 2 , doped with phosphates, potassium and aluminium, the brightness and grey tone were increasing but white tone decreased. The changes of the relative lightening power values were insignificant. Comparing the samples of TiO 2 -PKAlSb with the TiO 2 -PKAl composition it was observed that titanium dioxide doped with antimony had better white and grey tone. The increasing Sb 2 O 3 content in the TiO 2 caused the improvement of the photostability.

  14. 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.

  15. Lanthanide stannate pyrochlores (Ln2Sn2O7; Ln  =  Nd, Gd, Er) at high pressure

    Science.gov (United States)

    Turner, Katlyn M.; Tracy, Cameron L.; Mao, Wendy L.; Ewing, Rodney C.

    2017-12-01

    Lanthanide stannate pyrochlores (Ln2Sn2O7; Ln  =  Nd, Gd, and Er) were investigated in situ to 50 GPa in order to determine their structural response to compression and compare their response to that of lanthanide titanate, zirconate, and hafnate pyrochlores. The cation radius ratio of A3+/B4+ in pyrochlore oxides (A2B2O7) is thought to be the dominant feature that influences their response on compression. The ionic radius of Sn4+ is intermediate to that of Ti4+, Zr4+, and Hf4+, but the 〈Sn-O〉 bond in stannate pyrochlore is more covalent than the 〈B-O〉 bonds in titanates, zirconate, and hafnates. In stannates, based on in situ Raman spectroscopy, pyrochlore cation and anion sublattices begin to disorder with the onset of compression, first measured at 0.3 GPa. The extent of sublattice disorder versus pressure is greater in stannates with a smaller Ln3+ cation. Stannate pyrochlores (Fd-3m) begin a sluggish transformation to an orthorhombic, cotunnite-like structure at ~28 GPa similar transitions have been observed in titanate, zirconate, and hafnate pyrochlores at varying pressures (18-40 GPa) with cation radius ratio. The extent of the phase transition versus pressure varies directly with the size of the Ln3+ cation. Post-decompression from ~50 GPa, Er2Sn2O7 and Gd2Sn2O7 adopt a pyrochlore structure, rather than the multi-scale defect-fluorite  +  weberite-type structure adopted by Nd2Sn2O7 that is characteristic of titanate, zirconate, and hafnate pyrochlores under similar conditions. Like pyrochlore titanates, zirconates, and hafnates, the bulk modulus, B 0, of stannates varies linearly and inversely with cation radius ratio from 1 1 1 GPa (Nd2Sn2O7) to 251 GPa (Er2Sn2O7). The trends of bulk moduli in stannates in this study are in excellent agreement with previous experimental studies on stannates and suggest that the size of the Ln3+ cation is the primary determining factor of B 0. Additionally, when normalized to r A

  16. Highly efficient removal of chlorotetracycline from aqueous solution using graphene oxide/TiO2 composite: Properties and mechanism

    Science.gov (United States)

    Li, Zhaoqian; Qi, Mengyu; Tu, Chunyan; Wang, Weiping; Chen, Jianrong; Wang, Ai-Jun

    2017-12-01

    The extensive usage of chlorotetracycline (CTC) has caused the persistence of antibiotic residues in aquatic environments, resulting in serious threat to human health and ecosystems. In this study, graphene oxide/titanium dioxide (GO/TiO2) nanocomposite was successfully synthesized via in situ hydrolysis of tetra-n-butyl titanate (Ti(BuO)4) to TiO2 particles on GO sheets and used as adsorbent for efficient adsorptive removal of CTC from aqueous solution. The prepared GO/TiO2 was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), Raman spectroscopy and X-ray photoelectron (XPS). Adsorption kinetics, isotherms and thermodynamics were systematically investigated to evaluate the adsorption properties of GO/TiO2. Adsorption mechanism was further analyzed by FT-IR, UV-vis and XPS. The results indicated that adsorption kinetics closely followed the pseudo-second order model; the maximum adsorption capacity determined by Langmuir model was 261.10 mg g-1 at 298 K and the thermodynamic studies revealed that the adsorption of CTC onto the GO/TiO2 was a spontaneous and endothermic process. Moreover, the interactions between CTC and GO/TiO2 were presumed to be ligand exchange between CTC and TiO2, while the π-π electron donor-acceptor interaction, hydrogen bond and cation-π bonding were constructed between CTC and GO. Finally, the prepared GO/TiO2 was successfully applied for the efficient removal of CTC from Wu River water.

  17. LaNiO3 buffer layers for high critical current density YBa2Cu3O7-δ and Tl2Ba2CaCu2O8-δ films

    International Nuclear Information System (INIS)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-01-01

    We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5 K, H=0) than films grown directly on a bare LaAlO 3 substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. copyright 1999 American Institute of Physics

  18. LaNiO3 Buffer Layers for High Critical Current Density YBa2Cu3O7δ and Tl2Ba2CaCu2O8δ Films

    International Nuclear Information System (INIS)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-01-01

    We demonstrate high critical current density superconducting films of YBa 2 Cu 3 O 7-δ (YBCO) and Tl 2 Ba 2 CaCu 2 O 8-δ (Tl-2212) using LaNiO 3 (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J c (5K, H=0) than films grown directly on a bare LaAlO 3 substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J c at all temperatures and fields compared to those grown on bare LaAlO 3 , correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications

  19. Thermo-selective Tm(x)Ti(1-x)O(2-x/2) nanoparticles: from Tm-doped anatase TiO2 to a rutile/pyrochlore Tm2Ti2O7 mixture. An experimental and theoretical study with a photocatalytic application.

    Science.gov (United States)

    Navas, Javier; Sánchez-Coronilla, Antonio; Aguilar, Teresa; De los Santos, Desireé M; Hernández, Norge C; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín

    2014-11-07

    This is an experimental and theoretical study of thulium doped TiO2 nanoparticles. From an experimental perspective, a method was used to synthesize thulium-doped TiO2 nanoparticles in which Tm(3+) replaces Ti(4+) in the lattice, which to our knowledge has neither been reported nor studied theoretically so far. Different proportions of anatase and rutile phases were obtained at different annealing temperatures, and XRD and Raman spectroscopy also revealed the presence of a pyrochlore phase (Tm2Ti2O7) at 1173 K. Thus, the structure of the Tm-doped nanoparticles was thermally-controlled. Furthermore, XPS showed the presence of Tm(3+) in the samples synthesized, which produces oxygen vacancies to maintain the local neutrality in the lattice. The presence of Tm(3+) in the samples led to changes in the UV-Vis absorption spectra, so they showed photoluminescence properties and new states in the band gap, which produce a new lower energy electronic transition than the main TiO2 one. Periodic DFT calculations were performed to understand the experimentally produced structures. The production of oxygen vacancies was analysed and the changes generated in the structure were fully detailed. The DOS and PDOS analyses confirmed the experimental results obtained using UV-Vis spectroscopy, and showed that the new electronic states in the band gap are due to interactions of the f state of Tm and the p state of O. Likewise, the charge study and the ELF analysis indicate that when Tm is introduced into the TiO2 structure, the Ti-O bond around the oxygen vacancy is strengthened. Finally, an example of a photocatalytic application was developed to show the high efficiency of the samples due to the heterojunction in the interfaces of the phases in the samples, which improved the charge separation and the good charge carrier mobility due to the presence of the pyrochlore phase, as was also shown theoretically.

  20. Pressure and temperature phase diagram of Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Catillon, G. [Université Paris-Est, G2I, EA4119, 5 Blvd. Descartes, F-77454 Marne la Vallée Cedex 2 (France); Chartier, A., E-mail: alain.chartier@cea.fr [CEA, DEN, DMN, SCCME, F-91191 Gif-Sur-Yvette Cedex (France)

    2014-11-21

    The pressure and temperature phase diagram of Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation are calculated by means of molecular dynamics calculations. The critical temperature for amorphization obeys a linear law with pressure. Gd{sub 2}Ti{sub 2}O{sub 7} under irradiation transits towards the fluorite above this temperature and amorphizes below. The configuration of the Ti interstitial reveals to be the key of the amorphizability of Gd{sub 2}Ti{sub 2}O{sub 7}. Its stability depends upon disorder and pressure. Low pressure promotes the stabilization of Ti linked-polyhedra that drive the system to the amorphous state under irradiation. Conversely, high pressure activates its destabilization to interstitials that recombine with vacancies, driving the system to the fluorite structure under irradiation.

  1. Characterization, integration and reliability of HfO2 and LaLuO3 high-κ/metal gate stacks for CMOS applications

    International Nuclear Information System (INIS)

    Nichau, Alexander

    2013-01-01

    The continued downscaling of MOSFET dimensions requires an equivalent oxide thickness (EOT) of the gate stack below 1 nm. An EOT below 1.4 nm is hereby enabled by the use of high-κ/metal gate stacks. LaLuO 3 and HfO 2 are investigated as two different high-κ oxides on silicon in conjunction with TiN as the metal electrode. LaLuO 3 and its temperature-dependent silicate formation are characterized by hard X-ray photoemission spectroscopy (HAXPES). The effective attenuation length of LaLuO 3 is determined between 7 and 13 keV to enable future interface and diffusion studies. In a first investigation of LaLuO 3 on germanium, germanate formation is shown. LaLuO 3 is further integrated in a high-temperature MOSFET process flow with varying thermal treatment. The devices feature drive currents up to 70μA/μm at 1μm gate length. Several optimization steps are presented. The effective device mobility is related to silicate formation and thermal budget. At high temperature the silicate formation leads to mobility degradation due to La-rich silicate formation. The integration of LaLuO 3 in high-T processes delicately connects with the optimization of the TiN metal electrode. Hereby, stoichiometric TiN yields the best results in terms of thermal stability with respect to Si-capping and high-κ oxide. Different approaches are presented for a further EOT reduction with LaLuO 3 and HfO 2 . Thereby the thermodynamic and kinetic predictions are employed to estimate the behavior on the nanoscale. Based on thermodynamics, excess oxygen in the gate stack, especially in oxidized metal electrodes, is identified to prevent EOT scaling below 1.2 nm. The equivalent oxide thickness of HfO 2 gate stacks is scalable below 1 nm by the use of thinned interfacial SiO 2 . The prevention of oxygen incorporation into the metal electrode by Si-capping maintains the EOT after high temperature annealing. Redox systems are employed within the gate electrode to decrease the EOT of HfO 2 gate stacks

  2. Effect of Ce Doping on RGO-TiO2 Nanocomposite for High Photoelectrocatalytic Behavior

    Directory of Open Access Journals (Sweden)

    Md. Rakibul Hasan

    2014-01-01

    Full Text Available Ce doped RGO-TiO2 composite films on ITO substrates were prepared by sol-gel process using tetrabutyl titanate and reduced graphene oxide (RGO as the starting materials. The sample was designed for the photoelectrocatalytic applications. The obtained samples were characterized by X-ray diffraction, UV-vis absorption spectroscopy, scanning electron microscopy, and Fourier transformed infrared spectroscopy. The results showed that doping of Ce on RGO-TiO2 composite film inhibited the TiO2 anatase-rutile phase transformation. In this case, Ce atoms could serve as dispersion oxide and suppress the recombination of photoinduced electron-hole pairs. Besides, the change in absorbance from UV to visible region was observed in Ce doped RGO-TiO2 nanocomposite films. The Ce doped RGO-TiO2 composite film showed higher photoelectrochemical performance than that of RGO-TiO2 composite and pure TiO2 under solar simulator irradiation. The main reason might be attributed to the optimum content of Ce that could act as electrons acceptor to hinder the recombination loss and facilitate the better transportation for photoinduced charge carriers.

  3. Low Fatigue in Epitaxial Pb(Zr0.2Ti0.8)O3 on Si Substrates with LaNiO3 Electrodes by RF Sputtering

    Science.gov (United States)

    Wang, Chun; Kryder, Mark H.

    2009-09-01

    Epitaxial PZT (001) thin films with a LaNiO3 bottom electrode were deposited by radio-frequency (RF) sputtering onto Si(001) single-crystal substrates with SrTiO3/TiN buffer layers. Pb(Zr0.2Ti0.8)O3 (PZT) samples were shown to consist of a single perovskite phase and to have an (001) orientation. The orientation relationship was determined to be PZT(001)[110]∥LaNiO3(001)[110]∥SrTiO3 (001)[110]∥TiN(001)[110]∥Si(001)[110]. Atomic force microscope (AFM) measurements showed the PZT films to have smooth surfaces with a roughness of 1.15 nm. The microstructure of the multilayer was studied using transmission electron microscopy (TEM). Electrical measurements were conducted using both Pt and LaNiO3 as top electrodes. The measured remanent polarization P r and coercive field E c of the PZT thin film with Pt top electrodes were 23 μC/cm2 and 75 kV/cm, and were 25 μC/cm2 and 60 kV/cm for the PZT film with LaNiO3 top electrodes. No obvious fatigue after 1010 switching cycles indicated good electrical endurance of the PZT films using LaNiO3 electrodes, compared with the PZT film with Pt top electrodes showing a significant polarization loss after 108 cycles. These PZT films with LaNiO3 electrodes could be potential recording media for probe-based high-density data storage.

  4. Research Update: Enhanced energy storage density and energy efficiency of epitaxial Pb0.9La0.1(Zr0.52Ti0.48O3 relaxor-ferroelectric thin-films deposited on silicon by pulsed laser deposition

    Directory of Open Access Journals (Sweden)

    Minh D. Nguyen

    2016-08-01

    Full Text Available Pb0.9La0.1(Zr0.52Ti0.48O3 (PLZT relaxor-ferroelectric thin films were grown on SrRuO3/SrTiO3/Si substrates by pulsed laser deposition. A large recoverable storage density (Ureco of 13.7 J/cm3 together with a high energy efficiency (η of 88.2% under an applied electric field of 1000 kV/cm and at 1 kHz frequency was obtained in 300-nm-thick epitaxial PLZT thin films. These high values are due to the slim and asymmetric hysteresis loop when compared to the values in the reference undoped epitaxial lead zirconate titanate Pb(Zr0.52Ti0.48O3 ferroelectric thin films (Ureco = 9.2 J/cm3 and η = 56.4% which have a high remanent polarization and a small shift in the hysteresis loop, under the same electric field.

  5. High temperature crystallographic and thermodynamic investigations on synthetic calzirtite (Ca2Zr5Ti2O16)

    International Nuclear Information System (INIS)

    Jafar, M.; Phapale, S.; Achary, S.N.; Mishra, R.; Tyagi, A.K.

    2016-01-01

    Immobilization of actinides in the high level waste (HLW) produced from nuclear reactors in durable host matrix is one of the important concerns in nuclear power technology. Rock analogue (SYNROC) ceramic composites of titanates and zirconates namely zirconolite, calzirtite etc. have been proposed as alternate host matrix for disposal of long lived fission products. These minerals have ability to incorporate or immobilize a wider variety of ions simultaneously without further segregation to any other phases and are stable in geothermal conditions. Knowledge of thermodynamic stability of these minerals is important for their deployment as host matrix for actinide waste disposal. In this work crystal structure and thermodynamic parameters of a mineral analogous titanate termed as calzirtite (Ca 2 Zr 5 Ti 2 O 16 ) has been determined

  6. Synthesis and characterization of a-site doped LaTiO3 nano perovskites

    International Nuclear Information System (INIS)

    Bradha, M.; Ashok, Anuradha

    2013-01-01

    Nano-sized lanthanum titanate perovskites (La (1-x) A x TiO 3 ) (A= Ba, Sr, Ca) were prepared by sol-gel method and calcined at 800℃. The synthesised perovskites were characterized by Thermogravimetry/ Differential thermal analysis (TGA/DTA), X-ray diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM) etc. LaTiO 3 is a perovskite having prominent interest for a variety of applications such as dielectric, insulators, charge-transport properties etc. It is a defect perovskite, with transport properties varying from insulating to metallic based on oxygen stoichiometry. In a quest to observe the effect of the nano size on its properties, lanthanum titanate (LaTiO 3 ) nano perovskites with different dopants on the A-site were prepared by using sol-gel method. In the present work we discuss the synthesis and structural analysis of (La 0.8 A 0.2 TiO 3 ). Phase purity and structural analysis of the calcined samples were performed by powder X-ray diffraction (XRD, with CuKα radiation). In addition to this, morphology and crystal structure was examined by Transmission Electron Microscopy (TEM) using a JEOL JEM 2100 HRTEM. HRTEM studies indicate that the nano perovskites are of size around 20 nm. Ring pattern in SAED also confirms that the perovskite is polycrystalline/nanocrystalline. More detailed study on high resolution images and crystal structure shed light on the reason for the properties exhibited by this perovskites

  7. Collinear Order in Frustrated Quantum Antiferromagnet on Square Lattice (CuBr)LaNb2O7

    Science.gov (United States)

    Oba, Noriaki; Kageyama, Hiroshi; Kitano, Taro; Yasuda, Jun; Baba, Yoichi; Nishi, Masakazu; Hirota, Kazuma; Narumi, Yasuo; Hagiwara, Masayuki; Kindo, Koichi; Saito, Takashi; Ajiro, Yoshitami; Yoshimura, Kazuyoshi

    2006-11-01

    Magnetic susceptibility, heat capacity, high-field magnetization and neutron diffraction measurements have been performed on a two-dimensional S = 1/2 square-lattice system (CuBr)LaNb2O7, prepared by a topotactic ion-exchange reaction of a nonmagnetic double-layered perovskite RbLaNb2O7. (CuBr)LaNb2O7 exhibits a second-order magnetic transition at 32 K, in marked contrast to a spin-singlet nature for its Cl-based counterpart (CuCl)LaNb2O7, despite nearly identical structural parameters. The magnetic structure is a novel collinear antiferromagnetic (CAF) ordering characterized by a modulation vector q = (π, 0, π) with a reduced moment of 0.6μB. Mixed ferromagnetic nearest-neighbor (J1) and antiferromagnetic second-nearest-neighbor (J2) interactions are of comparable strength (J1/kB = -35.6 K and J2/kB = 41.3 K), placing the system in a more frustrated region of the CAF phase than ever reported.

  8. Competing magnetic fluctuations in Sr3Ru2O7 probed by Ti doping

    DEFF Research Database (Denmark)

    Hooper, J.; Fang, M.H.; Zhou, M.

    2007-01-01

    We report the effect of nonmagnetic Ti4+ impurities on the electronic and magnetic properties of Sr3Ru2O7. Small amounts of Ti suppress the characteristic peak in magnetic susceptibility near 16 K and result in a sharp upturn in specific heat. The metamagnetic quantum phase transition and related...... anomalous features are quickly smeared out by small amounts of Ti. These results provide strong evidence for the existence of competing magnetic fluctuations in the ground state of Sr3Ru2O7. Ti doping suppresses the low-temperature antiferromagnetic interactions that arise from Fermi surface nesting...

  9. High T/sub c/ screen-printed YBa2Cu3O/sub 7-//sub x/ films: Effect of the substrate material

    International Nuclear Information System (INIS)

    Bansal, N.P.; Simons, R.N.; Farrell, D.E.

    1988-01-01

    Thick films of YBa 2 Cu 3 O/sub 7-//sub x/ have been deposited on highly polished alumina, magnesia spinel, nickel aluminum titanate (Ni-Al-Ti), and barium tetratitanate (Ba-Ti) substrates by the screen printing technique. They were baked at 1000 0 C for 15 min, oxygen annealed at a lower temperature, and characterized by electrical resistivity measurements, x-ray diffraction, and optical and scanning electron microscopy. Properties of the films were found to be highly sensitive to the choice of the substrate material. The film on Ba-Ti turned green after firing, due to a reaction with the substrate and were insulating. A film on Ni-Al-Ti had a T/sub c/ (onset) ∼95 K and lost 90% of its resistance by ∼75 K. However, even at 4 K it was not fully superconducting, possibly due to a reaction between the film and the substrate and interdiffusion of the reaction products. The film on alumina had T/sub c/ (onset) ∼96 K, T/sub c/ (zero) ∼66 K, and ΔT/sub c/ (10--90%) ∼10 K. Our best film was obtained on spinel and had T/sub c/ (onset) ∼94 K, zero resistance at 81 K, and a transition width (10--90%) of ∼7 K

  10. High rate capacity nanocomposite lanthanum oxide coated lithium zinc titanate anode for rechargeable lithium-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Haoqing, E-mail: tanghaoqing@tju.edu.cn [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zan, Lingxing [Institute of Physical and Theoretical Chemistry, University of Bonn, Bonn 53117 (Germany); Zhu, Jiangtao; Ma, Yiheng [Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Zhao, Naiqin [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tang, Zhiyuan, E-mail: zytang46@163.com [Department of Applied Chemistry, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2016-05-15

    Lithium zinc titanate (Li{sub 2}ZnTi{sub 3}O{sub 8}) is an important titanium material of promising candidates for anode materials with superior electrochemical performance and thus has attracted extensive attention. Herein, high capacity, stable Li{sub 2}ZnTi{sub 3}O{sub 8}/La{sub 2}O{sub 3} nanocomposite for lithium-ion battery anode is prepared by a facile strategy. Compared to unmodified Li{sub 2}ZnTi{sub 3}O{sub 8}, the Li{sub 2}ZnTi{sub 3}O{sub 8}/La{sub 2}O{sub 3} electrode display a high specific capacity of 188.6 mAh g{sup −1} and remain as high as 147.7 mAh g{sup −1} after 100 cycles at 2.0 A g{sup −1}. Moreover, a reversible capacity of 76.3 mAh g{sup −1} can be obtained after 1000 cycles at 2.0 A g{sup −1} and the retention is 42.7% for Li{sub 2}ZnTi{sub 3}O{sub 8}/La{sub 2}O{sub 3}, which is much higher than un-coated Li{sub 2}ZnTi{sub 3}O{sub 8}. The superior lithium storage performances of the Li{sub 2}ZnTi{sub 3}O{sub 8}/La{sub 2}O{sub 3} can be ascribed to the stable layer of protection, small particle size and large surface area. Cyclic voltammograms result reveals that the La{sub 2}O{sub 3} coating layer reduces the polarization and improves the electrochemical activity of anode. - Highlights: • Nano layer La{sub 2}O{sub 3} coated Li{sub 2}ZnTi{sub 3}O{sub 8} particles have been prepared via a suspension mixing process followed by heat treatment. • Coated Li{sub 2}ZnTi{sub 3}O{sub 8} has enhanced high rate capability, cyclic stability and long lifespan performance. • Electrochemical properties were tested in a charge/discharge voltage range of 3.0–0.05 V (vs. Li/Li{sup +}).

  11. New theory of effective work functions at metal/high-k dielectric interfaces : application to metal/high-k HfO2 and la2O 3 dielectric interfaces

    OpenAIRE

    Shiraishi, Kenji; Nakayama, Takashi; Akasaka, Yasushi; Miyazaki, Seiichi; Nakaoka, Takashi; Ohmori, Kenji; Ahmet, Parhat; Torii, Kazuyoshi; Watanabe, Heiji; Chikyow, Toyohiro; Nara, Yasuo; Iwai, Hiroshi; Yamada, Keisaku

    2006-01-01

    We have constructed a universal theory of the work functions at metal/high-k HfO2 and La2O3 dielectric interfaces by introducing a new concept of generalized charge neutrality levels. Our theory systematically reproduces the experimentally observed work functions of various gate metals on Hf-based high-k dielectrics, including the hitherto unpredictable behaviors of the work functions of p-metals. Our new concept provides effective guiding principles to achieving near-bandedge work functions ...

  12. Carbon and TiO_2 synergistic effect on methylene blue adsorption

    International Nuclear Information System (INIS)

    Simonetti, Evelyn Alves Nunes; Simone Cividanes, Luciana de; Campos, Tiago Moreira Bastos; Rossi Canuto de Menezes, Beatriz; Brito, Felipe Sales; Thim, Gilmar Patrocínio

    2016-01-01

    Due to its high efficiency, low cost and a simple operation, the adsorption process is an important and widely used technique for industrial wastewater treatment. Recent studies on the removal of artificial dyes by adsorption include a large number of adsorbents, such as: activated carbon, silicates, carbon nanotube, graphene, fibers, titanates and doped titanates. The carbon insertion in the TiO_2 structure promotes a synergistic effect on the adsorbent composite, improving the adsorption and the charge-transfer efficiency rates. However, there are few studies regarding the adsorption capacity of TiO_2/Carbon composites with the carbon concentration. This study evaluates the effect of carbon (resorcinol/formaldehyde) insertion on TiO_2 structure through the adsorption process. Adsorbents were prepared by varying the carbon weight percentages using the sol-gel method. The physicochemical properties of the catalysts prepared, such as crystallinity, particle size, surface morphology, specific surface area and pore volume were investigated. The kinetic study, adsorption isotherm, pH effect and thermodynamic study were examined in batch experiments using methylene blue as organic molecule. In addition, the effect of carbon phase on the adsorption capacity of TiO_2-carbon composite was deeply investigated. SEM micrographs showed that TiO_2 phase grows along the carbon phase and FT-IR results showed the presence of Ti−O−C chemical bonding. The experiments indicate that the carbon phase acted as a nucleation agent for the growth of TiO_2 during the sol-gel step, with a TiO_2 structure suitable for blue methylene adsorption, resulting in a material with large surface area and slit-like or wedge-shaped pores. Further experiments will show the best carbon concentration for methylene blue adsorption using a TiO_2 based material. - Highlights: • This article deals with the adsorption of methylene blue onto TiO_2-Carbon composite. • The sol-gel synthesis was efficient

  13. Structure/Property Relationships for Sol-gel Derived YBa2Cu3O7-d and SrTiO3 Films

    Science.gov (United States)

    Dawley, Jeff; Clem, Paul; Siegal, Michael; Overmyer, Don

    2001-03-01

    Solution deposition of c-axis oriented YBa2Cu3O7-d (YBCO) films on buffered RABiT substrates is a potential method for rapid, low cost production of superconducting tapes for power transmission and other applications. For this work, 100-250 nm thick YBCO and SrTiO3 (STO) films have been prepared by spin-coating and dip-coating sol-gel solutions onto LaAlO3 (100) and RABiT Ni (200) substrates. Biaxially textured STO coatings have been deposited on LaAlO3 and RABiT Ni by using a "templating" technique and controlling growth temperature and pO2. YBCO films grown on STO coated LaAlO3 possess comparable superconducting properties to YBCO films grown directly on LaAlO3 ( 1 MA/cm2 at 77K), indicating that a high quality STO layer does not degrade the crystalline quality of the YBCO. The effects of processing parameters on the STO buffer layer and novel processing techniques for decreasing the processing time and simplifying the integration of sol-gel YBCO with Ni substrates will be discussed. Sandia is a multiprogram laboratory operated by Sandia Corp., a Lockheed Martin Company, for the US Dept. Of Energy under contract DE-AC04-94A185000.

  14. Synthesis and characterization of sodium cation-conducting Nax(MyL1-yO2 (M = Ni2+, Fe3+; L = Ti4+, Sb5+

    Directory of Open Access Journals (Sweden)

    Marques, F. M. B.

    2004-06-01

    Full Text Available The Na+-conducting ceramics of layered Na0.8Ni0.4Ti0.6O2, Na0.8Fe0.8Ti0.2O2, Na0.8Ni0.6Sb0.4O2 (structural type O3 and Na0.68Ni0.34Ti0.66O2 (P2 type with density higher than 91% were prepared via the standard solid-state synthesis route and characterized by the impedance spectroscopy, thermal analysis, scanning electron microscopy, structure refinement using X-ray powder diffraction data, measurements of Na+ concentration cell e.m.f., and dilatometry. The conductivity of antimonate Na0.8Ni0.6Sb0.4O2, synthesized first time, was found lower than that of isostructural Na0.8Ni0.4Ti0.6O2 due to larger ion jump distance between Na+ sites. At temperatures above 420 K, transport properties of sodium cationconducting materials are essentially independent of partial water vapor pressure. In the low-temperature range, the conductivity reversibly increases with water vapor pressure varied in the range from approximately 0 (dry air up to 0.46 atm. The sensitivity to air humidity is influenced by the ceramic microstructure, being favored by increasing boundary area. The average thermal expansion coefficients of layered materials at 300-1173 K are in the range (13.7-16.0×10-6 K-1.Se han preparado cerámicas conductoras conteniendo Na+ de composición Na0.8Ni0.4Ti0.6O2, Na0.8Fe0.8Ti0.2O2, Na0.8Ni0.6Sb0.4O2 (tipo estructural O3 y Na0.68Ni0.34Ti0.66O2 (tipo P2 con densidad mayor del 91%. Las vía de preparación fu la ruta de estandard de síntesis en estado sólido. Las composiciones se caracterizaron mediante espectroscopía de impedancia, análisis térmico, microscopía electrónica de barrido, refinamiento de la estructura usando datos de difracción de rayos X en polvo, medidas de concentración de Na+, f.e.m. de la célula y dilatometría. La conductividad del antimoniate, sintetizado por primera vez, Na0.8Ni0.6Sb0.4O2, era menor que la del compuesto isoestructural Na0.8Ni0.4Ti0.6O2 debido a la mayor distancia de salto iónico entre las posiciones de Na

  15. LaNiO(3) Buffer Layers for High Critical Current Density YBa(2)Cu(3)O(7-delta) and Tl(2)Ba(2)CaCu(2)O(8-delta) Films

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.-T.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-08-24

    We demonstrate high critical current density superconducting films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} (Tl-2212) using LaNiO{sub 3} (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J{sub c} (5K, H=0) than films grown directly on a bare LaAlO{sub 3} substrate. It is noteworthy that YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J{sub c} at all temperatures and fields compared to those grown on bare LaAlO{sub 3}, correlating to both a-axis grain and nonsuperconducting phase formation. With additional optimization, LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films, perhaps ideally suited for coated conductor applications.

  16. Synthesis and visible-light-induced catalytic activity of Ag{sub 2}S-coupled TiO{sub 2} nanoparticles and nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Xie Yi; Heo, Sung Hwan; Kim, Yong Nam; Yoo, Seung Hwa; Cho, Sung Oh, E-mail: socho@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong, Yuseong, Daejeon 305-701 (Korea, Republic of)

    2010-01-08

    We present the synthesis and visible-light-induced catalytic activity of Ag{sub 2}S-coupled TiO{sub 2} nanoparticles (NPs) and TiO{sub 2} nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag{sub 2}S NPs and TiO{sub 2} NPs with sizes of less than 7 nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag{sub 2}S NPs on TiO{sub 2} NWs was created. Due to the coupling with such a low bandgap material as Ag{sub 2}S, the TiO{sub 2} nanocomposites could have a visible-light absorption capability much higher than that of pure TiO{sub 2}. As a result, the synthesized Ag{sub 2}S/TiO{sub 2} nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO{sub 2} (Degussa P25, Germany) under visible light.

  17. Coexistence of an anatase/TiO2(B) heterojunction and an exposed (001) facet in TiO2 nanoribbon photocatalysts synthesized via a fluorine-free route and topotactic transformation.

    Science.gov (United States)

    Wang, Changhua; Zhang, Xintong; Liu, Yichun

    2014-05-21

    In this work, we report a novel approach to fabricate hierarchical TiO2 microspheres (HTMS) assembled by ultrathin nanoribbons where an anatase/TiO2(B) heterojunction and high energy facet coexist. The as-adopted approach involves (1) nonaqueous solvothermal treatment of a mixture of tetrabutyl titanate and acetic acid and (2) topotactical transformation into HTMS via thermal annealing. By this approach, the TiO2(B) phase usually synthesized from an alkaline treatment route could be initially formed. Subsequently, phase transition from TiO2(B) to anatase TiO2 occurs upon thermal treatment. It is demonstrated that such phase transition is accompanied by crystallographic orientation along the c-axis of anatase and TiO2(B) crystals, resulting in not only a coherent interface between two phases but also oriented attachment of anatase mesocrystals along the [001] direction, and finally high-energy (001) facet exposure. Interestingly, this work provides an alternative fluorine-free route for the synthesis of TiO2 crystals with high-energy (001) facet exposure. The structural analysis reveals that lattice-match induced topotactic transformation from TiO2(B) to anatase is the sole reason for the (001) facet exposure of anatase TiO2. The photocatalytic test for acetaldehyde decomposition shows that HTMS with anatase/TiO2(B) heterojunction and high-energy (001) facet exhibits superior photocatalytic efficiency compared with the relevant commercial product P25, which can be ascribed to the synergistic effect of large surface area, anatase/TiO2(B) heterojunction as well as high-energy facet exposure.

  18. Coexistence of an anatase/TiO2(B) heterojunction and an exposed (001) facet in TiO2 nanoribbon photocatalysts synthesized via a fluorine-free route and topotactic transformation

    Science.gov (United States)

    Wang, Changhua; Zhang, Xintong; Liu, Yichun

    2014-04-01

    In this work, we report a novel approach to fabricate hierarchical TiO2 microspheres (HTMS) assembled by ultrathin nanoribbons where an anatase/TiO2(B) heterojunction and high energy facet coexist. The as-adopted approach involves (1) nonaqueous solvothermal treatment of a mixture of tetrabutyl titanate and acetic acid and (2) topotactical transformation into HTMS via thermal annealing. By this approach, the TiO2(B) phase usually synthesized from an alkaline treatment route could be initially formed. Subsequently, phase transition from TiO2(B) to anatase TiO2 occurs upon thermal treatment. It is demonstrated that such phase transition is accompanied by crystallographic orientation along the c-axis of anatase and TiO2(B) crystals, resulting in not only a coherent interface between two phases but also oriented attachment of anatase mesocrystals along the [001] direction, and finally high-energy (001) facet exposure. Interestingly, this work provides an alternative fluorine-free route for the synthesis of TiO2 crystals with high-energy (001) facet exposure. The structural analysis reveals that lattice-match induced topotactic transformation from TiO2(B) to anatase is the sole reason for the (001) facet exposure of anatase TiO2. The photocatalytic test for acetaldehyde decomposition shows that HTMS with anatase/TiO2(B) heterojunction and high-energy (001) facet exhibits superior photocatalytic efficiency compared with the relevant commercial product P25, which can be ascribed to the synergistic effect of large surface area, anatase/TiO2(B) heterojunction as well as high-energy facet exposure.

  19. High pressure structural phase transitions of TiO2 nanomaterials

    International Nuclear Information System (INIS)

    Li Quan-Jun; Liu Bing-Bing

    2016-01-01

    Recently, the high pressure study on the TiO 2 nanomaterials has attracted considerable attention due to the typical crystal structure and the fascinating properties of TiO 2 with nanoscale sizes. In this paper, we briefly review the recent progress in the high pressure phase transitions of TiO 2 nanomaterials. We discuss the size effects and morphology effects on the high pressure phase transitions of TiO 2 nanomaterials with different particle sizes, morphologies, and microstructures. Several typical pressure-induced structural phase transitions in TiO 2 nanomaterials are presented, including size-dependent phase transition selectivity in nanoparticles, morphology-tuned phase transition in nanowires, nanosheets, and nanoporous materials, and pressure-induced amorphization (PIA) and polyamorphism in ultrafine nanoparticles and TiO 2 -B nanoribbons. Various TiO 2 nanostructural materials with high pressure structures are prepared successfully by high pressure treatment of the corresponding crystal nanomaterials, such as amorphous TiO 2 nanoribbons, α -PbO 2 -type TiO 2 nanowires, nanosheets, and nanoporous materials. These studies suggest that the high pressure phase transitions of TiO 2 nanomaterials depend on the nanosize, morphology, interface energy, and microstructure. The diversity of high pressure behaviors of TiO 2 nanomaterials provides a new insight into the properties of nanomaterials, and paves a way for preparing new nanomaterials with novel high pressure structures and properties for various applications. (topical review)

  20. High-Temperature Heat Capacity of Germanates Pr2Ge2O7 and Nd2Ge2O7 within 350-1000 K

    Science.gov (United States)

    Denisova, L. T.; Irtyugo, L. A.; Beletskii, V. V.; Belousova, N. V.; Denisov, V. M.

    2018-03-01

    Pr2Ge2O7 and Nd2Ge2O7 were obtained via solid-phase synthesis from Pr2O3 ( Nd2O3) and GeO2 with multistage firing in air within 1273-1473 K. A temperature effect on molar heat capacity of the oxide compounds was measured with a differential scanning calorimetry. Their thermodynamic properties were calculated from the C P = f( T) dependences.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-15

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

  2. Structural and electrical properties of Barium Titanate (BaTiO3 and Neodymium doped BaTiO3 (Ba0.995Nd0.005TiO3

    Directory of Open Access Journals (Sweden)

    Tuan Sulong Tuan Amirah

    2017-01-01

    Full Text Available Barium titanate (BaTiO3 and Neodymium (Nd doped BaTiO3 with composition Ba0.995Nd0.005TiO3 were prepared using conventional solid state reaction method to study the dielectric properties of materials. Pure phase samples were found at final heating temperature of 1400°C for overnight. X-ray diffraction analysis reveals the changes in the lattice parameter and unit cell volume of the pure perovskite tetragonal structure with space group (P4mm. Electrical analysis is carried out to investigate the dielectric properties, conductivity behaviour and dielectric loss of BaTiO3 and Ba0.995Nd0.005TiO3. Ba0.995Nd0.005TiO3 have a broaden dielectric peaks with high permittivity of 8000 and reasonably low loss tan δ which is about 0.004 (1 kHz.

  3. Highly Al-doped TiO2 nanoparticles produced by Ball Mill Method: structural and electronic characterization

    International Nuclear Information System (INIS)

    Santos, Desireé M. de los; Navas, Javier; Sánchez-Coronilla, Antonio; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín

    2015-01-01

    Highlights: • Highly Al-doped TiO 2 nanoparticles were synthesized using a Ball Mill Method. • Al doping delayed anatase to rutile phase transformation. • Al doping allow controlling the structural and electronic properties of nanoparticles. - Abstract: This study presents an easy method for synthesizing highly doped TiO 2 nanoparticles. The Ball Mill method was used to synthesize pure and Al-doped titanium dioxide, with an atomic percentage up to 15.7 at.% Al/(Al + Ti). The samples were annealed at 773 K, 973 K and 1173 K, and characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, TG, STEM, XPS, and UV–vis spectroscopy. The effect of doping and the calcination temperature on the structure and properties of the nanoparticles were studied. The results show high levels of internal doping due to the substitution of Ti 4+ ions by Al 3+ in the TiO 2 lattice. Furthermore, anatase to rutile transformation occurs at higher temperatures when the percentage of doping increases. Therefore, Al doping allows us to control the structural and electronic properties of the nanoparticle synthesized. So, it is possible to obtain nanoparticles with anatase as predominant phase in a higher range of temperature

  4. Energetics of stepwise disordering transformation in pyrochlores, RE2Ti2O7 (RE = Y, Gd and Dy)

    International Nuclear Information System (INIS)

    Hayun, Shmuel; Tran, Tien B.; Lian, Jie; Fuentes, Antonio F.; Navrotsky, Alexandra

    2012-01-01

    Graphical abstract: The transformation from disordered to more order state in the pyrochlore system go through multiple energetics steps; the cation sublattice rearrangement is control by the diffusion of the cations while the anion sublattice display an irreversible transformation from a disordered to a higher-ordered state via diffusionless transformation. - Abstract: The capacity to incorporate actinide cations makes pyrochlore titanates first-choice phases in titanate-based waste form ceramics. Despite broad interest in the pyrochlore order–disorder transformation due to the cumulative effects of 238 U, 235 U and 232 Th radioactive decay and their daughter products, only limited thermodynamic data, mainly based on simulations of ion-beam irradiation experiments, have been reported. In this work, for the first time, heavily disordered pyrochlores, RE 2 Ti 2 O 7 (RE = Y, Gd and Dy), from mechanical milling of their constituent oxides, were thermochemically investigated. Two types of thermal events were identified using high-temperature differential scanning calorimetry and correlated to the structural disorder in the cation and anion sublattices. Moreover, the excess formation energy measured by oxide melt solution calorimetry shows that the smaller the ionic radius of the RE, the easier it is to remove damage domains.

  5. Study on mechanism of photocatalytic performance of La-doped TiO2/Ti photoelectrodes by theoretical and experimental methods

    International Nuclear Information System (INIS)

    Xin Yanjun; Liu Huiling

    2011-01-01

    TiO 2 photoelectrodes with various nanostructures have been successfully prepared by the anodization method. The morphology, microstructure and optical properties of as-prepared photoelectrodes were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet/visible light diffuse reflectance spectra (UV/vis/DRS), surface photovoltage spectroscopy (SPS) and photocurrent. The electronic structure and optical properties of La doped/undoped TiO 2 photoelectrodes with different crystal structures were calculated by the density function theory. The photocatalytic and photoelectrocatalytic activities of as-prepared photoelectrodes were evaluated. The results showed that the anodization potentials played a crucial role in the surface morphology and microstructure. Both results of theoretical calculations and experimental tests demonstrated that La-doped photoelectrodes were more sensitive to light than undoped one. The difference of photoelectrodes performance was ascribed to the crystal configuration, impurity energy levels and long-range orientation moving of photogenerated carriers. - Graphical abstract: Photophysical chemistry processes in as-prepared TiO 2 photoelectrodes. Overall scheme of TiO 2 photoelectrodes: (A) movement of photoelectrons and holes without bias potentials; (B) movement of photoelectrons and holes at applied bias potentials; (a) and (b) were the transmission of photogenerated electrons and holes of local enlargement of (A) (black open circle): (a) photoelectrons movement in P-TiO 2 photoelectrodes and La-TiO 2 photoelectrodes, the red dot line denotes the top of valence band (VB) and the bottom of conduction band (CB) of pure photoelectrodes; (b) photoelectrons movement in P-160 and La-160 TiO 2 photoelectrodes (mixed crystal phase). The number refers to as follows: (1) transmission process of photoelectrons and holes; (2) recombination process of photoelectrons and holes. Arrows represent the moving direction of

  6. Collinear order in frustrated quantum antiferromagnet on square lattice (CuBr)LaNb2O7

    International Nuclear Information System (INIS)

    Oba, Noriaki; Kageyama, Hiroshi; Kitano, Taro

    2006-01-01

    Magnetic susceptibility, heat capacity, high-field magnetization and neutron diffraction measurements have been performed on a two-dimensional s=1/2 square-lattice system (CuBr)LaNb 2 O 7 , prepared by a topotactic ion-exchange reaction of a nonmagnetic double-layered perovskite RbLaNb 2 O 7 . (CuBr)LaNb 2 O 7 exhibits a second-order magnetic transition at 32K, in marked contrast to a spin-singlet nature for its Cl-based counterpart (CuCl)LaNb 2 O 7 , despite nearly identical structural parameters. The magnetic structure is a novel collinear antiferromagnetic (CAF) ordering characterized by a modulation vector q=(π, 0, π) with a reduced moment of 0.6μ B . Mixed ferromagnetic nearest-neighbor (J 1 ) and antiferromagnetic second-nearest-neighbor (J 2 ) interactions are of comparable strength (J 1 /k B =-35.6K and J 2 /k B =41.3K), placing the system in a more frustrated region of the CAF phase than ever reported. (author)

  7. Doping-induced quantum crossover in Er2Ti2 -xSnxO7

    Science.gov (United States)

    Shirai, M.; Freitas, R. S.; Lago, J.; Bramwell, S. T.; Ritter, C.; Živković, I.

    2017-11-01

    We present the results of the investigation of magnetic properties of the Er2Ti2 -xSnxO7 series. For small doping values, the ordering temperature decreases linearly with x , while the moment configuration remains the same as in the x =0 parent compound. Around x =1.7 doping level, we observe a change in the behavior, where the ordering temperature starts to increase and new magnetic Bragg peaks appear. For the first time, we present evidence of a long-range order (LRO) in Er2Sn2O7 (x =2.0 ) below TN=130 mK. It is revealed that the moment configuration corresponds to a Palmer-Chalker type with a value of the magnetic moment significantly renormalized compared to x =0 . We discuss our results in the framework of a possible quantum phase transition occurring close to x =1.7 .

  8. Influence of Mg O and B2O3 addition on reaction sintering, properties and microstructure of Aluminum titanate

    International Nuclear Information System (INIS)

    Ajami, R.; Sarpoolaki, H.; Akbari, G. H.

    2007-01-01

    The effect of Mg O and B 2 O 3 on the formation, physical properties, phase analysis and microstructure of aluminum titanate was investigated. Density results showed the sample containing of 1 wt percent B 2 O 3 and 2 wt percent Mg O leads to the highest density while the lowest density was seen in samples containing 1 wt percent B 2 O 3 compared to pure aluminum titanate. Regarding the phase analysis of samples, Mg O was found most effective additive on reaction sintering of aluminum titanate through the intermediate phases. Furthermore at the temperatures above 1350 d eg C , B 2 O 3 promote the formation reaction of aluminum titanate. Microstructural analysis showed the samples containing Mg O are fine grain and homogeneous. Thermal expansion coefficient of samples with additives is greater than pure aluminum titanate. Pure aluminum titanate samples and one containing B 2 O 3 additive decompose to Al 2 O 3 and TiO 2 after 5 hours heat treatment at 1150 d eg C while the samples containing 2 wt percent Mg O was stable even after 25 hours

  9. Effects of La{sub 2}O{sub 3} on microstructure and wear properties of laser clad {gamma}/Cr{sub 7}C{sub 3}/TiC composite coatings on TiAl intermatallic alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiubo [Laboratory for Laser Intelligent Manufacturing, Institute of Mechanics, Chinese Academy of Sciences, 15 Beisihuanxi Road, Beijing 100080 (China) and School of Materials and Chemical Engineering, Zhongyuan Institute of Technology, 41 Zhongyuan Western Road, Zhengzhou 450007, Henan Province (China)]. E-mail: liubobo0828@yahoo.com.cn; Yu Rongli [School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100083 (China)

    2007-02-15

    The effects of La{sub 2}O{sub 3} addition on the microstructure and wear properties of laser clad {gamma}/Cr{sub 7}C{sub 3}/TiC composite coatings on {gamma}-TiAl intermetallic alloy substrates with NiCr-Cr{sub 3}C{sub 2} precursor mixed powders have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive spectrometer (EDS) and block-on-ring wear tests. The responding wear mechanisms are discussed in detail. The results are compared with that for composite coating without La{sub 2}O{sub 3}. The comparison indicates that no evident new crystallographic phases are formed except a rapidly solidified microstructure consisting of the primary hard Cr{sub 7}C{sub 3} and TiC carbides and the {gamma}/Cr{sub 7}C{sub 3} eutectics distributed in the tough {gamma} nickel solid solution matrix. Good finishing coatings can be achieved under a proper amount of La{sub 2}O{sub 3}-addition and a suitable laser processing parameters. The additions of rare-earth oxide La{sub 2}O{sub 3} can refine and purify the microstructure of coatings, relatively decrease the volume fraction of primary blocky Cr{sub 7}C{sub 3} to Cr{sub 7}C{sub 3}/{gamma} eutectics, reduce the dilution of clad material from base alloy and increase the microhardness of the coatings. When the addition of La{sub 2}O{sub 3} is approximately 4 wt.%, the laser clad composite coating possesses the highest hardness and toughness. The composite coating with 4 wt.%La{sub 2}O{sub 3} addition can result the best enhancement of wear resistance of about 30%. However, too less or excessive addition amount of La{sub 2}O{sub 3} have no better influence on wear resistance of the composite coating.

  10. Use of linear free energy relationship to predict Gibbs free energies of formation of zirconolite phases (MZrTi2O7 and MHfTi2O7)

    International Nuclear Information System (INIS)

    Xu, H.

    1999-01-01

    In this letter, the Sverjensky-Molling equation derived from a linear free energy relationship is used to calculate the Gibbs free energies of formation of zirconolite crystalline phases (MZrTi 2 O 7 and MHfTi 2 O 7 ) from the known thermodynamic properties of the corresponding aqueous divalent cations (M 2+ ). Sverjensky-Molling equation is expressed as ΔG 0 f,M v X =a M v X ΔG 0 n,M 2+ +b M v X +β M v X r M 2+ , where the coefficients a M v X , b M v X , and β M v X characterize a particular structural family of M v X, r M 2+ is the ionic radius of M 2+ cation, ΔG f,M v X 0 is the standard Gibbs free energy of formation of M v X, and ΔG 0 n,M 2+ is the standard non-solvation energy of cation M 2+ . This relationship can be used to predict the Gibbs free energies of formation of various fictive phases (such as BaZrTi 2 O 7 , SrZrTi 2 O 7 , PbZrTi 2 O 7 , etc.) that may form solid solution with CaZrTi 2 O 7 in actual Synroc-based nuclear waste forms. Based on obtained linear free energy relationships, it is predicted that large cations (e.g., Ba and Ra) prefer to be in perovskite structure, and small cations (e.g., Ca, Zn, and Cd) prefer to be in zirconolite structure. (orig.)

  11. Dynamical magnetic properties of the spin ice crystal Dy2Ti2O7

    International Nuclear Information System (INIS)

    Shi Jing; Tang, Z.; Zhu, B.P.; Huang, P.; Yin, D.; Li, C.Z.; Wang, Y.; Wen, H.

    2007-01-01

    The measurements of AC susceptibility between 2 and 40 K from zero field to 4 T both along the (0 0 1) and (1 1 1) axis in single-crystal Dy 2 Ti 2 O 7 show that the spin freezing along the (1 1 1) axis has stronger frequency dependence and magnetic field dependence, and the starting freezing frequency of the single crystal is higher than that of the polycrystalline sample

  12. Recovery TiO2 by leaching process of carbothermic reduced Kalimantan ilmenite

    Science.gov (United States)

    Wahyuningsih, S.; Sari, P. P.; Ramelan, A. H.

    2018-05-01

    Ilmenite naturally occurred in iron titanate (FeTiO3) minerals. The separation of natural ilmenite into TiO2 and Fe2O3 need to be explored to gain the high purity separation product. A new combination method named of carbothermic reduction, acidic-leaching and complexation by EDTA were proposed for separation TiO2 from Ilmenite. Roasting of ilmenite was carried out at 950 °C for 1 h by the addition of activated carbon with mass ratio of ilmenite : activated carbon =4:3. The carbothermic reduction was carried out to yield a high separation of initial content of ilmenite that will be easily to dissolve within hydrochloric acid solution in leaching process. The composition of ilmenite observed by X-Ray Fluoresences (XRF) changed after the carbothermic reduction process and the dominant content is TiO2 (57.56%). X-Ray Diffraction (XRD) of roasted ilmenite composed of decomposed product of ilmenite i.e. hematite (Fe2O3), TiO2 anatase, TiO2 rutile, and inorganic salt. The leaching of the roasted ilmenite has been done by sulphuric acid solution (6 M) to gain the titanyl sulphate solution. Separation of iron impurities of TiO2 gel from titanyl sulphate (TiOSO4) solution was conducted by complexation method using EDTA as a complexation agent. The characteristic of TiO2 obtained using XRD showed that TiO2 is anatase type and the percentage of TiO2 using XRF showed that TiO2 content of 86,03%.

  13. Hydrothermal growth of highly textured BaTiO3 films composed of nanowires

    International Nuclear Information System (INIS)

    Zhou Zhi; Tang Haixiong; Sodano, Henry A; Lin Yirong

    2013-01-01

    Textured barium titanate (BaTiO 3 ) films are attracting immense research interest due to their lead-free composition and excellent piezoelectric and dielectric properties. Most synthesis methods for these films require a high temperature, leading to the formation of a secondary phase and an overall decrease in the electrical properties of the ceramic. In order to alleviate these issues, a novel fabrication method is introduced by transferring oriented rutile TiO 2 nanowires to a textured BaTiO 3 film at temperatures below 160 °C. The microstructure and thickness of the fabricated BaTiO 3 films were characterized by scanning electron microscopy, and the crystal structure and degree of orientation were evaluated by x-ray diffraction patterns using the Lotgering method. It is shown that the thickness of the BaTiO 3 film can be controlled by the length of TiO 2 nanowire array template, and the degree of orientation of the textured BaTiO 3 films is highly dependent on the film thickness; the crystallographic orientation has been measured to reach up to 87%. The relative dielectric constant (ε r = 1300) and ferroelectric properties (P r = 2.7 μC cm −2 , E c = 4.0 kV mm −1 ) of the textured BaTiO 3 films were also characterized to demonstrate their potential application in sensors, random access memory, and micro-electromechanical systems. (paper)

  14. High pressure synthesis of amorphous TiO2 nanotubes

    Directory of Open Access Journals (Sweden)

    Quanjun Li

    2015-09-01

    Full Text Available Amorphous TiO2 nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO2 nanotubes. The structural phase transitions of anatase TiO2 nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD method. The starting anatase structure is stable up to ∼20GPa, and transforms into a high-density amorphous (HDA form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO2 nanoparticles and nanoribbons. The relationship between the LDA form and α-PbO2 phase was revealed by high-resolution transmission electron microscopy (HRTEM study. In addition, the bulk modulus (B0 = 158 GPa of the anatase TiO2 nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa. We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO2 nanotubes.

  15. Perovskite oxynitride LaTiO{sub x}N{sub y} thin films: Dielectric characterization in low and high frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Y.; Ziani, A. [Institut d' Electronique et de Telecommunications de Rennes (IETR) UMR-CNRS 6164, groupe ' Antennes et Hyperfrequences' , University of Rennes 1, UEB, IUT Saint Brieuc, 18 rue Henri Wallon, 22004 Saint Brieuc cedex (France); Le Paven-Thivet, C., E-mail: claire.lepaven@univ-rennes1.fr [Institut d' Electronique et de Telecommunications de Rennes (IETR) UMR-CNRS 6164, groupe ' Antennes et Hyperfrequences' , University of Rennes 1, UEB, IUT Saint Brieuc, 18 rue Henri Wallon, 22004 Saint Brieuc cedex (France); Benzerga, R.; Le Gendre, L. [Institut d' Electronique et de Telecommunications de Rennes (IETR) UMR-CNRS 6164, groupe ' Antennes et Hyperfrequences' , University of Rennes 1, UEB, IUT Saint Brieuc, 18 rue Henri Wallon, 22004 Saint Brieuc cedex (France); Fasquelle, D. [Laboratoire d' Etude des Materiaux et des Composants pour l' Electronique (LEMCEL) UPRES-EA 2601, University of Littoral-Cote d' Opale, 50 rue Ferdinand Buisson, F-62228 Calais cedex (France); Kassem, H. [Laboratoire de l' Integration du Materiau au Systeme(IMS) UMR-CNRS 5218, groupe Materiaux, University of Bordeaux 1, 16 avenue Pey-Berland, 33607 Pessac (France); and others

    2011-11-01

    Lanthanum titanium oxynitride (LaTiO{sub x}N{sub y}) thin films are studied with respect to their dielectric properties in low and high frequencies. Thin films are deposited by radio frequency magnetron sputtering on different substrates. Effects of nitrogen content and crystalline quality on dielectric properties are investigated. In low-frequency range, textured LaTiO{sub x}N{sub y} thin films deposited on conductive single crystal Nb-STO show a dielectric constant {epsilon} Prime Almost-Equal-To 140 with low losses tan{delta} = 0.012 at 100 kHz. For the LaTiO{sub x}N{sub y} polycrystalline films deposited on conductive silicon substrates with platinum (Pt/Ti/SiO{sub 2}/Si), the tunability reached up to 57% for a weak electric field of 50 kV/cm. In high-frequency range, epitaxial LaTiO{sub x}N{sub y} films deposited on MgO substrate present a high dielectric constant with low losses ({epsilon} Prime Almost-Equal-To 170, tan{delta} = 0.011, 12 GHz).

  16. Dielectric studies on cerium doped BaLa2Ti3O10

    Directory of Open Access Journals (Sweden)

    Parshuram B. Abhange

    2015-12-01

    Full Text Available The BaLa2-xCexTi3O10 samples (with x = 0.2, 0.4, 0.6 and 0.8 were prepared by hydroxide co-precipitation method and finally sintered at 1150 °C. The structure of the prepared samples was characterized by XRD and SEM. The single phase material was confirmed only for the BaLa1.8Ce0.2Ti3O10 ceramics. However, at higher cerium concentration secondary phase was observed. The characteristic plate-like structure, having grains with submicrometer thickness and high aspect ratio, was clearly observed by SEM. The results of dielectric measurement suggest that the appropriate adjustment of doping (with x between 0.2 and 0.8 will give sufficient high dielectric constant at very low loss. The resistivity of samples decreases with increase in temperature indicating the normal semiconducting electrical behaviour.

  17. ADSORCIÓN DE ALDEHÍDOS INSATURADOS SOBRE TiO2

    Directory of Open Access Journals (Sweden)

    Natalia Ortega

    2012-01-01

    Full Text Available En el presente trabajo se estudió la adsorción de aldehídos insaturados sobre la superficie del TiO2. Para evaluar su eficiencia como catalizador, se realizaron experimentos de fotocatálisis heterogénea de p-nitrofenol (PNF y una muestra proveniente de efluentes industriales. Se empleó un simulador solar y cuatro sistemas de TiO2: el TiO2-sólo (sin modificar y los sistemas TiO2-dienal constituidos por la adsorción química de 2,4 hexadienal, 2,4 heptadienal y el trans-cinamaldehído sobre la superficie del TiO2. La adsorción de los aldehídos insaturados sobre el TiO2 se cuantificó empleando los modelos de adsorción de Langmuir y Freundlich. Se evaluó la influencia del pH en los sistemas TiO2-dienal y su efecto en la degradación fotocatalítica del PNF. En condiciones básicas, la constante de velocidad del PNF es mayor al emplear los sistemas TiO2-dienal en comparación con el TiO2-sólo, mientras que en condiciones ácidas se encontró la tendencia opuesta. El sistema TiO2-cina resultó ser el fotocatalizador de mayor eficiencia.

  18. Growth and characterization of epitaxial anatase TiO2(001) on SrTiO3-buffered Si(001) using atomic layer deposition

    International Nuclear Information System (INIS)

    McDaniel, M.D.; Posadas, A.; Wang, T.; Demkov, A.A.; Ekerdt, J.G.

    2012-01-01

    Epitaxial anatase titanium dioxide (TiO 2 ) films have been grown by atomic layer deposition (ALD) on Si(001) substrates using a strontium titanate (STO) buffer layer grown by molecular beam epitaxy (MBE) to serve as a surface template. The growth of TiO 2 was achieved using titanium isopropoxide and water as the co-reactants at a substrate temperature of 225–250 °C. To preserve the quality of the MBE-grown STO, the samples were transferred in-situ from the MBE chamber to the ALD chamber. After ALD growth, the samples were annealed in-situ at 600 °C in vacuum (10 −7 Pa) for 1–2 h. Reflection high-energy electron diffraction was performed during the MBE growth of STO on Si(001), as well as after deposition of TiO 2 by ALD. The ALD films were shown to be highly ordered with the substrate. At least four unit cells of STO must be present to create a stable template on the Si(001) substrate for epitaxial anatase TiO 2 growth. X-ray diffraction revealed that the TiO 2 films were anatase with only the (004) reflection present at 2θ = 38.2°, indicating that the c-axis is slightly reduced from that of anatase powder (2θ = 37.9°). Anatase TiO 2 films up to 100 nm thick have been grown that remain highly ordered in the (001) direction on STO-buffered Si(001) substrates. - Highlights: ► Epitaxial anatase films are grown by atomic layer deposition (ALD) on Si(001). ► Four unit cells of SrTiO 3 on silicon create a stable template for ALD. ► TiO 2 thin films have a compressed c-axis and an expanded a-axis. ► Up to 100 nm thick TiO 2 films remain highly ordered in the (001) direction.

  19. Electrochemical Behavior of Molten V2O5-K2S2O7-KHSO4 Systems

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Berg, Rolf W.

    1997-01-01

    The electrochemical behavior of K2S2O7-KHSO4-V2O5, K2S2O7-V2O4 and K2S2O7-KHSO4-V2O4 melts was studied in argon and SO2/air atmospheres using a gold electrode. In order to identify the voltammetric waves due to KHSO4, molten KHSO4 and mixtures of K2S2O7-KHSO4 were investigated by voltammetry...

  20. ZnO@TiO2 Architectures for a High Efficiency Dye-Sensitized Solar Cell

    International Nuclear Information System (INIS)

    Lei, Jianfei; Liu, Shuli; Du, Kai; Lv, Shijie; Liu, Chaojie; Zhao, Lingzhi

    2015-01-01

    Graphical Abstract: A fast and improved electrochemical process was reported to fabricate ZnO@TiO 2 heterogeneous architectures with enhanced power conversion efficiency (ƞ = 2.16%). This paper focuses on achieving high dye loading via binding noncorrosive TiO 2 nanocones to the outermost layer, while retaining the excellent electron transport behavior of the ZnO-based internal layer. Display Omitted -- Highlights: • Nanoconic TiO 2 particles are loaded on the surface of aligned ZnO NWs successfully by a liquid phase deposition method. • ZnO@TiO 2 architectures exhibit high efficiency of the DSSCs. -- Abstract: Instead of the spin coating step, an improved electrochemical process is reported in this paper to prepare ZnO seeded substrates and ZnO nanowires (ZnO NWs). Vertically aligned ZnO NWs are deposited electrochemically on the ZnO seeded substrates directly forming backbones for loading nanoconic TiO 2 particles, and hence ZnO@TiO 2 heterogeneous architectures are obtained. When used as photoanode materials of the dye-sensitized solar cells (DSSCs), ZnO@TiO 2 architectures exhibit enhanced power conversion efficiency (PCE) of the DSSCs. Results of the solar cell testing show that addition of TiO 2 shells to the ZnO NWs significantly increases short circuit current (from 2.6 to 4.7 mA cm −2 ), open circuit voltage (from 0.53 V to 0.77 V) and fill factor (from 0.30 to 0.59). The PCE jumped from 0.4% for bare ZnO NWs to 2.16% for ZnO@TiO 2 architectures under 100 mW cm −2 of AM 1.5 G illumination

  1. In-situ YBa2Cu3O7/SrTiO3/YBa2Cu3O7 a-b plane Josephson edge junctions

    International Nuclear Information System (INIS)

    Aharoni, E.; Koren, G.; Polturak, E.; Cohen, D.; Iskevitch, E.

    1992-01-01

    YBCO/SrTiO 3 /YBCO thin film edge junctions were prepared in-situ and characterized. The epitaxial growth of SrTiO 3 on YBCO led to a sharp and well defined junction edge with a very high yield. Typical junctions showed critical currents up to 83 K, with I c ∝ (1 - T/Tc) 2 temperature dependence. Sharp Shapiro steps were observed under microwave radiation at temperatures up to 82 K. A typical diffraction pattern was found in the voltage response of the junctions to transverse magnetic field. (orig.)

  2. Facile synthesis of a conjugation-grafted-TiO2 nanohybrid with enhanced visible-light photocatalytic properties from nanotube titanic acid precursors

    Science.gov (United States)

    Guo, Yanru; Zhang, Min; Zhang, Zhihua; Li, Qiuye; Yang, Jianjun

    2016-08-01

    A conjugation-grafted-TiO2 nanohybrid was synthesized by chemically grafting conjugated structures on the surface of nanotube titanic acid (NTA) precursor-based TiO2 through the controlled thermal degradation of a coacervated polymer layer of polyvinyl alcohol (PVA). The interfacial interactions between the NTA precursor-based TiO2 and conjugated structures were characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Moreover, the effects of the NTA's pretreatment temperature and the weight ratio of NTA to PVA on the photocatalytic degradation of methyl orange were also investigated. A higher NTA pretreatment temperature and a lower NTA to PVA weight ratio were found to enhance photogenerated electron-hole separation efficiency and photocatalytic activity. Moreover, the conjugation-grafted-TiO2 nanohybrid synthesized from the NTA precursor displayed a much higher visible-light photocatalytic activity than that of the sample obtained from the P25 precursor. The origin of the enhanced photocatalytic activity under visible-light irradiation is also discussed in detail.

  3. Electronic and optical properties of layered RE{sub 2}Ti{sub 2}O{sub 7} (RE = Ce and Pr) from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Sayede, A. [Universite Lille Nord de France, F-59000 Lille (France); Khenata, R. [Laboratoire de Physique Quantique et de Modlisation Mathmatique, Universite de Mascara, Mascara, 29000 (Algeria); Chahed, A.; Benhelal, O. [Condensed Matter and Sustainable Development Laboratory, Djillali Liabes University of Sidi Bel-Abbes, Sidi Bel-Abbes 22000 (Algeria)

    2013-05-07

    We have studied the structural and electronic properties of Ce{sub 2}Ti{sub 2}O{sub 7} (CeTO) and Pr{sub 2}Ti{sub 2}O{sub 7} (PrTO) by first-principles density functional theory calculations. The computed structural parameters are in fairly good agreement with the available experimental findings. Band structure calculations using the GGA+U approach predict an insulating ground state for the herein studied compounds. The insulating band gaps of 2.00 eV and 2.83 eV are found for CeTO and PrTO, respectively. The analysis of the density of states reveals that the strongly localized RE 4f levels act as charge-trapping sites, predicting a lower photocatalytic activity for CeTO. We have also calculated the optical properties for both CeTO and PrTO. Based on these properties, it is predicted that these titanates are insensitive to ultra-violet radiation, while they are more sensitive to frequencies of the radiation in visible and early UV regions.

  4. Dielectric and thermodynamic measurements on the magnetoelectric perovskite EuTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Engelmayer, Johannes; Grams, Christoph; Hemberger, Joachim; Lorenz, Thomas [II. Physikalisches Institut, Universitaet zu Koeln (Germany)

    2016-07-01

    Various perovskite titanates ATiO{sub 3} are known to undergo ferroelectric phase transitions, e.g., for A=Ba,Pb,Cd. BaTiO{sub 3} is the only ferroelectric alkaline-earth titanate, since ferroelectric long-range order is suppressed in CaTiO{sub 3} and SrTiO{sub 3} by quantum fluctuations, which is referred to as quantum paraelectric behavior. The rare-earth titanate EuTiO{sub 3} is similar to SrTiO{sub 3}, since it has the same valencies (Eu{sup 2+},Ti{sup 4+}) and the same ionic radii. Both are cubic at room temperature and undergo a structural phase transition to tetragonal upon cooling. In contrast to the nonmagnetic Sr{sup 2+}, the half-filled 4f shell of Eu{sup 2+} with S=7/2 has a large magnetic moment of 7μ{sub B}. Below T{sub N}=5.5 K the localized 4f moments order antiferromagnetically, while rather small fields of 1.5 T are sufficient to saturate the magnetization. Here we present field- and temperature-dependent measurements of magnetization, specific heat, and thermal expansion, exhibiting characteristic anomalies at T{sub N}. Broadband measurements of the permittivity reveal the dynamics of polar domain walls at the onset of the structural phase transition, as well as the materials quantum paraelectric nature that is masked by high conductivity for low frequencies.

  5. Influence of Feedstock Powder Modification by Heat Treatments on the Properties of APS-Sprayed Al2O3-40% TiO2 Coatings

    Science.gov (United States)

    Berger, Lutz-Michael; Sempf, Kerstin; Sohn, Yoo Jung; Vaßen, Robert

    2018-04-01

    The formation and decomposition of aluminum titanate (Al2TiO5, tialite) in feedstock powders and coatings of the binary Al2O3-TiO2 system are so far poorly understood. A commercial fused and crushed Al2O3-40%TiO2 powder was selected as the feedstock for the experimental series presented in this paper, as the composition is close to that of Al2TiO5. Part of that powder was heat-treated in air at 1150 and 1500 °C in order to modify the phase composition, while not influencing the particle size distribution and processability. The powders were analyzed by thermal analysis, XRD and FESEM including EDS of metallographically prepared cross sections. Only a maximum content of about 45 wt.% Al2TiO5 was possible to obtain with the heat treatment at 1500 °C due to inhomogeneous distribution of Al and Ti in the original powder. Coatings were prepared by plasma spraying using a TriplexPro-210 (Oerlikon Metco) with Ar-H2 and Ar-He plasma gas mixtures at plasma power levels of 41 and 48 kW. Coatings were studied by XRD, SEM including EDS linescans of metallographically prepared cross sections, and microhardness HV1. With the exception of the powder heat-treated at 1500 °C an Al2TiO5-Ti3O5 (tialite-anosovite) solid solution Al2- x Ti1+ x O5 instead of Al2TiO5 existed in the initial powder and the coatings.

  6. TiO2 effect on crystallization mechanism and physical properties of nano glass-ceramics of MgO-Al2O3-SiO2 glass system.

    Science.gov (United States)

    Jo, Sinae; Kang, Seunggu

    2013-05-01

    The effect of TiO2 on the degree of crystallization, thermal properties and microstructure for MgO-Al2O3-SiO2 glass-ceramics system containing 0-13 wt% TiO2 and 0-1.5 wt% B2O3 in which the cordierite is the main phase was studied. Using Kissinger and Augis-Bennett equations, the activation energy, 510 kJ/mol and Avrami constant, 1.8 were calculated showing the surface-oriented crystallization would be preferred. The alpha-cordierite phase was generated in the glass-ceramics of containing TiO2 of 0-5.6 wt%. However, for the glass-ceramics of TiO2 content above 7 wt%, an alpha-cordierite disappeared and micro-cordierite phase was formed. The glass-ceramics of no TiO2 added had spherical crystals of few tens nanometer size spread in the matrix. As TiO2 content increased up to 5.6 wt%, a lump of dendrite was formed. In the glass-ceramics containing TiO2 7-13 wt%, in which the main phase is micro-cordierite, the dendrite crystal disappeared and a few hundred nanometer sized crystal particles hold tightly each other were generated. The thermal conductivity of glass-ceramics of both a-cordierite and micro-cordierite base decreased with TiO2 contend added. The thermal conductivity of glass-ceramics of 1.5 wt% TiO2 added was 3.4 W/mK which is 36% higher than that of glass-ceramics of no TiO2 added. The sintering temperature for 1.5 wt% TiO2 glass-ceramics was 965 degrees C which could be concluded as to apply to LTCC process for LED packaging.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-01

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

  8. Synthesis and characterization of K2Ln2/3Ta2O7·nH2O (Ln= La, Pr, Nd), layered tantalates photo catalysts for water splitting

    International Nuclear Information System (INIS)

    Valencia S, H.; Tavizon, G.; Pfeiffer, H.; Acosta, D.; Negron M, A.

    2015-01-01

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

  9. High dielectric constant and energy density induced by the tunable TiO2 interfacial buffer layer in PVDF nanocomposite contained with core-shell structured TiO2@BaTiO3 nanoparticles

    Science.gov (United States)

    Hu, Penghao; Jia, Zhuye; Shen, Zhonghui; Wang, Peng; Liu, Xiaoru

    2018-05-01

    To realize application in high-capacity capacitors and portable electric devices, large energy density is eagerly desired for polymer-based nanocomposite. The core-shell structured nanofillers with inorganic buffer layer are recently supposed to be promising in improving the dielectric property of polymer nanocomposite. In this work, core-shell structured TO@BT nanoparticles with crystalline TiO2 buffer layer coated on BaTiO3 nanoparticle were fabricated via solution method and heat treatment. The thickness of the TO buffer layer can be tailored by modulating the additive amount of the titanate coupling agent in preparation process, and the apparent dielectric properties of nanocomposite are much related to the thickness of the TO layer. The relatively thin TO layer prefer to generate high polarization to increase dielectric constant while the relatively thick TO layer would rather to homogenize field to maintain breakdown strength. Simulation of electric field distribution in the interfacial region reveals the improving effect of the TO buffer layer on the dielectric properties of nanocomposite which accords with the experimental results well. The optimized nanoparticle TO@BT-2 with a mean thickness of 3-5 nm buffer layer of TO is effective in increasing both the ε and Eb in the PVDF composite film. The maximal discharged energy density of 8.78 J/cm3 with high energy efficiency above 0.6 is obtained in TO@BT-2/PVDF nanocomposite with 2.5 vol% loading close to the breakdown strength of 380 kV/mm. The present study demonstrates the approach to optimize the structure of core-shell nanoparticles by modulating buffer layer and provides a new way to further enlarge energy density in polymer nanocomposite.

  10. Processing of La/sub 1.8/Sr/sub 0.2/CuO4 and YBa2Cu3O7 superconducting thin films by dual-ion-beam sputtering

    International Nuclear Information System (INIS)

    Madakson, P.; Cuomo, J.J.; Yee, D.S.; Roy, R.A.; Scilla, G.

    1988-01-01

    High quality La/sub 1.8/Sr/sub 0.2/CuO 4 and YBa 2 Cu 3 O 7 superconducting thin films, with zero resistance at 88 K, have been made by dual-ion-beam sputtering of metal and oxide targets at elevated temperatures. The films are about 1.0 μm thick and are single phase after annealing. The substrates investigated are Nd-YAP, MgO, SrF 2 , Si, CaF 2 , ZrO 2 -9% Y 2 O 3 , BaF 2 , Al 2 O 3 , and SrTiO 3 . Characterization of the films was carried out using Rutherford backscattering spectroscopy, resistivity measurements, transmission electron microscopy, x-ray diffraction, and secondary ion mass spectroscopy. Substrate/film interaction was observed in every case. This generally involves diffusion of the substrate into the film, which is accompanied by, for example, the replacement of Ba by Sr in the YBa 2 Cu 2 O 7 structure, in the case of SrTiO 3 substrate. The best substrates were those that did not significantly diffuse into the film and which did not react chemically with the film. In general, the superconducting transition temperature is found to depend on substrate temperature and ion beam energy, film composition, annealing conditions, and the nature and the magnitude of the substrate/film interaction

  11. Negative thermal expansion up to 1000 C of ZrTiO4-Al2TiO5 ceramics for high-temperature applications

    International Nuclear Information System (INIS)

    Kim, I.J.; Kim, H.C.; Han, I.S.; Aneziris, C.G.

    2005-01-01

    High temperature structural ceramics based on Al 2 TiO 5 -ZrTiO 4 (ZAT) having excellent thermal-shock-resistance were synthesized by a reaction sintering. The ZAT ceramics sintered at 1600 C had a negative thermal expansions up to 1000 C and a much lower thermal expansion coefficient (0.3 ∝ 1.3 x 10 -6 /K) than that of polycrystalline Al 2 TiO 5 (1.5 x 10 -6 /K). These low thermal expansion are apparently due to a combination of microcracking caused by the large thermal expansion anisotropy of the crystal axes of the Al 2 TiO 5 phase. The microstructural degradation of the composites after various thermal treatment for high temperature applications were analyzed by scanning electron microscopy, X-ray diffraction, ultrasonic and dilatometer. (orig.)

  12. Porous TiNb2O7 Nanospheres as ultra Long-life and High-power Anodes for Lithium-ion Batteries

    International Nuclear Information System (INIS)

    Cheng, Qiushi; Liang, Jianwen; Lin, Ning; Guo, Cong; Zhu, Yongchun; Qian, Yitai

    2015-01-01

    Graphical abstract: Due to the combinative merits of porosity and nanostructure, porous TiNb 2 O 7 nanospheres exhibit ultra long cyclic life and excellent rate performance for lithium ion batteries. - Highlights: • Porous TiNb 2 O 7 nanospheres have been fabricated with the assistance of block copolymer P123. • The as-prepared TiNb 2 O 7 anodes present a reversible capacity of 160 mA h/g after 10000 cycles at 5 C with a capacity loss of only 0.0033% per cycle. • The TiNb 2 O 7 anodes show good rate performance of 167 mA h/g at 50C. • The TiNb 2 O 7 materials maintain the morphology of nanospheres and the porous structure even after 10000 cycles. - Abstract: Porous TiNb 2 O 7 nanospheres comprised of nanoparticles have been synthesized with the assistance of block copolymer P123 (EO 20 PO 70 EO 20 ). Such porous TiNb 2 O 7 nanospheres, with diameter of 500 nm, exhibit a BET surface area of 23.4 m 2 /g and pore volume of 0.155 cm 3 /g. As the anodes for lithium-ion batteries, the TiNb 2 O 7 nanospheres present a reversible capacity of 160 mA h/g after 10000 cycles at 5 C with a capacity loss of only 0.0033% per cycle, and good rate performance of 167 mA h/g at 50 C. Furthermore, the TiNb 2 O 7 materials still maintain the morphology of nanospheres and the porous structure even after 10000 cycles

  13. Robust Strategy for Crafting Li5Cr7Ti6O25@CeO2 Composites as High-Performance Anode Material for Lithium-Ion Battery.

    Science.gov (United States)

    Mei, Jie; Yi, Ting-Feng; Li, Xin-Yuan; Zhu, Yan-Rong; Xie, Ying; Zhang, Chao-Feng

    2017-07-19

    A facile strategy was developed to prepare Li 5 Cr 7 Ti 6 O 25 @CeO 2 composites as a high-performance anode material. X-ray diffraction (XRD) and Rietveld refinement results show that the CeO 2 coating does not alter the structure of Li 5 Cr 7 Ti 6 O 25 but increases the lattice parameter. Scanning electron microscopy (SEM) indicates that all samples have similar morphologies with a homogeneous particle distribution in the range of 100-500 nm. Energy-dispersive spectroscopy (EDS) mapping and high-resolution transmission electron microscopy (HRTEM) prove that CeO 2 layer successfully formed a coating layer on a surface of Li 5 Cr 7 Ti 6 O 25 particles and supplied a good conductive connection between the Li 5 Cr 7 Ti 6 O 25 particles. The electrochemical characterization reveals that Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) electrode shows the highest reversibility of the insertion and deinsertion behavior of Li ion, the smallest electrochemical polarization, the best lithium-ion mobility among all electrodes, and a better electrochemical activity than the pristine one. Therefore, Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) electrode indicates the highest delithiation and lithiation capacities at each rate. At 5 C charge-discharge rate, the pristine Li 5 Cr 7 Ti 6 O 25 only delivers an initial delithiation capacity of ∼94.7 mAh g -1 , and the delithiation capacity merely achieves 87.4 mAh g -1 even after 100 cycles. However, Li 5 Cr 7 Ti 6 O 25 @CeO 2 (3 wt %) delivers an initial delithiation capacity of 107.5 mAh·g -1 , and the delithiation capacity also reaches 100.5 mAh g -1 even after 100 cycles. The cerium dioxide modification is a direct and efficient approach to improve the delithiation and lithiation capacities and cycle property of Li 5 Cr 7 Ti 6 O 25 at large current densities.

  14. Dielectric Performance of High Permitivity Nanocomposites: Impact of Polystyrene Grafting on BaTiO3 and TiO2

    Science.gov (United States)

    2016-09-22

    prepared using high-shear mixing (Ultra-Turrax T18, IKA). All BaTiO3 nanocomposites were solution cast from DMF onto aluminum-coated glass substrates...coated from chlorobenzene onto aluminum-coated glass substrates. Figure 3 a Real dielectric permittivity ε′ measured at 1 kHz for PS@BaTiO3 HNPs... SiO2 nanocomposites, where 15% v/v PS  +  SiO2 blends exhibited degraded energy storage efficiencies when driven above 100 V/μm, while 18% v/v PS@ SiO2

  15. Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction as a highly efficient and stable visible light photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Chengbin, E-mail: chem_cbliu@hnu.edu.cn [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Cao, Chenghao [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Luo, Xubiao [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Shenglian [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

    2015-03-21

    Graphical abstract: A unique Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction was fabricated by simple electrochemical method. The heterostructures exhibit high photocatalytic activity and excellent recycling performance. - Highlights: • Ag-bridged Ag{sub 2}O nanowire network self-stability structure. • Ag{sub 2}O nanowire network/TiO{sub 2} nanotube p–n heterojunction. • High visible light photocatalytic activity. • Highly stable recycling performance. - Abstract: A unique Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction (Ag–Ag{sub 2}O/TiO{sub 2} NT) was fabricated by simple electrochemical method. Ag nanoparticles were firstly electrochemically deposited onto the surface of TiO{sub 2} NT and then were partly oxidized to Ag{sub 2}O nanowires while the rest of Ag mother nanoparticles were located at the junctions of Ag{sub 2}O nanowire network. The Ag–Ag{sub 2}O/TiO{sub 2} NT heterostructure exhibited strong visible-light response, effective separation of photogenerated carriers, and high adsorption capacity. The integration of Ag–Ag{sub 2}O self-stability structure and p–n heterojunction permitted high and stable photocatalytic activity of Ag–Ag{sub 2}O/TiO{sub 2} NT heterostructure photocatalyst. Under 140-min visible light irradiation, the photocatalytic removal efficiency of both dye acid orange 7 (AO7) and industrial chemical p-nitrophenol (PNP) over Ag–Ag{sub 2}O/TiO{sub 2} NT reached nearly 100% much higher than 17% for AO7 or 13% for PNP over bare TiO{sub 2} NT. After 5 successive cycles under 600-min simulated solar light irradiation, Ag–Ag{sub 2}O/TiO{sub 2} NT remained highly stable photocatalytic activity.

  16. Electronic structures and Eu3+ photoluminescence behaviors in Y2Si2O7 and La2Si2O7

    International Nuclear Information System (INIS)

    Zhang Zhiya; Wang Yuhua; Zhang Feng; Cao Haining

    2011-01-01

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

  17. Characterization, integration and reliability of HfO{sub 2} and LaLuO{sub 3} high-κ/metal gate stacks for CMOS applications

    Energy Technology Data Exchange (ETDEWEB)

    Nichau, Alexander

    2013-07-15

    The continued downscaling of MOSFET dimensions requires an equivalent oxide thickness (EOT) of the gate stack below 1 nm. An EOT below 1.4 nm is hereby enabled by the use of high-κ/metal gate stacks. LaLuO{sub 3} and HfO{sub 2} are investigated as two different high-κ oxides on silicon in conjunction with TiN as the metal electrode. LaLuO{sub 3} and its temperature-dependent silicate formation are characterized by hard X-ray photoemission spectroscopy (HAXPES). The effective attenuation length of LaLuO{sub 3} is determined between 7 and 13 keV to enable future interface and diffusion studies. In a first investigation of LaLuO{sub 3} on germanium, germanate formation is shown. LaLuO{sub 3} is further integrated in a high-temperature MOSFET process flow with varying thermal treatment. The devices feature drive currents up to 70μA/μm at 1μm gate length. Several optimization steps are presented. The effective device mobility is related to silicate formation and thermal budget. At high temperature the silicate formation leads to mobility degradation due to La-rich silicate formation. The integration of LaLuO{sub 3} in high-T processes delicately connects with the optimization of the TiN metal electrode. Hereby, stoichiometric TiN yields the best results in terms of thermal stability with respect to Si-capping and high-κ oxide. Different approaches are presented for a further EOT reduction with LaLuO{sub 3} and HfO{sub 2}. Thereby the thermodynamic and kinetic predictions are employed to estimate the behavior on the nanoscale. Based on thermodynamics, excess oxygen in the gate stack, especially in oxidized metal electrodes, is identified to prevent EOT scaling below 1.2 nm. The equivalent oxide thickness of HfO{sub 2} gate stacks is scalable below 1 nm by the use of thinned interfacial SiO{sub 2}. The prevention of oxygen incorporation into the metal electrode by Si-capping maintains the EOT after high temperature annealing. Redox systems are employed within the

  18. Sol–gel hybrid membranes loaded with meso/macroporous SiO2, TiO2–P2O5 and SiO2TiO2–P2O5 materials with high proton conductivity

    International Nuclear Information System (INIS)

    Castro, Yolanda; Mosa, Jadra; Aparicio, Mario; Pérez-Carrillo, Lourdes A.; Vílchez, Susana; Esquena, Jordi; Durán, Alicia

    2015-01-01

    In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO 2 , TiO 2 –P 2 O 5 and SiO 2TiO 2 –P 2 O 5 meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m 2 /g (TiO 2 –P 2 O 5 ) and 300 m 2 /g (SiO 2TiO 2 –P 2 O 5 ). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion ® at higher temperatures (120 °C) (2·10 −2  S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure. - Highlights: • Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel. • Depositions of hybrid solutions by spraying onto glass substrates were performed. • Proton conductivity was evaluated as a function of composition and porous structure

  19. Carbon and TiO{sub 2} synergistic effect on methylene blue adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Simonetti, Evelyn Alves Nunes, E-mail: evelynalvesnunes@yahoo.com.br; Simone Cividanes, Luciana de; Campos, Tiago Moreira Bastos; Rossi Canuto de Menezes, Beatriz; Brito, Felipe Sales; Thim, Gilmar Patrocínio

    2016-07-01

    Due to its high efficiency, low cost and a simple operation, the adsorption process is an important and widely used technique for industrial wastewater treatment. Recent studies on the removal of artificial dyes by adsorption include a large number of adsorbents, such as: activated carbon, silicates, carbon nanotube, graphene, fibers, titanates and doped titanates. The carbon insertion in the TiO{sub 2} structure promotes a synergistic effect on the adsorbent composite, improving the adsorption and the charge-transfer efficiency rates. However, there are few studies regarding the adsorption capacity of TiO{sub 2}/Carbon composites with the carbon concentration. This study evaluates the effect of carbon (resorcinol/formaldehyde) insertion on TiO{sub 2} structure through the adsorption process. Adsorbents were prepared by varying the carbon weight percentages using the sol-gel method. The physicochemical properties of the catalysts prepared, such as crystallinity, particle size, surface morphology, specific surface area and pore volume were investigated. The kinetic study, adsorption isotherm, pH effect and thermodynamic study were examined in batch experiments using methylene blue as organic molecule. In addition, the effect of carbon phase on the adsorption capacity of TiO{sub 2}-carbon composite was deeply investigated. SEM micrographs showed that TiO{sub 2} phase grows along the carbon phase and FT-IR results showed the presence of Ti−O−C chemical bonding. The experiments indicate that the carbon phase acted as a nucleation agent for the growth of TiO{sub 2} during the sol-gel step, with a TiO{sub 2} structure suitable for blue methylene adsorption, resulting in a material with large surface area and slit-like or wedge-shaped pores. Further experiments will show the best carbon concentration for methylene blue adsorption using a TiO{sub 2} based material. - Highlights: • This article deals with the adsorption of methylene blue onto TiO{sub 2}-Carbon

  20. Production of Al-Ti-B grain refining master alloys from Na{sub 2}B{sub 4}O{sub 7} and K{sub 2}TiF{sub 6}

    Energy Technology Data Exchange (ETDEWEB)

    Birol, Yuecel [Materials Institute, Marmara Research Center, TUBITAK, Gebze, Kocaeli (Turkey)], E-mail: yucel.birol@mam.gov.tr

    2008-06-30

    It is very desirable to replace the KBF{sub 4} salt in the popular 'halide salt' process to reduce the volume of fluoride salts to be added to molten aluminium in the production of Al-Ti-B grain refiners. Being over 2 times richer in B, Na{sub 2}B{sub 4}O{sub 7} is a promising replacement for KBF{sub 4}, and is used in the present work to produce Al-Ti-B grain refiner master alloys. A fraction of the aluminide particles were entrapped in the spent salt giving a relatively lower Ti recovery when KBF{sub 4} was replaced by Na{sub 2}B{sub 4}O{sub 7}. The grain refining performance of the Al-Ti-B grain refiner alloy thus produced was nevertheless acceptable. The spent salt became too viscous with the oxides, aluminides and borides to be removed by decanting when Na{sub 2}B{sub 4}O{sub 7}.5H{sub 2}O was used to supply boron. The viscous spent salt, entrained in the grain refiner alloy, did not only impair its performance, but also hurt the fluidity of the molten alloy and made pouring difficult.

  1. Radiation Tolerance of A2Ti2O7 Materials - A Question of Bonding?

    International Nuclear Information System (INIS)

    Whittle, Karl R.; Lumpkin, Gregory R.; Smith, Katherine L.; Blackford, Mark G.; Harvey, Elizabeth J.; Zaluzec, Nestor J.

    2007-01-01

    The resistance of Ln 2 Ti 2 O 7 (Ln = lanthanide) compounds to radiation damage is an important topic in the understanding and development of new materials by which radioactive nuclear waste can safely be immobilised. A model has been developed, from previously published density functional theory and molecular orbital theory simulations of the band structure for Ln 2 Ti 2 O 7 materials. This model provides a chemical interpretation of radiation stability. (authors)

  2. Synthesis of N and La co-doped TiO{sub 2}/AC photocatalyst by microwave irradiation for the photocatalytic degradation of naphthalene

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Dandan; Wu, Zhansheng, E-mail: wuzhans@126.com; Tian, Fei; Ye, Bang-Ce; Tong, Yanbin, E-mail: tongyanbin@sina.com

    2016-08-15

    La and N co-doped TiO{sub 2} nanoparticles supported on activated carbon (TiO{sub 2}/AC) were synthesized through a microwave-assisted sol–gel method for the synergistic removal of naphthalene solution by photocatalytic degradation. Results showed that the La and N ions were incorporated into the TiO{sub 2} framework in both the anatase and rutile phases of TiO{sub 2} for single doped and co-doped samples, which narrowed the band gap of TiO{sub 2} from 2.82 to 2.20 eV. The PL spectra of the samples showed a decrease in the recombination centers when N and La were introduced in TiO{sub 2}/AC. The 0.001La-N-TiO{sub 2}/AC photocatalyst exhibited the highest degradation efficiency of 93.5% for naphthalene under visible light within 120 min. This result was attributed to a synergistic effect involving the efficient inhibition of the recombination of photogenerated electrons and holes, the increase in surface hydroxyl, surface area, volume pores, and the increase of uptake in the visible light region. In addition, the high apparent rate constant indicated that La and N co-doping result in the increase of photoactivity. This study demonstrated the co-doped TiO{sub 2}/AC is a highly efficient photocatalyst for the removal of naphthalene. The results provided valuable information on the mechanism of naphthalene decomposition. - Highlights: • N, La codoped TiO{sub 2}/AC catalysts were synthesized by microwave-assisted. • N and La doping inhibit the recombination of photogenerated electrons and holes. • 0.001La-N-TiO{sub 2}/AC obtains photodegradation efficiency of 93.5% for naphthalene. • The photocatalysts possess good photochemical stability and reusability.

  3. H-TiO2/C/MnO2 nanocomposite materials for high-performance supercapacitors

    Science.gov (United States)

    Di, Jing; Fu, Xincui; Zheng, Huajun; Jia, Yi

    2015-06-01

    Functionalized TiO2 nanotube arrays with decoration of MnO2 nanoparticles (denoted as H-TiO2/C/MnO2) have been synthesized in the application of electrochemical capacitors. To improve both areal and gravimetric capacitance, hydrogen treatment and carbon coating process were conducted on TiO2 nanotube arrays. By scanning electron microscopy and X-ray photoelectron spectroscopy, it is confirmed that the nanostructure is formed by the uniform incorporation of MnO2 nanoparticles growing round the surface of the TiO2 nanotube arrays. Impedance analysis proves that the enhanced capacitive is due to the decrease of charge transfer resistance and diffusion resistance. Electrochemical measurements performed on this H-TiO2/C/MnO2 nanocomposite when used as an electrode material for an electrochemical pseudocapacitor presents quasi-rectangular shaped cyclic voltammetry curves up to 100 mV/s, with a large specific capacitance (SC) of 299.8 F g-1 at the current density of 0.5 A g-1 in 1 M Na2SO4 electrolyte. More importantly, the electrode also exhibits long-term cycling stability, only 13 % of SC loss after 2000 continuous charge-discharge cycles. Based on the concept of integrating active materials on highly ordered nanostructure framework, this method can be widely applied to the synthesis of high-performance electrode materials for energy storage.

  4. Spin-strain effects in the frustrated magnet Tb{sub 2}Ti{sub 2}O{sub 7} at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Gritsenko, Y.; Wosnitza, J. [HZDR/HLD, Dresden (Germany); TUD/IFP, Dresden (Germany); Zherlitsyn, S. [HZDR/HLD, Dresden (Germany); Ruminy, M.; Fennell, T. [PSI/LNS, 5232 Villigen PSI (Switzerland); Kenzelmann, M. [PSI/LDM, 5232 Villigen PSI (Switzerland)

    2016-07-01

    Geometrically frustrated magnets have attracted much attention, due to their tendency to build unconventional ground states with exotic excitations. Tb{sub 2}Ti{sub 2}O{sub 7} possesses a pyrochlore lattice as building block of the crystallographic structure, providing a basis for geometric frustration. This cubic material features Curie-Weiss temperature of Θ{sub CW} = -19 K, but no long-range magnetic order has been detected down to 50 mK indicating a large frustration. The existence of a spin-liquid state has been suggested for Tb{sub 2}Ti{sub 2}O{sub 7}. Here, we present results of ultrasonic investigations of this material. The magnetic field was applied along the [110] direction at temperatures of 20, 150 and 300 mK. Clear anomalies were found for different acoustic modes. The temperature dependence of the sound velocity shows a softening at about 500 mK and step-like features at about 150 mK suggesting a low-temperature phase transformation. This investigation sheds new light on the role of lattice degrees of freedom and magneto-elastic interactions in this material.

  5. Oxygen nonstoichiometry and defects in Mn-doped Gd2Ti2O7+x

    International Nuclear Information System (INIS)

    Porat, O.; Tuller, H.L.

    1996-01-01

    The oxygen nonstoichiometry in Mn-doped Gd 2 Ti 2 O 7 , Gd 2 (Ti 0.975 Mn 0.025 ) 2 O 7+x , was measured electrochemically, as a function of temperature and oxygen partial pressure, with the aid of an oxygen titration cell. The analysis of the data shows that the defect equilibrium can be described by considering the dominant point defects to be neutral oxygen interstitials, doubly charged oxygen vacancies, and trivalent and quadrivalent Mn ions substituted in the Ti sites. The enthalpies for the formation of neutral oxygen interstitials and trivalent Mn are determined

  6. Solution-Processed Ultrathin TiO2 Compact Layer Hybridized with Mesoporous TiO2 for High-Performance Perovskite Solar Cells.

    Science.gov (United States)

    Jeong, Inyoung; Park, Yun Hee; Bae, Seunghwan; Park, Minwoo; Jeong, Hansol; Lee, Phillip; Ko, Min Jae

    2017-10-25

    The electron transport layer (ETL) is a key component of perovskite solar cells (PSCs) and must provide efficient electron extraction and collection while minimizing the charge recombination at interfaces in order to ensure high performance. Conventional bilayered TiO 2 ETLs fabricated by depositing compact TiO 2 (c-TiO 2 ) and mesoporous TiO 2 (mp-TiO 2 ) in sequence exhibit resistive losses due to the contact resistance at the c-TiO 2 /mp-TiO 2 interface and the series resistance arising from the intrinsically low conductivity of TiO 2 . Herein, to minimize such resistive losses, we developed a novel ETL consisting of an ultrathin c-TiO 2 layer hybridized with mp-TiO 2 , which is fabricated by performing one-step spin-coating of a mp-TiO 2 solution containing a small amount of titanium diisopropoxide bis(acetylacetonate) (TAA). By using electron microscopies and elemental mapping analysis, we establish that the optimal concentration of TAA produces an ultrathin blocking layer with a thickness of ∼3 nm and ensures that the mp-TiO 2 layer has a suitable porosity for efficient perovskite infiltration. We compare PSCs based on mesoscopic ETLs with and without compact layers to determine the role of the hole-blocking layer in their performances. The hybrid ETLs exhibit enhanced electron extraction and reduced charge recombination, resulting in better photovoltaic performances and reduced hysteresis of PSCs compared to those with conventional bilayered ETLs.

  7. Fabrication and characterization of 6Li-enriched Li2TiO3 pebbles for a high Li-burnup irradiation test

    International Nuclear Information System (INIS)

    Tsuchiya, Kunihiko; Kawamura, Hiroshi

    2006-10-01

    Lithium titanate (Li 2 TiO 3 ) pebbles are considered to be a candidate material of tritium breeders for fusion reactor from viewpoints of easy tritium release at low temperatures (about 300degC) and chemical stability. In the present study, trial fabrication tests of 6 Li-enriched Li 2 TiO 3 pebbles of 1mm in diameter were carried out by a wet process with a dehydration reaction, and characteristics of the 6 Li-enriched Li 2 TiO 3 pebbles were evaluated for preparation of a high Li-burnup test in a testing reactor. Powder of 96at% 6 Li-enriched Li 2 TiO 3 was prepared by a solid state reaction, and two kinds of 6 Li-enriched Li 2 TiO 3 pebbles, namely un-doped and TiO 2 -doped Li 2 TiO 3 pebbles, were fabricated by the wet process. Based on results of the pebble fabrication tests, two kinds of 6 Li-enriched Li 2 TiO 3 pebbles were successfully fabricated with target values (density: 80-85%T.D., grain size: 2 TiO 3 pebbles was a satisfying value of about 1.05. Contact strength of these pebbles was about 6300MPa, which was almost the same as that of the Li 2 TiO 3 pebbles with natural Li. (author)

  8. Synergistic effects between TiO2 and carbon nanotubes (CNTs) in a TiO2/CNTs system under visible light irradiation.

    Science.gov (United States)

    Wu, Chung-Hsin; Kuo, Chao-Yin; Chen, Shih-Ting

    2013-01-01

    This study synthesized a TiO2/carbon nanotubes (CNTs) composite via the sol-gel method. The surface characteristics of the TiO2/CNTs composite were determined by X-ray diffraction, transmission electron microscopy, specific surface area analyser, ultraviolent (UV)-vis spectroscopy, X-ray photoelectron spectroscopy and Raman spectrometer. The photocatalytic activity ofthe TiO2/CNTs composite was evaluated by decolourizing C.I. Reactive Red 2 (RR2) under visible light irradiation. Furthermore, the effects of calcination temperature, pH, RR2 concentration, and the TiO2/CNTs composite dosage on RR2 decolourization were determined simultaneously. The optimal calcination temperature to generate TiO2 and the TiO2/CNTs composite was 673 K, as the percentage of anatase crystallization at this temperature was highest. The specific surface area of the TiO2/CNTs composite and TiO2 were 45 and 42 m2/g, respectively. The band gap of TiO2 and the TiO2/CNTs composite was 2.97 and 2.71 eV by UV-vis measurements, respectively. Experimental data indicate that the Ti-O-C bond formed in the TiO2/CNTs composite. The RR2 decolourization rates can be approximated by pseudo-first-order kinetics; moreover, only the TiO2/CNTs composite had photocatalytic activity under visible light irradiation. At pH 7, the RR2 decolourization rate constant of 0.5, 1 and 2 g/L TiO2/CNTs addition was 0.005, 0.0015, and 0.0047 min(-1), respectively. Decolourization rate increased as pH and the RR2 concentration decreased. The CNTs functioned as electron acceptors, promoting separation of photoinduced electron-hole pairs to retard their recombination; thus, photocatalytic activity of the TiO2/CNTs composite exceeded that of TiO2.

  9. Thermal relaxation and heat transport in spin ice Dy{sub 2}Ti{sub 2}O{sub 7}

    Energy Technology Data Exchange (ETDEWEB)

    Klemke, Bastian; Meissner, M.; Tennant, D.A. [Helmholtz-Zentrum Berlin (Germany); Technische Universitaet Berlin (Germany); Strehlow, P. [Technische Universitaet Berlin (Germany); Physikalisch Technische Bundesanstalt, Institut Berlin (Germany); Kiefer, K. [Helmholtz-Zentrum Berlin (Germany); Grigera, S.A. [School of Physics and Astronomy, St. Andrews (United Kingdom); Instituto de Fisica de Liquidos y Sistemas Biologicos, CONICET, UNLP, La Plata (Argentina)

    2011-07-01

    The thermal properties of single crystalline Dy{sub 2}Ti{sub 2}O{sub 7} have been studied at temperature below 30 K and magnetic fields applied along [110] direction up to 1.5 T. Based on a thermodynamic field theory (TFT) various heat relaxation and thermal transport measurements were analysed. So we were able to present not only the heat capacity of Dy{sub 2}Ti{sub 2}O{sub 7}, but also for the first time the different contributions of the magnetic excitations and their corresponding relaxation times in the spin ice phase. In addition, the thermal conductivity and the shortest relaxation time were determined by thermodynamic analysis of steady state heat transport measurements. Finally, we were able to reproduce the temperature profiles recorded in heat pulse experiments on the basis of TFT using the previously determined heat capacity and thermal conductivity data without additional parameters. Thus, TFT has been proved to be thermodynamically consistent in describing three thermal transport experiments on different time scales. The observed temperature and field dependencies of heat capacity contributions and relaxation times indicate the magnetic excitations in the spin ice Dy{sub 2}Ti{sub 2}O{sub 7} as thermally activated monopole-antimonopole defects.

  10. High-resolution photoelectron spectroscopy of TiO3H2-: Probing the TiO2- + H2O dissociative adduct

    Science.gov (United States)

    DeVine, Jessalyn A.; Abou Taka, Ali; Babin, Mark C.; Weichman, Marissa L.; Hratchian, Hrant P.; Neumark, Daniel M.

    2018-06-01

    Slow electron velocity-map imaging spectroscopy of cryogenically cooled TiO3H2- anions is used to probe the simplest titania/water reaction, TiO20/- + H2O. The resultant spectra show vibrationally resolved structure assigned to detachment from the cis-dihydroxide TiO(OH)2- geometry based on density functional theory calculations, demonstrating that for the reaction of the anionic TiO2- monomer with a single water molecule, the dissociative adduct (where the water is split) is energetically preferred over a molecularly adsorbed geometry. This work represents a significant improvement in resolution over previous measurements, yielding an electron affinity of 1.2529(4) eV as well as several vibrational frequencies for neutral TiO(OH)2. The energy resolution of the current results combined with photoelectron angular distributions reveals Herzberg-Teller coupling-induced transitions to Franck-Condon forbidden vibrational levels of the neutral ground state. A comparison to the previously measured spectrum of bare TiO2- indicates that reaction with water stabilizes neutral TiO2 more than the anion, providing insight into the fundamental chemical interactions between titania and water.

  11. Electrical and microstructural properties of CaTiO3-doped K1/2Na1 ...

    Indian Academy of Sciences (India)

    KNN) and CaTiO3- modified K1/2Na1/2NbO3 (CTO-KNN) systems, were investigated. Discs doped with 0 to 0.55% mol of CaTiO3 (CTO) were sintered at 1125°C for 2 h. Although minority phases were found in doped samples, CaTiO3 was not ...

  12. Highly Al-doped TiO{sub 2} nanoparticles produced by Ball Mill Method: structural and electronic characterization

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Desireé M. de los, E-mail: desire.delossantos@uca.es; Navas, Javier, E-mail: javier.navas@uca.es; Sánchez-Coronilla, Antonio; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín

    2015-10-15

    Highlights: • Highly Al-doped TiO{sub 2} nanoparticles were synthesized using a Ball Mill Method. • Al doping delayed anatase to rutile phase transformation. • Al doping allow controlling the structural and electronic properties of nanoparticles. - Abstract: This study presents an easy method for synthesizing highly doped TiO{sub 2} nanoparticles. The Ball Mill method was used to synthesize pure and Al-doped titanium dioxide, with an atomic percentage up to 15.7 at.% Al/(Al + Ti). The samples were annealed at 773 K, 973 K and 1173 K, and characterized using ICP-AES, XRD, Raman spectroscopy, FT-IR, TG, STEM, XPS, and UV–vis spectroscopy. The effect of doping and the calcination temperature on the structure and properties of the nanoparticles were studied. The results show high levels of internal doping due to the substitution of Ti{sup 4+} ions by Al{sup 3+} in the TiO{sub 2} lattice. Furthermore, anatase to rutile transformation occurs at higher temperatures when the percentage of doping increases. Therefore, Al doping allows us to control the structural and electronic properties of the nanoparticle synthesized. So, it is possible to obtain nanoparticles with anatase as predominant phase in a higher range of temperature.

  13. Dynamic Hydrogen Production from Methanol/Water Photo-Splitting Using Core@Shell-Structured CuS@TiO2 Catalyst Wrapped by High Concentrated TiO2 Particles

    Directory of Open Access Journals (Sweden)

    Younghwan Im

    2013-01-01

    Full Text Available This study focused on the dynamic hydrogen production ability of a core@shell-structured CuS@TiO2 photocatalyst coated with a high concentration of TiO2 particles. The rectangular-shaped CuS particles, 100 nm in length and 60 nm in width, were surrounded by a high concentration of anatase TiO2 particles (>4~5 mol. The synthesized core@shell-structured CuS@TiO2 particles absorbed a long wavelength (a short band gap above 700 nm compared to that pure TiO2, which at approximately 300 nm, leading to easier electronic transitions, even at low energy. Hydrogen evolution from methanol/water photo-splitting over the core@shell-structured CuS@TiO2 photocatalyst increased approximately 10-fold compared to that over pure CuS. In particular, 1.9 mmol of hydrogen gas was produced after 10 hours when 0.5 g of 1CuS@4TiO2 was used at pH = 7. This level of production was increased to more than 4-fold at higher pH. Cyclic voltammetry and UV-visible absorption spectroscopy confirmed that the CuS in CuS@TiO2 strongly withdraws the excited electrons from the valence band in TiO2 because of the higher reduction potential than TiO2, resulting in a slower recombination rate between the electrons and holes and higher photoactivity.

  14. Formation and structural characterization of potassium titanates and the potassium ion exchange property

    International Nuclear Information System (INIS)

    Wang Qiang; Guo Zhanhu; Chung, Jong Shik

    2009-01-01

    In the present work, K 2 Ti 2 O 5 , K 2 Ti 4 O 9 and K 2 Ti 6 O 13 are synthesized by solid state method. Their structures and morphologies are characterized by X-ray diffraction, Raman spectra and scanning electron microscopy. The binding energies of K, Ti and O in potassium titanates were then evaluated by X-ray photoelectron spectroscopy and compared with those in K/TiO 2 . Finally the corresponding K ion exchange properties are investigated by synthesizing NO oxidation catalysts with Co(NO 3 ) 2 precursor. It is found that the binding energy of K in K 2 Ti 2 O 5 is much higher than those in K 2 Ti 4 O 9 and K 2 Ti 6 O 13 , and because of which, it shows quite different catalytic performances. Compared with other potassium titanates, the K in K 2 Ti 2 O 5 is much easier to be exchanged out.

  15. High pressure synthesis of amorphous TiO{sub 2} nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Quanjun; Liu, Ran; Wang, Tianyi; Xu, Ke; Dong, Qing; Liu, Bo; Liu, Bingbing, E-mail: liubb@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Liu, Jing [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China)

    2015-09-15

    Amorphous TiO{sub 2} nanotubes with diameters of 8-10 nm and length of several nanometers were synthesized by high pressure treatment of anatase TiO{sub 2} nanotubes. The structural phase transitions of anatase TiO{sub 2} nanotubes were investigated by using in-situ high-pressure synchrotron X-ray diffraction (XRD) method. The starting anatase structure is stable up to ∼20GPa, and transforms into a high-density amorphous (HDA) form at higher pressure. Pressure-modified high- to low-density transition was observed in the amorphous form upon decompression. The pressure-induced amorphization and polyamorphism are in good agreement with the previous results in ultrafine TiO{sub 2} nanoparticles and nanoribbons. The relationship between the LDA form and α-PbO{sub 2} phase was revealed by high-resolution transmission electron microscopy (HRTEM) study. In addition, the bulk modulus (B{sub 0} = 158 GPa) of the anatase TiO{sub 2} nanotubes is smaller than those of the corresponding bulks and nanoparticles (180-240 GPa). We suggest that the unique open-ended nanotube morphology and nanosize play important roles in the high pressure phase transition of TiO{sub 2} nanotubes.

  16. Simple fabrication of TiO2/C nanocomposite with enhanced electrochemical performance for lithium-ion batteries

    International Nuclear Information System (INIS)

    Bai, Xue; Li, Tao; Qi, Yong-Xin; Gao, Xue-Ping; Yin, Long-Wei; Li, Hui; Zhu, Hui-Ling; Lun, Ning; Bai, Yu-Jun

    2015-01-01

    TiO 2 /C nanocomposites were fabricated by simple hydrolysis of tetrabutyl titanate to yield TiO 2 nanoparticles followed by carbonizing the mixture of glucose and TiO 2 at 600 °C. By merely varying the weight ratio of glucose:TiO 2 , the electrochemical performance of the composites could be optimized significantly. At a ratio of 0.8, the composite exhibits a high reversible capacity of 283.7 mA h g −1 after cycling 100 times at a current density of 100 mA g −1 , as well as the capacities of 245.1, 213.6, 179.9 and 136.6 mA h g −1 at the corresponding densities of 200, 400, 800 and 1600 mA g −1 . After cycling 1000 times at 500 mA g −1 , a capacity of 122.8 mA h g −1 was retained for the composite with a ratio of 0.8, and even a capacity of 149.1 mA h g −1 for the composite with a ratio of 0.7. The enhanced performance is ascribed to the carbon-coated TiO 2 nanoparticles uniformly embedding in the carbon matrix with appropriate carbon content

  17. Large-scale synthesis of Pb1-xLa xTiO3 ceramic powders by molten salt method

    International Nuclear Information System (INIS)

    Cai Zongying; Xing Xianran; Yu Ranbo; Liu Guirong; Xing Qifeng

    2006-01-01

    The ferroelectric perovskite type lanthanum doped lead titanate (PLT) ceramic powders were synthesized in one step with the starting materials of PbC 2 O 4 , La 2 O 3 and TiO 2 in NaCl-KCl molten salts in the temperature range of 700-950 deg. C. It was found that molten salt method was a large scale and easy preparation way to produce PLT powders with high dispersity. Tetragonal phase Pb 1-x La x TiO 3 ceramic powders were identified by XRD in the composition range 0 ≤ x ≤ 0.3 and mono-dispersed particles with spheric shape and less than 100 nm size were observed by SEM. The grain sizes of Pb 1-x La x TiO 3 ceramic powders increased with the increase of La content and decreased with calcination temperature. The grain growth progress and the possible reaction mechanism in molten salts and its influencing factors were discussed in this work. The grain growth process was the main influencing factor of the grain size, which depended on the solubility in the flux

  18. Efectos de fotodegradación propiciados por recubrimientos de TiO2 y TiO2-SiO2 obtenidos por Sol-Gel

    Directory of Open Access Journals (Sweden)

    Rodriguez Paez, J. E.

    2008-10-01

    Full Text Available Photodegradation effect is widely used for water purification this contributes to preservation and protection of environment. Titanium oxide, (TiO2, is a compound that shows up this phenomenon. TiO2 is a semiconductor which may degradate pollutants through of a oxidation process. It permit the treatment of the residual water. It this work we has conformed coatings of TiO2 y TiO2-SiO2, utilized Sol-Gel method and investigated the degradation of the blue Methylene. For this, we introduced these coatings in the blue methylene solution which was illuminated with radiation of λ=365nm to activate its photocatilist properties. The structures of the coatings were characterized using Atomic Force Microscopy (AFM and X-ray Photoelectron Spectroscopy (XPS.El efecto de fotodegradación es ampliamente utilizado para la purificación del agua, acción que contribuye a la conservación y protección del medio ambiente; el óxido de titanio (TiO2 es uno de los semiconductores que pueden degradar contaminantes mediante procesos de oxidación, lo que lo hace apto para el tratamiento de aguas residuales. En este trabajo se conformaron recubrimientos de TiO2 y TiO2-SiO2, por el método Sol-Gel, y se estudio la degradación que experimentaba una solución de azul de metileno al introducirle estos recubrimientos e iluminarlos con una radiación de λ=365nm para activar su propiedad fotocatalítica. Los recubrimientos fueron caracterizados microestructuralmente utilizando Microscopía de Fuerza Atómica (MFA y Espectroscopía de Fotoelectrones de rayos X (XPS. Los resultados obtenidos de los ensayos de fotodegradación indican que los recubrimientos con una cantidad pequeña de silicio presentan un mayor efecto de fotodegradación indicando que el silicio puede generar puntos de anclaje que facilitan las reacciones de fotocatálisis. Por otro lado, la formación de centros activos, constituidos principalmente por carbono, también contribuyeron al desarrollo de estas

  19. Preparation and solar-light photocatalytic activity of TiO2 composites: TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite

    Science.gov (United States)

    Li, Y.; Li, S. G.; Wang, J.; Li, Y.; Ma, C. H.; Zhang, L.

    2014-12-01

    Three TiO2 loaded composites, TiO2/kaolin, TiO2/diatomite, and TiO2/zeolite, were prepared in order to improve the solar-light photocatalytic activity of TiO2. The results showed that the photocatalytic activity could obviously be enhanced by loading appropriate amount of inorganic mineral materials. Meanwhile, TiO2 content, heat-treatment temperature and heat-treatment time on the photocatalytic activity were reviewed. Otherwise, the effect of solar light irradiation time and dye concentration on the photocatalytic degradation of Acid Red B was investigated. Furthermore, the degradation mechanism and adsorption process were also discussed.

  20. Influence of Co or Ce addition on the NOx storage and sulfur-resistance performance of the lean-burn NOx trap catalyst Pt/K/TiO{sub 2}-ZrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zou Zhiqiang [Tianjin Key Laboratory of Applied Catalysis Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Meng, Ming, E-mail: mengm@tju.edu.cn [Tianjin Key Laboratory of Applied Catalysis Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Tsubaki, Noritatsu [Department of Applied Chemistry, School of Engineering, University of Toyama, Gofuku 3190, Toyama city, Toyama 930 8555 (Japan); He Junjun; Wang Gang; Li Xingang; Zhou Xiaoyan [Tianjin Key Laboratory of Applied Catalysis Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

    2009-10-15

    The Pt/K/TiO{sub 2}-ZrO{sub 2} catalysts promoted by Co or Ce were prepared by successive impregnation or mechanically mixing method. The influence of Co or Ce addition on the NOx storage and sulfur-resistance performance of the catalyst was investigated carefully. The techniques of XRD, FT-IR, in-situ DRIFTS, H{sub 2}-TPR and XPS were employed for catalyst characterization. The Co or Ce addition can greatly improve the NOx storage capacity of Pt/K/TiO{sub 2}-ZrO{sub 2} due to the enhanced oxidation ability and the release of more K sites. Ce addition induces higher K/Ti atomic ratio and larger NOx storage capacity as compared with Co addition. After sulfation and regeneration, the promoted catalysts shows more or less decreased NSC than Pt/K/TiO{sub 2}-ZrO{sub 2} due to the formation of more sulfates, especially for the Co-promoted catalysts, which possess better oxidation ability and facilitate the formation of large sulfates. The effect of Ce addition on Pt/K/TiO{sub 2}-ZrO{sub 2} largely depends on the addition mode. The high oxidation ability and the high K/Ti ratio of the mechanically prepared Ce-promoted catalyst make it still possess considerable NOx storage capacity (NSC) of 142 {mu}mol/g after sulfation and regeneration. With the decrease of sulfur content in fuels, the Co- and Ce-promoted catalysts possessing large NOx storage capacity, will be applicable to the purification of lean-burn NOx.

  1. Highly oriented as-deposited superconducting laser ablated thin films of Y1Ba2Cu3O/sub 7-//sub δ/ on SrTiO3, zirconia, and Si substrates

    International Nuclear Information System (INIS)

    Koren, G.; Polturak, E.; Fisher, B.; Cohen, D.; Kimel, G.

    1988-01-01

    KrF excimer laser ablation of an Y 1 Ba 2 Cu 3 O/sub 7-//sub δ/ pellet in 0.1--0.2 Torr of O 2 ambient was used to deposit thin superconducting films onto SrTiO 3 , yttria-stabilized zirconia (YSZ), and silicon substrates at 600--700 0 C. The as-deposited 1-μm-thick films at 650--700 0 C substrate temperature were superconducting, without further high-temperature annealing. All films had a similar T/sub c/ onset of ∼92 K but different zero-resistance T/sub c/ of 90, 85, and 70 K for the films on SrTiO 3 , YSZ, and Si substrates, respectively. Angular x-ray diffraction analysis showed that all the films were highly oriented with the c axis perpendicular to their surface. Critical current densities at 77 K were about 40 000 and 10 000 A/cm 2 for the films on SrTiO 3 and YSZ, respectively. Smooth surface morphology was observed in all films, with occasional defects and cracks in the films on YSZ, which seems to explain the lower critical current in these films

  2. High-performance thermoelectric materials based on ternary TiO2/CNT/PANI composites.

    Science.gov (United States)

    Erden, Fuat; Li, Hui; Wang, Xizu; Wang, FuKe; He, Chaobin

    2018-04-04

    In the present work, we report the fabrication of high-performance thermoelectric materials using TiO2/CNT/PANI ternary composites. We showed that a conductivity of ∼2730 S cm-1 can be achieved for the binary CNT (70%)/PANI (30%) composite, which is the highest recorded value for the reported CNT/PANI composites. We further demonstrated that the Seebeck coefficient of CNT/PANI composites could be enhanced by incorporating TiO2 nanoparticles into the binary CNT/PANI composites, which could be attributed to lower carrier density and the energy scattering of low-energy carriers at the interfaces of TiO2/a-CNT and TiO2/PANI. The resulting TiO2/a-CNT/PANI ternary system exhibits a higher Seebeck coefficient and enhanced thermoelectric power. Further optimization of the thermoelectric power was achieved by water treatment and by tuning the processing temperature. A high thermoelectric power factor of 114.5 μW mK-2 was obtained for the ternary composite of 30% TiO2/70% (a-CNT (70%)/PANI (30%)), which is the highest reported value among the reported PANI based ternary composites. The improvement of thermoelectric performance by incorporation of TiO2 suggests a promising approach to enhance power factor of organic thermoelectric materials by judicial tuning of the carrier concentration and electrical conductivity.

  3. Cluster self-organization of germanate systems: suprapolyhedral precursor clusters and self-assembly of K2Nd4Ge4O13(OH)4, K2YbGe4O10(OH), K2Sc2Ge2O7(OH)2, and KScGe2O6(PYR)

    International Nuclear Information System (INIS)

    Ilyushin, G.D.; Dem'yanets, L.N.

    2008-01-01

    One performed the computerized (the TOPOS 4.0 software package) geometric and topological analyses of all known types of K, TR-germanates (TR = La-Lu, Y, Sc, In). The skeleton structure are shown as three-dimensional 3D, K, TR, Ge-patterns (graphs) with remote oxygen atoms. TR 4 3 3 4 3 3 + T 4 3 4 3, K 2 YbGe 4 O 14 (OH) pattern, TR 6 6 3 6 + T1 6 8 6 + T2 3 6 8, K 2 Sc 2 Ge 2 O 7 (OH) 2 , TR 6 4 6 4 + T 6 4 6 and KScGe 2 O 6 - TR 6 6 3 6 3 4 + T1 6 3 6 + T2 6 4 3 patterns served as crystal-forming 2D TR,Ge-patterns for K 2 Nd 4 Ge 4 O 13 (OH) 4 . One performed the 3D-simulation of the mechanism of self-arrangement of the crystalline structures: cluster-precursor - parent chain - microlayer - microskeleton (super-precursor). Within K 2 Nd 4 Ge 4 O 13 (OH) 4 , K 2 Sc 2 Ge 2 O 7 (OH) 2 and KScGe 2 O 6 one identified the invariant type of the cyclic hexapolyhedral cluster-precursor consisting of TR-octahedrons linked by diorthogroups stabilized by K atoms. For K 2 Nd 4 Ge 4 O 13 (OH) 4 one determined the type of the cyclic tetrapolyhedral cluster-precursor consisting of TR-octavertices linked by tetrahedrons. The cluster CN within the layer just for KScGe 2 O 6 water-free germanate (the PYR pyroxene analog) is equal to 6 (the maximum possible value), while in the rest OH-containing germanates it constitutes 4. One studied the formation mechanism of Ge-radicals in the form of Ge 2 O 7 and Ge 4 O 13 groupings, GeO 3 chain and the tubular structure consisting of Ge 8 O 20 fixed cyclic groupings [ru

  4. Raman spectra of the solid-solution between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 and RbCa sub 2 Nb sub 3 O sub 1 sub 0

    CERN Document Server

    Kim, H J; Yun, H S

    2001-01-01

    A site preference of niobium atom in Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) and RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0), which are the solid-solutions between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 are RbCa sub 2 Nb sub 3 O sub 1 sub 0 , has been investigated by Raman spectroscopy. The Raman spectra of Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) gave an evidence that niobium atoms substituted for titanium atoms preferably occupy the highly distorted outer octahedral sites rather than the central ones in triple-octahedral perovskite layers. In contrast, the Raman spectra of RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0) showed no clear information for the cationic arrangement in perovskite slabs. This difference indicated that a site preference of niobium atoms is observed onl...

  5. VO2/TiO2 Nanosponges as Binder-Free Electrodes for High-Performance Supercapacitors

    Science.gov (United States)

    Hu, Chenchen; Xu, Henghui; Liu, Xiaoxiao; Zou, Feng; Qie, Long; Huang, Yunhui; Hu, Xianluo

    2015-11-01

    VO2/TiO2 nanosponges with easily tailored nanoarchitectures and composition were synthesized by electrostatic spray deposition as binder-free electrodes for supercapacitors. Benefiting from the unique interconnected pore network of the VO2/TiO2 electrodes and the synergistic effect of high-capacity VO2 and stable TiO2, the as-formed binder-free VO2/TiO2 electrode exhibits a high capacity of 86.2 mF cm-2 (~548 F g-1) and satisfactory cyclability with 84.3% retention after 1000 cycles. This work offers an effective and facile strategy for fabricating additive-free composites as high-performance electrodes for supercapacitors.

  6. VO2/TiO2 Nanosponges as Binder-Free Electrodes for High-Performance Supercapacitors.

    Science.gov (United States)

    Hu, Chenchen; Xu, Henghui; Liu, Xiaoxiao; Zou, Feng; Qie, Long; Huang, Yunhui; Hu, Xianluo

    2015-11-04

    VO2/TiO2 nanosponges with easily tailored nanoarchitectures and composition were synthesized by electrostatic spray deposition as binder-free electrodes for supercapacitors. Benefiting from the unique interconnected pore network of the VO2/TiO2 electrodes and the synergistic effect of high-capacity VO2 and stable TiO2, the as-formed binder-free VO2/TiO2 electrode exhibits a high capacity of 86.2 mF cm(-2) (~548 F g(-1)) and satisfactory cyclability with 84.3% retention after 1000 cycles. This work offers an effective and facile strategy for fabricating additive-free composites as high-performance electrodes for supercapacitors.

  7. Dielectric behaviour of (Ba,Sr)TiO3 perovskite borosilicate glass ceramics

    International Nuclear Information System (INIS)

    Yadav, Avadhesh Kumar; Gautam, C.R.

    2013-01-01

    Various perovskite (Ba,Sr)TiO 3 borosilicate glasses were prepared by rapid melt-quench technique in the glass system ((Ba 1-x Sr x ).TiO 3 )-(2SiO 2 .B 2 O 3 )-(K 2 O)-(La 2 O 3 ). On the basis of differential thermal analysis results, glasses were converted into glass ceramic samples by regulated heat treatment schedules. The dielectric behaviour of crystallized barium strontium titanate borosilicate glass ceramic samples shows diffuse phase transition. The study depicts the dielectric behaviour of glass ceramic sample BST5K1L0.2S814. The double relaxation was observed in glass ceramic samples corresponding 80/20% Ba/Sr due to change in crystal structure from orthorhombic to tetragonal and tetragonal to cubic with variation of temperature. The highest value of dielectric constant was found to be 48289 for the glass ceramic sample BST5K1L0.2S814. The high value of dielectric constant attributed to space charge polarization between the glassy phase and perovskite phase. Due to very high value of dielectric constant, such glass ceramics are used for high energy storage devices. La 2 O 3 acts as nucleating agent for crystallization of glass to glass ceramics and enhances the dielectric constant and retarded dielectric loss. Such glass ceramics can be used in high energy storage devices such as barrier layer capacitors, multilayer capacitors etc. (author)

  8. Low temperature synthesis and photoluminescence study of Y2Ti2O7:Eu nanoparticles

    International Nuclear Information System (INIS)

    Selvi, E.; Prasad, A.I.; Nigam, Sandeep; Sudarsan, V.; Vatsa, R.K.

    2014-01-01

    Very small nanoparticles both undoped and doped Y 2 Ti 2 O 7 were prepared at a low temperature (700℃). The obtained undoped and doped Y 2 Ti 2 O 7 samples exhibit good crystallinity, smaller average crystallite size. Based on the detailed luminescence studies, it is confirmed that the lanthanide doped nano-materials have improved luminescence properties compared to the corresponding bulk samples. (author)

  9. 2D Electron Gas with 100% Spin-Polarization in the (LaMnO3)2/(SrTiO3)2 Superlattice under Uniaxial Strain

    KAUST Repository

    Cossu, Fabrizio

    2014-07-28

    By first-principles calculations we investigate the structural, electronic, and magnetic properties of the (LaMnO3)2/(SrTiO3)2 superlattice. We find that a monoclinic C2h symmetry is energetically favorable and that the spins order ferromagnetically. Under both compressive and tensile uniaxial strain the electronic structure of the superlattice shows a half-metallic character. In particular, a fully spin-polarized two-dimensional electron gas, which traces back to the Ti 3dxy orbitals, is achieved under compressive uniaxial strain. The (LaMnO3)2/(SrTiO3)2 superlattice is analysed with respect to its structure, magnetism, and electronic properties. Our results demonstrate that uniaxial strain in an experimentally accessible range, both tensile and compressive, can be used to induce half-metallicity. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Comment on 'Pressure-induced changes in transport properties of layered La1.2Ca1.8Mn2O7'

    International Nuclear Information System (INIS)

    Ganguly, R.; Siruguri, V.; Gopalakrishnan, I.K.; Yakhmi, J.V.

    2000-01-01

    We show that the compound La 1.2 Ca 1.8 Mn 2 O 7 does not form with layered Sr 3 Ti 2 O 7 -type structure as reported by Kamenev et al. [Phys. Rev. B 56, R12 688 (1997)]. Detailed analysis of the powder x-ray diffraction pattern of this compound (synthesized by using the solid-state method) by Rietveld method shows that it forms a multiphase mixture comprising hole-doped perovskite manganates (La 1-x Ca x MnO 3 ) as the majority phases and CaO as the minority phase

  11. Existence region of phases of laminated perovskite-like structre of A/sub 2/B/sub 2/O/sub 7/ composition

    Energy Technology Data Exchange (ETDEWEB)

    Sych, A M; Titov, Yu A [Kievskij Gosudarstvennyj Univ. (Ukrainian SSR)

    1982-06-01

    Generalizing the known data for ferroelectrics of A/sub 2/B/sub 2/O/sub 7/ type (LnTi/sub 2/O/sub 7/, in particular) geometrical conditions of existence of laminated perovskite-like structure are determined: 0.603 A < anti Rsub(Bsup(6)) <= 0.665 A, anti Rsub(Asup(12))/Rsub(Bsup(6)) > 2.045. The geometrical conditions presented are necessary but not sufficient. A supposition is made that phases GaLnTiNbO/sub 7/ (Ln = Pr - Eu) and CaLnTiTaO/sub 7/ (Ln = La - Eu) with laminated perovskite-like structure can be prepared under high pressures.

  12. Structure refinement, far infrared spectroscopy, and dielectric characterization of (1-x)La(Mg1/2Ti1/2)O3-xLa2/3TiO3 solid solutions

    Science.gov (United States)

    Salak, Andrei N.; Khalyavin, Dmitry D.; Ferreira, Victor M.; Ribeiro, José L.; Vieira, Luís G.

    2006-05-01

    Dielectric properties of (1-x)La(Mg1/2Ti1/2)O3-xLa2/3TiO3 [(1-x)LMT-xLT] ceramics (0infrared (FIR) frequency ranges. The crystal structure sequence in (1-x)LMT-xLT reported by different authors has been analyzed and revised. FIR spectroscopy was used to characterize the lattice contribution to the dielectric response at microwave frequencies. The complex dielectric function was evaluated from the reflectivity data and extrapolated down to a gigahertz range. Compositional variations of the fundamental microwave dielectric parameters estimated by different methods are compared and discussed. The dependence of the quality factor on the composition in LMT-LT is interpreted in terms of the reduction of spatial phonon correlations originated from the increasing amount of La vacancies. This approach could account for the compositional behavior of the dielectric loss commonly observed in a number of microwave mixed systems.

  13. Synthesis, impedance and dielectric properties of LaBi5Fe2Ti3O18

    Indian Academy of Sciences (India)

    Unknown

    The compound, LaBi5Fe2Ti3O18, is a five-layered material belonging to the family of bismuth layered structure ... et al (1971) and. James et al (1998) also reported single-phase transition in ... ceramic method. ... 30 kV/cm field at 140°C.

  14. Direct Observation of Room-Temperature Stable Magnetism in LaAlO3/SrTiO3 Heterostructures.

    Science.gov (United States)

    Yang, Ming; Ariando; Zhou, Jun; Asmara, Teguh Citra; Krüger, Peter; Yu, Xiao Jiang; Wang, Xiao; Sanchez-Hanke, Cecilia; Feng, Yuan Ping; Venkatesan, T; Rusydi, Andrivo

    2018-03-21

    Along with an unexpected conducting interface between nonmagnetic insulating perovskites LaAlO 3 and SrTiO 3 (LaAlO 3 /SrTiO 3 ), striking interfacial magnetisms have been observed in LaAlO 3 /SrTiO 3 heterostructures. Interestingly, the strength of the interfacial magnetic moment is found to be dependent on oxygen partial pressures during the growth process. This raises an important, fundamental question on the origin of these remarkable interfacial magnetic orderings. Here, we report a direct evidence of room-temperature stable magnetism in a LaAlO 3 /SrTiO 3 heterostructure prepared at high oxygen partial pressure by using element-specific soft X-ray magnetic circular dichroism at both Ti L 3,2 and O K edges. By combining X-ray absorption spectroscopy at both Ti L 3,2 and O K edges and first-principles calculations, we qualitatively ascribe that this strong magnetic ordering with dominant interfacial Ti 3+ character is due to the coexistence of LaAlO 3 surface oxygen vacancies and interfacial (Ti Al -Al Ti ) antisite defects. On the basis of this new understanding, we revisit the origin of the weak magnetism in LaAlO 3 /SrTiO 3 heterostructures prepared at low oxygen partial pressures. Our calculations show that LaAlO 3 surface oxygen vacancies are responsible for the weak magnetism at the interface. Our result provides direct evidence on the presence of room-temperature stable magnetism and a novel perspective to understand magnetic and electronic reconstructions at such strategic oxide interfaces.

  15. High-temperature x-ray diffraction study of HfTiO4-HfO2 solid solutions

    International Nuclear Information System (INIS)

    Carpenter, D.A.

    1975-01-01

    High-temperature x-ray diffraction techniques were used to determine the axial thermal expansion curves of HfTiO 4 -HfO 2 solid solutions as a function of composition. Data show increasing anisotropy with increasing HfO 2 content. An orthorhombic-to-monoclinic phase transformation was detected near room temperature for compositions near the high HfO 2 end of the orthorhombic phase field and for compositions within the two-phase region (HfTiO 4 solid solution plus HfO 2 solid solution). An orthorhombic-to-cubic phase transformation is indicated by data from oxygen-deficient materials at greater than 1873 0 K. (U.S.)

  16. Concentration Dependence of Luminescent Properties for Sr2TiO4:Eu3+ Red Phosphor and Its Charge Compensation

    Directory of Open Access Journals (Sweden)

    Zhou Lu

    2012-01-01

    Full Text Available Sr2TiO4:Eu3+ phosphors using M+ (M = Li+, Na+, and K+ as charge compensators were prepared by the solid-state reaction. The powders were investigated by powder X-ray diffraction (XRD and photoluminescence spectra (PL to study the phase composition, structure, and luminescent properties. The results showed that Li+ ion was the best charge compensator. The phase was Sr2TiO4 when the doping concentration was small (x≤10.0%. When x reached 15.0%, the phase turned into Sr3Ti3O7 because of the structure damage. The phosphor could be effectively excited by ultraviolet (365, 395 nm and blue light (465 nm, and thenitemitted intense red light that peaked at around 620 nm (5D0→7F2. In addition, the emission of 700 nm (5D0→7F4 enhanced the red light color purity. The CIE chromaticity coordinates of samples with the higher red emission were between (0.650, 0.344 and (0.635, 0.352. Doped layered titanate Sr2TiO4:Eu3+ is a promising candidate red phosphor for white LEDs which can be suited for both near-UV LED chip and blue LED chip.

  17. Comparison of reduction agents in the synthesis of infinite-layer LaNiO2 films

    International Nuclear Information System (INIS)

    Ikeda, Ai; Manabe, Takaaki; Naito, Michio

    2014-01-01

    Highlights: • Reduction agents were compared from a viewpoint of the facility for topotactic reduction of LaNiO 3 to LaNiO 2 films. • TiH 2 and CaH 2 yielded infinite-layer LaNiO 2 with low and metallic resistivity. • H 2 released from metal hydrides plays a dominant role in the topotactic reduction. - Abstract: Reduction agents, such as activated carbon, TiH 2 , and CaH 2 , were compared from a viewpoint of the facility for the topotactic reduction of LaNiO 3 to LaNiO 2 films. Activated carbon did not yield infinite-layer LaNiO 2 whereas both of TiH 2 and CaH 2 yielded infinite-layer LaNiO 2 with low resistivity (∼1 mΩ cm at 300 K) as well as metallic behavior down to 70 K. Thermal desorption spectroscopy indicated that H 2 released from metal hydrides plays a dominant role in the topotactic reduction

  18. Transforming n=1 members of the Ruddlesden-Popper phases to a n=3 member through metathesis: synthesis of a new layered perovskite, Ca2La2CuTi2O10

    International Nuclear Information System (INIS)

    Sivakumar, T.; Lofland, S.E.; Ramanujachary, K.V.; Ramesha, K.; Subbanna, G.N.; Gopalakrishnan, J.

    2004-01-01

    We report the formation of a new n=3 Ruddlesden-Popper (R-P) layered perovskite oxide, Ca 2 La 2 CuTi 2 O 10 (I), in the metathesis reaction between NaLaTiO 4 and Ca 2 CuO 2 Cl 2 (n=1 R-P phases) at 700 deg. C in air. Rietveld refinement of powder XRD data shows that I is isostructural with Sr 4 Ti 3 O 10 (space group I4/mmm; a=3.8837(5), c=27.727(6) A), consisting of triple perovskite CuTi 2 O 10 sheets wherein Cu and Ti are ordered at the central and terminal octahedral sites, respectively. Magnetization data provide support for the presence of strong antiferromagnetically coupled CuO 2 sheets in the structure. I is metastable decomposing at higher temperatures (∼950 deg. C) to a mixture of perovskite-like CaLa 2 CuTi 2 O 9 and CaO. Interestingly, the reaction between NaLaTiO 4 and Sr 2 CuO 2 Cl 2 follows a different metathesis route, 2NaLaTiO 4 +Sr 2 CuO 2 Cl 2La 2 CuO 4 +2SrTiO 3 +2NaCl, revealing multiplicity of reaction pathways for solid-state metathesis reactions

  19. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials.

    Science.gov (United States)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-08

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO 2 epitaxial growth and BaTiO 3 conversion. Through the TiO 2 epitaxial growth on FTO substrate, (001) oriented TiO 2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO 2 NBA was conducted to enlarge the surface area for effective Ba 2+ ion diffusion during the perovskite conversion process from TiO 2 to BaTiO 3 . The final structure of perovskite BaTiO 3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO 3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  20. Highly piezoelectric BaTiO3 nanorod bundle arrays using epitaxially grown TiO2 nanomaterials

    Science.gov (United States)

    Jang, Seon-Min; Yang, Su Chul

    2018-06-01

    Low-dimensional piezoelectric nanostructures such as nanoparticles, nanotubes, nanowires, nanoribbons and nanosheets have been developed for potential applications as energy harvesters, tunable sensors, functional transducers and low-power actuators. In this study, lead-free BaTiO 3 nanorod bundle arrays (NBA) with highly piezoelectric properties were successfully synthesized on fluorine-doped tin oxide (FTO) substrate via a two-step process consisting of TiO2 epitaxial growth and BaTiO3 conversion. Through the TiO2 epitaxial growth on FTO substrate, (001) oriented TiO2 nanostructures formed vertically-aligned NBA with a bundle diameter of 80 nm and an aspect ratio of six. In particular, chemical etching of the TiO2 NBA was conducted to enlarge the surface area for effective Ba2+ ion diffusion during the perovskite conversion process from TiO2 to BaTiO3. The final structure of perovskite BaTiO3 NBA was found to exhibit a feasible piezoelectric response of 3.56 nm with a clear phase change of 180° from the single BaTiO3 bundle, by point piezoelectric forced microscopy (PFM) analysis. Consequently, highly piezoelectric NBA could be a promising nanostructure for various nanoscale electronic devices.

  1. Thermal properties of Na2MoO4(s) and Na2Mo2O7(s) by high-temperature Calvet calorimetry in the temperature range 335 K to 760 K

    International Nuclear Information System (INIS)

    Iyer, V.S.; Agarwal, Renu; Roy, K.N.; Venkateswaran, R.S.; Venugopal, V.; Sood, D.D.

    1990-01-01

    Enthalpy increment measurements were made on Na 2 MoO 4 and Na 2 Mo 2 O 7 in the temperature range 335 K to 760 K by the drop method using a high-temperature Calvet calorimeter. The calorimeter was calibrated using an electrical method and synthetic sapphire SRM-720(Al 2 O 3 ). An on-line computer was used for acquiring and processing results from the calorimeter. The enthalpy increments for Na 2 MoO 4 and Na 2 Mo 2 O 7 were least-squares fitted to a polynomial with temperature and are given. The thermal properties of Na 2 MoO 4 and Na 2 Mo 2 O 7 were obtained using the above experimental values. These are the first experimental results on the thermal properties of these compounds. (author)

  2. Influence of difference quantity La-doped TiO{sub 2} photoanodes on the performance of dye-sensitized solar cells: A strategy for choosing an appropriate doping quantity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zige; Li, Guoxiang; Cui, Zijian; Zhang, Kaiyue; Feng, Yaqing [School of Chemical Engineering and Technology, Tianjin University, Weijin Roard 92#, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Weijin Roard 92#, Tianjin 300072 (China); Meng, Shuxian, E-mail: msxmail@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Weijin Roard 92#, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Engineering, Weijin Roard 92#, Tianjin 300072 (China)

    2016-05-15

    Facilitated by TiO{sub 2} particles adsorbing lanthanide ions in hydrosol, La-doped TiO{sub 2} was produced by a hydrothermal method. The structure, optical and photoluminescence properties of down-converting photoelectrode with the La{sup 3+} were characterized by X-ray (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray detector (EDX) and N{sub 2} adsorption-desorption isotherms measurement. The photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs) fabricated with 0.05 g-La/TiO{sub 2} reached 7.02%, which gave an efficiency improved by 10.36% compared with that of cells fabricated from pure TiO{sub 2}. The improvement in efficiency was ascribed to more dyes adsorbed on the surface of TiO{sub 2}. - Graphical abstract: (a) J–V curves of La-doped photoelectrodes with different La(NO{sub 3}){sub 3}·6H{sub 2}O amounts; (b) the curves of efficiency changing with the amount of La(NO{sub 3}){sub 3}·6H{sub 2}O. The photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs) fabricated with 0.05 g-La/TiO{sub 2} reached 7.02%, which gave an efficiency improved by 10.36% compared with that of cells fabricated from pure TiO{sub 2}.

  3. Sandwich structured MoO2@TiO2@CNT nanocomposites with high-rate performance for lithium ion batteries

    International Nuclear Information System (INIS)

    Yuan, Dandan; Yang, Wanli; Ni, Jiangfeng; Gao, Lijun

    2015-01-01

    Titanium dioxide (TiO 2 ) is an important anode candidate for Li-ion battery (LIB) due to its properties of excellent cycle, high safety and low cost. However, the poor electrical conductivity of TiO 2 presents a significant challenge hampering its practical application in LIBs. Most researches have been concentrated on developing TiO 2 composites with metals, metal oxides and carbonaceous materials to improve its conductivity. In this work, we investigated a sandwich structured MoO 2 @TiO 2 @CNT nanocomposite through a simple three-step synthesis method. The CNT and highly conductive MoO 2 under/on the TiO 2 layer are served as flexible and strong electronic paths for rapid electron and ion transport. The resulting MoO 2 @TiO 2 @CNT hybrid structures show improved specific capacity and cycling stability compared with TiO 2 @CNT. In addition, the MoO 2 @TiO 2 @CNT composites also show a favorable rate capability, demonstrating its potential as anode material for LIBs

  4. Progress of studies on preparation of TiO2 photocatalysts with sol-gel auto igniting synthesis

    Science.gov (United States)

    Wu, Di; Shi, Zaifeng; Zhang, Xiaopeng; Xinghui, Wu

    2017-11-01

    In this article, influencing factors on the kinetics of the process of Sol-gel Auto igniting Synthesis (SAS) which is an advanced technology for preparing nanometer particles of inorganic materials were reviewed. The studies on preparing of nanometer TiO2 photocatalysts with SAS were focused. It was concluded that SAS will play an important role in practical preparing of high-pure nanometer TiO2 powder, and as a technical support, preparation of titania TiO2 from titanic iron ore with SAS is feasible and practicable.

  5. ADSORCIÓN DE ALDEHÍDOS INSATURADOS SOBRE TiO2

    OpenAIRE

    Natalia Ortega; Oswaldo Núñez

    2012-01-01

    En el presente trabajo se estudió la adsorción de aldehídos insaturados sobre la superficie del TiO2. Para evaluar su eficiencia como catalizador, se realizaron experimentos de fotocatálisis heterogénea de p-nitrofenol (PNF) y una muestra proveniente de efluentes industriales. Se empleó un simulador solar y cuatro sistemas de TiO2: el TiO2-sólo (sin modificar) y los sistemas TiO2-dienal constituidos por la adsorción química de 2,4 hexadienal, 2,4 heptadienal y el trans-cinamaldehído sobre la ...

  6. Batisite, Na2BaTi2(Si4O12)O2, from Inagli massif, Aldan, Russia: crystal-structure refinement and high-temperature X-ray diffraction study

    Science.gov (United States)

    Zolotarev, Andrey A.; Zhitova, Elena S.; Gabdrakhmanova, Faina A.; Krzhizhanovskaya, Maria G.; Zolotarev, Anatoly A.; Krivovichev, Sergey V.

    2017-12-01

    The crystal structure of batisite, Na2BaTi2 (Si4O12)O2, from the Inagli massif (Aldan, Yakutia, Russia) was refined to R 1 = 0.032 for 1449 unique observed reflections. The mineral is orthorhombic, Imma, a = 8.0921(5), b = 10.4751(7), c = 13.9054(9) Å, V = 1178.70(13) Å3. The mineral is based upon three-dimensional titanosilicate framework consisting of chains of corner-sharing MO6 octahedra ( M = Ti, Nb, Fe and Zr) and vierer chains of corner-sharing SiO4 tetrahedra. Both chains are parallel to the a axis and are linked by sharing peripheral O atoms. The octahedral chains display disorder of M atoms and bridging O sites related to the out-of-center distortion of octahedral geometry around Ti4+ cations. Electron microprobe analysis gives SiO2 39.46, TiO2 24.66, BaO 21.64, Na2O 7.56, K2O 4.38, Fe2O3 0.90, ZrO2 0.66, Nb2O5 0.36, (H2O)calc 0.58, sum 99.76 wt%. The seven strongest X-ray powder-diffraction lines [listed as d in Å (I) hkl] are: 8.39 (94) 011, 3.386 (56) 031, 3.191 (36) 123, 2.910 (46) 222, 2.896 (100) 024, 2.175 (45) 035, 1.673 (57) 055. The thermal behaviour of batisite in the temperature range from 25 to 950 °C was studied using high-temperature powder X-ray diffraction. The thermal expansion coefficients along the principal crystallographic axes are: α a = 14.4 × 10-6, α b = 8.7 × 10-6, α c = 8.4 × 10-6, α V = 31.5 °C-1 for the temperature range 25-500 °C and α a = 19.6 × 10-6, α b = 9.1 × 10-6, α c = 8.8 × 10-6, α V = 37.6 °C-1 for the temperature range 500-900 °C. The direction of maximal thermal expansion is parallel to the chains of both MO6 octahedra and SiO4 tetrahedra, which can be explained by the stretching of silicate chains due to the increasing thermal vibrations of the Ba2+ cations. At 1000 °C, the titanosilicate framework in batisite collapses with the formation of fresnoite, Ba2TiSi2O7O.

  7. Diffusion barrier performance of novel Ti/TaN double layers for Cu metallization

    International Nuclear Information System (INIS)

    Zhou, Y.M.; He, M.Z.; Xie, Z.

    2014-01-01

    Highlights: • Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum. • The Ti/TaN double layers improved the adhesion with Cu thin films and showed good diffusion barrier between Cu and SiO 2 /Si up to the annealing condition. • The failure mechanism of Ti/TaN bi-layer is similar with the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu 3 Si. - Abstract: Novel Ti/TaN double layers offering good stability as a barrier against Cu metallization have been made achievable by annealing in vacuum better than 1 × 10 −3 Pa. Ti/TaN double layers were formed on SiO 2 /Si substrates by DC magnetron sputtering and then the properties of Cu/Ti/TaN/SiO 2 /Si film stacks were studied. It was found that the Ti/TaN double layers provide good diffusion barrier between Cu and SiO 2 /Si up to 750 °C for 30 min. The XRD, Auger and EDS results show that the Cu–Si compounds like Cu 3 Si were formed by Cu diffusion through Ti/TaN barrier for the 800 °C annealed samples. It seems that the improved diffusion barrier property of Cu/Ti/TaN/SiO 2 /Si stack is due to the diffusion of nitrogen along the grain boundaries in Ti layer, which would decrease the defects in Ti film and block the diffusion path for Cu diffusion with increasing annealing temperature. The failure mechanism of Ti/TaN bi-layer is similar to the Cu/TaN/Si metallization system in which Cu atoms diffuse through the grain boundary of barrier and react with silicon to form Cu 3 Si

  8. Synthesis and Photocatalytic Activity of Anatase TiO2 Nanoparticles-coated Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Xie Yi

    2009-01-01

    Full Text Available Abstract A simple and straightforward approach to prepare TiO2-coated carbon nanotubes (CNTs is presented. Anatase TiO2 nanoparticles (NPs with the average size ~8 nm were coated on CNTs from peroxo titanic acid (PTA precursor even at low temperature of 100 °C. We demonstrate the effects of CNTs/TiO2 molar ratio on the adsorption capability and photocatalytic efficiency under UV–visible irradiation. The samples showed not only good optical absorption in visible range, but also great adsorption capacity for methyl orange (MO dye molecules. These properties facilitated the great enhancement of photocatalytic activity of TiO2 NPs-coated CNTs photocatalysts. The TiO2 NPs-coated CNTs exhibited 2.45 times higher photocatalytic activity for MO degradation than that of pure TiO2.

  9. Facile synthesis of a conjugation-grafted-TiO{sub 2} nanohybrid with enhanced visible-light photocatalytic properties from nanotube titanic acid precursors

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yanru; Zhang, Min, E-mail: zm1012@henu.edu.cn; Zhang, Zhihua; Li, Qiuye; Yang, Jianjun [Henan University, National and Local Joint Engineering Research Center for Applied Technology of Hybrid Nanomaterials (China)

    2016-08-15

    A conjugation-grafted-TiO{sub 2} nanohybrid was synthesized by chemically grafting conjugated structures on the surface of nanotube titanic acid (NTA) precursor-based TiO{sub 2} through the controlled thermal degradation of a coacervated polymer layer of polyvinyl alcohol (PVA). The interfacial interactions between the NTA precursor-based TiO{sub 2} and conjugated structures were characterized using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Moreover, the effects of the NTA’s pretreatment temperature and the weight ratio of NTA to PVA on the photocatalytic degradation of methyl orange were also investigated. A higher NTA pretreatment temperature and a lower NTA to PVA weight ratio were found to enhance photogenerated electron–hole separation efficiency and photocatalytic activity. Moreover, the conjugation-grafted-TiO{sub 2} nanohybrid synthesized from the NTA precursor displayed a much higher visible-light photocatalytic activity than that of the sample obtained from the P25 precursor. The origin of the enhanced photocatalytic activity under visible-light irradiation is also discussed in detail.

  10. Instability of Hydrogenated TiO2

    Energy Technology Data Exchange (ETDEWEB)

    Nandasiri, Manjula I.; Shutthanandan, V.; Manandhar, Sandeep; Schwarz, Ashleigh M.; Oxenford, Lucas S.; Kennedy, John V.; Thevuthasan, Suntharampillai; Henderson, Michael A.

    2015-11-06

    Hydrogenated TiO2 (H-TiO2) is toted as a viable visible light photocatalyst. We report a systematic study on the thermal stability of H-implanted TiO2 using X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA). Protons (40 keV) implanted at a ~2 atom % level within a ~120 nm wide profile of rutile TiO2(110) were situated ~300 nm below the surface. NRA revealed that this H-profile broadened preferentially toward the surface after annealing at 373 K, dissipated out of the crystal into vacuum at 473 K, and was absent within the beam sampling depth (~800 nm) at 523 K. Photoemission showed that the surface was reduced in concert with these changes. Similar anneals had no effect on pristine TiO2(110). The facile bulk diffusivity of H in rutile, as well as its activity toward interfacial reduction, significantly limits the utilization of H-TiO2 as a photocatalyst. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. The research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

  11. Structure determinations for Ca3Ti2O7, Ca4Ti3O10, Ca3.6Sr0.4Ti3O10 and a refinement of Sr3Ti2O7

    International Nuclear Information System (INIS)

    Elcombe, M.M.; Kisi, E.H.; Hawkins, K.D.; White, T.J.; Goodman, P.; Matheson, S.

    1991-01-01

    The structures of the orthorhombic Ruddlesden-Popper (A n+1 B n X 3n+1 ) phases Ca 3 Ti 2 O 7 (n=2) refined from neutron powder diffraction data at λ=1.893 A. They consist of coherent intergrowths of perovskite (CaTiO 3 ) blocks, n TiO 6 octahedra thick, with single layers of CaO having a distorted NaCl configuration. TiO 6 octahedra are tilted and distorted in a very similar fashion to those in CaTiO 3 (n=∞). This fact was used to determine the space groups of the layered structures. Convergent-beam electron diffraction patterns are best matched by calculations in the above space groups which are thus confirmed. Octahedral tilt angles increase slightly in the sequence n=2, 3, ∞. Strontium addition reduces the octahedral tilt angles because of preferential substitution of Sr on the Ca sites within the perovskite blocks of Ca 4 Ti 3 O 10 . The algorithm used to produce starting models for structure refinements is thought to be generally applicable to Ruddlesden-Popper and possibly other layered perovskite structures. It furnishes the predictions: (a) all n-even compounds in the Ca n+1 Ti n O 3n+1 series will have space group Ccm2 1 , (b) all n-odd compounds in this series will have space group Pcab, (c) all A n+1 B n X 3n+1 series for which the n=∞ end member (ABX 3 ) is isostructural with CaTiO 3 will be isostructural with the compounds reported above (e.g. Ca n+1 Zr n O 3n+1 ). (orig./WL)

  12. Comparison of reduction agents in the synthesis of infinite-layer LaNiO2 films

    Science.gov (United States)

    Ikeda, Ai; Manabe, Takaaki; Naito, Michio

    2014-11-01

    Reduction agents, such as activated carbon, TiH2, and CaH2, were compared from a viewpoint of the facility for the topotactic reduction of LaNiO3 to LaNiO2 films. Activated carbon did not yield infinite-layer LaNiO2 whereas both of TiH2 and CaH2 yielded infinite-layer LaNiO2 with low resistivity (∼1 mΩ cm at 300 K) as well as metallic behavior down to 70 K. Thermal desorption spectroscopy indicated that H2 released from metal hydrides plays a dominant role in the topotactic reduction.

  13. Fabrication and characterization of metal-ferroelectric (PbZr0.6Ti0.4O3)-insulator (La2O3)-semiconductor capacitors for nonvolatile memory applications

    Science.gov (United States)

    Juan, Trevor Pi-Chun; Lin, Cheng-Li; Shih, Wen-Chieh; Yang, Chin-Chieh; Lee, Joseph Ya-Min; Shye, Der-Chi; Lu, Jong-Hong

    2009-03-01

    Metal-ferroelectric-insulator-semiconductor thin-film capacitors with Pb(Zr0.6,Ti0.4)O3 (PZT) ferroelectric layer and high-k lanthanum oxide (La2O3) insulator layer were fabricated. The outdiffusion of atoms between La2O3 and silicon was examined by the secondary-ion-mass spectroscopy. The size of memory window as a function of PZT annealing temperature was discussed. The maximum memory window saturated to 0.7 V, which is close to the theoretical memory window ΔW ≈2dfEc≈0.8 V with higher annealing temperatures above 700 °C. The memory window starts to decrease due to charge injection when the sweep voltage is higher than 5 V at 600 °C-annealed samples. The C-V flatband voltage shift (ΔVFB) as a function of charge injection was characterized in this work. An energy band diagram of the Al/PZT//La2O3/p-Si system was proposed to explain the memory window and the flatband voltage shift.

  14. Synthesis of TiO{sub 2} sol in a neutral solution using TiCl{sub 4} as a precursor and H{sub 2}O{sub 2} as an oxidizing agent

    Energy Technology Data Exchange (ETDEWEB)

    Sasirekha, Natarajan; Rajesh, Baskaran [Department of Chemical Engineering, National Central University, Chung-Li 320, Taiwan (China); Chen, Yu-Wen, E-mail: ywchen@cc.ncu.edu.t [Department of Chemical Engineering, National Central University, Chung-Li 320, Taiwan (China)

    2009-11-02

    Nanosize TiO{sub 2} thin film on glass substrate was obtained through dip-coating method using TiO{sub 2} sol. Suspended nanosize TiO{sub 2} sols with anatase structure in aqueous solution were synthesized by sol-gel method using TiCl{sub 4} as a precursor. TiCl{sub 4} was reacted with an aqueous solution of NH{sub 4}OH to form Ti(OH){sub 4}, and H{sub 2}O{sub 2} was then added to form peroxo titanic acid. It was further heated in water and converted to TiO{sub 2}. The effects of the preparation parameters, viz., pH value of the Ti(OH){sub 4} gel, concentration of H{sub 2}O{sub 2}, and heating temperature and time, on the properties of the TiO{sub 2} sol were investigated. The materials were characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, and transmission electron microscopy. The results showed that the primary TiO{sub 2} particles were rhombus with the major axis ca. 10 nm and minor axis ca. 4 nm, and were in anatase structure. The sol was excellent in dispersibility and was stable in neutral and even slight basic conditions for at least 2 years without causing agglomeration. The best preparation condition was optimized with the pH value of Ti(OH){sub 4} gel at 8, H{sub 2}O{sub 2}/TiO{sub 2} mole ratio of 2, and heating at 97 {sup o}C for 8 h. The transparent adherent TiO{sub 2} film on glass substrates exhibits strong hydrophilicity after illuminating with ultraviolet light and it can be used as an efficient photocatalyst.

  15. Thermoplastic starch composites with TiO2 particles: Preparation, morphology, rheology and mechanical properties.

    Science.gov (United States)

    Ostafińska, A; Mikešová, J; Krejčíková, S; Nevoralová, M; Šturcová, A; Zhigunov, A; Michálková, D; Šlouf, M

    2017-08-01

    Composites of thermoplastic starch (TPS) with titanium dioxide particles (mTiO 2 ; average size 0.1μm) with very homogeneous matrix and well-dispersed filler were prepared by a two-step method, including solution casting (SC) followed by melt mixing (MM). Light and scanning electron microscopy confirmed that only the two-step procedure (SC+MM) resulted in ideally homogeneous TPS/mTiO 2 systems. The composites prepared by single-step MM contained non-plasticized starch granules and the composites prepared by single-step SC suffered from mTiO 2 agglomeration. Dynamic mechanical measurements showed an increase modulus with increasing filler concentration. In TPS containing 3wt.% of mTiO 2 the stiffness was enhanced by >40%. Further experiments revealed that the recommended addition of chitosan or the exchange of mTiO 2 for anisometric titanate nanotubes with high aspect ratio did not improve the properties of the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Systems Li2B4O7 (Na2B4O7, K2B4O7)-N2H3H4OH-H2O at 25 deg C

    International Nuclear Information System (INIS)

    Skvortsov, V.G.; Sadetdinov, Sh.V.; Akimov, V.M.; Mitrasov, Yu.N.; Petrova, O.V.; Klopov, Yu.N.

    1994-01-01

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

  17. Selective adsorption of thiophenic compounds from fuel over TiO2/SiO2 under UV-irradiation.

    Science.gov (United States)

    Miao, Guang; Ye, Feiyan; Wu, Luoming; Ren, Xiaoling; Xiao, Jing; Li, Zhong; Wang, Haihui

    2015-12-30

    This study investigates selective adsorption of thiophenic compounds from fuel over TiO2/SiO2 under UV-irradiation. The TiO2/SiO2 adsorbents were prepared and then characterized by N2 adsorption, X-ray diffraction and X-ray photoelectron spectroscopy. Adsorption isotherms, selectivity and kinetics of TiO2/SiO2 were measured in a UV built-in batch reactor. It was concluded that (a) with the employment of UV-irradiation, high organosulfur uptake of 5.12 mg/g was achieved on the optimized 0.3TiO2/0.7SiO2 adsorbent at low sulfur concentration of 15 ppmw-S, and its adsorption selectivity over naphthalene was up to 325.5; (b) highly dispersed TiO2 served as the photocatalytic sites for DBT oxidation, while SiO2 acted as the selective adsorption sites for the corresponding oxidized DBT using TiO2 as a promoter, the two types of active sites worked cooperatively to achieve the high adsorption selectivity of TiO2/SiO2; (c) The kinetic rate-determining step for the UV photocatalysis-assisted adsorptive desulfurization (PADS) over TiO2/SiO2 was DBT oxidation; (d) consecutive adsorption-regeneration cycles suggested that the 0.3TiO2/0.7SiO2 adsorbent can be regenerated by acetonitrile washing followed with oxidative air treatment. This work demonstrated an effective PADS approach to greatly enhance adsorption capacity and selectivity of thiophenic compounds at low concentrations for deep desulfurization under ambient conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Hierarchically multifunctional K-OMS-2/TiO2/Fe3O4 heterojunctions for the photocatalytic oxidation of humic acid under solar light irradiation.

    Science.gov (United States)

    Zhang, Tong; Yan, Xiaoli; Sun, Darren Delai

    2012-12-01

    A multifunctional heterojunctioned K-OMS-2/TiO(2)/Fe(3)O(4) (KTF) nanocomposite was successfully synthesized using a combination of hydrothermal and co-precipitation techniques. The resultant sample was characterized by XRD, FESEM, TEM, N(2) adsorption, XPS and VSM. Its photocatalytic activity was demonstrated in the photocatalytic degradation of humic acid (HA). Morphology characterization showed the hierarchical structure of the synthesized material, and XRD results revealed that both the rutile and anatase TiO(2) structures are present in the sample. The average pore diameters and BET surface area of the synthesized KTF heterojunctions were 40 nm and 134.42 m(2)/g, respectively. XPS spectra confirmed the presence of Fe(3)O(4) and TiO(2) in the synthesized material, and the valences of Mn were kept at +3 and +4 after the grafting of Fe(3)O(4) and TiO(2). The synthesized material showed good magnetic response and photocatalytic activity under simulated solar light irradiation, and 85.7% of HA was decomposed after 120 min in the presence of KTF nanocomposites. The reusability study suggested that the magnetic recovered material was stable enough for multiple recycling usages, verifying its potential application in water purification. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Hierarchical domain structure of lead-free piezoelectric (Na{sub 1/2} Bi{sub 1/2})TiO{sub 3}-(K{sub 1/2} Bi{sub 1/2})TiO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chengtao, E-mail: lchentao@vt.edu; Wang, Yaojin; Ge, Wenwei; Li, Jiefang; Viehland, Dwight [Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Delaire, Olivier [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Li, Xiaobin; Luo, Haosu [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China)

    2016-05-07

    We report a unique hierarchical domain structure in single crystals of (Na{sub 1/2}Bi{sub 1/2})TiO{sub 3}-xat. %(K{sub 1/2}Bi{sub 1/2})TiO{sub 3} for x = 5 and 8 by transmission electron microscopy (TEM). A high density of polar nano-domains with a lamellar morphology was found, which were self-assembled into a quadrant-like configuration, which then assembled into conventional ferroelectric macro-domains. Studies by high resolution TEM revealed that the polar lamellar regions contained a coexistence of in-phase and anti-phase oxygen octahedral tilt regions of a few nanometers in size. Domain frustration over multiple length scales may play an important role in the stabilization of the hierarchy, and in reducing the piezoelectric response of this Pb-free piezoelectric solid solution.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-25

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

  1. Comportamiento dinámico de la conductividad térmica de material cerámico de estructura (Al2O3(ZnO/SnO2+Ti0,1O2

    Directory of Open Access Journals (Sweden)

    Omar, Rodríguez P.

    2013-06-01

    Full Text Available Not availableEn este trabajo, se presentan los resultados del comportamiento simulado y la medición experimental de la conductividad térmica σT de material cerámico crudo de fases (Al2O3(ZnO/SnO2+Ti0,1O2, utilizado en la fabricación de sensores de radiación térmica para el control de procesos industriales. Los resultados anteriores se obtuvieron teniendo en cuenta la aplicación de un modelo matemático de radiación de cuerpo negro, como una función no lineal dependiente de: la temperatura, permitividad eléctrica relativa y variables como humedad relativa y voltaje medidos con un dispositivo electrónico desarrollado por el grupo ESSOPTO de la Universidad Central. Por otro lado, se calculó y se simuló el comportamiento térmico del potencial químico responsable de la propagación de la energía en la estructura del compuesto (Al2O3(ZnO/SnO2+Ti0,1O2, dependiendo del tipo de distribución del tipo de portador (n y (p del material.

  2. Synthesis and photoluminescence study of rare earth activated phosphor Na2La2B2O7

    International Nuclear Information System (INIS)

    Nagpure, P.A.; Omanwar, S.K.

    2012-01-01

    The photoluminescence properties in UV and N-UV excitable range for the phosphors of Na 2 La 2 B 2 O 7 : RE (RE=Eu, Tb, Ce, Sm, Gd) are investigated. The solution combustion synthesis technique was employed for the synthesis of the phosphors Na 2 La 2 B 2 O 7 : RE. The photoluminescence measurements of the phosphors were carried out on a HITACHI F7000 Fluorescence Spectrophotometer. The PL and PL excitation (PLE) spectra indicate that the main emission wavelength of Na 2 La 2 B 2 O 7 : Eu are 591 and 615 nm, Na 2 La 2 B 2 O 7 : Ce shows dominating emission peak at 387 nm and Na 2 La 2 B 2 O 7 : Tb displays green emission at 493, 544, 593 and 620 nm at 254 nm excitation, while Na 2 La 2 B 2 O 7 : Sm shows the main emission peak wavelengths 566 and 604 nm at 405 nm excitation and Na 2 La 2 B 2 O 7 : Gd shows dominating emission peak at 312 nm at 274 nm excitation. These phosphors may provide a new kind of luminescent materials under ultraviolet and near ultraviolet excitation for various applications. - Highlights: ► We use the combustion technique for synthesis of Na 2 La 2 B 2 O 7 : RE phosphor. ► Phosphor Na 2 La 2 B 2 O 7 : Eu 3+ shows intense red emission under UV excitation. ► Phosphor Na 2 La 2 B 2 O 7 : Tb 3+ shows intense green emission under UV excitation. ► Phosphor Na 2 La 2 B 2 O 7 : Sm 3+ shows orange red emission under near UV excitation. ► Phosphors Na 2 La 2 B 2 O 7 : Ce 3+ and Na 2 La 2 B 2 O 7 : Gd 3+ show near UV and UVB emissions under UV excitation.

  3. Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials

    International Nuclear Information System (INIS)

    Morgado, Edisson Jr; Jardim, P M; Marinkovic, Bojan A; Rizzo, Fernando C; Abreu, Marco A S de; Zotin, Jose L; Araujo, Antonio S

    2007-01-01

    H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO 2 followed by proton exchange were compared to their bulk H 2 Ti 3 O 7 counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H 2 Ti 3 O 7 nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H 2 Ti 3 O 7 converts into TiO 2 (B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 deg. C through topotactic mechanisms with the intermediate formation of nanostructured H 2 Ti 6 O 13 and H 2 Ti 12 O 25 , which are more condensed layered titanates eventually rearranging to TiO 2 (B). Our results suggest that the intermediate tunnel structure H 2 Ti 12 O 25 is the final layered intermediate phase, on which TiO 2 (B) nucleates and grows. The conversion of nanostructured TiO 2 (B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology

  4. Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials.

    Science.gov (United States)

    Morgado, Edisson; Jardim, P M; Marinkovic, Bojan A; Rizzo, Fernando C; de Abreu, Marco A S; Zotin, José L; Araújo, Antonio S

    2007-12-12

    H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO(2) followed by proton exchange were compared to their bulk H(2)Ti(3)O(7) counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H(2)Ti(3)O(7) nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H(2)Ti(3)O(7) converts into TiO(2)(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 degrees C through topotactic mechanisms with the intermediate formation of nanostructured H(2)Ti(6)O(13) and H(2)Ti(12)O(25), which are more condensed layered titanates eventually rearranging to TiO(2)(B). Our results suggest that the intermediate tunnel structure H(2)Ti(12)O(25) is the final layered intermediate phase, on which TiO(2)(B) nucleates and grows. The conversion of nanostructured TiO(2)(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

  5. Multistep structural transition of hydrogen trititanate nanotubes into TiO2-B nanotubes: a comparison study between nanostructured and bulk materials

    Science.gov (United States)

    Morgado, Edisson, Jr.; Jardim, P. M.; Marinkovic, Bojan A.; Rizzo, Fernando C.; de Abreu, Marco A. S.; Zotin, José L.; Araújo, Antonio S.

    2007-12-01

    H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO2 followed by proton exchange were compared to their bulk H2Ti3O7 counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H2Ti3O7 nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H2Ti3O7 converts into TiO2(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 °C through topotactic mechanisms with the intermediate formation of nanostructured H2Ti6O13 and H2Ti12O25, which are more condensed layered titanates eventually rearranging to TiO2(B). Our results suggest that the intermediate tunnel structure H2Ti12O25 is the final layered intermediate phase, on which TiO2(B) nucleates and grows. The conversion of nanostructured TiO2(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

  6. Directed laser processing of compacted powder mixtures Al2O3-TiO2-Y2O3

    Directory of Open Access Journals (Sweden)

    Vlasova M.

    2013-01-01

    Full Text Available The phase formation, microstructure and surface texture of laser treated ternary powder mixtures of Al2O3-TiO2-Y2O3 had been studied. Rapid high temperature heating and subsequent rapid cooling due to the directed movement of the laser beam forms concave ceramic tracks. Phase composition and microstructure of the tracks depends on the Al2O3 content and the TiO2/Y2O3 ratio of the initial mixtures. The main phases observed are Y3Al5O12, Y2Ti2O7, Al2O3 and Al2TiO5. Due to the temperature gradient in the heating zone, complex layered structures are formed. The tracks consist of three main layers: a thin surface layer, a layer of crystallization products of eutectic alloys, and a lower sintered layer. The thickness of the crystallization layer and the shrinkage of the irradiation zone depend on the amount of Y3Al5O12 and Al2O3 crystallized from the melt.

  7. Hydrogen isotope behavior on Li2TiO3

    International Nuclear Information System (INIS)

    Olivares, Ryan; Oda, Takuji; Tanaka, Satoru; Oya, Yasuhisa; Tsuchiya, Kunihiko

    2004-01-01

    The surface nature of Li 2 TiO 3 and the adsorption behavior of water on Li 2 TiO 3 surface were studied by XPS/UPS and FT/IR. Preliminary experiments by Ar ion sputtering, heating and water exposure were conducted, and the following results were obtained. (1) By Ar sputtering, Li deficient surface was made, and Ti was reduced from Ti 4+ to Ti 3+ . (2) By heating sputtered samples over 573-673 K, Li emerged on the surface and Ti was re-oxidized to Ti 4+ . The surface -OH was removed. The valence band of Li 2 TiO 3 became similar to that of TiO 2 . (3) By water exposure at 623 K, H 2 O could be adsorbed dissociatively on the surface. LiOH was not formed. (4) The nature of Li 2 TiO 3 surface resembles that of TiO 2 , rather than Li 2 O. (author)

  8. Threshold voltage control in TmSiO/HfO2 high-k/metal gate MOSFETs

    Science.gov (United States)

    Dentoni Litta, E.; Hellström, P.-E.; Östling, M.

    2015-06-01

    High-k interfacial layers have been proposed as a way to extend the scalability of Hf-based high-k/metal gate CMOS technology, which is currently limited by strong degradations in threshold voltage control, channel mobility and device reliability when the chemical oxide (SiOx) interfacial layer is scaled below 0.4 nm. We have previously demonstrated that thulium silicate (TmSiO) is a promising candidate as a high-k interfacial layer, providing competitive advantages in terms of EOT scalability and channel mobility. In this work, the effect of the TmSiO interfacial layer on threshold voltage control is evaluated, showing that the TmSiO/HfO2 dielectric stack is compatible with threshold voltage control techniques commonly used with SiOx/HfO2 stacks. Specifically, we show that the flatband voltage can be set in the range -1 V to +0.5 V by the choice of gate metal and that the effective workfunction of the stack is properly controlled by the metal workfunction in a gate-last process flow. Compatibility with a gate-first approach is also demonstrated, showing that integration of La2O3 and Al2O3 capping layers can induce a flatband voltage shift of at least 150 mV. Finally, the effect of the annealing conditions on flatband voltage is investigated, finding that the duration of the final forming gas anneal can be used as a further process knob to tune the threshold voltage. The evaluation performed on MOS capacitors is confirmed by the fabrication of TmSiO/HfO2/TiN MOSFETs achieving near-symmetric threshold voltages at sub-nm EOT.

  9. Microstructural and electronic properties of highly oriented Tl0.5Pb0.5Sr2CaCu2O7 films on LaAlO3

    International Nuclear Information System (INIS)

    Kountz, D.J.; Gai, P.L.; Wilker, C.; Holstein, W.L.; Pellicone, F.M.

    1992-01-01

    Epitaxial T1 0.5 Pb 0.5 Sr 2 CaCu 2 O 7 films produced by rf magnetron sputtering followed by annealing in the presence of thallium oxide vapor have been produced on (100) LaAl0 3 substrates. These films are highly c-axis oriented with rocking curve full width at half maximum less than 0.4 degrees. The resulting two copper oxide layer films exhibit microwave surface resistance at 10 GHz of 60 ± 3 μΩ at 4.2 K and 498 ± 10 μΩ at 70 K (T c =88 ± 2 K). The degree of lattice mismatch between this phase and the LaAl0 3 substrate is very small resulting in epitaxial thin films. This material exhibits very little intrinsic defect structure

  10. Impedance spectroscopy of Ba3Sr2DyTi3V7O30 ceramic

    Indian Academy of Sciences (India)

    Administrator

    Polycrystalline sample of Ba3Sr2DyTi3V7O30 was prepared at 950°C using a high-temperature solid-state ... Introduction. Though a large number of ferroelectric oxides of different .... change in its shape with rise in temperature suggesting a change in the .... Singh K S, Sati R and Choudhary R N P 1992 J. Mater. Sci. Lett.

  11. Geometrical frustration in the ferromagnetic pyrochlore Ho2Ti2O7

    DEFF Research Database (Denmark)

    Harris, M.J.; Bramwell, S.T.; McMorrow, D.F.

    1997-01-01

    We report a detailed study of the pyrochlore Ho2Ti2O7, in which the magnetic ions (Ho3+) are ferromagnetically coupled with J similar to 1 K. We show that the presence of local Ising anisotropy leads to a geometrically frustrated ground state, preventing long-range magnetic order down to at least 0...

  12. Synthesis of nanostructured TiO2 (anatase) and TiO2(B) in ionic liquids

    Czech Academy of Sciences Publication Activity Database

    Mansfeldová, Věra; Lásková, Barbora; Krýsová, Hana; Zukalová, Markéta; Kavan, Ladislav

    2014-01-01

    Roč. 230, JUL 2014 (2014), s. 85-90 ISSN 0920-5861 R&D Projects: GA ČR GA13-07724S; GA MŠk 7E09117 Grant - others:European Commission(XE) NMP-229036 Institutional support: RVO:61388955 Keywords : TiO2(B) * ionic liquid * electrochemistry Subject RIV: CG - Electrochemistry Impact factor: 3.893, year: 2014

  13. Fabrication of TiO{sub 2} hierarchical architecture assembled by nanowires with anatase/TiO{sub 2}(B) phase-junctions for efficient photocatalytic hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Yong; Ouyang, Feng, E-mail: ouyangfh@hit.edu.cn

    2017-05-01

    Highlights: • H-titanate nanowires hierarchical architectures (TNH) were prepared by a hydrothermal method. • Calcinations of TNH leads to the formation of anatase/TiO{sub 2}(B) phase-junctions. • The hierarchical architecture offered enhanced light harvesting and large specific surface area. • The 1D nanowires and anatase/TiO{sub 2}(B) phase-junctions both can enhance the separation of photoinduced electron-hole. • The products calcined at the optimum conditions (450 °C) exhibited a maximum hydrogenproduction rate of 7808 μmol g{sup −1} h{sup −1}. - Abstract: TiO{sub 2} hierarchical architecture assembled by nanowires with anatase/TiO{sub 2}(B) phase-junctions was prepared by a hydrothermal process followed by calcinations. The optimum calcination treatment (450 °C) not only led to the formation of anatase/TiO{sub 2}(B) phase-junctions, but also kept the morphology of 1D nanowire and hierarchical architecture well. The T-450 load 0.5 wt% Pt cocatalysts showed the best photocatalytic hydrogen production activity, with a maximum hydrogen production rate of 7808 μmol g{sup −1} h{sup −1}. The high photocatalytic activity is ascribed to the combined effects of the following three factors: (1) the hierarchical architecture exhibits better light harvesting; (2) the larger specific surface area provides more surface active sites for the photocatalytic reaction; (3) the 1D nanowires and anatase/TiO{sub 2}(B) phase-junctions both can enhance the separation of photoinduced electron-hole pairs and inhibit their recombination.

  14. Investigating the solubility and cytocompatibility of CaO-Na2 O-SiO2 /TiO2 bioactive glasses.

    Science.gov (United States)

    Wren, Anthony W; Coughlan, Aisling; Smith, Courtney M; Hudson, Sarah P; Laffir, Fathima R; Towler, Mark R

    2015-02-01

    This study aims to investigate the solubility of a series of titanium (TiO2 )-containing bioactive glasses and their subsequent effect on cell viability. Five glasses were synthesized in the composition range SiO2 -Na2 O-CaO with 5 mol % of increments TiO2 substituted for SiO2 . Glass solubility was investigated with respect to (1) exposed surface area, (2) particle size, (3) incubation time, and (4) compositional effects. Ion release profiles showed that sodium (Na(+) ) presented high release rates after 1 day and were unchanged between 7 and 14 days. Calcium (Ca(2+) ) release presented a significant change at each time period and was also composition dependent, where a reduction in Ca(2+) release is observed with an increase in TiO2 concentration. Silica (Si(4+) ) release did not present any clear trends while no titanium (Ti(4+) ) was released. Cell numbers were found to increase up to 44%, compared to the growing control population, with a reduction in particle size and with the inclusion of TiO2 in the glass composition. © 2014 Wiley Periodicals, Inc.

  15. Preparation, characterization and photocatalytic activity of TiO2 ...

    Indian Academy of Sciences (India)

    Photocatalyst; TiO2 nanoparticle; polyaniline; conducting polymer; core-shell nanocomposite. 1. Introduction ..... tine TiO2 nanoparticles, HCl-doped PANI and PANI/TiO2 ..... Karim M R, Lim K T, Lee M S, Kim K and Yeum J H 2009 Synth. Met.

  16. High-throughput identification of higher-κ dielectrics from an amorphous N2-doped HfO2TiO2 library

    International Nuclear Information System (INIS)

    Chang, K.-S.; Lu, W.-C.; Wu, C.-Y.; Feng, H.-C.

    2014-01-01

    Highlights: • Amorphous N 2 -doped HfO 2TiO 2 libraries were fabricated using sputtering. • Structure and quality of the dielectric and interfacial layers were investigated. • κ (54), J L < 10 −6 A/cm 2 , and equivalent oxide thickness (1 nm) were identified. - Abstract: High-throughput sputtering was used to fabricate high-quality, amorphous, thin HfO 2TiO 2 and N 2 -doped HfO 2TiO 2 (HfON–TiON) gate dielectric libraries. Electron probe energy dispersive spectroscopy was used to investigate the structures, compositions, and qualities of the dielectric and interfacial layers of these libraries to determine their electrical properties. A κ value of approximately 54, a leakage current density <10 −6 A/cm 2 , and an equivalent oxide thickness of approximately 1 nm were identified in an HfON–TiON library within a composition range of 68–80 at.% Ti. This library exhibits promise for application in highly advanced metal–oxide–semiconductor (higher-κ) gate stacks

  17. Perovskite oxynitride LaTiOxNy thin films: Dielectric characterization in low and high frequencies

    International Nuclear Information System (INIS)

    Lu, Y.; Ziani, A.; Le Paven-Thivet, C.; Benzerga, R.; Le Gendre, L.; Fasquelle, D.; Kassem, H.

    2011-01-01

    Lanthanum titanium oxynitride (LaTiO x N y ) thin films are studied with respect to their dielectric properties in low and high frequencies. Thin films are deposited by radio frequency magnetron sputtering on different substrates. Effects of nitrogen content and crystalline quality on dielectric properties are investigated. In low-frequency range, textured LaTiO x N y thin films deposited on conductive single crystal Nb–STO show a dielectric constant ε′ ≈ 140 with low losses tanδ = 0.012 at 100 kHz. For the LaTiO x N y polycrystalline films deposited on conductive silicon substrates with platinum (Pt/Ti/SiO 2 /Si), the tunability reached up to 57% for a weak electric field of 50 kV/cm. In high-frequency range, epitaxial LaTiO x N y films deposited on MgO substrate present a high dielectric constant with low losses (ε′ ≈ 170, tanδ = 0.011, 12 GHz).

  18. Effect of atomic-arrangement matching on La{sub 2}O{sub 3}/Ge heterostructures for epitaxial high-k-gate-stacks

    Energy Technology Data Exchange (ETDEWEB)

    Kanashima, T., E-mail: kanashima@ee.es.osaka-u.ac.jp; Zenitaka, M.; Kajihara, Y.; Yamada, S.; Hamaya, K. [Graduate School of Engineering Science, Osaka University, Machkaneyama 1-3, Toyonaka, Osaka 560-8531 (Japan); Nohira, H. [Tokyo City University, 1-28-1 Tamazutumi, Setagaya-ku, Tokyo 158-8557 (Japan)

    2015-12-14

    We demonstrate a high-quality La{sub 2}O{sub 3} layer on germanium (Ge) as an epitaxial high-k-gate-insulator, where there is an atomic-arrangement matching condition between La{sub 2}O{sub 3}(001) and Ge(111). Structural analyses reveal that (001)-oriented La{sub 2}O{sub 3} layers were grown epitaxially only when we used Ge(111) despite low growth temperatures less than 300 °C. The permittivity (k) of the La{sub 2}O{sub 3} layer is roughly estimated to be ∼19 from capacitance-voltage (C-V) analyses in Au/La{sub 2}O{sub 3}/Ge structures after post-metallization-annealing treatments, although the C-V curve indicates the presence of carrier traps near the interface. By using X-ray photoelectron spectroscopy analyses, we find that only Ge–O–La bonds are formed at the interface, and the thickness of the equivalent interfacial Ge oxide layer is much smaller than that of GeO{sub 2} monolayer. We discuss a model of the interfacial structure between La{sub 2}O{sub 3} and Ge(111) and comment on the C-V characteristics.

  19. Dependence of Photocatalytic Activity of TiO2-SiO2 Nanopowders

    Directory of Open Access Journals (Sweden)

    M. Riazian

    2014-10-01

    Full Text Available Structural properties and chemical composition change the photocatalytic activity in TiO2-SiO2 nanopowder composite. The SiO2-TiO2 nanostructure is synthesized based on sol–gel method. The nanoparticles are characterized by x-ray fluorescents (XRF, x- ray diffraction (XRD, tunneling electron microscopy (TEM, field emission scanning electron microscopy (FE-SEM, UV-vis. Spectrophotometer and furrier transmission create infrared absorption (FTIR techniques. The rate constant k for the degradation of methylen blue in its aqueous solution under UV irradiation is determined as a measure of photocatalytic activity. Dependence between photocatalytic activity and SiO2 content in the composite is determined. Rate constant k is found dependent on the content of SiO2 in the composite that calcined at 900 oC. The addition of low composition SiO2 to the TiO2 matrix (lower than 45% enhances the photocatalytic activity due to thermal stability and increasing in the surface area. The effects of chemical compositions on the surface topography and the crystallization of phases are studied.

  20. Boosted surface acidity in TiO{sub 2} and Al{sub 2}O{sub 3}-TiO{sub 2} nanotubes as catalytic supports

    Energy Technology Data Exchange (ETDEWEB)

    Camposeco, R. [Molecular Engineering Program, Mexican Institute of Petroleum, 07730, México, D.F. (Mexico); Department of Chemistry, UAM-A, 55534, México, D.F. (Mexico); Castillo, S., E-mail: scastill@imp.mx [Molecular Engineering Program, Mexican Institute of Petroleum, 07730, México, D.F. (Mexico); Department of Chemical Engineering, ESIQIE-IPN, 75876, México, D.F. (Mexico); Mejía-Centeno, Isidro; Navarrete, J.; Nava, N. [Molecular Engineering Program, Mexican Institute of Petroleum, 07730, México, D.F. (Mexico)

    2015-11-30

    Graphical abstract: - Highlights: • Surface acidity of NTs was modified by adding alumina. • Brönsted acid sites remain constant but Lewis acid sites are increased remarkably. • IR characterization by lutidine and pyridine confirms the surface acidity of NTs. • 98% of NO conversion was reached between 380 and 480 °C on NT-5Al. • The boosted surface acidity of NT-Al improves the catalytic activity for SCR-NO. - Abstract: In this study, titanate nanotubes (NT) and titanate nanotubes with alumina (NT-Al) were studied as solid acid catalytic supports to show the relationship between the kind of acidity and catalytic activity. The supports were characterized by XRD, TEM, FTIR, XPS, and tested in the SCR-NO with NH{sub 3}. It was found that the amount of Brönsted acid sites was maintained and the Lewis acid sites were significantly affected by the addition of alumina (1, 3, 5 and 10 wt.%); such acidity was higher than that of the titanate nanotubes (NT) by two-fold. To confirm the formation of titanate nanotubes and titanate nanotubes with alumina, transmission electron microscopy (TEM) was used. X-ray diffraction (XRD) revealed the formation of the H{sub 2}Ti{sub 4}O{sub 9}·H{sub 2}O phase. All NT and NT-Al supports presented catalytic activity to remove NO with NH{sub 3} under lean conditions, confirming the presence of an important amount of Brönsted and Lewis acid sites in both NT and NT-Al supports.

  1. The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

    Science.gov (United States)

    Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

    2013-09-01

    Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na2Ti2O5·H2O) particles (W = 9-12 nm and L = 82-115 nm) and rice like pure anatase-TNR particles (W = 8-13 nm and L = 81-134 nm) are obtained by the hydrothermal treatment of P25-TiO2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = -2.82 (P25-TiO2), -13.5 (TNT) and -22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C9H10ClN5O2) degradation to CO2 formation under UV irradiation because of its largest surface area 176 m2 g-1 among the catalysts studied.

  2. Effects of additives on microstructures of titanate based nanotubes prepared by the hydrothermal process

    International Nuclear Information System (INIS)

    Kubo, Takashi; Sugimoto, Keijiro; Onoki, Takamasa; Nakahira, Atsushi; Yamasaki, Yuki

    2009-01-01

    Silica-containing TiO 2 -derived titanate nanotubes were prepared by the addition of a small amount of tetraethyl orthosilicate (TEOS) to TiO 2 -derived titanate nanotubes prepared by the hydrothermal process and a subsequent heat-treatment at 473 K in air. The microstructure and thermal behavior of synthesized silica containing TiO 2 -derived titanate nanotubes were investigated by various methods such as X-ray diffraction (XRD), X-ray absorption fine structure (XAF), and X-ray photoelectron spectroscopy (XPS). As a result, the addition of a small amount of TEOS leaded to the improvement of the thermal stability for TiO 2 -derived titanate nanotubes. XPS results revealed that Si was combined onto the surface of TiO 2 -derived titanate nanotubes, forming partial Si-O-Ti chemical bonds. Therefore, it was inferred that the thermal stability could be modified by forming partial Si-O-Ti chemical bonds at interface of silica and TiO 2 -derived titanate nanotubes. (author)

  3. Sol-gel synthesis of TiO2-SiO2 photocatalyst for β-naphthol photodegradation

    International Nuclear Information System (INIS)

    Qourzal, S.; Barka, N.; Tamimi, M.; Assabbane, A.; Nounah, A.; Ihlal, A.; Ait-Ichou, Y.

    2009-01-01

    Silica gel supported titanium dioxide particles (TiO 2 -SiO 2 ) prepared by sol-gel method was as photocatalyst in the degradation of β-naphthol in water under UV-illumination. The prepared sample has been characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The supported catalyst had large surface area and good sedimentation ability. The photodegradation rate of β-naphthol under UV-irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The experiments were measured by high performance liquid chromatography (HPLC). The photodegradation rate of β-naphthol using 60% TiO 2 -SiO 2 particles was faster than that using TiO 2 'Degussa P-25', TiO 2 'PC-50' and TiO 2 'Aldrich' as photocatalyst by 2.7, 4 and 7.8 times, respectively. The kinetics of photocatalytic β-naphthol degradation was found to follow a pseudo-first-order rate law. The effect of the TiO 2 loading on the photoactivity of TiO 2 -SiO 2 particles was also discussed. With good photocatalytic activity under UV-irradiation and the ability to be readily separated from the reaction system, this novel kind of catalyst exhibited the potential effective in the treatment of organic pollutants in aqueous systems.

  4. Magnetic order, magnetic correlations, and spin dynamics in the pyrochlore antiferromagnet Er2Ti2O7

    Science.gov (United States)

    Dalmas de Réotier, P.; Yaouanc, A.; Chapuis, Y.; Curnoe, S. H.; Grenier, B.; Ressouche, E.; Marin, C.; Lago, J.; Baines, C.; Giblin, S. R.

    2012-09-01

    Er2Ti2O7 is believed to be a realization of an XY antiferromagnet on a frustrated lattice of corner-sharing regular tetrahedra. It is presented as an example of the order-by-disorder mechanism in which fluctuations lift the degeneracy of the ground state, leading to an ordered state. Here we report detailed measurements of the low-temperature magnetic properties of Er2Ti2O7, which displays a second-order phase transition at TN≃1.2 K with coexisting short- and long-range orders. Magnetic susceptibility studies show that there is no spin-glass-like irreversible effect. Heat capacity measurements reveal that the paramagnetic critical exponent is typical of a 3-dimensional XY magnet while the low-temperature specific heat sets an upper limit on the possible spin-gap value and provides an estimate for the spin-wave velocity. Muon spin relaxation measurements show the presence of spin dynamics in the nanosecond time scale down to 21 mK. This time range is intermediate between the shorter time characterizing the spin dynamics in Tb2Sn2O7, which also displays long- and short-range magnetic order, and the time scale typical of conventional magnets. Hence the ground state is characterized by exotic spin dynamics. We determine the parameters of a symmetry-dictated Hamiltonian restricted to the spins in a tetrahedron, by fitting the paramagnetic diffuse neutron scattering intensity for two reciprocal lattice planes. These data are recorded in a temperature region where the assumption that the correlations are limited to nearest neighbors is fair.

  5. “Ni{sub 5}TiO{sub 7}” is Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Nalbandyan, V.B.

    2017-05-15

    It is shown that the compound known as Ni{sub 5}TiO{sub 7} and considered as a promising catalyst and oxidation product of alloys does not exist and its XRD pattern actually corresponds to Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2} - Graphical abstract: XRD pattern of “Ni{sub 5}TiO{sub 7}” (top) is identical to that for Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2} (bottom) based on single-crystal structural data. - Highlights: • Popular catalyst known as Ni{sub 5}TiO{sub 7} is actually Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2}. • B{sub 2}O{sub 3} came from the flux used for crystal growth. • Some authors reporting this phase did not use any boron compounds.

  6. Numerical analysis of the influence of buffer layer thickness on the residual stresses in YBCO/La2Zr2O7/Ni superconducting materials

    International Nuclear Information System (INIS)

    Celik, Erdal; Sayman, Onur; Karakuzu, Ramazan; Ozman, Yilmaz

    2007-01-01

    The present paper addresses a numerical investigation of the influence of buffer layer thickness on the residual stress in YBCO/La 2 Zr 2 O 7 /Ni architectured materials under cryogenic conditions by using classical lamination theory (CLT) and finite element method (FEM) for coated conductor applications. YBCO/La 2 Zr 2 O 7 multilayer films were fabricated on Ni tape substrate using reel-to-reel sol-gel and pulse laser deposition (PLD) systems. The microstructural evolution of high temperature superconducting YBCO film and buffer layers with La 2 Zr 2 O 7 configuration grown on textured Ni tape substrates was investigated by using a scanning electron microscope (SEM). Thermal stress analysis of YBCO/La 2 Zr 2 O 7 /Ni multilayer sample was performed by using CLT in the temperature range of 298-175 K in liquid helium media. The YBCO/La 2 Zr 2 O 7 /Ni sample strip was solved by using FEM for linear or nonlinear cases in the temperature range of 298-3 K in liquid helium media. SEM observations revealed that crack-free, pinhole-free, continuous superconducting film and buffer layer were obtained by sol-gel and PLD systems. In addition to microstructural observations, it was found that the largest compressive stresses and failure occur in La 2 Zr 2 O 7 buffer layer due to its smallest thermal expansion coefficient. The thickness of La 2 Zr 2 O 7 buffer layer affects the failure. The stress component of σ x is the smallest in Ni tape substrate due to its largest thickness

  7. Cytotoxicity Evaluation of Anatase and Rutile TiO2 Thin Films on CHO-K1 Cells in Vitro

    Directory of Open Access Journals (Sweden)

    Blanca Cervantes

    2016-07-01

    Full Text Available Cytotoxicity of titanium dioxide (TiO2 thin films on Chinese hamster ovary (CHO-K1 cells was evaluated after 24, 48 and 72 h of culture. The TiO2 thin films were deposited using direct current magnetron sputtering. These films were post-deposition annealed at different temperatures (300, 500 and 800 °C toward the anatase to rutile phase transformation. The root-mean-square (RMS surface roughness of TiO2 films went from 2.8 to 8.08 nm when the annealing temperature was increased from 300 to 800 °C. Field emission scanning electron microscopy (FESEM results showed that the TiO2 films’ thickness values fell within the nanometer range (290–310 nm. Based on the results of the tetrazolium dye and trypan blue assays, we found that TiO2 thin films showed no cytotoxicity after the aforementioned culture times at which cell viability was greater than 98%. Independently of the annealing temperature of the TiO2 thin films, the number of CHO-K1 cells on the control substrate and on all TiO2 thin films was greater after 48 or 72 h than it was after 24 h; the highest cell survival rate was observed in TiO2 films annealed at 800 °C. These results indicate that TiO2 thin films do not affect mitochondrial function and proliferation of CHO-K1 cells, and back up the use of TiO2 thin films in biomedical science.

  8. Cytotoxicity Evaluation of Anatase and Rutile TiO2 Thin Films on CHO-K1 Cells in Vitro

    Science.gov (United States)

    Cervantes, Blanca; López-Huerta, Francisco; Vega, Rosario; Hernández-Torres, Julián; García-González, Leandro; Salceda, Emilio; Herrera-May, Agustín L.; Soto, Enrique

    2016-01-01

    Cytotoxicity of titanium dioxide (TiO2) thin films on Chinese hamster ovary (CHO-K1) cells was evaluated after 24, 48 and 72 h of culture. The TiO2 thin films were deposited using direct current magnetron sputtering. These films were post-deposition annealed at different temperatures (300, 500 and 800 °C) toward the anatase to rutile phase transformation. The root-mean-square (RMS) surface roughness of TiO2 films went from 2.8 to 8.08 nm when the annealing temperature was increased from 300 to 800 °C. Field emission scanning electron microscopy (FESEM) results showed that the TiO2 films’ thickness values fell within the nanometer range (290–310 nm). Based on the results of the tetrazolium dye and trypan blue assays, we found that TiO2 thin films showed no cytotoxicity after the aforementioned culture times at which cell viability was greater than 98%. Independently of the annealing temperature of the TiO2 thin films, the number of CHO-K1 cells on the control substrate and on all TiO2 thin films was greater after 48 or 72 h than it was after 24 h; the highest cell survival rate was observed in TiO2 films annealed at 800 °C. These results indicate that TiO2 thin films do not affect mitochondrial function and proliferation of CHO-K1 cells, and back up the use of TiO2 thin films in biomedical science. PMID:28773740

  9. Thermogravimetric study of the kinetics of lithium titanate reduction by hydrogen

    International Nuclear Information System (INIS)

    Sonak, Sagar; Rakesh, R.; Jain, Uttam; Mukherjee, Abhishek; Kumar, Sanjay; Krishnamurthy, Nagaiyar

    2014-01-01

    Highlights: • Li 2 TiO 3 powder is synthesized by the gel combustion route. • Activation energy of reduction of Li 2 TiO 3 by H 2 found out to be 27.45 kJ/mol H 2 . • Non-stoichiometric phase of Li 2 TiO 3 is formed in hydrogen atmosphere. • One-dimensional diffusion appears to be the most probable mechanism of reduction. - Abstract: The lithium titanate powder was synthesized by gel-combustion route. The mechanism and the kinetics of hydrogen interaction with lithium titanate powder were studied using non-isothermal thermogravimetric technique. Lithium titanate underwent reduction in hydrogen atmosphere which led to the formation of oxygen deficient non-stoichiometric compound in lithium titanate. One-dimensional diffusion appeared to be the most probable reaction mechanism. The activation energy for reduction of lithium titanate under hydrogen atmosphere was found to be 27.4 kJ/mol/K. Structural changes after hydrogen reduction in lithium titanate were observed in X-ray diffraction analysis

  10. Preparación y propiedades de materiales cerámicos bioinertes en el sistema Al2O3-TiO2-SiO2

    Directory of Open Access Journals (Sweden)

    Boccaccini, A. R.

    1998-12-01

    Full Text Available Very fine and sinterable ceramic powders (100-600 nm in the system Al2O3-TiO2-SiO2 were obtained by the method of cohydrolisis from organo-metallic precursors. Isostatically pressed powder compacts could be densified to a relative high density (~ 92 % th. density at relative low temperatures (1320-1380ºC. The technical coefficient of thermal expansion was measured by dilatometry. The value obtained (8.8 10-6 1/ºC corresponds closely to that of Ti, opening the possibility to use Al2O3-TiO2-SiO2 ceramics to fabricate metal/ceramic composite implants. The measured mechanical properties of dense sintered Al2O3-TiO2-SiO2 material: Young´s modulus, flexure strength and compression strength, are higher than those of pure TiO2. Highly porous Al2O3-TiO2-SiO2 ceramics (P~ 65% were obtained by the method of evaporation of hydrogen peroxide. These materials exhibited interconnected porosity and their properties, particularly the Young´s modulus, resulted very similar to those of bone, which is an important pre-requisite for the design of quirurgical implants.Se han obtenido polvos cerámicos muy finos (100- 600 nm y de alta sinterabilidad, en el sistema Al2O3-TiO2-SiO2, por el método de co-hidrólisis controlada a partir de precursores organo-metálicos. Los compactos fabricados a partir del polvo de cohidrólisis calcinado fueron sinterizados en el rango de temperaturas 1320-1380 ºC, obteniéndose densidades elevadas (~ 92% D.T.. El coeficiente de expansión térmica técnico del material cerámico sinterizado fue medido por dilatometría. El valor obtenido, 8.8 10-6 ºC-1, es muy similar al de titanio metálico y por lo tanto el material cerámico Al2O3-TiO2-SiO2 puede ser candidato para la fabricación de implantes compuestos cerámico/metal. Las propiedades mecánicas: módulo de elasticidad, resistencia a la flexión y resistencia a la compresión, del material denso sinterizado, fueron determinadas, resultando muy superiores a las de TiO2 puro

  11. Tunnel-Structured KxTiO2 Nanorods by in Situ Carbothermal Reduction as a Long Cycle and High Rate Anode for Sodium-Ion Batteries.

    Science.gov (United States)

    Zhang, Qing; Wei, Yaqing; Yang, Haotian; Su, Dong; Ma, Ying; Li, Huiqiao; Zhai, Tianyou

    2017-03-01

    The low electronic conductivity and the sluggish sodium-ion diffusion in the compact crystal structure of Ti-based anodes seriously restrict their development in sodium-ion batteries. In this study, a new hollandite K x TiO 2 with large (2 × 2) tunnels is synthesized by a facile carbothermal reduction method, and its sodium storage performance is investigated. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses illustrate the formation mechanism of the hollandite K x TiO 2 upon the carbothermal reduction process. Compared to the traditional layered or small (1 × 1) tunnel-type Ti-based materials, the hollandite K x TiO 2 with large (2 × 2) tunnels may accommodate more sodium ions and facilitate the Na + diffusion in the structure; thus, it is expected to get a large capacity and realize high rate capability. The synthesized K x TiO 2 with large (2 × 2) tunnels shows a stable reversible capacity of 131 mAh g -1 (nearly 3 times of (1 × 1) tunnel-structured Na 2 Ti 6 O 13 ) and superior cycling stability with no obvious capacity decay even after 1000 cycles, which is significantly better than the traditional layered Na 2 Ti 3 O 7 (only 40% of capacity retention in 20 cycles). Moreover, the carbothermal process can naturally introduce oxygen vacancy and low-valent titanium as well as the surface carbon coating layer to the structure, which would greatly enhance the electronic conductivity of K x TiO 2 and thus endow this material high rate capability. With a good rate capability and long cyclability, this hollandite K x TiO 2 can serve as a new promising anode material for room-temperature long-life sodium-ion batteries for large-scale energy storage systems, and the carbothermal reduction method is believed to be an effective and facile way to develop novel Ti-based anodes with simultaneous carbon coating and Ti(III) self-doping.

  12. Tuning TiO2 nanoparticle morphology in graphene-TiO2 hybrids by graphene surface modification

    Science.gov (United States)

    Sordello, Fabrizio; Zeb, Gul; Hu, Kaiwen; Calza, Paola; Minero, Claudio; Szkopek, Thomas; Cerruti, Marta

    2014-05-01

    truncated bipyramids, bonded to graphene via the {100} facets. Belted truncated bipyramids formed on unfunctionalized GNP too, however the NPs were more irregular and rounded. These effects were ascribed to pH variations in the proximity of the functionalized GNP sheets, due to the high density of COOH or NH2 groups. Because of the different reactivity of anatase {100} and {101} crystalline facets, we hypothesize that the hybrid materials will behave differently as photocatalysts, and that the COOH-GNP-TiO2 hybrids will be better photocatalysts for water splitting and H2 production. Electronic supplementary information (ESI) available: Statistical analysis of the D : G intensity ratio, additional XPS analysis and TEM micrographs. See DOI: 10.1039/c4nr01322k

  13. Structures and magnetic behaviours of TiO2–Mn–TiO2 multilayers

    International Nuclear Information System (INIS)

    Fa-Min, Liu; Peng, Ding; Jian-Qi, Li

    2010-01-01

    The TiO 2 -Mn-TiO 2 multilayers are successfully grown on glass and silicon substrates by alternately using radio frequency reactive magnetron sputtering and direct current magnetron sputtering. The structures and the magnetic behaviours of these films are characterised with x-ray diffraction, transmission electron microscope (TEM), vibrating sample magnetometer, and superconducting quantum interference device (SQUID). It is shown that the multi-film consists of a mixture of anatase and rutile TiO 2 with an embedded Mn nano-film. It is found that there are two turning points from ferromagnetic phase to antiferromagnetic phase. One is at 42 K attributed to interface coupling between ferromagnetic Mn 3 O 4 and antiferromagnetic Mn 2 O 3 , and the other is at 97 K owing to the interface coupling between ferromagnetic Mn and antiferromagnetic MnO. The samples are shown to have ferromagnetic behaviours at room temperature from hysteresis in the M-H loops, and their ferromagnetism is found to vary with the thickness of Mn nano-film. Moreover, the Mn nano-film has a critical thickness of about 18.5 nm, which makes the coercivity of the multi-film reach a maximum of about 3.965×10 −2 T. (cross-disciplinary physics and related areas of science and technology)

  14. Highly active sulfided CoMo catalysts supported on (ZrO{sub 2}–TiO{sub 2})/Al{sub 2}O{sub 3} ternary oxides

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, José, E-mail: jeaguila@imp.mx [Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, Gustavo A. Madero, México, D.F. 07730 (Mexico); De Los Reyes, José A., E-mail: jarh@xanum.uam.mx [Area de Ing. Química, UAM – Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, México, D.F. 09340 (Mexico); Ulín, Carlos A. [Area de Ing. Química, UAM – Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, México, D.F. 09340 (Mexico); Barrera, María C., E-mail: mcbdgavilan@gmail.com [Facultad de Ciencias Químicas, Universidad Veracruzana, Av. Universidad km. 7.5, Col. Santa Isabel, Coatzacoalcos, Veracruz, México, D.F. 96538 (Mexico)

    2013-12-16

    (ZrO{sub 2}–TiO{sub 2})/Al{sub 2}O{sub 3} ternary oxide at 20 mol% Al{sub 2}O{sub 3} (80% ZrO{sub 2}–TiO{sub 2}, in turn at 40–60 mol ratio) prepared by controlled co-precipitation (by urea thermal decomposition) of zirconium (ZrOCl{sub 2}·8H{sub 2}O) and titanium (TiCl{sub 4}) chlorides over a ground alumina substrate constitutes a promising material to be used as carrier of sulfided hydrodesulfurization (HDS) catalysts. After calcining (at 500 °C), the ternary oxide presented textural properties (S{sub g} = 387 m{sup 2} g{sup −1}, V{sub p} = 0.74 ml g{sup −1}, mean pore diameter = 7.6 nm) suitable to its utilization as carrier of catalysts applied in the oil-derived middle distillates HDS. As determined by temperature programmed-reduction and Raman and UV–vis spectroscopies ZrO{sub 2}–TiO{sub 2} deposition over alumina substrate resulted in decreased proportion of Mo{sup 6+} species in tetrahedral coordination on the oxidic impregnated material. As those species constitute hardly reducible precursors, their diminished concentration could be reflected in enhanced amount of Mo species susceptible of activation by sulfiding (H{sub 2}S/H{sub 2} at 400 °C) over our ternary carrier. Limiting the concentration of zirconia-titania (at 40–60 mol ratio) to 20 mol% in the mixed oxides support allowed the preparation of highly active promoted (by cobalt, at Co/(Co + Mo) = 0.3) MoS{sub 2} phase (at 2.8 atoms/nm{sup 2}), that formulation showing excellent properties in hydrodesulfurization (HDS) of both dibenzothiophene and highly-refractory 4,6-dimethyl-dibenzothiophene. Due to alike yields to various HDS products over CoMo/(ZrO{sub 2}–TiO{sub 2})/Al{sub 2}O{sub 3} and the corresponding Al{sub 2}O{sub 3}-supported formulation, presence of similar actives sites over those catalysts was strongly suggested. It seemed that enhanced concentration of octahedral Mo{sup 6+} over the oxidic impregnated precursor with (ZrO{sub 2}–TiO{sub 2})/Al{sub 2}O{sub 3

  15. Characterization and Comparison of Photocatalytic Activity Silver Ion doped on TiO2(TiO2/Ag+) and Silver Ion doped on Black TiO2(Black TiO2/Ag+)

    Science.gov (United States)

    Kim, Jin Yi; Sim, Ho Hyung; Song, Sinae; Noh, Yeoung Ah; Lee, Hong Woon; Taik Kim, Hee

    2018-03-01

    Titanium dioxide (TiO2) is one of the representative ceramic materials containing photocatalyst, optic and antibacterial activity. The hydroxyl radical in TiO2 applies to the intensive oxidizing agent, hence TiO2 is suitable to use photocatalytic materials. Black TiO2was prepared through reduction of amorphous TiO2 conducting under H2 which leads to color changes. Its black color is proven that absorbs 100% light across the whole-visible light, drawing enhancement of photocatalytic property. In this study, we aimed to compare the photocatalytic activity of silver ion doped on TiO2(TiO2/Ag+) and silver ion doped on black TiO2(black TiO2/Ag+) under visible light range. TiO2/Ag+ was fabricated following steps. 1) TiO2 was synthesized by a sol-gel method from Titanium tetraisopropoxide (TTIP). 2) Then AgNO3 was added during an aging process step for silver ion doping on the surface of TiO2. Moreover, Black TiO2/Ag+ was obtained same as TiO2/Ag+ except for calcination under H2. The samples were characterized X-ray diffraction (XRD), UV-visible reflectance (UV-vis DRS), and Methylene Blue degradation test. XRD analysis confirmed morphology of TiO2. The band gap of black TiO2/Ag+ was confirmed (2.6 eV) through UV-vis DRS, which was lower than TiO2/Ag+ (2.9 eV). The photocatalytic effect was conducted by methylene blue degradation test. It demonstrated that black TiO2/Ag+ had a photocatalytic effect under UV light also visible light.

  16. Pebble fabrication of super advanced tritium breeders using a solid solution of Li2+xTiO3+y with Li2ZrO3

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Hoshino

    2016-12-01

    Full Text Available Lithium titanate with excess lithium (Li2+xTiO3+y is one of the most promising candidates among advanced tritium breeders for demonstration power plant reactors because of its good tritium release characteristics. However, the tritium breeding ratio (TBR of Li2+xTiO3+y is smaller than that of e.g., Li2O or Li8TiO6 because of its lower Li density. Therefore, new Li-containing ceramic composites with both high stability and high Li density have been developed. Thus, this study focused on the development of a solid solution with a new characteristic. The solid-solution pebbles of Li2+xTiO3+y with Li2ZrO3 (Li2+x(Ti,ZrO3+y, designated as LTZO, were fabricated by an emulsion method. The X-ray diffraction patterns of sintered LTZO pebbles are approximately the same as those of Li2+xTiO3+y pebbles, and no peaks attributable to Li2ZrO3 are observed. These results demonstrate that LTZO pebbles are not a two-phase material but rather a solid solution. Furthermore, LTZO pebbles were easily sintered under air. Thus, the LTZO solid solution is a candidate breeder material for super advanced (SA tritium breeders.

  17. Simultaneous quantification of Li, Ti and O in Lithium titanate by particle induced gamma-ray emission using 8 MeV proton beam

    International Nuclear Information System (INIS)

    Chhillar, Sumit; Acharya, R.; Tripathi, R.; Sodaye, S.; Sudarshan, K.; Pujari, P.K.; Rout, P.C.; Mukherjee, S.K.

    2014-01-01

    Simultaneous quantification of Li, Ti and O in lithium titanate (Li 2 TiO 3 ) is difficult by particle induced gamma-ray emission (PIGE) using low energy (∼4 MeV) proton beam. PIGE method using 8 MeV proton beam at BARC-TIFR pelletron facility was standardized for compositional characterization of sol-gel synthesized Li 2 TiO 3 by determining concentrations of Li, Ti and O simultaneously. Thick targets of samples, synthetic samples and standards were prepared in graphite matrix. Beam current variation was normalized by Rutherford Backscattering Spectrometry (RBS) using a thin gold foil. The gamma-rays of 478, 981 and 6129 keV were measured from 7 Li(p, p'γ) 7 Li, 48 Ti(p, p'γ) 48 Ti and 16 O(p, p'γ) 16 O nuclear reactions for quantification of Li, Ti and O, respectively. The method was validated by determining concentrations of Li, TI and O in a synthetic sample. (author)

  18. Positron annihilation studies on the behaviour of vacancies in LaAlO3/SrTiO3 heterostructures

    Science.gov (United States)

    Yuan, Guoliang; Li, Chen; Yin, Jiang; Liu, Zhiguo; Wu, Di; Uedono, Akira

    2012-11-01

    The formation and diffusion of vacancies are studied in LaAlO3/SrTiO3 heterostructures. Oxygen vacancies (VOS) appear easily in the SrTiO3 substrate during LaAlO3 film growth at 700 °C and 10-4 Pa oxygen pressure rather than at 10-3-10-1 Pa, thus the latter two-dimensional electron gas should come from the polarity discontinuity at the (LaO)+/(TiO2)0 interface. For SrTiO3-δ/LaAlO3/SrTiO3, high-density VOS of the SrTiO3-δ film can pass through the LaAlO3 film and then diffuse to 1.7 µm depth in the SrTiO3 substrate, suggesting that LaAlO3 has VOS at its middle-deep energy levels within the band gap. Moreover, high-density VOS may combine with a strontium/titanium vacancy (VSr/Ti) to form VSr/Ti-O complexes in the SrTiO3 substrate at 700 °C.

  19. Heterogeneous Ag-TiO2-SiO2 composite materials as novel catalytic systems for selective epoxidation of cyclohexene by H2O2.

    Directory of Open Access Journals (Sweden)

    Xin Wang

    Full Text Available TiO2-SiO2 composites were synthesized using cetyl trimethyl ammonium bromide (CTAB as the structure directing template. Self-assembly hexadecyltrimethyl- ammonium bromide TiO2-SiO2/(CTAB were soaked into silver nitrate (AgNO3 aqueous solution. The Ag-TiO2-SiO2(Ag-TS composite were prepared via a precipitation of AgBr in soaking process and its decomposition at calcination stage. Structural characterization of the materials was carried out by various techniques including X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM, N2 adsorption-desorption and ultraviolet visible spectroscopy (UV-Vis. Characterization results revealed that Ag particles were incorporated into hierarchical TiO2-SiO2 without significantly affecting the structures of the supports. Further heating-treatment at 723 K was more favorable for enhancing the stability of the Ag-TS composite. The cyclohexene oxide was the major product in the epoxidation using H2O2 as the oxidant over the Ag-TS catalysts. Besides, the optimum catalytic activity and stability of Ag-TS catalysts were obtained under operational conditions of calcined at 723 K for 2 h, reaction time of 120 min, reaction temperature of 353 K, catalyst amount of 80 mg, aqueous H2O2 (30 wt.% as oxidant and chloroform as solvent. High catalytic activity with conversion rate up to 99.2% of cyclohexene oxide could be obtainable in water-bathing. The catalyst was found to be stable and could be reused three times without significant loss of catalytic activity under the optimized reaction conditions.

  20. Enhanced light harvesting of TiO{sub 2}/La{sub 0.95}Tb{sub 0.05}PO{sub 4} photoanodes for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongna; He, Benlin, E-mail: blhe@ouc.edu.cn; Tang, Qunwei, E-mail: tangqunwei@ouc.edu.cn

    2016-04-15

    With an aim of enhancing light harvesting for dye adsorption and therefore photovoltaic performances of dye-sensitized solar cells (DSSCs), we present here an employment of La{sub 0.95}Tb{sub 0.05}PO{sub 4} incorporated TiO{sub 2} nanocrystallites as photoanodes. The preliminary results demonstrate that the dye absorption and therefore electron generation have been markedly enhanced, arising from the conversion of ultraviolet to visible light by La{sub 0.95}Tb{sub 0.05}PO{sub 4}. The crystal structure and light harvesting performances of photoanodes are optimized by adjusting La{sub 0.95}Tb{sub 0.05}PO{sub 4} dosage. The power conversion efficiency is enhanced from 6.52% for pristine TiO{sub 2} based DSSC to 7.27% for the device employing TiO{sub 2}/0.5 wt% La{sub 0.95}Tb{sub 0.05}PO{sub 4}, yielding an efficiency enhancement by 11.35%. This study provides a new strategy for the fabrication of highly efficient DSSCs. - Highlights: • TiO{sub 2}/La{sub 0.95}Tb{sub 0.05}PO{sub 4} nanocrystallites are fabricated by a facile hydrothermal method. • The light intensity and therefore dye excitation have been markedly enhanced. • A conversion efficiency of 7.27% for the DSSC employing TiO{sub 2}/0.5 wt% La{sub 0.95}Tb{sub 0.05}PO{sub 4} is obtained. • The strategy provides new opportunities for efficient DSSCs.

  1. C60 and U ion irradiation of Gd2TixZr2-xO7 pyrochlore

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jiaming; Toulemonde, Marcel; Lang, Maik; Costantini, Jean Marc; Della-Negra, Serge; Ewing, Rodney C.

    2015-08-01

    Gd2TixZr2-xO7 (x = 0 to 2) pyrochlore was irradiated by 30 MeV C60 clusters, which provide an extremely high ionizing energy density. Here, high-resolution transmission electron microscopy revealed a complex ion-track structure in Gd2Ti2O7 and Gd2TiZrO7, consisting of an amorphous core and a shell of a disordered, defect-fluorite structure.

  2. X-ray diffraction and surface acoustic wave analysis of BST/Pt/TiO{sub 2}/SiO{sub 2}/Si thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mseddi, Souhir; Hedi Ben Ghozlen, Mohamed [Laboratoire de Physique des Materiaux, Faculte des Sciences de Sfax, Universite de Sfax, 3018 Sfax (Tunisia); Njeh, Anouar [Unite de Physique, Informatique et Matematiques, Faculte des Sciences de Gafsa, Universite de Gafsa, 2112 Gafsa (Tunisia); Schneider, Dieter [Fraunhofer-Institut fuer Material- und Strahltechnologie, Winterbergstrasse 28, 1277 Dresden (Germany); Fuess, Hartmut [Institute of Materials Science, University of Technology, Petersenstr.23, 64287 Darmstadt (Germany)

    2011-11-15

    High dielectric constant and electrostriction property of (Ba, Sr)Ti0{sub 3} (BST) thin films result in an increasing interest for dielectric devices and microwave acoustic resonator. Barium strontium titanate (Ba{sub 0.645}Sr{sub 0.355}TiO{sub 3}) films of about 300 nm thickness are grown on Pt(111)/TiO{sub 2}/SiO{sub 2}/Si(001) substrates by rf magnetron sputtering deposition techniques. X-ray diffraction is applied for the microstructural characterization. The BST films exhibit a cubic perovskite structure with a dense and smooth surface. A laser acoustic waves (LA-waves) technique is used to generate surface acoustic waves (SAW) propagating in the BST films. Young's modulus E and the Poisson ratio {nu} of TiO{sub 2,} Pt and BST films in different propagation directions are derived from the measured dispersion curves. Estimation of BST elastics constants are served in SAW studies. Impact of stratification process on SAW, propagating along [100] and [110] directions of silicon substrate, has been interpreted on the basis of ordinary differential equation (ODE) and stiffness matrix method (SMM). A good agreement is observed between experimental and calculated dispersion curves. The performed calculations are strongly related to the implemented crystallographic data of each layer. Dispersion curves are found to be sensitive to the SAW propagation direction and the stratification process for the explored frequency ranges 50-250 MHz, even though it corresponds to a wave length clearly higher than the whole films thickness.

  3. Transformation of hydrogen titanate nanoribbons to TiO2 nanoribbons and the influence of the transformation strategies on the photocatalytic performance

    Directory of Open Access Journals (Sweden)

    Melita Rutar

    2015-03-01

    Full Text Available The influence of the reaction conditions during the transformation of hydrogen titanate nanoribbons to TiO2 nanoribbons on the phase composition, the morphology, the appearance of the nanoribbon surfaces and their optical properties was investigated. The transformations were performed (i through a heat treatment in oxidative and reductive atmospheres in the temperature range of 400–650 °C, (ii through a hydrothermal treatment in neutral and basic environments at 160 °C, and (iii through a microwave-assisted hydrothermal treatment in a neutral environment at 200 °C. Scanning electron microscopy investigations showed that the hydrothermal processing significantly affected the nanoribbon surfaces, which became rougher, while the transformations based on calcination in either oxidative or reductive atmospheres had no effect on the morphology or on the surface appearance of the nanoribbons. The transformations performed in the reductive atmosphere, an NH3(g/Ar(g flow, and in the ammonia solution led to nitrogen doping. The nitrogen content increased with an increasing calcination temperature, as was determined by X-ray photoelectron spectroscopy. According to electron paramagnetic resonance measurements the calcination in the reductive atmosphere also resulted in a partial reduction of Ti4+ to Ti3+. The photocatalytic performance of the derived TiO2 NRs was estimated on the basis of the photocatalytic oxidation of isopropanol. After calcinating in air, the photocatalytic performance of the investigated TiO2 NRs increased with an increased content of anatase. In contrast, the photocatalytic performance of the N-doped TiO2 NRs showed no dependence on the calcination temperature. An additional comparison showed that the N-doping significantly suppressed the photocatalytic performance of the TiO2 NRs, i.e., by 3 to almost 10 times, in comparison with the TiO2 NRs derived by calcination in air. On the other hand, the photocatalytic performance of the

  4. Comparison of reduction agents in the synthesis of infinite-layer LaNiO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, Ai [Department of Applied Physics, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588 (Japan); Research Fellow of the Japan Society for the Promotion of Science, Ichiban-cho 8, Chiyoda, Tokyo 102-8472 (Japan); Manabe, Takaaki [National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan); Naito, Michio, E-mail: minaito@cc.tuat.ac.jp [Department of Applied Physics, Tokyo University of Agriculture and Technology, Naka-cho 2-24-16, Koganei, Tokyo 184-8588 (Japan)

    2014-11-15

    Highlights: • Reduction agents were compared from a viewpoint of the facility for topotactic reduction of LaNiO{sub 3} to LaNiO{sub 2} films. • TiH{sub 2} and CaH{sub 2} yielded infinite-layer LaNiO{sub 2} with low and metallic resistivity. • H{sub 2} released from metal hydrides plays a dominant role in the topotactic reduction. - Abstract: Reduction agents, such as activated carbon, TiH{sub 2}, and CaH{sub 2}, were compared from a viewpoint of the facility for the topotactic reduction of LaNiO{sub 3} to LaNiO{sub 2} films. Activated carbon did not yield infinite-layer LaNiO{sub 2} whereas both of TiH{sub 2} and CaH{sub 2} yielded infinite-layer LaNiO{sub 2} with low resistivity (∼1 mΩ cm at 300 K) as well as metallic behavior down to 70 K. Thermal desorption spectroscopy indicated that H{sub 2} released from metal hydrides plays a dominant role in the topotactic reduction.

  5. Optical properties of ZrO2, SiO2 and TiO2-SiO2 xerogels and coatings doped with Eu3+ and Eu2+

    Directory of Open Access Journals (Sweden)

    Gonçalves Rogéria R.

    1999-01-01

    Full Text Available Eu3+ doped bulk monoliths and thin films were obtained by sol-gel methods in the ZrO2, SiO2 and SiO2-TiO2 systems. Eu3+ 5D0 ® 7FJ emission and decay time characteristics were measured during the entire experimental preparation route from the initial sol to the final xerogels. The crystalline phases identified were tetragonal ZrO2 and mixtures of rutile and anatase TiO2 at high temperature treatments in bulk samples. Good quality thin films were obtained for all systems by dip-coating optical glasses (Schott BK270. The same spectroscopic features were observed either for the bulk monoliths or the films. By appropriate heat treatments under H2 atmosphere Eu2+ containing samples could be obtained in the SiO2-TiO2 system.

  6. Optical and structural properties of TiO2/Ti/Ag/TiO2 and TiO2/ITO/Ag/ITO/TiO2 metal-dielectric multilayers by RF magnetron sputtering for display application

    International Nuclear Information System (INIS)

    Lee, Jang-Hoon; Lee, Seung-Hyu; Hwangbo, Chang-Kwon; Lee, Kwang-Su

    2004-01-01

    Electromagnetic-interference (EMI) shielding and near-infrared (NIR) cutoff filters for plasma display panels, based on fundamental structures (ITO/Ag/ITO), (TiO 2 /Ti/Ag/TiO 2 ) and (TiO 2 /ITO/Ag/ITO/TiO 2 ), were designed and prepared by RF-magnetron sputtering. The optical, structural and electrical properties of the filters were investigated by using spectrophotometry, Auger electron spectroscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, atomic force microscopy and four-point-probe measurements. The results show that ITO films as the barriers and base layers lead to higher transmittance in the visible spectrum and smoother surface roughness than Ti metal barriers, while maintaining high NIR cutoff characteristics and chemical stability, which may be attributed to the lower absorption in the interfacial layers and better protection of the Ag layers by the ITO layers.

  7. Enhancement of the piezoelectric properties of sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15) through modification with cobalt

    International Nuclear Information System (INIS)

    Wang Chunming; Wang Jinfeng; Zheng Limei; Zhao Minglei; Wang Chunlei

    2010-01-01

    The dielectric, piezoelectric, and electromechanical properties of B-site cobalt-modified sodium lanthanum bismuth titanate (Na 0.5 La 0.5 Bi 4 Ti 4 O 15 , NLBT) piezoelectric ceramics were investigated. The piezoelectric properties of NLBT ceramics can be enhanced by cobalt modifications. The NLBT ceramics modified with 0.2 wt.% cobalt trioxide (NLBT-C4) possess good piezoelectric properties, with piezoelectric coefficient d 33 of 27 pC/N, electromechanical coupling factors (k p and k t ) of 6.5% and 28.5%, and mechanical quality factor Q m (k p mode) of 3400. The Curie temperature T c of cobalt-modified NLBT ceramics was found to slightly higher than that of pure NLBT ceramics. A large dielectric abnormity in dielectric loss tan δ was observed in NLBT ceramics, which can be significantly suppressed by cobalt modification. Thermal annealing studies presented the cobalt-modified NLBT ceramics possess stable piezoelectric properties.

  8. Surface modification of sol–gel synthesized TiO{sub 2} nanoparticles induced by La-doping

    Energy Technology Data Exchange (ETDEWEB)

    Grujić-Brojčin, M., E-mail: myramyra@ipb.ac.rs [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Armaković, S. [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovića 3, 21000 Novi Sad (Serbia); Tomić, N. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Abramović, B. [Department of Chemistry, Biochemistry and Environmental Protection, Faculty of Sciences, University of Novi Sad, Trg D. Obradovića 3, 21000 Novi Sad (Serbia); Golubović, A.; Stojadinović, B. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Kremenović, A. [Faculty of Mining and Geology, Laboratory for Crystallography, University of Belgrade, Đušina 7, 11000 Belgrade (Serbia); Babić, B. [Institute of Nuclear Sciences “Vinča”, University of Belgrade, 11001 Belgrade (Serbia); Dohčević-Mitrović, Z.; Šćepanović, M. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia)

    2014-02-15

    The influence of La-doping in the range of 0.5–6.0 mol% on structural and morphological properties of TiO{sub 2} nanopowders synthesized by sol–gel routine has been investigated by XRPD, AFM, EDS and BET measurements, as well as Raman spectroscopy. The XRPD and Raman measurements have revealed the anatase phase as dominant in all nanopowders, with crystallite size decreasing from ∼ 15 nm in pure TiO{sub 2} to ∼ 12 nm in La-doped samples. The BET data suggest that all samples are fully mesoporous, with mean pore diameters in the range of ∼ 6–8 nm. The specific surface area and the complexity of pore structure are greater in doped samples than in pure TiO{sub 2} sample. The spectroscopic ellipsometry has apparently shown that the band gap has been gradually increased with the increase of La content. The STM and STS techniques have been used successfully to evaluate the surface morphology and electronic properties of La-doped nanopowders. All investigated properties have been related to photocatalytic activity, tested in degradation of a metoprolol tartrate salt (0.05 mM), and induced by UV-radiation. All doped samples showed increased photocatalytic activity compared to pure TiO{sub 2}, among which the 0.65 mol% La-doped sample appeared to be the most efficient. - Highlights: • Effects of La-doping on structural, morphological and electronic properties of TiO{sub 2} nanopowders. • Surface morphology and electronic properties of La-doped nanopowders evaluated by STM/STS. • Spectroscopic ellipsometry shown gradual increase of bandgap with the increase of La content. • Photocatalytic activity of samples was tested in degradation of MET under UV light.

  9. Design and Synthesis of Hierarchical SiO2@C/TiO2 Hollow Spheres for High-Performance Supercapacitors.

    Science.gov (United States)

    Zhang, Ying; Zhao, Yan; Cao, Shunsheng; Yin, Zhengliang; Cheng, Li; Wu, Limin

    2017-09-06

    TiO 2 has been widely investigated as an electrode material because of its long cycle life and good durability, but the relatively low theoretical capacity restricts its practical application. Herein, we design and synthesize novel hierarchical SiO 2 @C/TiO 2 (HSCT) hollow spheres via a template-directed method. These unique HSCT hollow spheres combine advantages from both TiO 2 such as cycle stability and SiO 2 with a high accessible area and ionic transport. In particular, the existence of a C layer is able to enhance the electrical conductivity. The SiO 2 layer with a porous structure can increase the ion diffusion channels and accelerate the ion transfer from the outer to the inner layers. The electrochemical measurements demonstrate that the HSCT-hollow-sphere-based electrode manifests a high specific capacitance of 1018 F g -1 at 1 A g -1 which is higher than those for hollow TiO 2 (113 F g -1 ) and SiO 2 /TiO 2 (252 F g -1 ) electrodes, and substantially higher than those of all the previously reported TiO 2 -based electrodes.

  10. SO2 influence on the K/La2O3 soot combustion catalyst deactivation

    International Nuclear Information System (INIS)

    Peralta, M.A.; Ulla, M.A.; Querini, C.A.

    2008-01-01

    In the present work, K/La 2 O 3 was prepared and tested as a potential catalyst to be used in a diesel engine exhaust. The soot combustion activity was evaluated by temperature-programmed-oxidation (TPO), and the NO x -catalyst interaction was studied using a microbalance experiment. The SO 2 poisoning process and the regeneration of a poisoned K/La 2 O 3 catalyst were analyzed. The fresh catalyst presented a good soot combustion activity. After being treated with a 1000 ppm SO 2 stream, the catalyst was poisoned due to lanthanum sulfate and potassium sulfate formation. The NO x treatment contributed to the K 2 (SO 4 ) decomposition at the expense of extra La 2 (SO 4 ) 3 formation and the H 2 treatment contributed to the La 2 (SO 4 ) 3 decomposition. (author)

  11. Synthesis of anhydrous K2TiOF4 via a mild hydrothermal method

    Science.gov (United States)

    Felder, Justin B.; Yeon, Jeongho; zur Loye, Hans-Conrad

    2015-10-01

    The synthesis of anhydrous K2TiOF4 has been previously attempted by transforming precursor compounds, such as the peroxide (K2Ti(O2)F4), hydrate (K2TiOF4·H2O) and fluoride (K2TiF6). Due to the large structural differences between these precursors and the anhydrous oxyfluorides, however, these preparations have been unsuccessful. Therefore, a direct method of synthesis has been employed to grow single crystals of K2TiOF4 that were characterized by single crystal x-ray diffraction. K2TiOF4 was found to be isostructural with the previously known K2VOF4.

  12. Synthesis of highly monodispersed teardrop-shaped core–shell SiO{sub 2}/TiO{sub 2} nanoparticles and their photocatalytic activities

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Lihong; Zhou, Yifeng, E-mail: yifengzhou@126.com; Nie, Wangyan; Song, Linyong; Chen, Pengpeng, E-mail: chenpp@ahu.edu.cn

    2015-10-01

    Graphical abstract: - Highlights: • Uniform chitosan coated magnetic mesoporous silica nanoparticles (CMMSNs) were successfully synthesized. • The CMMSNs were applied to highly efficient methylene blue (MB) dyes removal, and the saturated adsorption capacity of MB was 43.03 mg/g. • The MB adsorption kinetic and adsorption isotherm analysis were studied. • The CMMSNs had a saturation magnetization of 12.6 emu/g and could be easily separated by a magnet after dye adsorption. - Abstract: In this study, teardrop-shaped SiO{sub 2}/TiO{sub 2} nanoparticles (TST-NPs) with core–shell structure were fabricated from tetraethoxysilane (TEOS) and tetrabutyl titanate (TBT) by sol–gel method. And these nanoparticles were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and UV–vis spectroscopy. Photocatalytic activity of teardrop-shaped SiO{sub 2}/TiO{sub 2} nanoparticles after calcination (CST-NPs) was studied towards degradation of methylene blue under sunlight irradiation. The result showed that CST-NPs possessed good photocatalytic activity. The photocatalytic mechanism was also studied by adding different capture agent. Results showed that addition of 0.003 M of I{sup −} decreased the degradation of MB more than same amount of Ag{sup +}, indicating that the photogenerated holes may play a more essential role than photoinjected electrons in the oxidation of MB.

  13. Microstructure and temperature dependence of the microhardness of W–4V–1La2O3 and W–4Ti–1La2O3

    International Nuclear Information System (INIS)

    Savoini, B.; Martínez, J.; Muñoz, A.; Monge, M.A.; Pareja, R.

    2013-01-01

    W–4V–1La 2 O 3 and W–4Ti–1La 2 O 3 (wt.%) alloys have been produced by mechanical alloying and subsequent hot isostatic pressing. Electron microscopy observations revealed that these alloys exhibit a submicron grain structure with a dispersion of La oxide nanoparticles. Large V or Ti pools with martensitic characteristics are found segregated in the interstices between the W particles of the respective alloys. Microhardness tests were carried out over the temperature range 300–1073 K in vacuum. The microhardness–temperature curve for W–4V–1La 2 O 3 exhibited the expected decreasing trend with increasing temperature although the microhardness stayed constant between ∼473 and 773 K. The W–4Ti–1La 2 O 3 presented quite different temperature dependence with an anomalous microhardness increase for temperatures above ∼473 K

  14. Photocatalytic activity of TiO2/Nb2O5/PANI and TiO2/Nb2O5/RGO as new nanocomposites for degradation of organic pollutants.

    Science.gov (United States)

    Zarrin, Saviz; Heshmatpour, Felora

    2018-06-05

    In this study, highly active titanium dioxide modified by niobium oxide (Nb 2 O 5 ), polymer (PANI) and reduced graphene oxide (RGO) were successfully prepared. The morphology, structure, surface area and light absorption properties of the present nanocomposites for removal of methylene blue (MB) and methyl orange (MO) were investigated and compared with those of TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. The characterization techniques such as XRD, FT-IR, UV-vis, SEM, EDX, BET and TEM were employed in order to identify the nanocomposites. Also, photocatalytic properties of TiO 2 /Nb 2 O 5 /PANI and TiO 2 /Nb 2 O 5 /RGO nanocomposites under visible light irradiation were studied. In this way, the obtained results were compared to each other and also compared to TiO 2 /Nb 2 O 5 and TiO 2 nanoparticles. In this context, the chemical oxygen demand (COD) removal follows the photodegradation in observed performance. The results indicate that reduced TiO 2 /Nb 2 O 5 nanocomposite is effectively modified by graphene oxide to give TiO 2 /Nb 2 O 5 /RGO composite. The TiO 2 /Nb 2 O 5 /RGO exhibits significantly higher photocatalytic activity in degradation of organic dyes under visible light rather than that of TiO 2 /Nb 2 O 5 /PANI, TiO 2 /Nb 2 O 5 and pure TiO 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Effect of rare earth La2O3 on the microstructure and mechanical properties of TiC/W composites

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this study,La2O3 was investigated as an additive to TiC/W composites.The composites were prepared by vacuum hot pressing,and the microstructure and mechanical properties of the composites were investigated.Experimental results show that the grain size of the TiC/W composites is reduced by TiC particles.When 0.5 wt.% La2O3 is added to the composites,the grain size is reduced further.According to TEM analysis,La2O3 can alleviate the aggregation of TiC particles.With La2O3 addition,the relative density of the TiC/W composites can be improved from 95.1% to 96.5%.The hardness and elastic modulus of the TiC/W + 0.5 wt.% La203 composite are little improved,but the composites.

  16. High-pressure synthesis and characterization of the effective pseudospin S =1 /2 XY pyrochlores R2P t2O7 (R =Er ,Yb )

    Science.gov (United States)

    Cai, Y. Q.; Cui, Q.; Li, X.; Dun, Z. L.; Ma, J.; dela Cruz, C.; Jiao, Y. Y.; Liao, J.; Sun, P. J.; Li, Y. Q.; Zhou, J. S.; Goodenough, J. B.; Zhou, H. D.; Cheng, J.-G.

    2016-01-01

    We report on the high-pressure syntheses and detailed characterizations of two effective pseudospin S =1 /2 XY pyrochlores E r2P t2O7 and Y b2P t2O7 via x-ray/neutron powder diffraction, dc and ac magnetic susceptibility, and specific-heat measurements down to 70 mK. We found that both compounds undergo long-range magnetic transitions at TN ,C≈0.3 K , which are ascribed to an antiferromagnetic- and ferromagnetic-type order for E r2P t2O7 and Y b2P t2O7 , respectively, based on the field dependence of their transition temperatures as well as the systematic comparisons with other similar pyrochlores R2B2O7 (R =Er ,Yb ;B =Sn ,Ti ,Ge ). The observed TN of E r2P t2O7 is much lower than that expected from the relationship of TN versus the ionic radius of B4 + derived from the series of E r2B2O7 , while the TC of Y b2P t2O7 is the highest among the series of ferromagnetic compounds Y b2B2O7 (B =Sn ,Pt ,Ti ). Given the monotonic variation of the lattice constant as a function of the B -cation size across these two series of R2B2O7 (R =Er ,Yb ), the observed anomalous values of TN ,C in the Pt-based XY pyrochlores imply that another important factor beyond the nearest-neighbor R -R distance is playing a role. In light of the anisotropic exchange interactions Jex={Jz z,J±,J±±,Jz ± } for the S =1 /2 XY pyrochlores, we have rationalized these observations by considering a weakened (enhanced) antiferromagnetic planar J± (ferromagnetic Ising-like Jz z) due to strong Pt 5 d -O 2 p hybridization within the plane perpendicular to the local [111] direction.

  17. Upconversion properties of Er3+/Yb3+ co-doped TeO2-TiO2-K2O glasses.

    Science.gov (United States)

    Su, Fangning; Deng, Zaide

    2006-01-01

    The Er3+/Yb3+ co-doped TeO2-TiO2-K2O glasses were prepared by conventional melting procedures, and their upconversion spectra were performed. The dependence of luminescence intensity on the ratio of Yb3+/Er3+ was studied, and the relationship between green upconversion luminescence intensity and Er3+ concentration is discussed in detail. The 546 nm green upconversion luminescence intensity is optimised in the studied glasses either when the Yb3+/Er3+ ratio is 25/1 and Er3+ concentration is 0.1 mol%, or when the Yb3+/Er3+ ratio is 10/1 and Er3+ concentration is 0.15 mol%. These glasses could be one of the potential candidates for LD pumping microchip solid-state lasers.

  18. Plateau on temperature dependence of magnetization of nanostructured rare earth titanates

    Science.gov (United States)

    Rinkevich, A. B.; Korolev, A. V.; Samoylovich, M. I.; Demokritov, S. O.; Perov, D. V.

    2018-05-01

    Magnetic properties of nanocomposite materials containing particles of rare earth titanates of R2Ti2O7 type, where R is a rare earth ion, including "spin ice" materials are investigated. The descending branches of hysteresis loop have been studied in detail in temperature range from 2 to 50 K. It has been shown that nanocomposites with Yb2Ti2O7, Dy2Ti2O7 and Er2Ti2O7 particles have one intersection point of the descending branches in some temperature range unlike many other nanocomposites. It is shown that magnetization has only weak temperature dependence near this point. It has been obtained that nanocomposites with Pr2Ti2O7 and Nd2Ti2O7 particles have no hysteresis loop. All above findings point out to unusual magnetic structures of the studied samples.

  19. Fabrication and properties of La2-xGdxHf2O7 transparent ceramics

    International Nuclear Information System (INIS)

    Wang, Zhengjuan; Zhou, Guohong; Zhang, Fang; Qin, Xianpeng; Ai, Jianping; Wang, Shiwei

    2016-01-01

    La 2-x Gd x Hf 2 O 7 (x=0–2.0) transparent ceramics were fabricated through vacuum sintering from nano-powders synthesized by a simple combustion method. The phase composition of the powders and final ceramics, the in-line transmittance, microstructures and density of the ceramics were investigated. With the increasing of Gd content, the ceramics maintained the cubic pyrochlore structure, and the lattice parameters decreased, whilst the densities increased linearly. All the ceramics were transparent. The highest in-line transmittance was 76.1% at 800 nm (x=1.2). With high density (7.91–8.88 g/cm 3 ) and effective atomic number, some of the La 2-x Gd x Hf 2 O 7 (x=0–2.0) transparent ceramics are promising candidates for scintillator hosts. - Highlights: • A new series of La 2-x Gd x Hf 2 O 7 transparent ceramics were fabricated by vacuum sintering using combustion-synthesized powders. • All the ceramics are transparent and the in-line transmittance can reach to 76.1% at 800 nm when x=1.2. • The Gd content has effects on the crystal structure, in-line transmittance, microstructures and densities of the ceramics. • With high density (7.91~8.88 g/cm3) and effective atomic number, some of the La2-xGdxHf2O7 transparent ceramics are promising candidates for scintillator hosts.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-01

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

  1. Improving chemical solution deposited YBa 2Cu 3O 7- δ film properties via high heating rates

    Science.gov (United States)

    Siegal, M. P.; Dawley, J. T.; Clem, P. G.; Overmyer, D. L.

    2003-12-01

    The superconducting and structural properties of YBa 2Cu 3O 7- δ (YBCO) films grown from chemical solution deposited (CSD) metallofluoride-based precursors improve by using high heating rates to the desired growth temperature. This is due to avoiding the nucleation of undesirable a-axis grains at lower temperatures, from 650 to 800 °C in p(O 2)=0.1%. Minimizing time spent in this range during the temperature ramp of the ex situ growth process depresses a-axis grain growth in favor of the desired c-axis orientation. Using optimized conditions, this results in high-quality YBCO films on LaAlO 3(1 0 0) with Jc(77 K) ∼ 3 MA/cm 2 for films thicknesses ranging from 60 to 140 nm. In particular, there is a dramatic decrease in a-axis grains in coated-conductors grown on CSD Nb-doped SrTiO 3(1 0 0) buffered Ni(1 0 0) tapes.

  2. Efecto de las nanopartículas industriales TiO 2 , SiO 2 y ZnO sobre la viabilidad celular y expresión génica en médula ósea roja de mus musculus

    Directory of Open Access Journals (Sweden)

    Jacquelyne Zarria-Romero

    Full Text Available RESUMEN Objetivos Evaluar el efecto de las nanopartículas de ZnO, TiO2 y SiO2 sobre la viabilidad celular y la expresión génica de las interleuquinas 7 y 3 y del factor estimulante de colonias de granulocito - macrófago (GM-CSF en Mus musculus. Materiales y métodos Se extrajo médula ósea roja de cinco roedores (Balb/c para el estudio de viabilidad celular mediante la prueba de MTT. Por otro lado, grupos cinco roedores fueron inoculados vía intraperitoneal con dosis de 0,5; 1; 2,5; 5 y 10 mg/kg de nanopartículas de ZnO y SiO2 y de 5; 10; 15; 20 y 25 mg/kg de nanopartículas de TiO2, 30 h después, se obtuvo el ARN a partir de la médula ósea roja para los análisis de expresión génica empleando las técnicas de PCR y RT-PCR cuantitativa. Resultados Las nanopartículas de ZnO y SiO2 redujeron la viabilidad celular de una manera dosis-dependiente en un 37 y 26%, respectivamente, a partir de una dosis de 1 mg/kg. En cuanto al efecto sobre la expresión génica, a las dosis 5 y 10 mg/kg, las nanopartículas de TiO2 redujeron en mayor porcentaje la expresión de las interleuquinas 7 y 3 (55,3 y 70,2% respectivamente, con respecto a la expresión del GM-CSF, el mayor porcentaje de reducción lo produjo las nanopartículas de SiO2 (91%. Las nanopartículas de ZnO redujeron a partir de las dosis de 20 y 25 mg/kg. Conclusiones Las nanopartículas de ZnO, SiO2 y TiO2 alteran la viabilidad celular y la expresión génica en la médula ósea de ratón.

  3. Syntheses, Structures, and Magnetic Properties of Nickel-Doped Lepidocrocite Titanates

    DEFF Research Database (Denmark)

    Gao, Tao; Norby, Poul; Okamoto, Hiroshi

    2009-01-01

    Ni-doped titanate CsxTi2−x/2Nix/2O4 and its protonic derivative HxTi2−x/2Nix/2O4·xH2O (x = 0.7) were synthesized and characterized by means of synchrotron X-ray diffraction, Raman scattering, X-ray photoelectron spectroscopy (XPS), and magnetic measurements. CsxTi2−x/2Nix/2O4 crystallizes......H2O. Ni- and Mg-codoped titanates CsxTi2−x/2(NiyMg1−y)x/2O4 (x = 0.7, 0 ≤ y ≤ 1) were also reported. The crystal structure, interlayer chemistry, and magnetic properties of the titanates depend on the Ni substitution levels, indicating opportunities for tuning of the properties by controlling...

  4. Simulated-sunlight-activated photocatalysis of Methyl Orange using carbon and lanthanum co-doped Bi{sub 2}O{sub 3}–TiO{sub 2} composite

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Hao [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Song, Mianxin, E-mail: songmianxin@swust.edu.cn [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Yi, Facheng [Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Bian, Liang [The Xinjiang Technical Institute of Physics & Chemistry, Urumqi 830011 (China); Liu, Pan [Institute of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China); Zhang, Shuai [Fundamental Science on Nuclear Wastes and Environment Safety Laboratory, Southwest University of Science and Technology, Mianyang 621010 (China)

    2016-09-25

    The C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite was prepared by sol-gel method. The physicochemical properties of as-synthesized samples were characterized by the TG-DSC, FESEM, EDS, XRD, XPS, TEM, HRTEM and UV–vis DRS. Besides, their photoactivities were valuated by degrading Methyl Orange. The experimental results showed that the C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite has anatase crystal structure and exhibits a remarkable optical absorption in UV–visible light region. In addition, carbon and lanthanum are deposited in the Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of amorphous carbon and oxide, respectively. When the concentration of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} loading was 2.5 g/L, the decomposition rate of 25 mg/L Methyl Orange reached 94.3% under the irradiation of the 500 W xenon lamp after 60 min. The corresponding degradation rate constant of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} was 2.1, 9.2, 1.3 and 6.8 times higher than that of P25, Bi{sub 2}O{sub 3}–TiO{sub 2}, C/Bi{sub 2}O{sub 3}–TiO{sub 2} and La/Bi{sub 2}O{sub 3}–TiO{sub 2}, respectively. The reuse evaluation of C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} indicated that its photocatalytic activity has good stability. - Highlights: • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} composite was prepared by sol-gel method. • Carbon is deposited in Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of amorphous carbon. • Lanthanum is deposited in Bi{sub 2}O{sub 3}–TiO{sub 2} composite in the form of oxide. • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} exhibited superior photocatalytic activity than Bi{sub 2}O{sub 3}–TiO{sub 2}, C/Bi{sub 2}O{sub 3}–TiO{sub 2} and La/Bi{sub 2}O{sub 3}–TiO{sub 2}. • C/La/Bi{sub 2}O{sub 3}–TiO{sub 2} has good stability.

  5. Photocatalytic degradation of commercial phoxim over La-doped TiO2 nanoparticles in aqueous suspension.

    Science.gov (United States)

    Dai, Ke; Peng, Tianyou; Chen, Hao; Liu, Juan; Zan, Lin

    2009-03-01

    Photocatalytic degradation of commercial phoxim emulsion in aqueous suspension was investigated by using La-doped mesoporous TiO2 nanoparticles (m-TiO2) as the photocatalyst under UV irradiation. Effects of La-doping level, calcination temperature, and additional amount of the photocatalyst on the photocatalytic degradation efficiency were investigated in detail. Experimental results indicate that 20 mg L(-1) phoxim in 0.5 g L(-1) La/m-TiO2 suspension (the initial pH 4.43) can be decomposed as prolonging the irradiation time. Almost 100% phoxim was decomposed after 4 h irradiation according to the spectrophotometric analyses, whereas the mineralization rate of phoxim just reached ca. 80% as checked by ion chromatography (IC) analyses. The elimination of the organic solvent in the phoxim emulsion as well as the formation and decomposition of some degradation intermediates were observed by high-performance liquid chromatography-mass spectroscopy (HPLC-MS). On the basis of the analysis results on the photocatalytic degradation intermediates, two possible photocatalytic degradation pathways are proposed under the present experimental conditions, which reveal that both the hydrolysis and adsorption of phoxim under UV light irradiation play important roles during the photocatalytic degradation of phoxim.

  6. Engineering of highly ordered TiO2 nanopore arrays by anodization

    Science.gov (United States)

    Wang, Huijie; Huang, Zhennan; Zhang, Li; Ding, Jie; Ma, Zhaoxia; Liu, Yong; Kou, Shengzhong; Yang, Hangsheng

    2016-07-01

    Finite element analysis was used to simulate the current density distributions in the TiO2 barrier layer formed at the initial stage of Ti anodization. The morphology modification of the barrier layer was found to induce current density distribution change. By starting the anodization with proper TiO2 barrier layer morphology, the current density distribution can be adjusted to favor the formation of either nanotube arrays or nanopore arrays of anodic TiO2. We also found that the addition of sodium acetate into the electrolyte suppressed both the field-assisted chemical dissolution of TiO2 and the TiF62- hydrolysis induced TiO2 deposition during anodization, and thus further favored the nanopore formation. Accordingly, highly ordered anodic TiO2 nanopore arrays, similar to anodic aluminum oxide nanopore arrays, were successfully prepared.

  7. Li{sub 4}SiO{sub 4} based breeder ceramics with Li{sub 2}TiO{sub 3}, LiAlO{sub 2} and Li{sub X}La{sub Y}TiO{sub 3} additions, part II: Pebble properties

    Energy Technology Data Exchange (ETDEWEB)

    Kolb, M.H.H., E-mail: Matthias.kolb@kit.edu [Karlsruhe Institute of Technology, Institute for Applied Materials, PO Box 3640, 76021, Karlsruhe (Germany); Knitter, R. [Karlsruhe Institute of Technology, Institute for Applied Materials, PO Box 3640, 76021, Karlsruhe (Germany); Hoshino, T. [Breeding Functional Materials Development Group, Department of Blanket Systems Research, Rokkasho Fusion Institute, Fusion Energy Research and Development Directorate, National Institutes for Quantum and Radiological Science and Technology (QST) (Japan)

    2017-02-15

    Highlights: • The mechanical strength of Li{sub 4}SiO{sub 4}-based breeder pebbles can be improved by adding either LMT, LAO or LLTO as second phase. • The increase in strength is closely linked to a reduction of the open porosity of the pebbles. • All fabricated pebbles show a highly homogenous microstructure with mostly low closed porosity. • Adding LLTO, although it decomposes during sintering, greatly improves the strength of the pebbles. - Abstract: The pebble properties of novel two-phase Li{sub 4}SiO{sub 4} pebbles of 1 mm diameter with additions of Li{sub 2}TiO{sub 3}, LiAlO{sub 2} or Li{sub x}La{sub y}TiO{sub 3} are evaluated in this work as a function of the second phase concentration and the microstructure of the pebbles. The characterization focused on the mechanical strength, microstructure and open as well as closed porosity. Therefore crush load tests, SEM analyses as well as helium pycnometry and optical image analysis were performed, respectively. This work shows that generally additions of a second phase to Li{sub 4}SiO{sub 4} considerably improve the mechanical strength. It also shows that the fabrication processes have to be well-controlled to achieve high mechanical strengths. When Li{sub 2}TiO{sub 3} is added in different concentrations, the determinant for the crush load seems to be the open porosity of the pebbles. The strengthening effect of LiAlO{sub 2} compared to Li{sub 2}TiO{sub 3} is similar, while additions of Li{sub x}La{sub y}TiO{sub 3} increase the mechanical strength much more. Yet, Li{sub 4}SiO{sub 4} and Li{sub x}La{sub y}TiO{sub 3} react with each other to a number of different phases upon sintering. In general the pebble properties of all samples are favorable for use within a fusion breeder blanket.

  8. The ceramic SiO2 and SiO2-TiO2 coatings on biomedical Ti6Al4VELI titanium alloy

    International Nuclear Information System (INIS)

    Surowska, B.; Walczak, M.; Bienias, J.

    2004-01-01

    The paper presents the study of intermediate SiO 2 and SiO 2 -TiO 2 sol-gel coatings and dental porcelain coatings on Ti6Al4VELI titanium alloy. Surface microstructures and wear behaviour by pin-on-disc method of the ceramic coatings were investigated. The analysis revealed: (1) a compact, homogeneous SiO 2 and SiO 2 -TiO 2 coating and (2) that intermediate coatings may provide a durable joint between metal and porcelain, and (3) that dental porcelain on SiO 2 and TiO 2 coatings shows high wear resistance. (author)

  9. 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.

  10. Magnetic behavior of La2/3Ca1/3MnO3 / BaTiO3 bilayers

    Science.gov (United States)

    Ordonez, John E.; Gomez, Maria E.; Lopera, Wilson; Marin, Lorena; Pardo, Jose A.; Morellon, Luis; Algarabel, Pedro; Prieto, Pedro

    2013-03-01

    We have grown ferroelectric BaTiO3(BTO) and ferromagnetic La2/3Ca1/3MnO3 (LCMO) onto (001) SrTiO3 and Nb:SrTiO3 by pulsed laser deposition (PLD) at pure oxygen atmosphere, and a substrate temperature of 820° C, seeking for a multiferroic behavior in this structure. From x-ray diffraction (XRD) we found lattice parameter aBTO=4.068 Å, and aLCMO=3.804 Å, for each individual layer. In the BTO/LCMO bilayer, (002)-Bragg peak for BTO maintain its position whereas (002) LCMO peak shift to lower Bragg angle indicating a strained LCMO film. Magnetization measurements reveal an increase in the Curie temperature from 170 K to 220 K for the bilayer when LCMO (t = 47 nm) is deposited on BTO (t=52 nm) film, while depositing the BTO (50 nm) above LCMO (48 nm) the Curie temperature remains at values close to that obtained for a LCMO single layer (~175 K), deposited under identical growth parameters This work has been supported by Instituto de Nanociencias de Aragón, Zaragoza, Spain, ``El Patrimonio Autónomo Fondo Nacional de Financiamiento para CT&I FJC'' COLCIENCIAS-CENM Contract RC 275-2011 and Research Project COLCIENCIAS-UNIVALLE.

  11. Solubility and precipitation of Fe on reduced TiO{sub 2}(001)

    Energy Technology Data Exchange (ETDEWEB)

    Busiakiewicz, Adam, E-mail: adambus@uni.lodz.pl

    2014-01-01

    The solubility of Fe in reduced rutile TiO{sub 2} crystals and the followed precipitation on the (001) surface have been studied using X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) in ultra-high vacuum. The first step includes dissolving Fe in reduced TiO{sub 2} at 1073 K by the means of thermal diffusion and as a result the saturated solid solution is formed. Then, it undergoes fast cooling which leads to obtaining a supersaturated solid solution. When this supersaturated crystal is annealed at low temperatures of about 500 K, Fe starts to precipitate on the (001) surface forming spherical Fe-containing nanoparticles. The fast migration of Fe cations to the surface and their precipitation at relatively low temperatures are caused by high diffusion anisotropy and the reduction of the TiO{sub 2}. At about 900 K, the size of nanoparticles increases and they are transformed into nanocrystals with clearly visible facets. Simultaneously, the number of the nanocrystals substantially decreases. The partial oxidation of Fe is also observed around 900 K, which is related to strong metal support interaction between Fe and reduced TiO{sub 2}(001). The XPS and STM results suggest that the nanocrystals are mostly composed of mixed Fe/Ti oxides like FeTiO{sub 3} of ilmenite structure. Above 973 K, the nanocrystals disappear which is explained by the restored solubility of Fe cations in the reduced TiO{sub 2}. The process of the nanoparticle precipitation at lower temperatures is repeatable and the precipitation and disappearance of Fe-containing nanocrystals on TiO{sub 2}(001) are also a fully reversible phenomenon easily controlled by annealing temperature. - Highlights: • The supersaturated solid solution of Fe in TiO{sub 2}(001) is obtained at 1073 K. • Fe precipitates forming nanoparticles above 500 K and nanocrystals above 900 K. • Nanocrystals are ascribed to formation of FeTiO{sub 3} compound.

  12. TiO2 beads and TiO2-chitosan beads for urease immobilization

    International Nuclear Information System (INIS)

    Ispirli Doğaç, Yasemin; Deveci, İlyas; Teke, Mustafa; Mercimek, Bedrettin

    2014-01-01

    The aim of the present study is to synthesize TiO 2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO 2 beads. In the first method (A), urease enzyme was immobilized onto TiO 2 beads by adsorption and then crosslinking. In the second method (B), TiO 2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2 mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5 mg/ml for A and 1.0 mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0 mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4–70 °C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30 °C (A), 40 °C (B) and 35 °C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65 °C. However, at this temperature free urease protected only 15% activity. - Highlights: • TiO 2 and TiO 2 -chitosan beads for urease immobilization have been prepared and characterized. • The beads used in this work are good matrices for the immobilization of urease. • The immobilized urease was shown to have good properties and stabilities (pH and thermal stability, operational stability). • The 50

  13. Giant strain with low cycling degradation in Ta-doped [Bi_1_/_2(Na_0_._8K_0_._2)_1_/_2]TiO_3 lead-free ceramics

    International Nuclear Information System (INIS)

    Liu, Xiaoming; Tan, Xiaoli

    2016-01-01

    Non-textured polycrystalline [Bi_1_/_2(Na_0_._8K_0_._2)_1_/_2](Ti_1_−_xTa_x)O_3 ceramics are fabricated and their microstructures and electrical properties are characterized. Transmission electron microscopy reveals the coexistence of the rhombohedral R3c and tetragonal P4bm phases in the form of nanometer-sized domains in [Bi_1_/_2(Na_0_._8K_0_._2)_1_/_2]TiO_3 with low Ta concentration. When the composition is x = 0.015, the electrostrain is found to be highly asymmetric under bipolar fields of ±50 kV/cm. A very large value of 0.62% is observed in this ceramic, corresponding to a large-signal piezoelectric coefficient d_3_3* of 1240 pm/V (1120 pm/V under unipolar loading). These values are greater than most previously reported lead-free polycrystalline ceramics and can even be compared with some lead-free piezoelectric single crystals. Additionally, this ceramic displays low cycling degradation; its electrostrain remains above 0.55% even after undergoing 10 000 cycles of ±50 kV/cm bipolar fields at 2 Hz. Therefore, Ta-doped [Bi_1_/_2(Na_0_._8K_0_._2)_1_/_2]TiO_3 ceramics show great potential for large displacement devices.

  14. Effect of TiCl{sub 4} treatment on the photoelectrochemical properties of LaTiO{sub 2}N electrodes for water splitting under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Naoyuki [Department of Chemical System Engineering, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo (Japan); Raphael, Biet [Groupe Antennes et Hyperfre quences, I.E.T.R. UMR-CNRS 6164, Universite de Rennes 1, IUT Saint Brieuc, 18 rue Henri Wallon 22004 Saint Brieuc cedex (France); Maeda, Kazuhiko [Department of Chemical System Engineering, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo (Japan); Le Gendre, Laurent [Groupe Antennes et Hyperfre quences, I.E.T.R. UMR-CNRS 6164, Universite de Rennes 1, IUT Saint Brieuc, 18 rue Henri Wallon 22004 Saint Brieuc cedex (France); Abe, Ryu [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Kubota, Jun [Department of Chemical System Engineering, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo (Japan); Domen, Kazunari, E-mail: domen@chemsys.t.u-tokyo.ac.j [Department of Chemical System Engineering, University of Tokyo, 7-3-1 Hongo Bunkyoku, Tokyo (Japan)

    2010-08-02

    A lanthanum titanium oxynitride (LaTiO{sub 2}N) electrode was studied as a visible-light driven photoelectrode for water splitting. The electrode was prepared by casting a LaTiO{sub 2}N powder on a fluorine-doped tin oxide glass substrate, followed by calcination under dinitrogen. The as-prepared electrode exhibited an anodic photocurrent based on water oxidation under visible-light irradiation ({lambda} > 420 nm) in an electrolyte (Na{sub 2}SO{sub 4}) solution. This current was increased by post-treatment with titanium(IV) chloride (TiCl{sub 4}) solution. Scanning electron microscopy and X-ray photoelectron spectroscopy revealed that the titanium species introduced by the post-treatment were titanium oxide, and that they were embedded within LaTiO{sub 2}N particles. Resistance measurements of LaTiO{sub 2}N electrodes suggested that the increase in the electrode photocurrent after TiCl{sub 4} treatment was due to the improvement of inter-particle electron transfer in the LaTiO{sub 2}N thin film.

  15. Complex impedance study on nano-CeO2 coating TiO2

    International Nuclear Information System (INIS)

    Zhang Mei; Wang Honglian; Wang Xidong; Li Wenchao

    2006-01-01

    Titanium dioxide (TiO 2 ) nanoparticles and cerium dioxide (CeO 2 ) nanoparticles coated titanium dioxide (TiO 2 ) nanoparticles (CeO 2 -TiO 2 nanoparticles) have been successfully synthesized by sol-gel method. The complex impedance of the materials was investigated. The grain resistance, boundary resistance and activation energy of the nanoparticles were calculated according to Arrhenius equation. According to calculating results, the active capacity of pure TiO 2 nanoparticles has been improved because of nano-CeO 2 coating. An optimal CeO 2 content of 4.9 mol% was achieved. The high resolution electron microscopy images of CeO 2 -TiO 2 nanoparticles showed that TiO 2 nanoparticles, as a core, were covered by CeO 2 nanoparticles. The average size of CeO 2 coating TiO 2 nanoparticles was about 70 nm. Scanning electron microscopy observation indicted that CeO 2 nanoparticle coating improved the separation, insulation, and stability the CeO 2 -TiO 2 nanoparticles, which was benefit to the activity of materials

  16. Solvothermal preparation of micro/nanostructured TiO_2 with enhanced lithium storage capability

    International Nuclear Information System (INIS)

    Li, Jie; Wang, Chao; Zheng, Ping; Zhang, Lei; Chen, Gongxuan; Tang, Chengchun; Wu, Tian

    2017-01-01

    Facile and controllable preparation of TiO_2 is of prime importance to elaborately tailor and then fully exploit its intriguing functionalities in energy storage, catalysis and environmental remediation. Herein, a solvothermal method combined with post annealing is conducted, in which the hydrolysis of tetrabutyl titanate is controlled by the in-situ generated water during solvothermal treatment. By controlling synthetic conditions (i.e. reactant ratio, solvothermal temperature and reaction time), we manage to tailor the morphologies of TiO_2. Specially, three typical structures (nanoparticle, nanoneedle and nanorod) are studied to reveal the growth mechanism and the effects of the synthesis conditions. Nanoneedle-structured TiO_2 shows higher specific capacity and enhanced cycle stability as anode material for lithium ion batteries. - Highlights: • Controllable preparation of nano-TiO_2 is achieved by a solvothermal method. • TiO_2 morphology is tailored by tuning reactant ratio, temperature and duration. • Needle structured TiO_2 shows enhanced lithium storage capability.

  17. Effect of donor and acceptor dopants on crystallization, microstructural and dielectric behaviors of barium strontium titanate glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Avadhesh Kumar, E-mail: yadav.av11@gmail.com [Department of Physics, Dr. Bheem Rao Ambedkar Government Degree College, Anaugi, Kannauj (India); Gautam, C.R. [Department of Physics, University of Lucknow, Lucknow 226007 (India); Singh, Prabhakar [Department of Physics, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

    2016-07-05

    Bulk transparent barium strontium titanate borosilicate glasses in glass system (65-x)[(Ba{sub 0.6}Sr{sub 0.4}).TiO{sub 3}]-30[2SiO{sub 2}.B{sub 2}O{sub 3}]-5[K{sub 2}O]-x[A{sub 2}O{sub 3}], A = La, Fe (x = 2, 5 and 10) were prepared by rapid melt-quench technique and subsequently, converted into glass ceramics by regulated heat treatment process. The phase identification was carried out by X-ray powder diffraction and their surface morphology was studied by scanning electron microscopy. The dielectric properties were studied by impedance spectroscopic technique. Investigated glass samples were crystallized into major and secondary phases of Ba{sub 1.91}Sr{sub 0.09}TiO{sub 4} and Ba{sub 2}TiSi{sub 2}O{sub 8}, respectively. A very high dielectric constant having value upto 68000 was found in glass ceramic sample BST5K10F. This high value of dielectric constant was attributed to interfacial polarization, which arose due to conductivity difference among semiconducting crystalline phases, conducting grains and insulating grain boundaries. Donor dopant La{sub 2}O{sub 3} and acceptor dopant Fe{sub 2}O{sub 3} play an important role for enhancing crystallization, dielectric constant and retardation of dielectric loss in the samples. Moreover, higher value of dielectric constant and lower value of dielectric loss was found in Fe{sub 2}O{sub 3} doped samples in comparison to La{sub 2}O{sub 3} doped samples. - Highlights: • Bulk transparent barium strontium titanate glasses are successfully prepared. • A very high dielectric constant upto 68000 was found in glass ceramics. • La{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} play role for enhancing value of dielectric constant. • Higher dielectric constant with low dielectric loss was found in Fe{sub 2}O{sub 3} doped sample. • Such glass ceramics may be used in making capacitors for high energy storage.

  18. Multilevel Resistance Switching Memory in La2/3Ba1/3MnO3/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (011) Heterostructure by Combined Straintronics-Spintronics.

    Science.gov (United States)

    Zhou, Weiping; Xiong, Yuanqiang; Zhang, Zhengming; Wang, Dunhui; Tan, Weishi; Cao, Qingqi; Qian, Zhenghong; Du, Youwei

    2016-03-02

    We demonstrate a memory device with multifield switchable multilevel states at room temperature based on the integration of straintronics and spintronics in a La2/3Ba1/3MnO3/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) (011) heterostructure. By precisely controlling the electric field applied on the PMN-PT substrate, multiple nonvolatile resistance states can be generated in La2/3Ba1/3MnO3 films, which can be ascribed to the strain-modulated metal-insulator transition and phase separation of Manganite. Furthermore, because of the strong coupling between spin and charge degrees of freedom, the resistance of the La2/3Ba1/3MnO3 film can be readily modulated by magnetic field over a broad temperature range. Therefore, by combining electroresistance and magnetoresistance effects, multilevel resistance states with excellent retention and endurance properties can be achieved at room temperature with the coactions of electric and magnetic fields. The incorporation of ferroelastic strain and magnetic and resistive properties in memory cells suggests a promising approach for multistate, high-density, and low-power consumption electronic memory devices.

  19. Fabrication of TiNb{sub 2}O{sub 7} thin film electrodes for Li-ion micro-batteries by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Daramalla, V. [Materials Research Centre, Indian Institute of Science, Bengalore 560012 (India); Penki, Tirupathi Rao; Munichandraiah, N. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengalore 560012 (India); Krupanidhi, S.B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bengalore 560012 (India)

    2016-11-15

    Graphical abstract: The TiNb{sub 2}O{sub 7} thin film electrodes as anode material in Li-ion rechargeable micro-batteries are successfully demonstrated. The pulsed laser deposited TiNb{sub 2}O{sub 7} thin film electrode delivers high discharge specific capacity of 143 μAh μm{sup −1} cm{sup −2} at 50 μA cm{sup −2} current density, with 92% coulombic efficiency. The thin films are very stable in crystal structure, with good fast reversible reaction at average Li-insertion voltage 1.65 V. - Highlights: • TiNb{sub 2}O{sub 7} thin films fabricated by pulsed laser deposition. • TiNb{sub 2}O{sub 7} as anode thin films demonstrated successfully. • High discharge specific capacity with 92% coulombic efficiency. • Excellent crystal stability and good reversible reaction. - Abstract: Pulsed laser deposited TiNb{sub 2}O{sub 7} thin films are demonstrated as anode materials in rechargeable Li-ion micro-batteries. The monoclinic and chemically pure TiNb{sub 2}O{sub 7} films in different morphologies were successfully deposited at 750 °C. The single phase formation was confirmed by grazing incident X-ray diffraction, micro-Raman spectroscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The oxygen partial pressure during the deposition significantly influenced the properties of TiNb{sub 2}O{sub 7} films. The TiNb{sub 2}O{sub 7} thin films exhibited excellent stability with fast kinetics reversible reaction. The TiNb{sub 2}O{sub 7} films showed initial discharge specific capacity of 176, 143 μAh μm{sup −1} cm{sup −2} at 30, 50 μA cm{sup −2} current densities respectively with 92% coulombic efficiency in a non-aqueous electrolyte consisting of Li{sup +} ions. The high discharge specific capacity of TiNb{sub 2}O{sub 7} thin films may be attributed to nanometer grain size with high roughness which offers high surface area for Li-diffusion during charge and discharge

  20. The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

    International Nuclear Information System (INIS)

    Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

    2013-01-01

    Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO 2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na 2 Ti 2 O 5 ·H 2 O) particles (W = 9–12 nm and L = 82–115 nm) and rice like pure anatase-TNR particles (W = 8–13 nm and L = 81–134 nm) are obtained by the hydrothermal treatment of P25-TiO 2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = −2.82 (P25-TiO 2 ), −13.5 (TNT) and −22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C 9 H 10 ClN 5 O 2 ) degradation to CO 2 formation under UV irradiation because of its largest surface area 176 m 2 g −1 among the catalysts studied.

  1. Selective adsorption of thiophenic compounds from fuel over TiO{sub 2}/SiO{sub 2} under UV-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Miao, Guang [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China); Ye, Feiyan [Key Laboratory of Enhanced Heat Transfer and Energy Conservation of the Ministry of Education South China University of Technology, Guangzhou 510640 (China); Wu, Luoming; Ren, Xiaoling [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China); Xiao, Jing, E-mail: cejingxiao@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640 (China); Li, Zhong, E-mail: cezhli@scut.edu.cn [Key Laboratory of Enhanced Heat Transfer and Energy Conservation of the Ministry of Education South China University of Technology, Guangzhou 510640 (China); Wang, Haihui [Key Laboratory of Enhanced Heat Transfer and Energy Conservation of the Ministry of Education South China University of Technology, Guangzhou 510640 (China)

    2015-12-30

    Highlights: • TiO{sub 2}/SiO{sub 2} was developed for selective adsorption of DBTs under UV irradiation. • Remarkable adsorption uptake and selectivity were achieved for deep desulfurization. • Introduction of TiO{sub 2} into SiO{sub 2} enhanced its adsorption for DBTO{sub 2}. • Adsorption mechanism using TiO{sub 2}/SiO{sub 2} under UV irradiation was elucidated. - Abstract: This study investigates selective adsorption of thiophenic compounds from fuel over TiO{sub 2}/SiO{sub 2} under UV-irradiation. The TiO{sub 2}/SiO{sub 2} adsorbents were prepared and then characterized by N{sub 2} adsorption, X-ray diffraction and X-ray photoelectron spectroscopy. Adsorption isotherms, selectivity and kinetics of TiO{sub 2}/SiO{sub 2} were measured in a UV built-in batch reactor. It was concluded that (a) with the employment of UV-irradiation, high organosulfur uptake of 5.12 mg/g was achieved on the optimized 0.3TiO{sub 2}/0.7SiO{sub 2} adsorbent at low sulfur concentration of 15 ppmw-S, and its adsorption selectivity over naphthalene was up to 325.5; (b) highly dispersed TiO{sub 2} served as the photocatalytic sites for DBT oxidation, while SiO{sub 2} acted as the selective adsorption sites for the corresponding oxidized DBT using TiO{sub 2} as a promoter, the two types of active sites worked cooperatively to achieve the high adsorption selectivity of TiO{sub 2}/SiO{sub 2}; (c) The kinetic rate-determining step for the UV photocatalysis-assisted adsorptive desulfurization (PADS) over TiO{sub 2}/SiO{sub 2} was DBT oxidation; (d) consecutive adsorption-regeneration cycles suggested that the 0.3TiO{sub 2}/0.7SiO{sub 2} adsorbent can be regenerated by acetonitrile washing followed with oxidative air treatment. This work demonstrated an effective PADS approach to greatly enhance adsorption capacity and selectivity of thiophenic compounds at low concentrations for deep desulfurization under ambient conditions.

  2. Fabrication of Li_2TiO_3 pebbles by a selective laser sintering process

    International Nuclear Information System (INIS)

    Zhou, Qilai; Gao, Yue; Liu, Kai; Xue, Lihong; Yan, Youwei

    2015-01-01

    Highlights: • Selective laser sintering (SLS) is employed to fabricate ceramic pebbles. • Quantities and diameter of the pebbles could be easily controlled by adjusting the model of pebbles. • All the pebbles could be prepared at a time within several minutes. • The Li_2TiO_3 pebbles sintered at 1100 °C show a notable crush load of 43 N. - Abstract: Lithium titanate, Li_2TiO_3, is an important tritium breeding material for deuterium (D)–tritium (T) fusion reactor. In test blanket module (TBM) design of China, Li_2TiO_3 is considered as one candidate material of tritium breeders. In this study, selective laser sintering (SLS) technology was introduced to fabricate Li_2TiO_3 ceramic pebbles. This fabrication process is computer assisted and has a high level of flexibility. Li_2TiO_3 powder with a particle size of 1–3 μm was used as the raw material, whilst epoxy resin E06 was adopted as a binder. Green Li_2TiO_3 pebbles with certain strengths were successfully prepared via SLS. Density of the green pebbles was subsequently increased by cold isostatic pressing (CIP) process. Li_2TiO_3 pebbles with a diameter of about 2 mm were obtained after high temperature sintering. Density of the pebbles reaches 80% of theoretical density (TD) with a comparable crush load of 43 N. This computer assisted approach provides a new efficient route for the production of Li_2TiO_3 ceramic pebbles.

  3. The Effects of Leaching Process to the TiO2 Synthesis from Bangka Ilmenite

    Science.gov (United States)

    Wahyuningsih, S.; Ramelan, A. H.; Pramono, E.; Argawan, P.; Djatisulistya, A.; Firdiyono, F.; Sulistiyono, E.; Sari, P. P.

    2018-03-01

    Ilmenite mineral is a naturally occurring iron titanate (FeTiO3) and is abundant in nature. The separation of components into TiO2 and Fe2O3 must be expand. The purpose of this research is to synthesis TiO2 nanoparticles from the filtrate of Bangka ilmenite leaching process. Leaching of ilmenite was done with H2SO4 and HCl at various concentrations. The formation of TiO2 crystal determined by hydrolysis conditions and condensation reaction. TiO2 synthesized from the filtrate of sulfuric acid leaching that produced from TiO2 anatase phase when hydrolyzed in an aquaregia solvent and low concentrations of HCl (0.1M). Hydrolysis conditions at higher concentrations of HCl (1M) was produced TiO2 anatase-rutile phase. The synthesis of TiO2 from the filtrate of hydrochloric acid leaching was produced anatase phase. While the condition under the alcoholic solvent (2-propanol: H2O (v/v) = 9: 1) anatase phase crystallites grow in the temperature range up to 550 °C, above this temperature, TiO2 transform into rutile phase.

  4. An innovative approach to synthesize highly-ordered TiO2 nanotubes.

    Science.gov (United States)

    Isimjan, Tayirjan T; Yang, D Q; Rohani, Sohrab; Ray, Ajay K

    2011-02-01

    An innovative route to prepare highly-ordered and dimensionally controlled TiO2 nanotubes has been proposed using a mild sonication method. The nanotube arrays were prepared by the anodization of titanium in an electrolyte containing 3% NH4F and 5% H2O in glycerol. It is demonstrated that the TiO2 nanostructures has two layers: the top layer is TiO2 nanowire and underneath is well-ordered TiO2 nanotubes. The top layer can easily fall off and form nanowires bundles by implementing a mild sonication after a short annealing time. We found that the dimensions of the TiO2 nanotubes were only dependent on the anodizing condition. The proposed technique may be extended to fabricate reproducible well-ordered TiO2 nanotubes with large area on other metals.

  5. Chemically synthesized TiO2 and PANI/TiO2 thin films for ethanol sensing applications

    Science.gov (United States)

    Gawri, Isha; Ridhi, R.; Singh, K. P.; Tripathi, S. K.

    2018-02-01

    Ethanol sensing properties of chemically synthesized titanium dioxide (TiO2) and polyaniline/titanium dioxide nanocomposites (PANI/TiO2) had been performed at room temperature. In-situ oxidative polymerization process had been employed with aniline as a monomer in presence of anatase titanium dioxide nanoparticles. The prepared samples were structurally and morphologically characterized by x-ray diffraction, fourier transform infrared spectra, high resolution-transmission electron microscopy and field emission-scanning electron microscopy. The crystallinity of PANI/TiO2 nanocomposite was revealed by XRD and FTIR spectra confirmed the presence of chemical bonding between the polymer chains and metal oxide nanoparticles. HR-TEM micrographs depicted that TiO2 particles were embedded in polymer matrix, which provides an advantage over pure TiO2 nanoparticles in efficient adsorption of vapours. These images also revealed that the TiO2 nanoparticles were irregular in shape with size around 17 nm. FE-SEM studies revealed that in the porous structure of PANI/TiO2 film, the intercalation of TiO2 in PANI chains provides an advantage over pure TiO2 film for uniform interaction with ethanol vapors. The sensitivity values of prepared samples were examined towards ethanol vapours at room temperature. The PANI/TiO2 nanocomposite exhibited better sensing response and faster response-recovery examined at different ethanol concentrations ranging from 5 ppm to 20 ppm in comparison to pure TiO2 nanoparticles. The increase in vapour sensing of PANI/TiO2 sensing film as compared to pure TiO2 film had been explained in detail with the help of gas sensing mechanism of TiO2 and PANI/TiO2. This provides strong evidence that gas sensing properties of TiO2 had been considerably improved and enhanced with the addition of polymer matrix.

  6. Design of flexible PANI-coated CuO-TiO2-SiO2 heterostructure nanofibers with high ammonia sensing response values

    Science.gov (United States)

    Pang, Zengyuan; Nie, Qingxin; Lv, Pengfei; Yu, Jian; Huang, Fenglin; Wei, Qufu

    2017-06-01

    We report a room-temperature ammonia sensor with extra high response values and ideal flexibility, including polyaniline (PANI)-coated titanium dioxide-silicon dioxide (TiO2-SiO2) or copper oxide-titanium dioxide-silicon dioxide (CuO-TiO2-SiO2) composite nanofibers. Such flexible inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers were prepared by electrospinning, followed by calcination. Then, in situ polymerization of aniline monomers was carried out with inorganic TiO2-SiO2 and CuO-TiO2-SiO2 composite nanofibers as templates. Gas sensing tests at room temperature indicated that the obtained CuO-TiO2-SiO2/PANI composite nanofibers had much higher response values to ammonia gas (ca. 45.67-100 ppm) than most of those reported before as well as the prepared TiO2-SiO2/PANI composite nanofibers here. These excellent sensing properties may be due to the P-N, P-P heterojunctions and a structure similar to field-effect transistors formed on the interfaces between PANI, TiO2, and CuO, which is p-type, n-type, and p-type semiconductor, respectively. In addition, the prepared free-standing CuO-TiO2-SiO2/PANI composite nanofiber membrane was easy to handle and possessed ideal flexibility, which is promising for potential applications in wearable sensors in the future.

  7. Chemical and structural effects on the high-temperature mechanical behavior of (1−x)(Na{sub 1/2}Bi{sub 1/2})TiO{sub 3}-xBaTiO{sub 3} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Deluca, Marco [Materials Center Leoben Forschung GmbH, Roseggerstraße 12, 8700 Leoben (Austria); Institut für Struktur- und Funktionskeramik, Montanuniversitaet Leoben, Peter Tunner Straße 5, 8700 Leoben (Austria); Picht, Gunnar [Institute of Applied Materials, Ceramics in Mechanical Engineering, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Robert Bosch GmbH, Corporate Sector Research and Advance Engineering Applied Research 1, Robert Bosch Platz 1, 70839 Gerlingen (Germany); Hoffmann, Michael J. [Institute of Applied Materials, Ceramics in Mechanical Engineering, Karlsruhe Institute of Technology, 76131 Karlsruhe (Germany); Rechtenbach, Annett; Töpfer, Jörg [Department of SciTec, University of Applied Sciences Jena, Carl-Zeiß-Promenade 2, 07745 Jena (Germany); Schader, Florian H.; Webber, Kyle G., E-mail: webber@ceramics.tu-darmstadt.de [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2015-04-07

    Bismuth sodium titanate–barium titanate [(1−x)(Na{sub 1/2}Bi{sub 1/2})TiO{sub 3}-xBaTiO{sub 3}, NBT-100xBT] is one of the most well studied lead-free piezoelectric materials due in large part to the high field-induced strain attainable in compositions near the morphotropic phase boundary (x = 0.06). The BaTiO{sub 3}-rich side of the phase diagram, however, has not yet been as comprehensively studied, although it might be important for piezoelectric and positive temperature coefficient ceramic applications. In this work, we present a thorough study of BaTiO{sub 3}-rich NBT-100xBT by ferroelastic measurements, dielectric permittivity, X-ray diffraction, and Raman spectroscopy. We show that the high-temperature mechanical behavior, i.e., above the Curie temperature, T{sub C}, is influenced by local disorder, which appears also in pure BT. On the other hand, in NBT-100xBT (x < 1.0), lattice distortion, i.e., tetragonality, increases, and this impacts both the mechanical and dielectric properties. This increase in lattice distortion upon chemical substitution is counterintuitive by merely reasoning on the ionic size, and is due to the change in the A-O bond character induced by the Bi{sup 3+} electron lone pair, as indicated by Raman spectroscopy.

  8. Dielectric behaviors of Pb1-3x/2LaxTiO3 derived from mechanical activation

    International Nuclear Information System (INIS)

    Soon, H.P.; Xue, J.M.; Wang, J.

    2004-01-01

    To investigate the origin of ultrahigh relative permittivity that has been observed for lanthanum-doped lead titanate, Pb 1-3x/2 La x TiO 3 (PLT-A) with x ranging from 0.10 to 0.25 were synthesized by mechanical activation of constituent oxides. Their sintered density, grain size and relative permittivity demonstrated a steady increase with increasing of La doping. Upon thermal annealing in oxygen, the relative permittivity of Pb 0.70 La 0.2 TiO 3 (PLT-A20) at T c showed an initial rise and a peak at 4h of annealing, and then a steady fall with further increase in annealing time. In contrast, when annealed in nitrogen for 4 h, a significant rise in relative permittivity was observed, although the increase rate falls with prolonged annealing. The observed dependence of relative permittivity and dielectric loss for PLT-A20 on the initial annealing in both oxygen and nitrogen demonstrated the domination of space charge polarization as a result of PbO loss through evaporation from the surface region. While the high activation energy for Pb 2+ and O 2- diffusion through the surface scale slows down the rate of PbO loss through evaporation, excess loss of PbO adversely affect space charge polarization, leading to a fall in relative permittivity of PLT-A20, upon prolonged annealing in oxygen. In addition to PbO loss, prolonged annealing in nitrogen generated oxygen vacancies, which played an important role in affecting the relative permittivity

  9. New metal-organic frameworks of [M(C6H5O7)(C6H6O7)(C6H7O7)(H2O)] . H2O (M=La, Ce) and [Ce2(C2O4)(C6H6O7)2] . 4H2O

    International Nuclear Information System (INIS)

    Weng Shengfeng; Wang, Yun-Hsin; Lee, Chi-Shen

    2012-01-01

    Two novel materials, [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2), with a metal-organic framework (MOF) were prepared with hydrothermal reactions and characterized with photoluminescence, magnetic susceptibility, thermogravimetric analysis and X-ray powder diffraction in situ. The crystal structures were determined by single-crystal X-ray diffraction. Compound 1 crystallized in triclinic space group P1-bar (No. 2); compound 2 crystallized in monoclinic space group P2 1 /c (No. 14). The structure of 1 is built from a 1D MOF, composed of deprotonated citric ligands of three kinds. Compound 2 contains a 2D MOF structure consisting of citrate and oxalate ligands; the oxalate ligand arose from the decomposition in situ of citric acid in the presence of Cu II ions. Photoluminescence spectra of compounds 1b and 2 revealed transitions between the 5d 1 excited state and two levels of the 4f 1 ground state ( 2 F 5/2 and 2 F 7/2 ). Compounds 1b and 2 containing Ce III ion exhibit a paramagnetic property with weak antiferromagnetic interactions between the two adjacent magnetic centers. - Graphical Abstract: [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2)—with 1D and 2D structures were synthesized and characterized. Highlights: ► Two MOF – [M(C 6 H 5 O 7 )(C 6 H 6 O 7 )(C 6 H 7 O 7 )(H 2 O)] . H 2 O (M=La(1a), Ce(1b)) and [Ce 2 (C 2 O 4 )(C 6 H 6 O 7 ) 2 ] . 4H 2 O (2) – with 1D and 2D structures. ► The adjacent chains of the 1D framework were correlated with each other through an oxalate ligand to form a 2D layer structure. ► The source of the oxalate ligand was the decomposition in situ of citric acid oxidized in the presence of Cu II ions.

  10. Photocatalytic Reduction of CO2 to Methane on Pt/TiO2 Nanosheet Porous Film

    Directory of Open Access Journals (Sweden)

    Li Qiu-ye

    2014-01-01

    Full Text Available Anatase TiO2 nanosheet porous films were prepared by calcination of the orthorhombic titanic acid films at 400°C. They showed an excellent photocatalytic activity for CO2 photoreduction to methane, which should be related to their special porous structure and large Brunauer-Emmett-Teller (BET surface area. In order to further improve the photocatalytic activity, Pt nanoparticles were loaded uniformly with the average size of 3-4 nm on TiO2 porous films by the photoreduction method. It was found that the loading of Pt expanded the light absorption ability of the porous film and improved the transformation efficiency of CO2 to methane. The conversion yield of CO2 to methane on Pt/TiO2 film reached 20.51 ppm/h·cm2. The Pt/TiO2 nanosheet porous film was characterized by means of X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscope (TEM, and ultraviolet-visible light diffuse reflectance spectra (UV-vis DRS. Moreover, the transient photocurrent-time curves showed that the Pt/TiO2 nanosheet porous film exhibited higher photocurrent, indicating that the higher separation efficiency of the photogenerated charge carriers was achieved.

  11. Thermal Spray Deposition, Phase Stability and Mechanical Properties of La2Zr2O7/LaAlO3 Coatings

    Science.gov (United States)

    Lozano-Mandujano, D.; Poblano-Salas, C. A.; Ruiz-Luna, H.; Esparza-Esparza, B.; Giraldo-Betancur, A. L.; Alvarado-Orozco, J. M.; Trápaga-Martínez, L. G.; Muñoz-Saldaña, J.

    2017-08-01

    This paper deals with the deposition of La2Zr2O7 (LZO) and LaAlO3 (LAO) mixtures by air plasma spray (APS). The raw material for thermal spray, single phase LZO and LAO in a 70:30 mol.% ratio mixture was prepared from commercial metallic oxides by high-energy ball milling (HEBM) and high-temperature solid-state reaction. The HEBM synthesis route, followed by a spray-drying process, successfully produced spherical agglomerates with adequate size distribution and powder-flow properties for feeding an APS system. The as-sprayed coating consisted mainly of a crystalline LZO matrix and partially crystalline LAO, which resulted from the high cooling rate experienced by the molten particles as they impact the substrate. The coatings were annealed at 1100 °C to promote recrystallization of the LAO phase. The reduced elastic modulus and hardness, measured by nanoindentation, increased from 124.1 to 174.7 GPa and from 11.3 to 14.4 GPa, respectively, after the annealing treatment. These values are higher than those reported for YSZ coatings; however, the fracture toughness ( K IC) of the annealed coating was only 1.04 MPa m0.5.

  12. H–TiO{sub 2}/C/MnO{sub 2} nanocomposite materials for high-performance supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Di, Jing; Fu, Xincui; Zheng, Huajun, E-mail: zhenghj@zjut.edu.cn [Zhejiang University of Technology, Department of Applied Chemistry (China); Jia, Yi [Griffith University, Nathan Campus, Queensland Micro and Nanotechnology Centre (Australia)

    2015-06-15

    Functionalized TiO{sub 2} nanotube arrays with decoration of MnO{sub 2} nanoparticles (denoted as H–TiO{sub 2}/C/MnO{sub 2}) have been synthesized in the application of electrochemical capacitors. To improve both areal and gravimetric capacitance, hydrogen treatment and carbon coating process were conducted on TiO{sub 2} nanotube arrays. By scanning electron microscopy and X-ray photoelectron spectroscopy, it is confirmed that the nanostructure is formed by the uniform incorporation of MnO{sub 2} nanoparticles growing round the surface of the TiO{sub 2} nanotube arrays. Impedance analysis proves that the enhanced capacitive is due to the decrease of charge transfer resistance and diffusion resistance. Electrochemical measurements performed on this H–TiO{sub 2}/C/MnO{sub 2} nanocomposite when used as an electrode material for an electrochemical pseudocapacitor presents quasi-rectangular shaped cyclic voltammetry curves up to 100 mV/s, with a large specific capacitance (SC) of 299.8 F g{sup −1} at the current density of 0.5 A g{sup −1} in 1 M Na{sub 2}SO{sub 4} electrolyte. More importantly, the electrode also exhibits long-term cycling stability, only ∼13 % of SC loss after 2000 continuous charge–discharge cycles. Based on the concept of integrating active materials on highly ordered nanostructure framework, this method can be widely applied to the synthesis of high-performance electrode materials for energy storage.

  13. Vibrational modes and Structure of Niobium(V) Oxosulfato Complexes in the Molten Nb2O5-K2S2O7-K2SO4 System Studied by Raman Spectroscopy

    DEFF Research Database (Denmark)

    Paulsen, Andreas L.; Borup, Flemming; Berg, Rolf W.

    2010-01-01

    The structural and vibrational properties of NbV oxosulfato complexes formed in Nb2O5-K2S2O7 and Nb2O5-K2S2O7-K2SO4 molten mixtures with 0 ... for the binary Nb2O5-K2S2O7 molten system indicate that the dissolution of Nb2O5 proceeds with consumption of S2O7 leading to the formation of a NbV oxosulfato complex according to Nb2O5 + nS2O7 --> C2n-; a simple formalism exploiting the relative Raman band intensities is used for determining the stoichiometric...... coefficient, n, pointing to n = 3 and to the following reaction: Nb2O5 + 3S2O7 --> 2NbO(SO4)3, which is consistent with the Raman spectra of the molten mixtures. Nb2O5 could be dissolved much easier when K2SO4 was present in an equimolar (1:1) SO4/Nb ratio; the incremental presence of K2SO4 in Nb2O5-K2S2O7...

  14. Multistep structural transition of hydrogen trititanate nanotubes into TiO{sub 2}-B nanotubes: a comparison study between nanostructured and bulk materials

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, Edisson Jr [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Jardim, P M [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Marinkovic, Bojan A [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Rizzo, Fernando C [Department of Materials Science and Metallurgy, Pontifical Catholic University, CP 38008, 22453-900 Rio de Janeiro-RJ (Brazil); Abreu, Marco A S de [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Zotin, Jose L [PETROBRAS S.A./CENPES, Research and Development Centre, Avenida Horacio Macedo, 950, Cidade Universitaria, Quadra 7, 21941-598 Rio de Janeiro-RJ (Brazil); Araujo, Antonio S [Department of Chemistry, Federal University of Rio Grande do Norte, CP 1662, 59078-970 Natal-RN (Brazil)

    2007-12-12

    H-trititanate nanotubes obtained by alkali hydrothermal treatment of TiO{sub 2} followed by proton exchange were compared to their bulk H{sub 2}Ti{sub 3}O{sub 7} counterpart with respect to their thermally induced structural transformation paths. As-synthesized and heat-treated samples were characterized by XRD, TEM/SAED, DSC and spectroscopy techniques, indicating that H{sub 2}Ti{sub 3}O{sub 7} nanotubes showed the same sequence of structural transformations as their bulk counterpart obtained by conventional solid state reaction. Nanostructured H{sub 2}Ti{sub 3}O{sub 7} converts into TiO{sub 2}(B) via multistep transformation without losing its nanotubular morphology. The transformation occurs between 120 and 400 deg. C through topotactic mechanisms with the intermediate formation of nanostructured H{sub 2}Ti{sub 6}O{sub 13} and H{sub 2}Ti{sub 12}O{sub 25}, which are more condensed layered titanates eventually rearranging to TiO{sub 2}(B). Our results suggest that the intermediate tunnel structure H{sub 2}Ti{sub 12}O{sub 25} is the final layered intermediate phase, on which TiO{sub 2}(B) nucleates and grows. The conversion of nanostructured TiO{sub 2}(B) into anatase is completed at a much lower temperature than its bulk counterpart and is accompanied by loss of the nanotubular morphology.

  15. Anisotropic thermal expansion of La(n)(Ti,Fe)(n)O(3n + 2) (n = 5 and 6).

    Science.gov (United States)

    Wölfel, Alexander; Dorscht, Philipp; Lichtenberg, Frank; van Smaalen, Sander

    2013-04-01

    Crystal structures are reported for two perovskite-related compounds with nominal compositions La5(Ti(0.8)Fe(0.2))5O17 and La6(Ti(0.67)Fe(0.33))6O20 at seven different temperatures between 90 and 350 K. For both compounds no evidence of a structural phase transition in the investigated range of temperatures was found. The thermal expansions are found to be anisotropic, with the largest thermal expansion along a direction parallel to the slabs of these layered compounds. The origin of this anisotropy is proposed to be a temperature dependence of tilts of the octahedral (Ti,Fe)O6 groups. It is likely that the same mechanism will determine similar anisotropic thermal behaviour of other compounds A(n)B(n)O(3n + 2). The crystal structures have revealed partial chemical order of Ti/Fe over the B sites, with iron concentrated towards the centers of the slabs. Local charge compensation is proposed as the driving force for the chemical order, where the highest-valent cation moves to sites near the oxygen-rich borders of the slabs. A linear dependence on the site occupation fraction by Fe of the computed valences leads to extrapolated valence values close to the formal valence of Ti(4+) for sites fully occupied by Ti, and of Fe(3+) for sites fully occupied by Fe. These results demonstrate the power of the bond-valence method, and they show that refined oxygen positions are the weighted average of oxygen positions in TiO6 and FeO6 octahedral groups.

  16. La_2O_3-TiO_2系多孔質ガラスセラミックスの湿度センサーへの応用

    OpenAIRE

    清水, 康博; 岡田, 英昭; 荒井, 弘通

    1987-01-01

    The sodium borate glass system containing La2O3 and TiO2 shows a marked trend toward microphase separation after heat treatment, resulting in water-soluble sodium borate and water-insoluble La2O3-TiO2 ceramic phases. Then La2O3-TiO2-rich skeletons can be obtained by leaching out the sodium borate phase. The application of thus obtained porous glass-ceramics with interconnected pores to a humidity sensor is of interest. Microstructure, such as surface area and pore size distibution, of the ...

  17. Sol–gel hybrid membranes loaded with meso/macroporous SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} materials with high proton conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Yolanda, E-mail: castro@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Mosa, Jadra, E-mail: jmosa@icv.csic.es [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Aparicio, Mario [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain); Pérez-Carrillo, Lourdes A.; Vílchez, Susana; Esquena, Jordi [Instituto de Química Avanzada de Cataluña, Consejo Superior de Investigaciones Científicas (IQAC-CSIC), CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Jordi Girona 18-26, 08034 Barcelona (Spain); Durán, Alicia [Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), Campus de Cantoblanco, 28049 Madrid (Spain)

    2015-01-15

    In this work, highly conductive hybrid organic–inorganic membranes loaded with SiO{sub 2}, TiO{sub 2}–P{sub 2}O{sub 5} and SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5} meso/macroporous particles were prepared via a sol–gel process. Meso/macroporous particles were incorporated to hybrid membranes, for improving water retention and enhancing electrochemical performance. These particles with a polymodal pore size distribution were prepared by templating in highly concentrated emulsions, the particles showed a specific surface area between 50 m{sup 2}/g (TiO{sub 2}–P{sub 2}O{sub 5}) and 300 m{sup 2}/g (SiO{sub 2}–TiO{sub 2}–P{sub 2}O{sub 5}). The particles were dispersed in a hybrid silica sol and further sprayed onto glass paper. The films were polymerized and sintered; those loaded with meso/macroporous particles had a homogenous distribution. High temperature proton conductivity measurements confirmed a high water retention. Conductivity of these materials is higher than that of Nafion{sup ®} at higher temperatures (120 °C) (2·10{sup −2} S/cm). This study provides processing guideline to achieve hybrid electrolytes for efficient conduction of protons due to their high surface area and porous structure. - Highlights: • Hybrid electrolyte with meso/macroporous particles were synthesized by sol–gel. • Depositions of hybrid solutions by spraying onto glass substrates were performed. • Proton conductivity was evaluated as a function of composition and porous structure.

  18. Effects of sintering and paste-baking conditions on PTCR characteristic of (Ba,Sr)TiO{sub 3} vacuum-sintered compact added with TiO{sub 2}(Ti) powder; TiO{sub 2}(ti) fun tenka (Ba,Sr)TiO{sub 3} shinku shoketsutai no PTCR tokusei ni oyobosu shoketsu oyobi paste yakitsuke joken no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.; Hayashi, K. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science

    1999-04-15

    The effects of sintering temperature (T{sub s}; 1,573 {approx} 1,748K) and time (t{sub s}; 0.6 {approx} 14.4ks) and paste-baking-temperature or heating temperature (T{sub b} or T{sub h}; 673 {approx} 1,273K; t{sub b} is 0.3ks) on PTCR characteristic were investigated for (Ba, Sr)TiO{sub 3} vacuum-sintered compact added with 3.9mass% TiO{sub 2}(Ti) powder of 12.5mass% TiO{sub 2}. The results obtained were as follows; (1) PTCR characteristic developed at all T{sub s} (t{sub s}=3.6ks, T{sub b}=853K). The electrical resistivity at room temperature ({rho}{sub rt}) showed a minimum value of 1.8 times 10{sup 2}ohmcenter dotcm and the {rho}{sub max}/{rho}{sub rt} showed a maximum value of about 10{sup 6} at 1,723K. (2)For all t{sub s} (T{sub s}=1,623K, T{sub b}=853K), PTCR characteristic developed. The {rho}{sub rt} showed a minimum value of 2.6 times 10{sup 3}ohmcenter dotcm at 7.2ks. (3) At T{sub b} above 823K (T{sub s}=1,623K, t{sub s}=3.6ks), PTCR characteristic developed. The {rho}{sub rt} showed a minimum value of 1.0 times 10{sup 3}ohmcenter dotcm. (4)The {rho}-T curve of (Ba, Sr)TiO{sub 3}+TiO{sub 2}(Ti) vacuum-sintered compact was affected more largely by T{sub s}, t{sub s} and T{sub b} than that of (Ba, Sr)TiO{sub 3} air-sintered compact. This was considered to be mainly due to the porous and fine gained microstructure in the former compact. (author)

  19. Hierarchical architectures of ZnS–In2S3 solid solution onto TiO2 nanofibers with high visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Liu, Chengbin; Meng, Deshui; Li, Yue; Wang, Longlu; Liu, Yutang; Luo, Shenglian

    2015-01-01

    Graphical abstract: A unique hierarchical architecture of ZnS–In 2 S 3 solid solution onto TiO 2 nanofibers was fabricated. The hierarchical heterostructures exhibit high visible light photocatalytic activity and outstanding recycling performance. - Highlights: • Novel hierarchical heterostructure of TiO 2 @ZnS–In 2 S 3 solid solution. • Efficient inhibition of ZnS–In 2 S 3 solid solution aggregation. • High visible light photocatalytic activity. • Highly stable recycling performance. - Abstract: A unique hierarchical architecture of ZnS–In 2 S 3 solid solution nanostructures onto TiO 2 nanofibers (TiO 2 @ZnS–In 2 S 3 ) has been successfully fabricated by simple hydrothermal method. The ZnS–In 2 S 3 solid solution nanostructures exhibit a diversity of morphologies: nanosheet, nanorod and nanoparticle. The porous TiO 2 nanofiber templates effectively inhibit the aggregation growth of ZnS–In 2 S 3 solid solution. The formation of ZnS–In 2 S 3 solid solution is proved by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the intimate contact between TiO 2 nanofibers and ZnS–In 2 S 3 solid solution favors fast transfer of photogenerated electrons. The trinary TiO 2 @ZnS–In 2 S 3 heterostructures exhibit high adsorption capacity and visible light photocatalytic activity for the degradation of rhodamine B dye (RhB), remarkably superior to pure TiO 2 nanofibers or binary structures (ZnS/TiO 2 nanofibers, In 2 S 3 /TiO 2 nanofibers and ZnS–In 2 S 3 solid solution). Under visible light irradiation the RhB photocatalytic degradation rate over TiO 2 @ZnS–In 2 S 3 heterostructures is about 16.7, 12.5, 6.3, 5.9, and 2.2 times that over pure TiO 2 nanofibers, ZnS nanoparticles, In 2 S 3 /TiO 2 nanofibers, ZnS/TiO 2 nanofibers, and ZnS-In 2 S 3 solid solution, respectively. Furthermore, the TiO 2 @ZnS–In 2 S 3 heterostructures show highly stable recycling performance

  20. Characteristics of (Ti,Ta)N thin films prepared by using pulsed high energy density plasma

    Energy Technology Data Exchange (ETDEWEB)

    Feng Wenran [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Chen Guangliang [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Li Li [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Lv Guohua [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Zhang Xianhui [College of Science, Changchun University of Science and Technology, Changchun 130022, Jilin Province (China); Niu Erwu [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Liu Chizi [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China); Yang Size [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

    2007-07-21

    (Ti,Ta)N films were prepared by pulsed high energy density plasma (PHEDP) from a coaxial gun in N{sub 2} gas. The coaxial gun is composed of a tantalum inner electrode and a titanium outer one. Material characteristics of the (Ti,Ta)N film were investigated by x-ray photoelectron spectroscopy and x-ray diffraction. The microstructure of the film was observed by a scanning electron microscope. The elemental composition and the interface of the film/substrate were analysed using Auger electron spectrometry. Our results suggest that the binary metal nitride film (Ti,Ta)N, can be prepared by PHEDP. It also shows that dense nanocrystalline (Ti,Ta)N film can be achieved.

  1. High photocatalytic activity of immobilized TiO{sub 2} nanorods on carbonized cotton fibers

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Bin, E-mail: bwang23@cityu.edu.hk [Ability R and D Energy Research Center, School of Energy and Environment, City University of Hong Kong, Hong Kong (China); Karthikeyan, Rengasamy; Lu, Xiao-Ying [Ability R and D Energy Research Center, School of Energy and Environment, City University of Hong Kong, Hong Kong (China); Xuan, Jin [Ability R and D Energy Research Center, School of Energy and Environment, City University of Hong Kong, Hong Kong (China); State-Key Laboratory of Chemical Engineering, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai 200237 (China); Leung, Michael K.H., E-mail: mkh.leung@cityu.edu.hk [Ability R and D Energy Research Center, School of Energy and Environment, City University of Hong Kong, Hong Kong (China)

    2013-12-15

    Highlights: • Hollow carbon fibers derived from natural cotton was successfully prepared by pyrolysis method. • TiO{sub 2} nanorods immobilized on carbon fibers by a facile hydrothermal method showed high photocatalytic activity. • The enhancement was due to the reduced band gap, improved dye adsorption capacity and effective electron–hole separation. -- Abstract: In this study, TiO{sub 2} nanorods were successfully immobilized on carbon fibers by a facile pyrolysis of natural cotton in nitrogen atmosphere followed by a one-pot hydrothermal method. Carbonized cotton fibers (CCFs) and TiO{sub 2}-CCFs composites were characterized using field-emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffractometer (XRD), diffuse reflectance UV–vis spectroscopy (DRS) and photoluminescence (PL) spectroscopy. Results implied that the band gap narrowing of TiO{sub 2} was achieved after integration of CCFs. Dye adsorption isotherm indicated that the maximum dye adsorption capacity (q{sub m}) of CCFs-1000 (13.4 mg/g) was 2 times higher than that of cotton fibers and q{sub m} of TiO{sub 2}-CCFs-1000 (9.0 mg/g) was 6–7 times higher than that of TiO{sub 2} nanorods. Photocatalytic activity of TiO{sub 2} nanorods prepared with 3 mL Ti(OBu){sub 4} showed the highest photocatalytic activity. TiO{sub 2}-CCFs-1000 exhibited higher activity than TiO{sub 2} immobilized on CCFs-400, CCFs-600 and CCFs-800. Good photostability of TiO{sub 2}-CCFs-1000 was found for dye degradation under visible light irradiation. The enhancement of photocatalytic dye degradation was due to the high adsorptivity of dye molecules, enhanced light adsorption and effective separation of electron–hole pairs. This work provides a low-cost and sustainable approach to immobilize nanostructured TiO{sub 2} on carbon fibers for environmental remediation.

  2. Study of directionally solidified eutectic Al2O3-ZrO2(3%Y2O3 doped with TiO2

    Directory of Open Access Journals (Sweden)

    Peña, J. I.

    2007-06-01

    Full Text Available An study of directionally grown samples of the eutectic composition in the Al2O3-ZrO2 (3 mol% Y2O3 system, with small TiO2 additions (1 wt%, is presented. The microstructural changes induced by this addition are analysed using SEM (EDX techniques. The mechanical changes, when TiO2 is added, are studied by measuring the flexural strength by three point bending. Also, the toughness is determined by Vickers indentation method. When slow growth rates (10 mm/h are used, interpenetratred and homogeneous microstructure is obtained, independently of the TiO2 doping. When growth rates are higher (300 and 1000 mm/h the structure changes and the phases are organized in form of colonies or cells, which have smaller size when TiO2 is present. This size reduction is accompanied with an increase of the toughness.Este trabajo presenta un estudio de muestras crecidas direccionalmente del sistema Al2O3-ZrO2 (3 mol% Y2O3 en su composición eutéctica con pequeñas adiciones de óxido de titanio (1% de TiO2 en peso. Se analizan los cambios microestructurales inducidos por esta adición mediante SEM (EDX y se estudian los cambios en su comportamiento mecánico medido por flexión en tres puntos, así como la tenacidad de fractura mediante indentación Vickers. Con velocidades lentas de solidificación (10 mm/h se obtiene en ambos casos una microestructura homogénea e interpenetrada, mientras que a velocidades mayores, 300 y 1000 mm/h, se forma una estructura en las que las fases se organizan en forma de colonias o células, siendo éstas de menor tamaño en las muestras dopadas. Esta disminución en el tamaño viene acompañada de un aumento de la tenacidad de fractura medida por indentación.

  3. Thermal Annealing Effect on Optical Properties of Binary TiO2-SiO2 Sol-Gel Coatings

    Directory of Open Access Journals (Sweden)

    Xiaodong Wang

    2012-12-01

    Full Text Available TiO2-SiO2 binary coatings were deposited by a sol-gel dip-coating method using tetrabutyl titanate and tetraethyl orthosilicate as precursors. The structure and chemical composition of the coatings annealed at different temperatures were analyzed by Raman spectroscopy and Fourier Transform Infrared (FTIR spectroscopy. The refractive indices of the coatings were calculated from the measured transmittance and reflectance spectra. An increase in refractive index with the high temperature thermal annealing process was observed. The Raman and FTIR results indicate that the refractive index variation is due to changes in the removal of the organic component, phase separation and the crystal structure of the binary coatings.

  4. Enhanced electrical and magnetic properties in La0.7Sr0.3MnO3 thin films deposited on CaTiO3-buffered silicon substrates

    Directory of Open Access Journals (Sweden)

    C. Adamo

    2015-06-01

    Full Text Available We investigate the suitability of an epitaxial CaTiO3 buffer layer deposited onto (100 Si by reactive molecular-beam epitaxy (MBE for the epitaxial integration of the colossal magnetoresistive material La0.7Sr0.3MnO3 with silicon. The magnetic and electrical properties of La0.7Sr0.3MnO3 films deposited by MBE on CaTiO3-buffered silicon (CaTiO3/Si are compared with those deposited on SrTiO3-buffered silicon (SrTiO3/Si. In addition to possessing a higher Curie temperature and a higher metal-to-insulator transition temperature, the electrical resistivity and 1/f noise level at 300 K are reduced by a factor of two in the heterostructure with the CaTiO3 buffer layer. These results are relevant to device applications of La0.7Sr0.3MnO3 thin films on silicon substrates.

  5. Fabrication of La-doped TiO2 Film Electrode and investigation of its electrocatalytic activity for furfural reduction

    International Nuclear Information System (INIS)

    Wang, Fengwu; Xu, Mai; Wei, Lin; Wei, Yijun; Hu, Yunhu; Fang, Wenyan; Zhu, Chuan Gao

    2015-01-01

    Lanthanum trivalent ions (La 3+ ) doped nano-TiO 2 film electrode was prepared by the sol–gel method. The prepared electrode was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The electrocatalytic properties of the roughened TiO 2 film electrode towards the electrocatalytic reduction of furfural to furfural alcohol were evaluated by CV and preparative electrolysis experiments. The results of the optimum molar ratio of La: Ti was 0.005:1. Experimental evidence was presented that the La nano-TiO 2 electrode exhibited higher electrocatalytic activity for the reduction of furfural than the undoped nano-TiO 2 electrode in N,N-dimethylformamide medium. Bulk electrolysis studies were also carried out for the reduction of furfural and the product was confirmed by NMR

  6. Intergrown SnO{sub 2}–TiO{sub 2}@graphene ternary composite as high-performance lithium-ion battery anodes

    Energy Technology Data Exchange (ETDEWEB)

    Jiao, Zheng; Gao, Renmei [Shanghai University, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering (China); Tao, Haihua [Inspection Center of Industrial Products and Raw Materials of SHCIQ (China); Yuan, Shuai [Shanghai University, Research Center of Nanoscience and Nanotechnology (China); Xu, Laiqiang; Xia, Saisai; Zhang, Haijiao, E-mail: hjzhang128@shu.edu.cn [Shanghai University, Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering (China)

    2016-10-15

    In recent years, a lot of metal oxides with high theoretical capacity have widely investigated as the high-performance anode materials for lithium-ion batteries (LIBs). In this work, a simple, facile and effective one-pot hydrothermal strategy toward ternary SnO{sub 2}–TiO{sub 2}@graphene composite has been developed by using SnCl{sub 2} and TiOSO{sub 4} as the starting materials. The obtained composite demonstrates a unique structure and high surface areas, in which both SnO{sub 2} and TiO{sub 2} nanoparticles are well grown on the surface of graphene. More interestingly, the SnO{sub 2} and TiO{sub 2} nanoparticles are intergrowth together, totally different with the traditional ternary hybrids. When used as anode material for LIBs, the introduction of TiO{sub 2} plays a crucial role in maintaining the structural stability of the electrode during Li{sup +} insertion/extraction, which can effectively prevent the aggregation of SnO{sub 2} nanoparticles. The electrochemical tests indicate that as-prepared SnO{sub 2}–TiO{sub 2}@graphene composite exhibits a high capacity of 1276 mA h g{sup −1} after 200 cycles at the current density of 200 mA g{sup −1}. Furthermore, the composite also maintains the specific capacity of 611 mA h g{sup −1} at an ultrahigh current density of 2000 mA g{sup −1}, which is superior to those of the reported SnO{sub 2} and SnO{sub 2}/graphene hybrids. Accordingly, the remarkable electrochemical performance of ternary SnO{sub 2}–TiO{sub 2}@graphene composites is mainly attributed to their unique nanostructure, high surface areas, and the synergistic effect not only between graphene and metal oxides but also between the intergrown SnO{sub 2} and TiO{sub 2} nanoparticles.Graphical abstractIntergrown SnO{sub 2} and TiO{sub 2} nanoparticles have been successfully anchored onto the graphene nanosheets as high-performance lithium-ion battery anodes.

  7. Investigation of Titanium Sesquioxide Ti2O3: Synthesis and Physical Properties

    KAUST Repository

    Li, Yangyang

    2016-11-08

    layer structure floating on top surface of water subjected to the white light illumination of 7 kW/cm2. Furthermore, room temperature mid-infrared (10 μm) photodetectors based on Ti2O3/graphene hybrid structure was fabricated and studied. The photoresponsivity of this hybrid device, operated from 4.5 to 10 μm, is above ~ 100 A/W, which, to our knowledge, is the highest value for the mid-infrared photodetectors operating in the photocurrent (PC) mode. In chapter 5, structure, optical, transport properties of Ti2O3 epitaxial thin films on sapphire fabricated by pulsed laser deposition (PLD) will be discussed. By tailoring growth conditions, two different: trigonal and orthorhombic, of Ti2O3 were stabilized on Al2O3 substrates. More interestingly, the orthorhombic Ti2O3 has never been reported, and, moreover, superconductivity (~8 K) and high temperature ferromagnetism (up to 700 K) was discovered in this new stabilized phase. More details of the physical properties of Ti2O3 will be discussed in the following chapters of this dissertation.

  8. High Ic, YBa2Cu3O7-x films grown at very high rates by liquid assisted growth incorporating lightly Au-doped SrTiO3 buffers

    International Nuclear Information System (INIS)

    Kursumovic, A; Durrell, J H; Harrington, S; Wimbush, S; MacManus-Driscoll, J L; Maiorov, B; Zhou, H; Stan, L; Holesinger, T G; Wang, H

    2009-01-01

    YBa 2 Cu 3 O 7-x (YBCO) thick films were grown by hybrid liquid phase epitaxy (HLPE) on (001) SrTiO 3 (STO) substrates. In the presence of a 100 nm thick, 5 mol% Au-doped STO buffer, self-field critical current densities, J c sf , at 77 K of ∼2.4 MA cm -2 and critical currents, I c sf , up to 700 A (cm-width) -1 were achieved. The J c value is virtually independent of thickness and the growth rates are very high (∼1 μm min -1 ). From transmission electron microscopy (TEM), Y 2 O 3 nanocloud extended defects (∼100 nm in size) were identified as the pinning defects in the films. Enhanced random pinning was induced by the presence of Au in the buffer.

  9. Cellulose acetate-based SiO2/TiO2 hybrid microsphere composite aerogel films for water-in-oil emulsion separation

    Science.gov (United States)

    Yang, Xue; Ma, Jianjun; Ling, Jing; Li, Na; Wang, Di; Yue, Fan; Xu, Shimei

    2018-03-01

    The cellulose acetate (CA)/SiO2-TiO2 hybrid microsphere composite aerogel films were successfully fabricated via water vapor-induced phase inversion of CA solution and simultaneous hydrolysis/condensation of 3-aminopropyltrimethoxysilane (APTMS) and tetrabutyl titanate (TBT) at room temperature. Micro-nano hierarchical structure was constructed on the surface of the film. The film could separate nano-sized surfactant-stabilized water-in-oil emulsions only under gravity. The flux of the film for the emulsion separation was up to 667 L m-2 h-1, while the separation efficiency was up to 99.99 wt%. Meanwhile, the film exhibited excellent stability during multiple cycles. Moreover, the film performed excellent photo-degradation performance under UV light due to the photocatalytic ability of TiO2. Facile preparation, good separation and potential biodegradation maked the CA/SiO2-TiO2 hybrid microsphere composite aerogel films a candidate in oil/water separation application.

  10. LaNiO{sub 3} buffer layers for high critical current density YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} films

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, C.M.; Parilla, P.A.; Siegal, M.P.; Ginley, D.S.; Wang, Y.; Blaugher, R.D.; Price, J.C.; Overmyer, D.L.; Venturini, E.L.

    1999-10-01

    We demonstrate high critical current density superconducting films of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} (YBCO) and Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8{minus}{delta}} (Tl-2212) using LaNiO{sub 3} (LNO) buffer layers. YBCO films grown on an LNO buffer layer have only a slightly lower J{sub c} (5 K, H=0) than films grown directly on a bare LaAlO{sub 3} substrate. YBCO films grown on LNO buffer layers exhibit minor microstructural disorder and enhanced flux pinning. LNO-buffered Tl-2212 samples show large reductions in J{sub c} at all temperatures and fields compared to those grown on bare LaAlO{sub 3}, correlating to both {ital a}-axis grain and nonsuperconducting phase formation. LNO could be a promising buffer layer for both YBCO and Tl-based superconducting films in coated conductor applications. {copyright} {ital 1999 American Institute of Physics.}

  11. High performance GaN-based LEDs on patterned sapphire substrate with patterned composite SiO2/Al2O3 passivation layers and TiO2/Al2O3 DBR backside reflector.

    Science.gov (United States)

    Guo, Hao; Zhang, Xiong; Chen, Hongjun; Zhang, Peiyuan; Liu, Honggang; Chang, Hudong; Zhao, Wei; Liao, Qinghua; Cui, Yiping

    2013-09-09

    GaN-based light-emitting diodes (LEDs) on patterned sapphire substrate (PSS) with patterned composite SiO(2)/Al(2)O(3) passivation layers and TiO(2)/Al(2)O(3) distributed Bragg reflector (DBR) backside reflector have been proposed and fabricated. Highly passivated Al(2)O(3) layer deposited on indium tin oxide (ITO) layer with excellent uniformity and quality has been achieved with atomic layer deposition (ALD) technology. With a 60 mA current injection, an enhancement of 21.6%, 59.7%, and 63.4% in the light output power (LOP) at 460 nm wavelength was realized for the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layers, the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layers and Ag mirror + 3-pair TiO(2)/SiO(2) DBR backside reflector, and the LED with the patterned composite SiO(2)/Al(2)O(3) passivation layer and Ag mirror + 3-pair ALD-grown TiO(2)/Al(2)O(3) DBR backside reflector as compared with the conventional LED only with a single SiO(2) passivation layer, respectively.

  12. Low-Temperature Transformations of Protonic Forms of Layered Complex Oxides HLnTiO4 and H2Ln2Ti3O10 (Ln = La, Nd)

    International Nuclear Information System (INIS)

    Abdulaeva, L.D.; Silyukov, O.I.; Zvereva, I.A.; Petrov, Yu.V.

    2013-01-01

    In the present work protonic forms of layered Ruddlesden-Popper oxides HLnTiO 4 and H 2 Ln 2 Ti 3 O 10 (Ln = La, Nd) were used as the starting point for soft chemistry synthesis of two series of perovskite-like compounds by acid leaching and exfoliation, promoted by vanadyl sulfate. The last route leads to the nano structured VO 2+ containing samples. Characterization by SEM, powder XRD, and TGA has been performed for the determination of the structure and composition of synthesized oxides

  13. Growth and properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/YBa{sub 2}Cu{sub 3}O{sub 7−δ}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3} epitaxial trilayer films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Minaxi, E-mail: meenanith@gmail.com; Kumar, Arvind; Sharma, K. K. [Department of Physics, National Institute of Technology, Hamirpur -177005 (India); Kumar, Ravi [Centre for Materials Science and Engineering, National Institute of Technology, Hamirpur -177005 (India); Beant College of Engineering and Technology, Gurdaspur Punjab-143521 (India); Choudhary, R. J. [UGC-DAE-Consortium for Scientific Research, Khandwa Road, Indore-452001 (India)

    2015-08-28

    We report the growth and properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3}/YBa{sub 2}Cu{sub 3}O{sub 7−δ}/La{sub 0.7}Sr{sub 0.3}MnO{sub 3} LSMO/YBCO/LSMO epitaxial trilayer films, fabricated on SrTiO{sub 3} substrate using pulsed laser deposition technique. From x-ray diffraction and high resolution x-ray diffraction measurements, it is confirmed that the grown trilayered films are single phase and epitaxial in nature. Magneto-transport and magnetic properties are found to be dependent on the thickness of YBCO spacer layer. We infer that for fixed thickness of top and bottom LSMO layers, superconductivity is completely suppressed. At 100 K, the hysteresis loops reveal the ferromagnetic signature of trilayered film. At room temperature, we obtain a butterfly type scenario, signifies the co-existence of ferromagnetic and antiferromagnetic interaction. In addition, at room temperature, the YBCO spacer layer allowing the top and bottom LSMO layers to interact antiferromagnetically.

  14. Decontamination of 2-chloroethyl ethylsulfide using titanate nanoscrolls

    Science.gov (United States)

    Kleinhammes, Alfred; Wagner, George W.; Kulkarni, Harsha; Jia, Yuanyuan; Zhang, Qi; Qin, Lu-Chang; Wu, Yue

    2005-08-01

    Titanate nanoscrolls, a recently discovered variant of TiO 2 nanocrystals, are tested as reactive sorbent for chemical warfare agent (CWA) decontamination. The large surface area of the uncapped tubules provides the desired rapid absorption of the contaminant while water molecules, intrinsic constituents of titanate nanoscrolls, provide the necessary chemistry for hydrolytic reaction. In this study the decomposition of 2-chloroethyl ethylsulfide (CEES), a simulant for the CWA mustard, was monitored using 13C NMR. The NMR spectra reveal reaction products as expected from the hydrolysis of CEES. This demonstrates that titanate nanoscrolls could potentially be employed as a decontaminant for CWAs.

  15. Lattice defects in rutile, TiO2

    International Nuclear Information System (INIS)

    Nakagawa, M.; Itoh, H.; Nakanishi, S.; Kondo, K.; Okada, M.; Atobe, K.

    1991-01-01

    Rutile, TiO 2 , having a relatively high melting point exhibits strong optical absorption after neutron irradiation (8 x 10 16 n f /cm 2 ) at 15K. The band peak is located near 0.96 μ, having a FWHM of 0.87 eV (at liquid nitrogen temperature). After inverse recovery at 120K, lattice defects due probably to F centers are annealed out at about 220K. (author)

  16. Solid Phase Equilibrium Relations in the CaO-SiO2-Nb2O5-La2O3 System at 1273 K

    Science.gov (United States)

    Qiu, Jiyu; Liu, Chengjun

    2018-02-01

    Silicate slag system with additions Nb and RE formed in the utilization of REE-Nb-Fe ore deposit resources in China has industrial uses as a metallurgical slag system. The lack of a phase diagram, theoretical, and thermodynamic information for the multi-component system restrict the comprehensive utilization process. In the current work, solid phase equilibrium relations in the CaO-SiO2-Nb2O5-La2O3 quaternary system at 1273 K (1000 °C) were investigated experimentally by the high-temperature equilibrium experiment followed by X-ray diffraction, scanning electron microscope, and energy dispersive spectrometer. Six spatial independent tetrahedron fields in the CaO-SiO2-Nb2O5-La2O3 system phase diagram were determined by the Gibbs Phase Rule. The current work combines the mass fraction of equilibrium phase and corresponding geometric relation. A determinant method was deduced to calculate the mass fraction of equilibrium phase in quaternary system according to the Mass Conservation Law, the Gibbs Phase Rule, the Lever's Rule, and the Cramer Law.

  17. Synthesis of CaTiO 3 from calcium titanyl oxalate hexahydrate (CTO)

    Indian Academy of Sciences (India)

    Calcium titanate, CaTiO3, an important microwave dielectric material and one of major phases in synroc (synthetic rock), a titanate ceramic with potential application for fixation of high level nuclear waste was synthesized from calcium titanyl oxalate [CaTiO (C2O4)2.6H2O] (CTO) by employing microwave heating technique.

  18. Preparation, characterization and activity evaluation of CaZrTi2O7 photocatalyst

    International Nuclear Information System (INIS)

    Chen Shifu; Ji Mingsong; Yuang Yunguang; Liu Wei

    2012-01-01

    CaZrTi 2 O 7 photocatalyst sample was prepared by a polymerizable complex method. The photocatalyst was characterized by X-ray powder diffraction, scanning electron microscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence emission spectroscopy, Brunauer–Emmett–Teller analysis, N 2 adsorption measurements, and terephthalic acid probed fluorescence technique. The photocatalytic activity of the sample was evaluated by photocatalytic oxidation of methyl orange and photocatalytic reduction of Cr 2 O 7 2− and nitrobenzene. The results showed that when the reaction solution was illuminated by UV light for 50 min, the photooxidation efficiency of methyl orange and the photoreduction efficiency of Cr 2 O 7 2− were 83.1% and 87.9%, respectively. When methanol was used as the holes scavengers and the illumination time was 10 h in the photocatalytic reduction experiment of nitrobenzene, the production efficiency of aniline was 70.3%. The effect of the heat treatment conditions on the photocatalytic activity was also investigated. The optimum preparation condition for CaZrTi 2 O 7 sample is 800 °C for 12 h. The mechanisms of influence on the photocatalytic activity of the sample were also discussed with the valance band theory. - Highlights: ► CaZrTi 2 O 7 photocatalyst was prepared by a polymerizable complex method. ► The heat treatment has a significant influence on the photocatalytic activity. ► The optimal heat treatment condition is approximately 800 °C for 12 h. ► The CaZrTi 2 O 7 has the band bap of about 2.89 eV with particle size of about 80 nm.

  19. Electrochemical and safety characteristics of TiP2O7–graphene nanocomposite anode for rechargeable lithium-ion batteries

    International Nuclear Information System (INIS)

    Rai, Alok Kumar; Gim, Jihyeon; Song, Jinju; Mathew, Vinod; Anh, Ly Tuan; Kim, Jaekook

    2012-01-01

    This paper reports a co-precipitation synthesis of TiP 2 O 7 –graphene (10 wt%) nanocomposite and pure TiP 2 O 7 nanoparticles for the use as an advanced anode material for high performance lithium-ion batteries. The structure and morphology of the compounds are characterized by powder X-ray diffraction, field-emission scanning electron microscopy and field-emission transmission electron microscopy techniques. The electrochemical performances were evaluated in coin type Li-ion test cells. This TiP 2 O 7 –graphene nanocomposite displayed superior Li-ion battery performance with a large reversible capacity, excellent cyclic performance and good rate capability at a current density of 0.1 mA cm −2 . At an elevated current density of 6.4 mA cm −2 , the nanocomposite anode delivered a capacity of 98.4 mAh g −1 , which is much higher than that of pure TiP 2 O 7 (0.56 mAh g −1 ). The impressive electrochemical performance of the nanocomposite was ascribed to the synergistic effect of the high surface area nanoparticles in conjunction with the good electronic conductivity of graphene. The graphene nanosheets not only provide an electronically conducting network, but also tend to prevent the aggregation of the high surface area TiP 2 O 7 nanoparticles. Further, the graphene nanosheets can act as buffer layers to accommodate the volume change during the Li-ion insertion/extraction processes in the TiP 2 O 7 nanoparticles.

  20. The role of magnetoelastic strain on orbital control and transport properties in an LaTiO(3)-CoFe(2)O(4) heterostructure.

    Science.gov (United States)

    Li, J; Chu, H F; Zhang, Y; Wang, J; Zheng, D N; Song, Q; Wang, P; Ma, Y G; Ong, C K; Wang, S J

    2009-07-08

    Epitaxial heterostructures of CoFe(2)O(4)/LaTiO(3)/LaAlO(3) have been successfully prepared by using the pulsed laser deposition technique. The magnetoresistance (MR) of the samples is negative and linear with field at H≥2 T, exhibiting no dependence on field directions. Nevertheless, when Hstrains on the bottom LaTiO(3) layer. Apparently the orbital status and the one-electron bandwidth in the LaTiO(3) layer are altered, which leads to a change in resistance.

  1. Reflectance spectroscopy from TiO2 particles embedded in polyurethane

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Johansen, Villads Egede

    2013-01-01

    This paper presents the results of a physical simulation carried out using TiO2-Polyurethane composite coating on bright aluminium surface to understand the light scattering effect for designing white surfaces. Polyurethane matrix is selected due to the matching refractive index (1.7) with Al2O3...... layer on anodized aluminium surfaces. Three different TiO2 particle distributions were dispersed in polyurethane and spin coated onto high gloss and caustic etched aluminium substrates. Reflectance spectra of TiO2-polyurethane films of various concentrations were analysed using an integrating sphere....... The results show that the TiO2-polyurethane coatings have a high diffuse reflectance as a result of multiple scattering from TiO2 particles. Diffuse reflectance spectra of TiO2 containing films vary weakly with particle concentration and reach a steady state value at a concentration of 0.75 wt.%. Using...

  2. Preparation and characterization of mesoporous TiO{sub 2}-sphere-supported Au-nanoparticle catalysts with high activity for CO oxidation at ambient temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lili; Huang, Shouying; Zhu, Baolin; Zhang, Shoumin; Huang, Weiping, E-mail: hwp914@nankai.edu.cn [Nankai University, College of Chemistry, The Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), and Tianjin Key Lab of Metal and Molecule-based Material Chemistry (China)

    2016-11-15

    Mesoporous TiO{sub 2}-sphere-supported Au-nanoparticles (Au/m-TiO{sub 2}-spheres) catalysts have been synthesized by a simple method using tetrabutyl titanate as TiO{sub 2} precursor and characterized with XRD, BET, ICP, SEM, TEM, UV-Vis DRS, XPS, as well as FT-IR. The samples with the size in the range of 200–400 nm were almost perfectly spherical. The average diameter of pores was about 3.6 nm, and the mesopore size distribution was in the range of 2–6 nm with a narrow distribution. When the catalyst was calcined at 300 °C, the Au NPs with the size ca. 5 nm were highly dispersed on the surfaces of m-TiO{sub 2} spheres and partially embedded in the supports. Remarkably, the specific surface area of the Au/m-TiO{sub 2}-spheres was as high as 117 m{sup 2} g{sup −1}. The CO-adsorbed catalyst showed an apparent IR adsorption peak at 1714 cm{sup −1} that matched with bridging model CO. It means the catalysts should be of high catalytic activity for the CO oxidation due to they could adsorb and activate CO commendably. When Au-content was 0.48 wt.%, the Au/m-TiO{sub 2}-spheres could convert CO completely into CO{sub 2} at ambient temperature.

  3. Preparation and characterization of titanate nanotubes/carbon composites

    International Nuclear Information System (INIS)

    Wang Xiaodong; Pan Hui; Xue Xiaoxiao; Qian Junjie; Yu Laigui; Yang Jianjun; Zhang Zhijun

    2011-01-01

    Highlights: → Titanate nanotubes/carbon composites were synthesized from TiO 2 -carbon composites. → The carbon shell of TiO 2 particles obstructed the reaction between TiO 2 and NaOH. → TEM, XRD, and Raman spectra reveal the formation processes of the TNT/CCs. - Abstract: Titanate nanotubes/carbon composites(TNT/CCs) were synthesized by allowing carbon-coated TiO 2 (CCT) powder to react with a dense aqueous solution of NaOH at 120 deg. C for a proper period of time. As-prepared CCT and TNT/CCs were characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectrometry. The processes for formation of titanate nanotubes/carbon composites were discussed. It was found that the TiO 2 particles in TiO 2 -carbon composite were enwrapped by a fine layer of carbon with a thickness of about 4 nm. This carbon layer functioned to inhibit the transformation from anatase TiO 2 to orthorhombic titanate. As a result, the anatase TiO 2 in CCT was incompletely transformed into orthorhombic titanate nanotubes upon 24 h of reaction in the dense and hot NaOH solution. When the carbon layers were gradually peeled off along with the formation of more orthorhombic titanate nanotubes at extended reaction durations (e.g., 72 h), anatase TiO 2 particles in CCT were completely transformed into orthorhombic titanate nanotubes, yielding TNT/CCs whose morphology was highly dependent on the reaction time and temperature.

  4. Structure and physical properties for a new layered pnictide-oxide: BaTi2As2O

    International Nuclear Information System (INIS)

    Wang, X F; Yan, Y J; Ying, J J; Li, Q J; Zhang, M; Xu, N; Chen, X H

    2010-01-01

    We have successfully synthesized a new layered pnictide-oxide: BaTi 2 As 2 O. It shares similar characteristics with Na 2 Ti 2 Sb 2 O. The crystal has a layered structure with a tetragonal P4/nmm group (a = 4.047(3) A, c = 7.275(4) A). The resistivity shows an anomaly at 200 K, which should be ascribed to an SDW or structural transition. The SDW or structural transition is confirmed by magnetic susceptibility and heat capacity measurements. These behaviors are very similar to those observed in parent compounds of high-T c iron-based pnictide superconductors, in which the superconductivity shows up when the anomaly due to the SDW or structural transition is suppressed. Therefore, the new layered pnictide-oxide, BaTi 2 As 2 O, could be a potential parent compound for superconductivity. It is found that Li + doping significantly suppresses the anomaly, but no superconductivity emerges so far.

  5. Magnetocaloric properties of Eu{sub 1−x}La{sub x}TiO{sub 3} (0.01 ≤ x ≤ 0.2) for cryogenic magnetic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Rubi, Km; Midya, A.; Mahendiran, R., E-mail: phyrm@nus.edu.sg [Physics Department, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore, Singapore 117551 (Singapore); Maheswar Repaka, D. V.; Ramanujan, R. V. [School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, Singapore 639798 (Singapore)

    2016-06-28

    We report magnetic and magnetocaloric (MCE) properties of polycrystalline Eu{sub 1−x}La{sub x}TiO{sub 3} samples over a wide composition range (0.01 ≤ x ≤ 0.20). It is found that the ground state changes from antiferromagnetic for x = 0.01 (T{sub N} = 5.2K) to ferromagnetic for x ≥ 0.03 and the ferromagnetic Curie temperature increases from T{sub C} = 5.7K for x = 0.03 to T{sub C} = 7.9 K for x = 0.20. The x = 0.01 sample shows a large reversible isothermal magnetic entropy change of −ΔS{sub m} = 23 (41.5) J/kg K and adiabatic temperature change of ΔT{sub ad} = 9 (17.2) K around 6.7K for a field change of μ{sub 0}ΔH = 2 (5) Tesla. Although the peak value of −ΔS{sub m} decreases as La content increases, it is impressive in x = 0.2(−ΔS{sub m} = 31.41 J/kg K at T = 7.5 K for μ{sub 0}ΔH = 5 T). The large value of MCE arises from suppression of the spin entropy associated with the localized moment (J = 7/2) of Eu{sup 2+}:4f{sup 7} ions. This large MCE over a wide compositional range suggests that the Eu{sub 1−x}La{sub x}TiO{sub 3} series could be useful for magnetic cooling below 40 K.

  6. H_2O_2-assisted photocatalysis on flower-like rutile TiO_2 nanostructures: Rapid dye degradation and inactivation of bacteria

    International Nuclear Information System (INIS)

    Kőrösi, László; Prato, Mirko; Scarpellini, Alice; Kovács, János; Dömötör, Dóra; Kovács, Tamás; Papp, Szilvia

    2016-01-01

    Graphical abstract: - Highlights: • Hierarchically assembled rutile TiO_2 was synthesized at room temperature. • Hydrothermal treatment enhanced the crystallinity, while morphology was maintained. • Hydrothermal treatment also led to larger crystallites and a lower surface area. • Effective K. pneumoniae killing and MO degradation were achieved with the use of H_2O_2. • Higher crystallinity enhanced the reaction rate in the presence of H_2O_2. - Abstract: Hierarchically assembled flower-like rutile TiO_2 (FLH-R-TiO_2) nanostructures were successfully synthesized from TiCl_4 at room temperature without the use of surfactants or templates. An initial sol–gel synthesis at room temperature allowed long-term hydrolysis and condensation of the precursors. The resulting FLH-R-TiO_2 possessed relatively high crystallinity (85 wt%) and consisted of rod-shaped subunits assembling into cauliflower-like nanostructures. Hydrothermal evolution of FLH-R-TiO_2 at different temperatures (150, 200 and 250 °C) was followed by means of X-ray diffraction, transmission and scanning electron microscopy. These FLH-R-TiO_2 nanostructures were tested as photocatalysts under simulated daylight (full-spectrum lighting) in the degradation of methyl orange and in the inactivation of a multiresistant bacterium, Klebsiella pneumoniae. The effects of hydrothermal treatment on the structure, photocatalytic behavior and antibacterial activity of FLH-R-TiO_2 are discussed.

  7. TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

    KAUST Repository

    Shi, Le

    2015-05-01

    Water splitting through photoelectrochemical reaction is widely regarded as a major method to generate H2 , a promising source of renewable energy to deal with the energy crisis faced up to human being. Efficient exploitation of visible light in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination with the short distance for charge carrier diffusion and light-scattering properties. This work is based on TiO2 NTPC electrode by the optimized two-step anodization method from our group. A highly crystalized p-type Cu2O layer was deposited by optimized pulse potentiostatic electrochemical deposition onto TiO2 nanotubes to enhance the visible light absorption of a pure p-type TiO2 substrate and to build a p-n junction at the interface to improve the PEC performance. However, because of the real photocurrent of Cu2O is far away from its theoretical limit and also poor stability in the aqueous environment, a design of rGO medium layer was added between TiO2 nanotube and Cu2O layer to enhance the photogenerated electrons and holes separation, extend charge carrier diffusion length (in comparison with those of conventional pure TiO2 or Cu2O materials) which could significantly increase photocurrent to 0.65 mA/cm2 under visible light illumination (>420 nm) and also largely improve the stability of Cu2O layer, finally lead to an enhancement of water splitting performance.

  8. A Designed TiO2 /Carbon Nanocomposite as a High-Efficiency Lithium-Ion Battery Anode and Photocatalyst.

    Science.gov (United States)

    Peng, Liang; Zhang, Huijuan; Bai, Yuanjuan; Feng, Yangyang; Wang, Yu

    2015-10-12

    Herein, a peapod-like TiO2 /carbon nanocomposite has successfully been synthesized by a rational method for the first time. The novel nanostructure exhibits a distinct feature of TiO2 nanoparticles encapsulated inside and the carbon fiber coating outside. In the synthetic process, H2 Ti3 O7 nanotubes serve as precursors and templates, and glucose molecules act as the green carbon source. With the alliciency of hydrogen bonding between H2 Ti3 O7 and glucose, a thin polymer layer is hydrothermally assembled and subsequently converted into carbon fibers through calcinations under an inert atmosphere. Meanwhile, the precursors of H2 Ti3 O7 nanotubes are transformed into the TiO2 nanoparticles encapsulated in carbon fibers. The achieved unique nanocomposites can be used as excellent anode materials in lithium-ion batteries (LIBs) and photocatalytic reagents in the degradation of rhodamine B. Due to the synergistic effect derived from TiO2 nanoparticles and carbon fibers, the obtained peapod-like TiO2 /carbon cannot only deliver a high specific capacity of 160 mAh g(-1) over 500 cycles in LIBs, but also perform a much faster photodegradation rate than bare TiO2 and P25. Furthermore, owing to the low cost, environmental friendliness as well as abundant source, this novel TiO2 /carbon nanocomposite will have a great potential to be extended to other application fields, such as specific catalysis, gas sensing, and photovoltaics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Optical and structural properties of TiO{sub 2}/Ti/Ag/TiO{sub 2} and TiO{sub 2}/ITO/Ag/ITO/TiO{sub 2} metal-dielectric multilayers by RF magnetron sputtering for display application

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jang-Hoon; Lee, Seung-Hyu; Hwangbo, Chang-Kwon [Inha University, Incheon (Korea, Republic of); Lee, Kwang-Su [Quantum Photonic Science Research Center, Hanyang University, Seoul (Korea, Republic of)

    2004-03-15

    Electromagnetic-interference (EMI) shielding and near-infrared (NIR) cutoff filters for plasma display panels, based on fundamental structures (ITO/Ag/ITO), (TiO{sub 2}/Ti/Ag/TiO{sub 2}) and (TiO{sub 2}/ITO/Ag/ITO/TiO{sub 2}), were designed and prepared by RF-magnetron sputtering. The optical, structural and electrical properties of the filters were investigated by using spectrophotometry, Auger electron spectroscopy, X-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, atomic force microscopy and four-point-probe measurements. The results show that ITO films as the barriers and base layers lead to higher transmittance in the visible spectrum and smoother surface roughness than Ti metal barriers, while maintaining high NIR cutoff characteristics and chemical stability, which may be attributed to the lower absorption in the interfacial layers and better protection of the Ag layers by the ITO layers.

  10. Incorporation of La in epitaxial SrTiO{sub 3} thin films grown by atomic layer deposition on SrTiO{sub 3}-buffered Si (001) substrates

    Energy Technology Data Exchange (ETDEWEB)

    McDaniel, Martin D.; Ngo, Thong Q.; Ekerdt, John G., E-mail: ekerdt@utexas.edu [University of Texas at Austin, Department of Chemical Engineering, Austin, Texas 78712 (United States); Posadas, Agham; Demkov, Alexander A. [University of Texas at Austin, Department of Physics, Austin, Texas 78712 (United States); Karako, Christine M. [University of Dallas, Department of Chemistry, Irving, Texas 75062 (United States); Bruley, John; Frank, Martin M.; Narayanan, Vijay [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

    2014-06-14

    Strontium titanate, SrTiO{sub 3} (STO), thin films incorporated with lanthanum are grown on Si (001) substrates at a thickness range of 5–25 nm. Atomic layer deposition (ALD) is used to grow the La{sub x}Sr{sub 1−x}TiO{sub 3} (La:STO) films after buffering the Si (001) substrate with four-unit-cells of STO deposited by molecular beam epitaxy. The crystalline structure and orientation of the La:STO films are confirmed via reflection high-energy electron diffraction, X-ray diffraction, and cross-sectional transmission electron microscopy. The low temperature ALD growth (∼225 °C) and post-deposition annealing at 550 °C for 5 min maintains an abrupt interface between Si (001) and the crystalline oxide. Higher annealing temperatures (650 °C) show more complete La activation with film resistivities of ∼2.0 × 10{sup −2} Ω cm for 20-nm-thick La:STO (x ∼ 0.15); however, the STO-Si interface is slightly degraded due to the increased annealing temperature. To demonstrate the selective incorporation of lanthanum by ALD, a layered heterostructure is grown with an undoped STO layer sandwiched between two conductive La:STO layers. Based on this work, an epitaxial oxide stack centered on La:STO and BaTiO{sub 3} integrated with Si is envisioned as a material candidate for a ferroelectric field-effect transistor.

  11. Effects of the TiO2 high-k insulator material on the electrical characteristics of GaAs based Schottky barrier diodes

    Science.gov (United States)

    Zellag, S.; Dehimi, L.; Asar, T.; Saadoune, A.; Fritah, A.; Özçelik, S.

    2018-01-01

    The effects of the TiO2 high-k insulator material on Au/n-GaAs/Ti/Au Schottky barrier diodes have been studied by means of the numerical simulation and experimental results at room temperature. The Atlas-Silvaco-TCAD numerical simulator has been used to explain the behavior of different physical phenomena of Schottky diode. The experimental values of ideality factor, barrier height, and series resistance have been determined by using the various techniques such as Cheung's method, forward bias ln I- V and reverse capacitance-voltage behaviors. The experimental ideality factor and barrier height values have been found to be 4.14 and 0.585 eV for Au/n-GaAs/Ti/Au Schottky barrier diode and 4.00 and 0.548 eV for that structure with 16 nm thick TiO2 film and 3.92, 0.556 eV with 100 nm thick TiO2 film. The diodes show a non-ideal current-voltage behavior that of the ideality factor so far from unity. The extraction of N ss interface distribution profile as a function of E c -E ss is made using forward-bias I- V measurement by considering the bias dependence of ideality factor, the effective barrier height, and series resistance for Schottky barrier diodes. The N ss calculated values with consideration of the series resistance are lower than the calculated ones without series resistance. The current-voltage results of diodes reveal an abnormal increase in leakage current with an increase in thickness of high-k interfacial insulator layer. However, the simulation agrees in general with the experimental results.

  12. Structure compatibility of TiO{sub 2} and SiO{sub 2} surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Tokarský, Jonáš, E-mail: jonas.tokarsky@vsb.cz; Čapková, Pavla

    2013-11-01

    A simple method for the estimation of the most suitable mutual crystallographic orientations of TiO{sub 2} nanoparticles anchored on SiO{sub 2} substrate is presented in this work. Number of overlapping titanium and oxygen atoms creating atomic pairs can be used to quantify the structure compatibility. These atomic pairs are obtained directly from non-optimized TiO{sub 2} and SiO{sub 2} atomic planes. The descriptions of algorithms being implemented as scripts into the MATLAB environment in order to make the method more effective are also provided. This method can help with the selection of the most promising (h k l) planes of TiO{sub 2} and SiO{sub 2} adjacent surfaces and the outputs are in good agreement with results of molecular modeling of TiO{sub 2} nanoparticles anchored on SiO{sub 2} surfaces within the meaning of ability to determine the optimized models with the highest and the lowest TiO{sub 2}–SiO{sub 2} adhesion energies. To the best of our knowledge, there is no other such simple and efficient method providing this information, which is very important for molecular modeling of nanoparticle-crystalline substrate systems.

  13. A graphene–SnO_2TiO_2 ternary nanocomposite electrode as a high stability lithium-ion anode material

    International Nuclear Information System (INIS)

    Liang, Jicai; Wang, Juan; Zhou, Meixin; Li, Yi; Wang, Xiaofeng; Yu, Kaifeng

    2016-01-01

    In this work, a solvothermal method combined with a hydrothermal two-step method is developed to synthesize graphene–SnO_2TiO_2 ternary nanocomposite, in which the nanometer-sized TiO_2 and SnO_2 nanoparticles form in situ uniformly anchored on the surface of graphene sheets, as high stability and capacity lithium-ion anode materials. Compared to graphene–TiO_2, bulk TiO_2 and grapheme–SnO_2 composites, the as-prepared nanocomposite delivers a superior rate performance of 499.3 mAhg"−"1 at 0.2 C and an outstanding stability cycling capability (1073.4 mAhg"−"1 at 0.2 C after 50 cycles), due to the synergistic effects contributed from individual components, for example, high specific capacity of SnO_2, excellent conductivity of 3D graphene networks. - Graphical abstract: Graphene–SnO_2TiO_2 nanocomposite is synthesized by a hydrothermal two-step method. The composite exhibits higher reversible capacity and better cycle/rate performance due to the unique structure. - Highlights: • We have synthesized a graphene–SnO_2TiO_2 nanocomposite by a two-step method to improve the cycling performance. • Graphene–SnO_2TiO_2 nanocomposite is synthesized by a hydrothermal two-step method. • The composite exhibits higher reversible capacity and better cycle/rate performance due to the unique structure.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-01

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

  15. cis-Thioindigo (TI) - a new ligand with accessible radical anion and dianion states. Strong magnetic coupling in the {[TI-(μ2-O),(μ-O)]Cp*Cr}2 dimers.

    Science.gov (United States)

    Konarev, Dmitri V; Khasanov, Salavat S; Shestakov, Alexander F; Fatalov, Alexey M; Batov, Mikhail S; Otsuka, Akihiro; Yamochi, Hideki; Kitagawa, Hiroshi; Lyubovskaya, Rimma N

    2017-10-24

    Reaction of decamethylchromocene (Cp* 2 Cr) with thioindigo (TI) yields a coordination complex {[TI-(μ 2 -O), (μ-O)]Cp*Cr} 2 ·C 6 H 14 (1) in which one Cp* ligand in Cp* 2 Cr is substituted by TI. TI adopts cis-conformation in 1 allowing the coordination of both carbonyl groups to chromium. Additionally, one oxygen atom of TI becomes a μ 2 -bridge for two chromium atoms to form {[TI-(μ 2 -O), (μ-O)]Cp*Cr} 2 dimers with a CrCr distance of 3.12 Å. According to magnetic data, diamagnetic TI 2- dianions and two Cr 3+ atoms with a high S = 3/2 spin state are present in a dimer allowing strong antiferromagnetic coupling between two Cr 3+ spins with an exchange interaction of -35.4 K and the decrease of molar magnetic susceptibility below 140 K. Paramagnetic TI˙ - radical anions with the S = 1/2 spin state have also been obtained and studied in crystalline {cryptand[2,2,2](Na + )}(TI˙ - ) (2) salt showing that both radical anion and dianion states are accessible for TI.

  16. Synthesis of anatase TiO2 nanoparticles with beta-cyclodextrin as a supramolecular shell.

    Science.gov (United States)

    Li, Landong; Sun, Xiaohong; Yang, Yali; Guan, Naijia; Zhang, Fuxiang

    2006-11-20

    We report a novel, green hydrothermal-synthesis route to well-dispersed anatase TiO2 nanoparticles with particle sizes of 9-16 nm in the presence of beta-CD (beta-cyclodextrin). During the synthesis process, the CD-containing synthesis mixture assembled in both longitudinal and latitudinal directions. Driven by the interaction between molecules, the beta-CDs assembled in the longitudinal direction to form long-chain compounds, whereas in the latitudinal direction, they tended to form regular aggregates through coordination with the Ti species from the hydrolysis of tetrabutyl titanate. In view of the effect of the coordination and the steric hindrance of beta-CDs as a supramolecular shell, homogeneous nuclei and slow growth of TiO2 crystals during the synthesis process was observed, which was responsible for the formation of uniform TiO2 nanoparticles. The low beta-CD dosage and the high product yield (>90%) demonstrated well the potential of this synthesis route in the large-scale industrial production of anatase nanoparticles.

  17. Hot corrosion performance of LVOF sprayed Al2O3–40% TiO2 ...

    Indian Academy of Sciences (India)

    ficients of thermal expansions of the two. ... size 40 mesh just prior to deposition of the coating. Al2O3–. 40% TiO2 ... the laboratory Kanthal wire tube furnace, which was cali- ... formation of TiO2, Al2O3 and Al2Ti7O15 phases in the coat- ing.

  18. Sol-gel synthesis of TiO{sub 2}-SiO{sub 2} photocatalyst for {beta}-naphthol photodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Qourzal, S., E-mail: samir_qourzal@yahoo.fr [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Barka, N.; Tamimi, M.; Assabbane, A. [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Nounah, A. [Ecole Superieure de Technologie, Avenue Prince Heritier Sidi Mohamed, B. P. 227, Sale-Medina (Morocco); Ihlal, A. [Laboratoire de Physique des Semi-conducteurs et Energie Solaire, Departement de Physique, Faculte, des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco); Ait-Ichou, Y. [Equipe de Materiaux Photocatalyse et Environnement, Departement de Chimie, Faculte des Sciences, Universite Ibn Zohr, B. P. 8106 Cite Dakhla, Agadir (Morocco)

    2009-06-01

    Silica gel supported titanium dioxide particles (TiO{sub 2}-SiO{sub 2}) prepared by sol-gel method was as photocatalyst in the degradation of {beta}-naphthol in water under UV-illumination. The prepared sample has been characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). The supported catalyst had large surface area and good sedimentation ability. The photodegradation rate of {beta}-naphthol under UV-irradiation depended strongly on adsorption capacity of the catalyst, and the photoactivity of the supported catalyst was much higher than that of the pure titanium dioxides. The experiments were measured by high performance liquid chromatography (HPLC). The photodegradation rate of {beta}-naphthol using 60% TiO{sub 2}-SiO{sub 2} particles was faster than that using TiO{sub 2} 'Degussa P-25', TiO{sub 2} 'PC-50' and TiO{sub 2} 'Aldrich' as photocatalyst by 2.7, 4 and 7.8 times, respectively. The kinetics of photocatalytic {beta}-naphthol degradation was found to follow a pseudo-first-order rate law. The effect of the TiO{sub 2} loading on the photoactivity of TiO{sub 2}-SiO{sub 2} particles was also discussed. With good photocatalytic activity under UV-irradiation and the ability to be readily separated from the reaction system, this novel kind of catalyst exhibited the potential effective in the treatment of organic pollutants in aqueous systems.

  19. First principles investigation of structural, electronic, elastic and thermal properties of rare-earth-doped titanate Ln2TiO5

    Directory of Open Access Journals (Sweden)

    Hui Niu

    2012-09-01

    Full Text Available Systematic first-principles calculations based on density functional theory were performed on a wide range of Ln2TiO5 compositions (Ln = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Y in order to investigate their structural, elastic, electronic, and thermal properties. At low temperature, these compounds crystallize in orthorhombic structures with a Pnma symmetry, and the calculated equilibrium structural parameters agree well with experimental results. A complete set of elastic parameters including elastic constants, Hill's bulk moduli, Young's moduli, shear moduli and Poisson's ratio were calculated. All Ln2TiO5 are ductile in nature. Analysis of densities of states and charge densities and electron localization functions suggests that the oxide bonds are highly ionic with some degree of covalency in the Ti-O bonds. Thermal properties including the mean sound velocity, Debye temperature, and minimum thermal conductivity were obtained from the elastic constants.

  20. High Photocatalytic Activity of Fe3O4-SiO2-TiO2 Functional Particles with Core-Shell Structure

    Directory of Open Access Journals (Sweden)

    Chenyang Xue

    2013-01-01

    Full Text Available This paper describes a novel method of synthesizing Fe3O4-SiO2-TiO2 functional nanoparticles with the core-shell structure. The Fe3O4 cores which were mainly superparamagnetic were synthesized through a novel carbon reduction method. The Fe3O4 cores were then modified with SiO2 and finally encapsulated with TiO2 by the sol-gel method. The results of characterizations showed that the encapsulated 700 nm Fe3O4-SiO2-TiO2 particles have a relatively uniform size distribution, an anatase TiO2 shell, and suitable magnetic properties for allowing collection in a magnetic field. These magnetic properties, large area, relative high saturation intensity, and low retentive magnetism make the particles have high dispersibility in suspension and yet enable them to be recovered well using magnetic fields. The functionality of these particles was tested by measuring the photocatalytic activity of the decolouring of methyl orange (MO and methylene blue (MB under ultraviolet light and sunlight. The results showed that the introduction of the Fe3O4-SiO2-TiO2 functional nanoparticles significantly increased the decoloration rate so that an MO solution at a concentration of 10 mg/L could be decoloured completely within 180 minutes. The particles were recovered after utilization, washing, and drying and the primary recovery ratio was 87.5%.

  1. Changes in the microbiological and chemical characteristics of white bread during storage in paper packages modified with Ag/TiO2-SiO2, Ag/N-TiO2 or Au/TiO2.

    Science.gov (United States)

    Peter, Anca; Mihaly-Cozmuta, Leonard; Mihaly-Cozmuta, Anca; Nicula, Camelia; Ziemkowska, Wanda; Basiak, Dariusz; Danciu, Virginia; Vulpoi, Adriana; Baia, Lucian; Falup, Anca; Craciun, Grigore; Ciric, Alexandru; Begea, Mihaela; Kiss, Claudia; Vatuiu, Daniela

    2016-04-15

    Microbiological and chemical characteristics of white bread during storage in paper-packages modified with Ag/TiO2-SiO2, Ag/N-TiO2 or Au/TiO2 were investigated. The whiteness and the water retention of the modified packages were slightly superior to those exhibited by the reference sample, as the color of the composite was lighter. The water retention was very good especially for the Ag/TiO2-SiO2-paper. These improvements can be associated with the high specific surface area and with the low agglomeration tendency of Ag nanoparticles in comparison with the Au ones. The preservation activity of the composites for the bread storage is positively influenced by photoactivity and presence of nano-Ag. Packages Ag/TiO2-SiO2-paper and Ag/N-TiO2-paper can find their applicability for extending the shelf life of bread by 2 days as compared with the unmodified paper-package. No influence of the Au/TiO2 on the extending the shelf life of bread was observed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Synthesis, Property Characterization and Photocatalytic Activity of the Novel Composite Polymer Polyaniline/Bi2SnTiO7

    Directory of Open Access Journals (Sweden)

    Yunjun Yang

    2012-03-01

    Full Text Available A novel polyaniline/Bi2SnTiO7 composite polymer was synthesized by chemical oxidation in-situ polymerization method and sol-gel method for the first time. The structural properties of novel polyaniline/Bi2SnTiO7 have been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray spectrometry. The lattice parameter of Bi2SnTiO7 was found to be a = 10.52582(8 Å. The photocatalytic degradation of methylene blue was realized under visible light irradiation with the novel polyaniline/Bi2SnTiO7 as catalyst. The results showed that novel polyaniline/Bi2SnTiO7 possessed higher catalytic activity compared with Bi2InTaO7 or pure TiO2 or N-doped TiO2 for photocatalytic degradation of methylene blue under visible light irradiation. The photocatalytic degradation of methylene blue with the novel polyaniline/Bi2SnTiO7 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01504 or 0.00333 min−1. After visible light irradiation for 220 minutes with novel polyaniline/Bi2SnTiO7 as catalyst, complete removal and mineralization of methylene blue was observed. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of methylene blue during the photocatalytic process. The possible photocatalytic degradation pathway of methylene blue was obtained under visible light irradiation.

  3. Photocatalytic performance of TiO2 catalysts modified by H3PW12O40, ZrO2 and CeO2

    Institute of Scientific and Technical Information of China (English)

    CAI Tiejun; LIAO Yuchao; PENG Zhenshan; LONG Yunfei; WEI Zongyuan; DENG Qian

    2009-01-01

    The binary composite photo-catalysts CeO2/TiO2, ZrO2/TiO2 and the ternary composite photo-catalysts H3PW12O40-CeO2/TiO2,H2PW12O40-ZrO2/TiO2 were prepared by sol-gel method. The catalysts were characterized by thermogravimetric-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The photocatalyfic elimination of methanol was used as model reaction to evaluate the photocatalytic activity of the composite catalysts under ultraviolet light irradiation. The effects of doped content, activation temperature, time, initial concentration of methanol and gas flow rate on the catalytic activity were investigated. The results showed that after doping a certain amount of CeO2 and ZrO2, crystaniTation process of TiO2 was restrained, particles of catalysts are smaller and more uniform. Doping ZrO2 not only significantly improved the catalytic activity, but also increased thermal stability. Doping H3PW12O40 also enhanced the catalytic activity. The catalytic activities of binary and ternary composite photocatalysts were significantly higher than tin-doped TiO2. The dynamics law of photocatalytic reaction over the binary CeO2/TiO2 and ZrO2/TiO2 catalysts has been studied. The activation energy 15.627 and 15.631 kJ/mol and pre-exponential factors 0.5176 and 0.9899 s-1 over each corresponding catalyst were obtained. This reaction accords to the first order dynamics law.

  4. Ni/TiO2 composite electrocoatings

    Directory of Open Access Journals (Sweden)

    Kollia, C.

    2005-12-01

    Full Text Available Nickel composite coatings have been studied in order to provide increased properties on engineering materials surfaces, such as higher electrical conductivity, wear and corrosion resistance and to decrease the end product manufacturing cost by plating on cheap materials. Adding TiO2 particles in the bath during the deposition process produced composite coatings. This was tried on electrodeposition from a Watts bath by conventional DC conditions and by pulse plating. The surfaces were studied by SEM, by profilometry and by Vickers microhardness, and its structure by X-ray diffraction. The incorporation percentage of TiO2 particles in the metallic matrix was estimated by EDS analysis. Corrosion measurements of the deposits were taken by Tafel curves. The results obtained show that particle incorporation percentage is higher for the Ni/TiO2 electrodeposits produced by pulse current and the microhardness is significantly increased compared to the electrodeposits produced by DC.

    Los electrodepósitos compuestos de níquel confieren mejores propiedades a la superficies de los materiales utilizados en ingeniería, tales como conductividad eléctrica, desgaste y resistencia a la corrosión, y disminuyen el costo del producto manufacturado al utilizarse como recubrimiento de acabado sobre materiales base más económicos. La adición de partículas de TiO2 al baño durante la electrodeposicion da lugar a la formación de recubrimientos compuestos. La electrodeposicion se llevó cabo en un baño Watts en condiciones convencionales de corriente continua y por electrodepósito pulsante. Las superficies fueron estudiadas por SEM y microanálisis EDS; se midió su microrrugosidad y microdureza Vickers; y su estructura se analizó mediante Difracción de Rayos X. Las medidas de corrosión de los depósitos se realizaron a partir del trazado de curvas de Tafel. Los resultados muestran que el porcentaje de

  5. High temperature dielectric and ferroelectric properties of La-modified PbTiO3 nanoceramics

    International Nuclear Information System (INIS)

    Shukla, Archana; Shukla, Namrata; Choudhary, R.N.P.

    2016-01-01

    Ferroelectric materials with high Curie temperature (higher than 300 °C) are highly desirable to construct transducers for high-temperature piezoelectric applications. Among the ferroelectric materials, PbTiO 3 (PT) is considered to be one of the most promising materials. However, the fabrication of high density pure PT ceramics is very difficult because of the highly anisotropy, which limited the use in piezoelectric transducers. Usually, substitutions towards A or B-site of PT may reduce the high anisotropy. The present work reports the experimental investigations on the effect of lanthanum (La 3+ ) substitution on the structural, dielectric and piezoelectric properties of lead titanate (PT) ceramic at high-temperature (RT ∼ 600°C)

  6. The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO{sub 2} nanostructures of different shapes

    Energy Technology Data Exchange (ETDEWEB)

    Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali, E-mail: bpal@thapar.edu

    2013-09-01

    Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO{sub 2} catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na{sub 2}Ti{sub 2}O{sub 5}·H{sub 2}O) particles (W = 9–12 nm and L = 82–115 nm) and rice like pure anatase-TNR particles (W = 8–13 nm and L = 81–134 nm) are obtained by the hydrothermal treatment of P25-TiO{sub 2} with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = −2.82 (P25-TiO{sub 2}), −13.5 (TNT) and −22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C{sub 9}H{sub 10}ClN{sub 5}O{sub 2}) degradation to CO{sub 2} formation under UV irradiation because of its largest surface area 176 m{sup 2} g{sup −1} among the catalysts studied.

  7. Rapid fabrication of TiO2@carboxymethyl cellulose coatings capable of shielding UV, antifog and delaying support aging.

    Science.gov (United States)

    Li, Xiaozhou; Lv, Junping; Li, Dehuai; Wang, Lin

    2017-08-01

    Agricultural plastic films capable of shielding UV, filtering visible light and antifog are important to prolong their life and protect safeties of agriculturists and crops. In this work, high stable and small size TiO 2 @polymer nanoparticles (NPs) were prepared by an efficient one-pot microwave synthesis using titanic sulfate as Ti resource, carboxymethyl cellulose sodium (CMC) as complexing agent and stabilizer. The TiO 2 @CMC NPs obtained were then utilized to fabricate poly(ethylene imine) (PEI)/TiO 2 @CMC coatings on the surface of polypropylene films by a layer-by-layer assembly technique. The TiO 2 @CMC NPs show rapid deposition rate because small, spherical and anion-rich TiO 2 @CMC NPs possess large specific surface area and fast diffusion rate. More importantly, property experiments confirm that (PEI/TiO 2 @CMC)*15 coatings can not only effectively shield UV rays, filter visible light and prevent fogging but also delay the aging of their supports. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Controllable hydrothermal synthesis of rutile TiO2 hollow nanorod arrays on TiCl4 pretreated Ti foil for DSSC application

    International Nuclear Information System (INIS)

    Xi, Min; Zhang, Yulan; Long, Lizhen; Li, Xinjun

    2014-01-01

    Rutile TiO 2 nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl 4 pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO 2 nanorod arrays (H-TNRs). The TiCl 4 pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl 4 concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ∼1.5 μm and diameter of ∼200 nm, obtained on 0.15 M TiCl 4 pretreated Ti foil with 0.6 mL TTB, exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl 4 -TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode. - Graphical abstract: Rutile hollow TiO 2 nanorod array photoanode obtained from original TiO 2 nanorod array photoanode by hydrothermal etching demonstrates enhanced photoelectric efficiency of DSSC. - Highlights: • TiO 2 nanorods are prepared via hydrothermal process on TiCl 4 -pretreated Ti foil. • Hollow TiO 2 nanorods are obtained by hydrothermal etching of TiO 2 nanorods. • TiCl 4 pretreatment plays a key role in protecting Ti foil from chemical corrosion. • Hollow TiO 2 nanorods photoanode shows enhanced photoelectric efficiency for DSSC

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-15

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

  10. 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)

  11. Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers

    Science.gov (United States)

    Liu, Hao; Wei, Nan; Wang, Zhou-fu; Wang, Xi-tang; Ma, Yan

    2017-11-01

    To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol-gel process. During the preparation process, the fiber surface was coated with K2Ti6O13 whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K2Ti6O13 whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.

  12. Optical spectroscopy of rare earth ion-doped TiO2 nanophosphors.

    Science.gov (United States)

    Chen, Xueyuan; Luo, Wenqin

    2010-03-01

    near-infrared regions through the high-resolution experiments at 10 K. The CF experienced by Er3+ in TiO2 nanocrystal was systematically studied by means of the energy level fitting.

  13. Hybrid improper ferroelectricity in Ruddlesden-Popper Ca{sub 3}(Ti,Mn){sub 2}O{sub 7} ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X. Q., E-mail: xqliu@zju.edu.cn, E-mail: xmchen59@zju.edu.cn; Wu, J. W.; Shi, X. X.; Zhao, H. J.; Zhou, H. Y.; Chen, X. M., E-mail: xqliu@zju.edu.cn, E-mail: xmchen59@zju.edu.cn [Laboratory of Dielectric Materials, School of Materials Science and Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Qiu, R. H.; Zhang, W. Q. [Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444 (China)

    2015-05-18

    The hybrid improper ferroelectricity (HIF) has been proposed as a promising way to create multiferroic materials with strong magnetoelectric coupling by the first-principle calculation, and the experimental evidences of HIF in Ruddlesden-Poper Ca{sub 3}(Ti{sub 1−x}Mn{sub x}){sub 2}O{sub 7} (x = 0, 0.05, 0.1, and 0.15) ceramics have been shown in the present work. The room temperature ferroelectric hysteresis loops are observed in these ceramics, and a polar orthorhombic structure with two oxygen tilting modes has been confirmed by the X-ray powder diffraction. A first-order phase transition around 1100 K in Ca{sub 3}Ti{sub 2}O{sub 7} was evidenced, and the temperatures of phase transitions decrease linearly with increasing of the contents of Mn{sup 4+} ions. Based on the result of first-principle calculations, the polarization should be reversed by switching through the mediated Amam phase in Ca{sub 3}Ti{sub 2}O{sub 7} ceramics.

  14. Photocatalytic application of TiO2/SiO2-based magnetic nanocomposite (Fe3O4@SiO2/TiO2 for reusing of textile wastewater

    Directory of Open Access Journals (Sweden)

    Laleh Enayati Ahangar

    2016-01-01

    Full Text Available In this research we have developed a treatment method for textile wastewater by TiO2/SiO2-based magnetic nanocomposite. Textile wastewater includes a large variety of dyes and chemicals and needs treatments. This manuscript presents a facile method for removing dyes from the textile wastewater by using TiO2/SiO2-based nanocomposite (Fe3O4@SiO2/TiO2 under UV irradiation. This magnetic nanocomposite, as photocatalytically active composite, is synthesized via solution method in mild conditions. A large range of cationic, anionic and neutral dyes including: methyl orange, methylene blue, neutral red, bromocresol green and methyl red are used for treatment investigations. Neutral red and bromocresol green have good results in reusing treatment. The high surface area of nanocomposites improve the kinetic of wastewater treatment. In this method, by using the magnetic properties of Fe3O4 nanoparticles, TiO2-based photocatalyst could be separated and reused for 3 times. The efficiency of this method is respectively 100% and 65% for low concentration (10 ppm and high concentration (50 ppm of neutral red and bromocrosol green after 3 h treatment. The efficiency of treatment using the second used nanocomposite was 90% for 10 ppm of the same dyes.

  15. Electrophoretic deposition of nanocrystalline TiO2 films on Ti substrates for use in flexible dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Tan Weiwei; Yin Xiong; Zhou Xiaowen; Zhang Jingbo; Xiao Xurui; Lin Yuan

    2009-01-01

    Nanocrystalline TiO 2 films were prepared on flexible Ti-metal sheets by electrophoretic deposition followed by chemical treatment with tetra-n-butyl titanate (TBT) and sintering at 450 deg. C. X-ray diffraction (XRD) analysis indicates that TBT treatment led to the formation of additional anatase TiO 2 , which plays an important role in improving the interconnection between TiO 2 particles, as well as the adherence of the film to the substrate, and in modifying the surface properties of the nanocrystalline particles. The effect of TBT treatment on the electron transport in the nanocrystalline films was studied by intensity-modulated photocurrent spectroscopy (IMPS). An increase in the conversion efficiency was obtained for the dye-sensitized solar cells with TBT-treated nanocrystalline TiO 2 films. The cell performance was further optimized by designing nanocrystalline TiO 2 films with a double-layer structure composed of a light-scattering layer and a transparent layer. The light-scattering effect of the double-layer nanocrystalline films was evaluated by diffuse reflectance spectra. Employing the double-layer nanocrystalline films as the photoelectrodes resulted in a significant improvement in the incident photo-to-current conversion efficiency of the corresponding cells due to enhanced solar absorption by light scattering. A high conversion efficiency of 6.33% was measured under illumination with 100 mW cm -2 (AM 1.5) simulated sunlight.

  16. Li depletion effects on Li2TiO3 reaction with H2 in thermo-chemical environment relevant to breeding blanket for fusion power plants

    International Nuclear Information System (INIS)

    Alvani, Carlo; Casadio, Sergio; Contini, Vittoria; Giorgi, Rossella; Mancini, Maria Rita; Tsuchiya, Kunihiko; Kawamura, Hiroshi

    2005-07-01

    This is a report of the Working Group in the Subtask on Solid Breeder Blankets under the Implementing Agreement on a Co-operative Programme on Nuclear Technology of Fusion Reactors (International Energy Agency (IEA)). This Working Group (Task F and WG-F) was performed from 2000 to 2004 by a collaboration of European Union (EU) and Japan (JA). In this report, lithium depletion effects on the reaction of lithium titanate (Li 2 TiO 3 ) with hydrogen (H 2 ) in thermo-chemical environment were discussed. The reaction of Li 2 TiO 3 ceramics with H 2 was studied in a thermo-chemical environment simulating (excepting irradiation) that of the hottest pebble-bed zone of breeding-blanket actually designed for fusion power plants. This 'reduction' as performed at 900degC in Ar+0.1%H, purge gas (He+0.1%H 2 being the designed reference') was found to be enhanced by TiO 2 doping of the specimens of simulate 6 Li-burn-up expected to reach 20% at their end-of-life. The reaction rates, however, were so slow to be not significantly extrapolated to the breeder material service time (years). In Ar+3%H 2 , faster reaction rates allowed a better identification of the process evolution (kinetics) by Temperature-Programmed Reduction' (TPR) and 'Oxidation' (TPO), and combined TG-DTA thermal analysis. The reduction of pure Li 4/5 TiO 12/5 spinel phase to Li 4/5 TiO 12/5-y was found to reach in one day the steady state at the O-vacancy concentration y=0.2. Complimentary microscopy (SEM) and spectroscopy (XRD, XPS) techniques were used to characterize the reaction products among which the presence of the orthorhombic Li v TiO 2 (0 ≤ v ≤ 1/2) and Li 2 TiO 3 could be diagnosed. So that the complete spinel reduction to Li 1/2 TiO 2 was obtained according to a scheme involving the Li 1/2 TiO 2 -Li 4/5 TiO 12/5 spinel phase solid solution for which y=3v/(10-5v). The reduction rate of pure meta-titanate to Li 2 TiO 3-x was found much lower (x approx. = 0.01) and even possibly due to the presence

  17. Photocatalytic Removal of Phenol under Natural Sunlight over N-TiO2-SiO2 Catalyst: The Effect of Nitrogen Composition in TiO2-SiO2

    Directory of Open Access Journals (Sweden)

    Viet-Cuong Nguyen

    2009-01-01

    Full Text Available In this present work, high specific surface area and strong visible light absorption nitrogen doped TiO2-SiO2 photocatalyst was synthesized by using sol-gel coupled with hydrothermal treatment method. Nitrogen was found to improve the specific surface area while it also distorted the crystal phase of the resulting N-TiO2-SiO2 catalyst. As the N/ (TiO2-SiO2 molar ratio was more than 10%, the derived catalyst presented the superior specific surface area up to 260 m2/g. Nevertheless, its photoactivity towards phenol removal was observed to significantly decrease, which could results from the too low crystallinity. The nitrogen content in N-TiO2-SiO2 catalyst was therefore necessary to be optimized in terms of phenol removal efficiency and found at ca. 5%. Under UVA light and natural sunlight irradiation of 80 min, N(5%-TiO2-SiO2 catalyst presented the phenol decomposition efficiencies of 68 and 100%, respectively. It was also interestingly found in this study that the reaction rate was successfully expressed using a Langmuir-Hinshelwood (L-H model, indicating the L-H nature of photocatalytic phenol decomposition reaction on the N-TiO2-SiO2 catalyst.

  18. Photocatalytic Oxidation of Acetone Over High Thermally Stable TiO2 Nanosheets With Exposed (001) Facets.

    Science.gov (United States)

    Shi, Ting; Duan, Youyu; Lv, Kangle; Hu, Zhao; Li, Qin; Li, Mei; Li, Xiaofang

    2018-01-01

    Anatase TiO 2 (A-TiO 2 ) usually exhibits superior photocatalytic activity than rutile TiO 2 (R-TiO 2 ). However, the phase transformation from A-TiO 2 to R-TiO 2 will inevitably happens when the calcination temperature is up to 600°C, which hampers the practical applications of TiO 2 photocatalysis in hyperthermal situations. In this paper, high energy faceted TiO 2 nanosheets (TiO 2 -NSs) with super thermal stability was prepared by calcination of TiOF 2 cubes. With increase in the calcination temperature from 300 to 600°C, TiOF 2 transforms into TiO 2 hollow nanoboxes (TiO 2 -HNBs) assembly from TiO 2 -NSs via Ostwald Rippening process. Almost all of the TiO 2 -HNBs are disassembled into discrete TiO 2 -NSs when calcination temperature is higher than 700°C. Phase transformation from A-TiO 2 to R-TiO 2 begins at 1000°C. Only when the calcination temperature is higher than 1200°C can all the TiO 2 -NSs transforms into R-TiO 2 . The 500°C-calcined sample (T500) exhibits the highest photoreactivity toward acetone oxidation possibly because of the production of high energy TiO 2 -NSs with exposed high energy (001) facets and the surface adsorbed fluorine. Surface oxygen vacancy, due to the heat-induced removal of surface adsorbed fluoride ions, is responsible for the high thermal stability of TiO 2 -NSs which are prepared by calcination of TiOF 2 cubes.

  19. Effect of alkali and heat treatments for bioactivity of TiO{sub 2} nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seo young, E-mail: mast6269@nate.com [Dept. of Dental Biomaterials and Institute of Bio degradable material, Institute of Oral Bioscience and BK21 plus project, School of Dentistry, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of); Kim, Yu kyoung, E-mail: yk0830@naver.com [Dept. of Dental Biomaterials and Institute of Bio degradable material, Institute of Oral Bioscience and BK21 plus project, School of Dentistry, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of); Park, Il song, E-mail: ilsong@jbnu.ac.kr [Division of Advanced Materials Engineering, Research Center for Advanced Materials Development and Institute of Biodegradable Materials, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Jin, Guang chun, E-mail: jingc88@126.com [Oral Medical College, Beihua University, Jilin City 132013 (China); Bae, Tae sung, E-mail: bts@jbnu.ac.kr [Dept. of Dental Biomaterials and Institute of Bio degradable material, Institute of Oral Bioscience and BK21 plus project, School of Dentistry, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of); Lee, Min ho, E-mail: mh@jbnu.ac.kr [Dept. of Dental Biomaterials and Institute of Bio degradable material, Institute of Oral Bioscience and BK21 plus project, School of Dentistry, Chonbuk National University, Jeonju, 561-756 (Korea, Republic of)

    2014-12-01

    Highlights: • TiO{sub 2} nanotubes formed via anodization were treated by alkali and heat. • The surface roughness was increased after alkali treatment (p < 0.05). • After alkali and heat treatment, the wettability was better than before treatment. • Alkali treated TiO{sub 2} nanotubes were shown higher HAp formation in SBF. • Heat treatment affected on the attachment of cells for alkali treated nanotubes. - Abstract: In this study, for improving the bioactivity of titanium used as an implant material, alkali and heat treatments were carried out after formation of the nanotubes via anodization. Nanotubes with uniform length, diameter, and thickness were formed by anodization. The alkali and heat-treated TiO{sub 2} nanotubes were covered with the complex network structure, and the Na compound was generated on the surface of the specimens. In addition, after 5 and 10 days of immersion in the SBF, the crystallized OCP and HAp phase was significantly increased on the surface of the alkali-treated TiO{sub 2} nanotubes (PNA) and alkali and heat-treated TiO{sub 2} nanotubes (PNAH) groups. Cell proliferation was decreased due to the formation of amorphous sodium titanate (Na{sub 2}TiO{sub 3}) layer on the surface of the PNA group. However, anatase and crystalline sodium titanate were formed on the surface of the PNAH group after heat treatment at 550 °C, and cell proliferation was improved. Thus, PNA group had higher HAp forming ability in the simulated body fluid. Additional heat treatment affected on enhancement of the bioactivity and the attachment of osteoblasts for PNA group.

  20. Enhancement of the photocatalytic activity of TiO2 nanoparticles by surface-capping DBS groups

    International Nuclear Information System (INIS)

    Wang Baiqi; Jing Liqiang; Qu Yichun; Li Shudan; Jiang Baojiang; Yang Libin; Xin Baifu; Fu Honggang

    2006-01-01

    TiO 2 nanoparticles capped with sodium dodecylbenzenesulfonate (DBS) are synthesized by a sol-hydrothermal process using tetrabutyl titanate and DBS as raw materials. The effects of surface-capping DBS on the surface photovoltage spectroscopy (SPS), photoluminescence (PL) and photocatalytic performance of TiO 2 nanoparticles are principally investigated together with their relationships. The results show that the surface of TiO 2 nanoparticles can be well capped by DBS groups while the pH value and added DBS amount are controlled at 5.0 and 2% of TiO 2 mass weight, respectively, and the linkage between DBS groups and TiO 2 surfaces is mainly by means of quasi-sulphonate bond. The intensities of SPS and PL spectra of TiO 2 obviously decrease after DBS-capping, while the activity can greatly increase during the photocatalytic degradation of Rhodamine B (RhB) solution, which are mainly attributed to the electron-withdrawing character of the DBS groups. Moreover, the enhancement of photocatalytic activity of DBS-capped TiO 2 is also related to the increase in the capability for adsorbing RhB

  1. Crystallographic orientations and electrical properties of Bi sub 3 sub . sub 4 sub 7 La sub 0. sub 8 sub 5 Ti sub 3 O sub 1 sub 2 thin films on Pt/Ti/SiO sub 2 /Si and Pt/SiO sub 2 /Si substrates

    CERN Document Server

    Ryu, S O; Lee, W J

    2003-01-01

    We report on the crystallization and electrical properties of Bi sub 3 sub . sub 4 sub 7 La sub 0 sub . sub 8 sub 5 Ti sub 3 O sub 1 sub 2 (BLT) thin films for possible ferroelectric non-volatile memory applications. The film properties were found to be strongly dependent on process conditions especially on the intermediate heat treatment conditions. The crystallographic orientation of the films showed sharp changes at the intermediate rapid thermal annealing (RTA) temperature of 450degC. Below 450degC, BLT thin films have (117) orientation while they have preffered c-axis orientation above 450degC. We found that RTA conditions of the first coating layer play a major role in determining the entire crystallographic orientation of the films. The films also showed of ferroelectric hysterisis behavior strongly dependent on RTA treatment. In fact, the remanent polarization of Bi sub 3 sub . sub 4 sub 6 sub 5 La sub 0 sub . sub 8 sub 5 Ti sub 3 O sub 1 sub 2 thin films having (001) preferred crystallographic orient...

  2. Eu"2"+ doped TiO_2 nano structures synthesized by HYSYCVD for thermoluminescence dosimetry

    International Nuclear Information System (INIS)

    Perez A, J. A.; Leal C, A. L.; Melendrez A, R.; Barboza F, M.

    2016-10-01

    Titania (TiO_2) has attracted interest owing his potential applications as dosimetry material given his excellent optical, electrical and thermal properties and the ability to shape his structure make TiO_2 suitable for research and dosimetry applications. In this work, a systematic study to know the magnitude of processing parameters influence on thermoluminescent properties of undoped (TiO_2) and doped (TiO_2:Eu"2"+) nano materials obtained by hybrid precursor systems chemical vapor deposition (HYSYCVD) technique is presented. Synthesis of one dimension nano structures of TiO_2:Eu"2"+ was carried out using K_2TiF_6 and EuCl_2 as dopant at 0.5, 1, 2.5 and 5 wt %. The nano structures samples were irradiated with β-ray in a doses range of 0.083-3000 Gy. All thermoluminescence (Tl) glow curves showed 3 broad Tl peaks around 373, 473 and 573 K, and a dosimetric linear behavior from 0.083 to 300 Gy. The Tl has a good reproducibility, with deviations of around 5%, making these TiO_2:Eu"2"+ nano materials suitable for dosimetric applications. (Author)

  3. Effect of Al2O3 and TiO2 nanoparticles on aquatic organisms

    International Nuclear Information System (INIS)

    Gosteva, I; Morgalev, Yu; Morgaleva, T; Morgalev, S

    2015-01-01

    Environmental toxicity of aqueous disperse systems of nanoparticles of binary compounds of titanium dioxides (with particle size Δ 50 =5 nm, Δ 50 =50 nm, Δ 50 =90 nm), aluminum oxide alpha-forms (Δ 50 =7 nm and Δ 50 =70 nm) and macro forms (TiO 2 Δ 50 =350 nm, Al 2 O 3 A 50 =4000 nm) were studied using biological testing methods. The bioassay was performed using a set of test organisms representing the major trophic levels. We found the dependence of the toxic effect concentration degree of nTiO 2 and nAl 2 O 3 on the fluorescence of the bacterial biosensor 'Ekolyum', the chemotactic response of ciliates Paramecium caudatum, the growth of unicellular algae Chlorella vulgaris Beijer and mortality of entomostracans Daphnia magna Straus. We revealed the selective dependence of nTiO 2 and nAl 2 O 3 toxicity on the size, concentration and chemical nature of nanoparticles. The minimal concentration causing an organism's response on nTiO 2 and nAl 2 O 3 effect depends on the type of the test- organism and the test reaction under study. We specified L(E)C 50 and acute toxicity categories for all the studied nanoparticles. We determined that nTiO 2 (Δ 50 =5 nm) belong to the category «Acute toxicity 1», nTiO 2 (A 50 =90 nm) and nAl 2 O 3 (Δ 50 =70 nm) – to the category «Acute toxicity 2», nAl 2 O 3 (Δ 50 =7 nm) – to the category «Acute toxicity 3». No acute toxicity was registered for nTiO 2 (Δ 50 =50 nm) and macro form TiO 2 . (paper)

  4. Effect of AL2O3 and TiO2 nanoparticles on aquatic organisms

    Science.gov (United States)

    Gosteva, I.; Morgalev, Yu; Morgaleva, T.; Morgalev, S.

    2015-11-01

    Environmental toxicity of aqueous disperse systems of nanoparticles of binary compounds of titanium dioxides (with particle size Δ50=5 nm, Δ50=50 nm, Δ50=90 nm), aluminum oxide alpha-forms (Δ50=7 nm and Δ50=70 nm) and macro forms (TiO2 Δ50=350 nm, Al2O3 A50=4000 nm) were studied using biological testing methods. The bioassay was performed using a set of test organisms representing the major trophic levels. We found the dependence of the toxic effect concentration degree of nTiO2 and nAl2O3 on the fluorescence of the bacterial biosensor "Ekolyum", the chemotactic response of ciliates Paramecium caudatum, the growth of unicellular algae Chlorella vulgaris Beijer and mortality of entomostracans Daphnia magna Straus. We revealed the selective dependence of nTiO2 and nAl2O3 toxicity on the size, concentration and chemical nature of nanoparticles. The minimal concentration causing an organism's response on nTiO2 and nAl2O3 effect depends on the type of the test- organism and the test reaction under study. We specified L(E)C50 and acute toxicity categories for all the studied nanoparticles. We determined that nTiO2 (Δ50=5 nm) belong to the category «Acute toxicity 1», nTiO2 (A50=90 nm) and nAl2O3 (Δ50=70 nm) - to the category «Acute toxicity 2», nAl2O3 (Δ50=7 nm) - to the category «Acute toxicity 3». No acute toxicity was registered for nTiO2 (Δ50=50 nm) and macro form TiO2.

  5. Effect of Nb-doped TiO{sub 2} on nanocomposited aligned ZnO nanorod/TiO{sub 2}:Nb for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Saurdi, I., E-mail: saurdy788@gmail.com; Ishak, A. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); UiTM Sarawak Kampus Kota Samarahan Jalan Meranek, Sarawak (Malaysia); Shafura, A. K.; Azhar, N. E. A.; Mamat, M. H. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); Malek, M. F.; Rusop, M. [NANO-ElecTronic Centre (NET), Faculty of Electrical Engineering, Universiti Teknologi MARA (UiTM),40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre (NST), (Centre for Nano-Science and Nano-Technology), Institute of Science, Universiti Teknologi MARA - UiTM, 40450 Shah Alam, Selangor (Malaysia); Alrokayan, A. H. Salman; Khan, Haseeb A. [Department of Biochemistry, College of Science, Bldg. 5, King Saud University (KSU) P.O: 2455 Riyadh 1145 (Saudi Arabia)

    2016-07-06

    The Nb-doped TiO{sub 2} films were deposited on glass substrate at different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively and their electrical and structural properties were investigated. Subsequently, the Nb-doped TiO{sub 2} films were deposited on top of aligned ZnO Nanorod on ITO glass substrates using spin coating technique. The nanocomposited aligned ZnO nanorod/Nb-doped TiO{sub 2} (TiO{sub 2}:Nb) were coated with different Nb concentrations of 0 at.%, 1 at.%, 3 at.%, 5 at.% and 7 at.%, respectively. The Dye-sensitized solar cells were fabricated from the nanocomposited aligned ZnO nanorod/TiO{sub 2}:Nb photoanodes and their effects on the performance of the DSSCs were investigated. From the solar simulator measurement of DSSC the solar energy conversion efficiency (η) of 5.376% under AM 1.5 was obtained for the ZnO nanorod/TiO{sub 2}:Nb-5at.%.

  6. Thin film nano-photocatalyts with low band gap energy for gas phase degradation of p-xylene: TiO2 doped Cr, UiO66-NH2 and LaBO3 (B  =  Fe, Mn, and Co)

    Science.gov (United States)

    Loc Luu, Cam; Thuy Van Nguyen, Thi; Nguyen, Tri; Nguyen, Phung Anh; Hoang, Tien Cuong; Ha, Cam Anh

    2018-03-01

    By dip-coating technique the thin films of nano-photocatalysts TiO2, Cr-doped TiO2, LaBO3 perovskites (B  =  Fe, Mn, and Co) prepared by sol-gel method, and UiO66-NH2 prepared by a solvothermal were obtained and employed for gas phase degradation of p-xylene. Physicochemical characteristics of the catalysts were examined by the methods of BET, SEM, TEM, XRD, FT-IR, TGA, Raman and UV-vis spectroscopies. The thickness of film was determined by a Veeco-American Dektek 6M instrument. The activity of catalysts was evaluated in deep photooxidation of p-xylene in a microflow reactor at room temperature with the radiation sources of a UV (λ  =  365 nm) and LED lamps (λ  =  400-510 nm). The obtained results showed that TiO2 and TiO2 doped Cr thin films was featured by an anatase phase with nanoparticles of 10-100 nm. Doping TiO2 with 0.1%mol Cr2O3 led to reduce band gap energy from 3.01 down to 1.99 eV and extend the spectrum of photon absorption to the visible region (λ  =  622 nm). LaBO3 perovkite thin films were also featured by a crystal phase with average particle nanosize of 8-40 nm, a BET surface area of 17.6-32.7 m2 g-1 and band gap energy of 1.87-2.20 eV. UiO66-NH2 was obtained in the ball shape of 100-200 nm, a BET surface area of 576 m2 g-1 and a band gap energy of 2.83 eV. The low band gap energy nano-photocatalysts based on Cr-doped TiO2 and LaBO3 perovskites exhibited highly stable and active for photo-degradation of p-xylene in the gas phase under radiation of UV-vis light. Perovskite LaFeO3 and Cr-TiO2 thin films were the best photocatalysts with a decomposition yield being reached up to 1.70 g p-xylene/g cat.

  7. Nb-doped TiO2 cathode catalysts for oxygen reduction reaction of polymer electrolyte fuel cells

    KAUST Repository

    Arashi, Takuya

    2014-09-01

    Nb-doped TiO2 particles were studied as electrocatalysts for the oxygen reduction reaction (ORR) under acidic conditions. The Nb-doped TiN nanoparticles were first synthesized by meso-porous C3N4 and then fully oxidized to Nb-doped TiO2 by immersing in 0.1 M H 2SO4 at 353 K for 24 h. Although the ORR activity of the as-obtained sample was low, a H2 treatment at relatively high temperature (1173 K) dramatically improved the ORR performance. An onset potential as high as 0.82 VRHE was measured. No degradation of the catalysts was observed during the oxidation-reduction cycles under the ORR condition for over 127 h. H2 treatment at temperatures above 1173 K caused the formation of a Ti4O7 phase, resulting in a decrease in ORR current. Elemental analysis indicated that the Nb-doped TiO 2 contained 25 wt% residual carbon. Calcination in air at 673 or 973 K eliminated the residual carbon in the catalyst, which was accompanied by a dramatic decrease in ORR activity. This post-calcination process may reduce the conductivity of the sample by filling the oxygen vacancies, and the carbon residue in the particle aggregates may enhance the electrocatalytic activity for ORR. The feasibility of using conductive oxide materials as electrocatalysts is discussed. © 2013 Elsevier B.V.

  8. Nb-doped TiO2 cathode catalysts for oxygen reduction reaction of polymer electrolyte fuel cells

    KAUST Repository

    Arashi, Takuya; Seo, Jeongsuk; Takanabe, Kazuhiro; Kubota, Jun; Domen, Kazunari

    2014-01-01

    Nb-doped TiO2 particles were studied as electrocatalysts for the oxygen reduction reaction (ORR) under acidic conditions. The Nb-doped TiN nanoparticles were first synthesized by meso-porous C3N4 and then fully oxidized to Nb-doped TiO2 by immersing in 0.1 M H 2SO4 at 353 K for 24 h. Although the ORR activity of the as-obtained sample was low, a H2 treatment at relatively high temperature (1173 K) dramatically improved the ORR performance. An onset potential as high as 0.82 VRHE was measured. No degradation of the catalysts was observed during the oxidation-reduction cycles under the ORR condition for over 127 h. H2 treatment at temperatures above 1173 K caused the formation of a Ti4O7 phase, resulting in a decrease in ORR current. Elemental analysis indicated that the Nb-doped TiO 2 contained 25 wt% residual carbon. Calcination in air at 673 or 973 K eliminated the residual carbon in the catalyst, which was accompanied by a dramatic decrease in ORR activity. This post-calcination process may reduce the conductivity of the sample by filling the oxygen vacancies, and the carbon residue in the particle aggregates may enhance the electrocatalytic activity for ORR. The feasibility of using conductive oxide materials as electrocatalysts is discussed. © 2013 Elsevier B.V.

  9. Advanced nanoporous TiO2 photocatalysts by hydrogen plasma for efficient solar-light photocatalytic application

    Science.gov (United States)

    An, Ha-Rim; Park, So Young; Kim, Hyeran; Lee, Che Yoon; Choi, Saehae; Lee, Soon Chang; Seo, Soonjoo; Park, Edmond Changkyun; Oh, You-Kwan; Song, Chan-Geun; Won, Jonghan; Kim, Youn Jung; Lee, Jouhahn; Lee, Hyun Uk; Lee, Young-Chul

    2016-01-01

    We report an effect involving hydrogen (H2)-plasma-treated nanoporous TiO2(H-TiO2) photocatalysts that improve photocatalytic performance under solar-light illumination. H-TiO2 photocatalysts were prepared by application of hydrogen plasma of assynthesized TiO2(a-TiO2) without annealing process. Compared with the a-TiO2, the H-TiO2 exhibited high anatase/brookite bicrystallinity and a porous structure. Our study demonstrated that H2 plasma is a simple strategy to fabricate H-TiO2 covering a large surface area that offers many active sites for the extension of the adsorption spectra from ultraviolet (UV) to visible range. Notably, the H-TiO2 showed strong ·OH free-radical generation on the TiO2 surface under both UV- and visible-light irradiation with a large responsive surface area, which enhanced photocatalytic efficiency. Under solar-light irradiation, the optimized H-TiO2 120(H2-plasma treatment time: 120 min) photocatalysts showed unprecedentedly excellent removal capability for phenol (Ph), reactive black 5(RB 5), rhodamine B (Rho B) and methylene blue (MB) — approximately four-times higher than those of the other photocatalysts (a-TiO2 and P25) — resulting in complete purification of the water. Such well-purified water (>90%) can utilize culturing of cervical cancer cells (HeLa), breast cancer cells (MCF-7), and keratinocyte cells (HaCaT) while showing minimal cytotoxicity. Significantly, H-TiO2 photocatalysts can be mass-produced and easily processed at room temperature. We believe this novel method can find important environmental and biomedical applications. PMID:27406992

  10. Solvothermal preparation of micro/nanostructured TiO{sub 2} with enhanced lithium storage capability

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jie [School of Physics and Mechanical & Electronical Engineering, Hubei University of Education, Wuhan, 430205 (China); Wang, Chao [Department of Architecture and Material Engineering, Hubei University of Education, Wuhan, 430205 (China); Zheng, Ping; Zhang, Lei; Chen, Gongxuan [College of Chemistry and Life Science, Hubei University of Education, Wuhan, 430205 (China); Tang, Chengchun [School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130 (China); Wu, Tian, E-mail: twu@whu.edu.cn [School of Physics and Mechanical & Electronical Engineering, Hubei University of Education, Wuhan, 430205 (China); College of Chemistry and Life Science, Hubei University of Education, Wuhan, 430205 (China); Department of Architecture and Material Engineering, Hubei University of Education, Wuhan, 430205 (China)

    2017-04-01

    Facile and controllable preparation of TiO{sub 2} is of prime importance to elaborately tailor and then fully exploit its intriguing functionalities in energy storage, catalysis and environmental remediation. Herein, a solvothermal method combined with post annealing is conducted, in which the hydrolysis of tetrabutyl titanate is controlled by the in-situ generated water during solvothermal treatment. By controlling synthetic conditions (i.e. reactant ratio, solvothermal temperature and reaction time), we manage to tailor the morphologies of TiO{sub 2}. Specially, three typical structures (nanoparticle, nanoneedle and nanorod) are studied to reveal the growth mechanism and the effects of the synthesis conditions. Nanoneedle-structured TiO{sub 2} shows higher specific capacity and enhanced cycle stability as anode material for lithium ion batteries. - Highlights: • Controllable preparation of nano-TiO{sub 2} is achieved by a solvothermal method. • TiO{sub 2} morphology is tailored by tuning reactant ratio, temperature and duration. • Needle structured TiO{sub 2} shows enhanced lithium storage capability.

  11. Damage evolution of ion irradiated defected-fluorite La 2 Zr 2 O 7 epitaxial thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kaspar, Tiffany C.; Gigax, Jonathan G.; Shao, Lin; Bowden, Mark E.; Varga, Tamas; Shutthanandan, Vaithiyalingam; Spurgeon, Steven R.; Yan, Pengfei; Wang, Chongmin; Ramuhalli, Pradeep; Henager, Charles H.

    2017-05-01

    Pyrochlore-structure oxides, A2B2O7, may exhibit remarkable radiation tolerance due to the ease with which they can accommodate disorder by transitioning to a defected fluorite structure. The mechanism of defect formation was explored by evaluating the radiation damage behavior of high quality epitaxial La2Zr2O7 thin films with the defected fluorite structure, irradiated with 1 MeV Zr+ at doses up to 10 displacements per atom (dpa). The level of film damage was evaluated as a function of dose by Rutherford backscattering spectrometry in the channeling geometry (RBS/c) and scanning transmission electron microscopy (STEM). At lower doses, the surface of the La2Zr2O7 film amorphized, and the amorphous fraction as a function of dose fit well to a stimulated amorphization model. As the dose increased, the surface amorphization slowed, and amorphization appeared at the interface. Even at a dose of 10 dpa, the core of the film remained crystalline, despite the prediction of amorphization from the model. To inform future ab initio simulations of La2Zr2O7, the bandgap of a thick La2Zr2O7 film was measured to be indirect at 4.96 eV, with a direct transition at 5.60 eV.

  12. PREPRARATION OF CoPcS/TiO2/BEADS AND THEIR PHOTOCATALYTIC REACTIVITY FOR PHOTODEGRADATION OF VEGETABLE OIL FLOATING ON WATER

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The paper introduces the preparation of floating TiO2/beads photocalyst attached to the hollow glass micro-beads surface by sol-gel technique using tetrabutyl titanate as material and the preparation of floating CoPcS/TiO2/beads by dip-coatig technique. The optimal factor of degradation of vegetable oil floating on water using CoPcS/TiO2/beads was studied. The result showed that the removal rate of vegetable oil floating on water can highly reach 90% at the optimal condition (acidity or neutrality, 375W medium-pressure mercury vapour lamp, illumination 2h~3h, 1g CoPcS/TiO2/beads). The photocatalytic removal efficiency causing by CoPcS/TiO2/beads was increased rapidly by adding a trace amount of H2O2.

  13. PREPRARATION OF CoPcS/TiO2/BEADS AND THEIR PHOTOCATALYTIC REACTIVITY FOR PHOTODEGRADATION OF VEGETABLE OIL FLOATING ON WATER

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaoye; YAN Yongsheng; KONG Feng; WANG Yun

    2007-01-01

    The paper introduces the preparation of floating TiO2/beads photocalyst attached to the hollow glass micro-beads surface by sol-gel technique using tetrabutyl titanate as material and the preparation of floating CoPcS/TiO2/beads by dip-coatig technique. The optimal factor of degradation of vegetable oil floating on water using CoPcS/TiO2/beads was studied. The result showed that the removal rate of vegetable oil floating on water can highly reach 90% at the optimal condition (acidity or neutrality, 375W medium-pressure mercury vapour lamp, illumination 2h~3h, 1g CoPcS/TiO2/beads). The photocatalytic removal efficiency causing by CoPcS/TiO2/beads was increased rapidly by adding a trace amount of H2O2.

  14. Effect of TiO2 Nanofiller Concentration on the Mechanical, Thermal and Biological Properties of HDPE/TiO2 Nanocomposites

    Science.gov (United States)

    Mozumder, Mohammad Sayem; Mourad, Abdel-Hamid I.; Mairpady, Anusha; Pervez, Hifsa; Haque, Md Emdadul

    2018-05-01

    The necessity for advanced and effective biomimetic tissue engineering materials has increased massively as bone diseases such as osteoporosis and bone cancer have become a major public health problem. Therefore, the objective of this study is to develop titanium dioxide (TiO2) nanoparticles-enriched high-density polyethylene (HDPE) nanocomposites that could serve as potential biomaterials. HDPE/TiO2 nanocomposites with varying TiO2 nanoparticles content were fabricated by using injection molding technique and were subjected to mechanical, thermal and biological characterization. SEM-EDS analysis confirmed even dispersion of TiO2 nanoparticles into the HDPE matrix. It was observed from the mechanical testing that the addition of TiO2 nanoparticles to HDPE noticeably improved the stiffness (from 345 to 378 MPa) while maintaining almost similar yield strength of pure HDPE. The thermal analyses revealed that TiO2 nanoparticles inclusion to HDPE matrix enhanced the thermal stability of nanocomposites, as the overall rate of crystallization increased by almost 4%. Furthermore, biocompatibility of nanocomposites was also studied by means of various cell culture experiments; human osteoblasts (hFOB) were seeded on the HDPE/TiO2 nanocomposites and were visualized through SEM after 72 h of incubation; surface morphology revealed normal cell growth and spreading with more attachment on PNC-10 that contains 10 wt.% of TiO2. Moreover, cell viability assays (i.e., MTT and cell attachment) revealed consistent increase in cell count and metabolic activity when triplicate cultures were incubated for 1, 3 and 7 days.

  15. Effect of TiO2 Nanofiller Concentration on the Mechanical, Thermal and Biological Properties of HDPE/TiO2 Nanocomposites

    Science.gov (United States)

    Mozumder, Mohammad Sayem; Mourad, Abdel-Hamid I.; Mairpady, Anusha; Pervez, Hifsa; Haque, Md Emdadul

    2018-03-01

    The necessity for advanced and effective biomimetic tissue engineering materials has increased massively as bone diseases such as osteoporosis and bone cancer have become a major public health problem. Therefore, the objective of this study is to develop titanium dioxide (TiO2) nanoparticles-enriched high-density polyethylene (HDPE) nanocomposites that could serve as potential biomaterials. HDPE/TiO2 nanocomposites with varying TiO2 nanoparticles content were fabricated by using injection molding technique and were subjected to mechanical, thermal and biological characterization. SEM-EDS analysis confirmed even dispersion of TiO2 nanoparticles into the HDPE matrix. It was observed from the mechanical testing that the addition of TiO2 nanoparticles to HDPE noticeably improved the stiffness (from 345 to 378 MPa) while maintaining almost similar yield strength of pure HDPE. The thermal analyses revealed that TiO2 nanoparticles inclusion to HDPE matrix enhanced the thermal stability of nanocomposites, as the overall rate of crystallization increased by almost 4%. Furthermore, biocompatibility of nanocomposites was also studied by means of various cell culture experiments; human osteoblasts (hFOB) were seeded on the HDPE/TiO2 nanocomposites and were visualized through SEM after 72 h of incubation; surface morphology revealed normal cell growth and spreading with more attachment on PNC-10 that contains 10 wt.% of TiO2. Moreover, cell viability assays (i.e., MTT and cell attachment) revealed consistent increase in cell count and metabolic activity when triplicate cultures were incubated for 1, 3 and 7 days.

  16. Investigation of the photocatalytic transformation of acesulfame K in the presence of different TiO2-based materials.

    Science.gov (United States)

    López-Muňoz, M J; Daniele, A; Zorzi, M; Medana, C; Calza, P

    2018-02-01

    The photocatalytic transformation of acesulfame K - an artificial sweetener that has gained popularity over the last decades for being a calorie-free additive in food, beverages and several pharmaceutical products - was studied using three different photocatalysts, the benchmark TiO 2 -P25 and two other forms of synthetized titanium oxides named TiO 2 -SG1 and TiO 2 -SG2. The two latter materials were synthesized by a sol gel process in which the hydrolysis rate of titanium n-butoxide was controlled by the water formed in situ through an esterification reaction between ethanol and acetic acid. The investigation included monitoring the sweetener disappearance, identifying its intermediate compounds, assessing mineralization and evaluating toxicity. The analyses were carried out using high-performance liquid chromatography (HPLC) coupled with a LTQ-Orbitrap analyzer via an electrospray ionization (ESI) in the negative ion mode. This is a powerful tool for the identification, characterization and measurement of the transformation products (TPs); overall 13 species were identified. The use of several semiconductors has pointed out differences in terms of both photocatalytic efficiency and mechanism: the assessment of the evolution kinetics of each species (TPs, total organic carbon and inorganic ions) has brought to the elaboration of a general transformation pathway of acesulfame K. TiO 2 -SG2 proved to be the most efficient material in degrading the artificial sweetener and leads to the complete mineralization within 6 h of irradiation, while up to 16 h are required for TiO 2 -P25. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Plasma plume effects on the conductivity of amorphous-LaAlO3/SrTiO3 interfaces grown by pulsed laser deposition in O2 and Ar

    DEFF Research Database (Denmark)

    Sambri, A.; Christensen, Dennis; Trier, Felix

    2012-01-01

    Amorphous-LaAlO3/SrTiO3 interfaces exhibit metallic conductivity similar to those found for the extensively studied crystalline-LaAlO3/SrTiO3 interfaces. Here, we investigate the conductivity of the amorphous-LaAlO3/SrTiO3 interfaces grown in different pressures of O2 and Ar background gases...

  18. Heteroepitaxial growth of Ba1 - xSrxTiO3/YBa2Cu3O7 - x by plasma-enhanced metalorganic chemical vapor deposition

    Science.gov (United States)

    Chern, C. S.; Liang, S.; Shi, Z. Q.; Yoon, S.; Safari, A.; Lu, P.; Kear, B. H.; Goodreau, B. H.; Marks, T. J.; Hou, S. Y.

    1994-06-01

    Epitaxial Ba1-xSrxTiO3(BST)/YBa2Cu3O7-x heterostructures with superior electrical and dielectric properties have been fabricated by plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD). Data of x-ray diffraction and high resolution transmission electron microscopy showed that oriented Ba1-xSrxTiO3 layers were epitaxially deposited on epitaxial (001) YBa2Cu3O7-x layers. The leakage current density through the Ba1-xSrxTiO3 films was about 10-7 A/cm2 at 2 V (about 2×105 V/cm) operation. Moreover, the results of capacitance-temperature measurements showed that the PE-MOCVD Ba1-xSrxTiO3 films had Curie temperatures of about 30 °C and a peak dielectric constant of 600 at zero bias voltage. The Rutherford backscattering spectrometry and x-ray diffraction results showed that the BST film composition was controlled between Ba0.75Sr0.25TiO3 and Ba0.8Sr0.2TiO3. The structural and electrical properties of the Ba1-xSrxTiO3/YBa2Cu3O7-x heterostructure indicated that conductive oxide materials with close lattice to Ba1-xSrxTiO3 can be good candidates for the bottom electrode.

  19. Characterization of ultra-thin TiO2 films grown on Mo(112)

    International Nuclear Information System (INIS)

    Kumar, D.; Chen, M.S.; Goodman, D.W.

    2006-01-01

    Ultra-thin TiO 2 films were grown on a Mo(112) substrate by stepwise vapor depositing of Ti onto the sample surface followed by oxidation at 850 K. X-ray photoelectron spectroscopy showed that the Ti 2p peak position shifts from lower to higher binding energy with an increase in the Ti coverage from sub- to multilayer. The Ti 2p peak of a TiO 2 film with more than a monolayer coverage can be resolved into two peaks, one at 458.1 eV corresponding to the first layer, where Ti atoms bind to the substrate Mo atoms through Ti-O-Mo linkages, and a second feature at 458.8 eV corresponding to multilayer TiO 2 where the Ti atoms are connected via Ti-O-Ti linkages. Based on these assignments, the single Ti 2p 3/2 peak at 455.75 eV observed for the Mo(112)-(8 x 2)-TiO x monolayer film can be assigned to Ti 3+ , consistent with our previous results obtained with high-resolution electron energy loss spectroscopy

  20. Anisotropic electrical properties of epitaxial Yba2Cu3O7-gd films on (110) SrTiO3

    International Nuclear Information System (INIS)

    Gupta, A.; Koren, G.; Baseman, R.J.; Segmuller, A.; Holber, W.

    1989-01-01

    Epitaxial thin films of YBa 2 Cu 3 O 7 - δ were deposited on (110) SrTiO 3 at 600 degrees C in the presence of atomic oxygen using the laser ablation technique. X-ray diffraction patterns in the standard Bragg and grazing incidence modes show epitaxial growth of the films with their c-axis and axis parallel to the and directions in the plane of the substrate, respectively. Superconductivity with T c (R = ) = 82 K was found along the direction in the basal plane, whereas finite resistivity down to 5 k was observed along the c-axis direction. The authors maintain that these preliminary results suggest that YBa 2 Cu 3 O 7 - δ behaves like a true two-dimensional superconductor

  1. Effects of deposition rates on laser damage threshold of TiO2/SiO2 high reflectors

    International Nuclear Information System (INIS)

    Yao Jianke; Xu Cheng; Ma Jianyong; Fang Ming; Fan Zhengxiu; Jin Yunxia; Zhao Yuanan; He Hongbo; Shao Jianda

    2009-01-01

    TiO 2 single layers and TiO 2 /SiO 2 high reflectors (HR) are prepared by electron beam evaporation at different TiO 2 deposition rates. It is found that the changes of properties of TiO 2 films with the increase of rate, such as the increase of refractive index and extinction coefficient and the decrease of physical thickness, lead to the spectrum shift and reflectivity bandwidth broadening of HR together with the increase of absorption and decrease of laser-induced damage threshold. The damages are found of different morphologies: a shallow pit to a seriously delaminated and deep crater, and the different amorphous-to-anatase-to-rutile phase transition processes detected by Raman study. The frequency shift of Raman vibration mode correlates with the strain in film. Energy dispersive X-ray analysis reveals that impurities and non-stoichiometric defects are two absorption initiations resulting to the laser-induced transformation.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-04-14

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

  3. Efficient removal of Co(II) from aqueous solution by titanate sodium nanotubes

    Institute of Scientific and Technical Information of China (English)

    Dong-Mei Li; Ning Liu; Fei-Ze Li; Jia-Li Liao; Ji-Jun Yang; Bing Li; Yun-Ming Chen; Yuan-You Yang; Jin-Song Zhang; Jun Tang

    2016-01-01

    In this paper, a novel material for Co(II) adsorption, titanate sodium nanotubes (Na2Ti2O5-NTs) were synthesized and characterized, and then they were used to remove Co(II) from aqueous solution and compared with titanic acid nanotubes (H2Ti2O5-NTs) and potassium hexatitanate whiskers (K2Ti6O13). The results showed that the adsorption of Co(II) on the materials was dependent on pH values and was a spontaneous, endothermic process. Specifically, Na2Ti2O5-NTs exhibited much more efficient ability to adsorb Co(II) from aqueous solution, with the maximum adsorption capacity of 85.25 mg/g. Furthermore, Na2Ti2O5-NTs could selectively adsorb Co(II) from aque-ous solution containing coexisting ions (Na+, K+, Mg2+, and Ca2+). The results suggested that Na2Ti2O5-NTs were potential effective adsorbents for removal of Co(II) or cobalt-60 from wastewater.

  4. Ab initio investigation of helium in Y_2Ti_2O_7: Mobility and effects on mechanical properties

    International Nuclear Information System (INIS)

    Danielson, T.; Tea, E.; Hin, C.

    2016-01-01

    Oxide nanoclusters (NCs) in nanostructured ferritic alloys (NFAs) are known to be efficient trapping sites for the transmutation product helium. In this study, the migration barriers and potential energy surfaces of helium in Y_2Ti_2O_7 are presented to explain the mobility of helium through oxide NCs and shed light on the accumulation of helium and the trapping mechanisms of the oxides. A complex tunnel-shaped potential energy surface is identified and gives rise to relatively large migration barriers. Subsequently, the effect of helium accumulation on the mechanical properties of Y_2Ti_2O_7 oxide nanoclusters is investigated and it is shown that the mechanical properties of the oxide do not significantly degrade as helium accumulates. - Highlights: • Migration barriers of helium in Y_2Ti_2O_7 are calculated using the climbing image nudged elastic band. • Helium Potential energy surfaces are calculated. • Mechanical properties of varying helium concentrations are presented.

  5. TiO{sub 2} and TiO{sub 2}-SiO{sub 2} thin films and powders by one-step soft-solution method: Synthesis and characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Ennaoui, A.; Sankapal, B.R.; Skryshevsky, V.; Lux-Steiner, M.Ch. [Division Solar Energy Research, Department Heterogeneous Material Systems, Hahn-Meitner-Institut, Glienicker Strasse 100, 14109 Berlin (Germany)

    2006-06-15

    Simple soft-solution method has been developed to synthesize films and powders of TiO{sub 2} and mixed TiO{sub 2}-SiO{sub 2} at relatively low temperatures. This method is simple and inexpensive. Furthermore, reactor can be designed for large-scale applications as well as to produce large quantities of composite powders in a single step. For the preparation of TiO{sub 2}, we used aqueous acidic medium containing TiOSO{sub 4} and H{sub 2}O{sub 2}, which results in a peroxo-titanium precursor while colloidal SiO{sub 2} has been added to the precursor for the formation of TiO{sub 2}-SiO{sub 2}. Post annealing at 500{sup o}C is necessary to have anatase structure. Resulting films and powders were characterized by different techniques. TiO{sub 2} (anatase) phase with (101) preferred orientation has been obtained. Also in TiO{sub 2}-SiO{sub 2} mixed films and powders, TiO{sub 2} (anatase) phase was found. Fourier transform infrared spectroscopy (FTIR) results for TiO{sub 2} and mixed TiO{sub 2}-SiO{sub 2} films have been presented and discussed. The method developed in this paper allowed obtaining compact and homogeneous TiO{sub 2} films. These compact films are highly photoactive when TiO{sub 2} is used as photo anode in an photoelectrochemical cell. Nanoporous morphology is obtained when SiO{sub 2} colloids are added into the solution. (author)

  6. Synthesis of Fe2O3/TiO2 nanorod-nanotube arrays by filling TiO2 nanotubes with Fe

    International Nuclear Information System (INIS)

    Mohapatra, Susanta K; Banerjee, Subarna; Misra, Mano

    2008-01-01

    Synthesis of hematite (α-Fe 2 O 3 ) nanostructures on a titania (TiO 2 ) nanotubular template is carried out using a pulsed electrodeposition technique. The TiO 2 nanotubes are prepared by the sonoelectrochemical anodization method and are filled with iron (Fe) by pulsed electrodeposition. The Fe/TiO 2 composite is then annealed in an O 2 atmosphere to convert it to Fe 2 O 3 /TiO 2 nanorod-nanotube arrays. The length of the Fe 2 O 3 inside the TiO 2 nanotubes can be tuned from 50 to 550 nm by changing the deposition time. The composite material is characterized by scanning electron microscopy, transmission electron microscopy and diffuse reflectance ultraviolet-visible studies to confirm the formation of one-dimensional Fe 2 O 3 /TiO 2 nanorod-nanotube arrays. The present approach can be used for designing variable one-dimensional metal oxide heterostructures

  7. Synthesis of LaVO4/TiO2 heterojunction nanotubes by sol-gel coupled with hydrothermal method for photocatalytic air purification.

    Science.gov (United States)

    Zou, Xuejun; Li, Xinyong; Zhao, Qidong; Liu, Shaomin

    2012-10-01

    With the aim of improving the effective utilization of visible light, the LaVO(4)/TiO(2) heterojunction nanotubes were fabricated by sol-gel coupled with hydrothermal method. The photocatalytic ability was demonstrated through catalytic removal of gaseous toluene species. The nanotube samples were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), surface photovoltage (SPV), Raman spectra and N(2) adsorption-desorption measurements. The characterization results showed that the samples with high specific surface areas were of typical nanotubular morphology, which would lead to the high separation and transfer efficiency of photo induced electron-hole pairs. The as-prepared nanotubes exhibited high photocatalytic activity in decomposing toluene species under visible light irradiation with fine photochemical stability. The enhanced photocatalytic performance of LaVO(4)/TiO(2) nanotubes might be attributed to the matching band potentials, the interconnected heterojunction of LaVO(4) versus TiO(2), and the large specific surface areas of nanotubes. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Polyaniline/TiO2/kaolinite: The composite material with high electrical anisotropy

    International Nuclear Information System (INIS)

    Tokarský, Jonáš; Neuwirthová, Lucie; Peikertová, Pavlína; Kulhánková, Lenka; Mamulová Kutláková, Kateřina; Matějka, Vlastimil; Čapková, Pavla

    2014-01-01

    Kaolinite–TiO 2 nanocomposite matrix (KATI) coated with polyaniline (PANI) layer has been prepared in powder form and pressed into tablets. The conductivity was studied in dependence on (1) wt.% of TiO 2 in KATI matrix and (2) thermal pre-treatment of KATI matrix. The anisotropy factor α, i.e. the ratio of in-plane conductivity and conductivity in the direction perpendicular to the tablet plane, was found to be very high for PANI/KATI tablet (α is of the order of 10 3 –10 4 ) in comparison with pure PANI tablet (α is of the order of 10 2 ). Structure has been studied using Raman spectroscopy, X-ray diffraction analysis, scanning electron microscopy and molecular modeling. The possibility of using the tablets as a load sensors have been tested and tablets pressed from composites containing calcined KATI seem to be promising material for this purpose. - Graphical abstract: Tablets pressed from powder form of polyaniline/TiO 2 /kaolinite composites exhibit very high electrical anisotropy and were found to be suitable as load sensors. - Highlights: • Kaolinite/TiO 2 /polyaniline composites exhibit very high electrical anisotropy. • Presence of TiO 2 helps polyaniline to fully cover the kaolinite particles. • Tablets pressed from these composites can be used as load sensors. • Calcination of kaolinite/TiO 2 matrix improves the sensing properties

  9. 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.

  10. Bismuth titanate nanorods and their visible light photocatalytic properties

    International Nuclear Information System (INIS)

    Pei, L.Z.; Liu, H.D.; Lin, N.; Yu, H.Y.

    2015-01-01

    Highlights: • Bismuth titanate nanorods have been synthesized by a simple hydrothermal process. • The size of bismuth titanate nanorods can be controlled by growth conditions. • Bismuth titanate nanorods show good photocatalytic activities of methylene blue and Rhodamine B. - Abstract: Bismuth titanate nanorods have been prepared using a facile hydrothermal process without additives. The bismuth titanate products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) and UV-vis diffusion reflectance spectrum. XRD pattern shows that the bismuth titanate nanorods are composed of cubic Bi 2 Ti 2 O 7 phase. Electron microscopy images show that the length and diameter of the bismuth titanate nanorods are 50-200 nm and 2 μm, respectively. Hydrothermal temperature and reaction time play important roles on the formation and size of the bismuth titanate nanorods. UV-vis diffusion reflectance spectrum indicates that bismuth titanate nanorods have a band gap of 2.58 eV. The bismuth titanate nanorods exhibit good photocatalytic activities in the photocatalytic degradation of methylene blue (MB) and Rhodamine B (RB) under visible light irradiation. The bismuth titanate nanorods with cubic Bi 2 Ti 2 O 7 phase are a promising candidate as a visible light photocatalyst

  11. TiO2 and Cu/TiO2 Thin Films Prepared by SPT

    Directory of Open Access Journals (Sweden)

    S. S. Roy

    2015-12-01

    Full Text Available Titanium oxide (TiO2 and copper (Cu doped titanium oxide (Cu/TiO2 thin films have been prepared by spray pyrolysis technique. Titanium chloride (TiCl4 and copper acetate (Cu(CH3COO2.H2O were used as source of Ti and Cu. The doping concentration of Cu was varied from 1-10 wt. %. The X-ray diffraction studies show that TiO2 thin films are tetragonal structure and Cu/TiO2 thin films implies CuO has present with monoclinic structure. The optical properties of the TiO2 thin films have been investigated as a function of Cu-doping level. The optical transmission of the thin films was found to increase from 88 % to 94 % with the addition of Cu up to 8 % and then decreases for higher percentage of Cu doping. The optical band gap (Eg for pure TiO2 thin film is found to be 3.40 eV. Due to Cu doping, the band gap is shifted to lower energies and then increases further with increasing the concentration of Cu. The refractive index of the TiO2 thin films is found to be 2.58 and the variation of refractive index is observed due to Cu doped. The room temperature resistivity of the films decreases with increasing Cu doping and is found to be 27.50 - 23.76 W·cm. It is evident from the present study that the Cu doping promoted the thin film morphology and thereby it is aspect for various applications.

  12. Microstructure and temperature dependence of the microhardness of W–4V–1La{sub 2}O{sub 3} and W–4Ti–1La{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Savoini, B., E-mail: begona.savoini@uc3m.es; Martínez, J.; Muñoz, A.; Monge, M.A.; Pareja, R.

    2013-11-15

    W–4V–1La{sub 2}O{sub 3} and W–4Ti–1La{sub 2}O{sub 3} (wt.%) alloys have been produced by mechanical alloying and subsequent hot isostatic pressing. Electron microscopy observations revealed that these alloys exhibit a submicron grain structure with a dispersion of La oxide nanoparticles. Large V or Ti pools with martensitic characteristics are found segregated in the interstices between the W particles of the respective alloys. Microhardness tests were carried out over the temperature range 300–1073 K in vacuum. The microhardness–temperature curve for W–4V–1La{sub 2}O{sub 3} exhibited the expected decreasing trend with increasing temperature although the microhardness stayed constant between ∼473 and 773 K. The W–4Ti–1La{sub 2}O{sub 3} presented quite different temperature dependence with an anomalous microhardness increase for temperatures above ∼473 K.

  13. Effect of TiO2 on the Gas Sensing Features of TiO2/PANi Nanocomposites

    Directory of Open Access Journals (Sweden)

    Duong Ngoc Huyen

    2011-02-01

    Full Text Available A nanocomposite of titanium dioxide (TiO2 and polyaniline (PANi was synthesized by in-situ chemical polymerization using aniline (ANi monomer and TiCl4 as precursors. SEM pictures show that the nanocomposite was created in the form of long PANi chains decorated with TiO2 nanoparticles. FTIR, Raman and UV-Vis spectra reveal that the PANi component undergoes an electronic structure modification as a result of the TiO2 and PANi interaction. The electrical resistor of the nanocomposite is highly sensitive to oxygen and NH3 gas, accounting for the physical adsorption of these gases. A nanocomposite with around 55% TiO2 shows an oxygen sensitivity of 600–700%, 20–25 times higher than that of neat PANi. The n-p contacts between TiO2 nanoparticles and PANi matrix give rise to variety of shallow donors and acceptor levels in the PANi band gap which enhance the physical adsorption of gas molecules.

  14. C, N co-doped TiO_2/TiC_0_._7N_0_._3 composite coatings prepared from TiC_0_._7N_0_._3 powder using ball milling followed by oxidation

    International Nuclear Information System (INIS)

    Hao, Liang; Wang, Zhenwei; Zheng, Yaoqing; Li, Qianqian; Guan, Sujun; Zhao, Qian; Cheng, Lijun; Lu, Yun; Liu, Jizi

    2017-01-01

    Highlights: • TiO_2/TiC_0_._7N_0_._3 coatings were prepared by ball milling followed by oxidation. • In situ co-doping of C and N with simultaneous TiO_2 formation was observed. • Improved photocatalytic activity under UV/visible light was noticed. • Synergism in co-doping and heterojunction formation promoted carrier separation. - Abstract: Ball milling followed by heat oxidation was used to prepared C, N co-doped TiO_2 coatings on the surfaces of Al_2O_3 balls from TiC_0_._7N_0_._3 powder. The as-prepared coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible spectrophotometer (UV–vis). The results show that continuous TiC_0_._7N_0_._3 coatings were formed after ball milling. C, N co-doped TiO_2/TiC_0_._7N_0_._3 composite coatings were prepared after the direct oxidization of TiC_0_._7N_0_._3 coatings in the atmosphere. However, TiO_2 was hardly formed in the surface layer of TiC_0_._7N_0_._3 coatings within a depth less than 10 nm during the heat oxidation of TiC_0_._7N_0_._3 coatings in carbon powder. Meanwhile, the photocatalytic activity evaluation of these coatings was conducted under the irradiation of UV and visible light. All the coatings showed photocatalytic activity in the degradation of MB no matter under the irradiation of UV or visible light. The C, N co-doped TiO_2/TiC_0_._7N_0_._3 composite coatings showed the most excellent performance. The enhancement under visible light irradiation should attribute to the co-doping of carbon and nitrogen, which enhances the absorption of visible light. The improvement of photocatalytic activity under UV irradiation should attribute to the synergistic effect of C, N co-doping, the formation of rutile-anatase mixed phases and the TiO_2/TiC_0_._7N_0_._3 composite microstructure.

  15. HIDROGENACIÓN DE CROTONALDEHÍDO SOBRE CATALIZADORES Ir/TiO2-SiO2

    Directory of Open Access Journals (Sweden)

    HUGO ROJAS

    2009-01-01

    Full Text Available Se estudió la hidrogenación de crotonaldehído en fase líquida, sobre catalizadores Ir/TiO2-SiO2; este aldehído es altamente contaminante y proviene de fuentes tan diversas como humo de tabaco, gases de escape de motores de gasolina o diesel y humo de combustión de madera [1]. El objetivo principal de esta investigación fue la obtención del alcohol insaturado (crotil alcohol. A partir de los estudios realizados logró demostrarse que un aumento en el contenido de TiO2, lo mismo que la reducción de los catalizadores a altas temperaturas favorece parámetros como selectividad hacia el producto de interés, actividad catalítica y en general se logró mejorar de manera notable los niveles de conversión. El comportamiento observado se atribuyó principalmente a la fuerte influencia del efecto SMSI (Strong Metal Support Interaction, presente a altas temperaturas en óxidos parcialmente reducibles.

  16. Highly stable colloidal TiO2 nanocrystals with strong violet-blue emission

    International Nuclear Information System (INIS)

    Ghamsari, Morteza Sasani; Gaeeni, Mohammad Reza; Han, Wooje; Park, Hyung-Ho

    2016-01-01

    Improved sol–gel method has been applied to prepare highly stable colloidal TiO 2 nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO 2 colloidal nanocrystals. HRTEM showed that the diameter of TiO 2 colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO 2 colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO 2 sample has enough potential for optoelectronics applications.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-03-02

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

  18. The Synthesis of Eu3+ Doped with TiO2 Nano-Powder and Application as a Pesticide Sensor

    International Nuclear Information System (INIS)

    Yao, Fei; Sun, Yang; Tan, Chunlei; Wei, Song; Zhang, Xiaojuan; Hu, Xiaoyun; Fan, Jun

    2011-01-01

    Using tetrabutyl titanate as precursor, Eu 3+ doped TiO 2 nano-powder was prepared by sol-gel method, the nature of luminescence of nano-powder was studied. The interaction of chlorpyrifos with Eu 3+ doped TiO 2 was studied by absorption and fluorescence spectroscopy. The results indicated the fluorescence intensity of Eu 3+ doped TiO 2 was quenched by chlorpyrifos and the quenching rate constant (kq) was 1.24Χ10 11 L/mol·s according to the Stern-Volmer equation. The dynamics of photoinduced electron transfer from chlorpyrifos to conduction band of TiO 2 nanoparticle was observed and the mechanism of electron transfer had been confirmed by the calculation of free energy change (ΔG et ) by applying Rehm-Weller equation as well as energy level diagram. A new rapid method for detection of chlorpyrifos was established according to the fluorescence intensity of Eu 3+ doped TiO 2 was proportional to chlorpyrifos concentration. The range of detection was 5.0Χ10 -10 -2.5Χ10 -7 mol/L and the detection limit (3σ) was 3.2Χ10 -11 mol/L

  19. High-pressure behavior of A 2 B 2 O 7 pyrochlore (A=Eu, Dy; B=Ti, Zr)

    Energy Technology Data Exchange (ETDEWEB)

    Rittman, Dylan R.; Turner, Katlyn M.; Park, Sulgiye; Fuentes, Antonio F.; Yan, Jinyuan; Ewing, Rodney C.; Mao, Wendy L.

    2017-01-28

    In situ high-pressure X-ray diffraction and Raman spectroscopy were used to determine the influence of composition on the high-pressure behavior of A2B2O7 pyrochlore (A=Eu, Dy; B=Ti, Zr) up to ~50GPa. Based on X-ray diffraction results, all compositions transformed to the high-pressure cotunnite structure. The B-site cation species had a larger effect on the transition pressure than the A-site cation species, with the onset of the phase transformation occurring at ~41 GPa for B=Ti and ~16 GPa B=Zr. However, the A-site cation affected the kinetics of the phase transformation, with the transformation for compositions with the smaller ionic radii, i.e., A=Dy, proceeding faster than those with a larger ionic radii, i.e., A=Eu. These results were consistent with previous work in which the radius-ratio of the A- and B-site cations determined the energetics of disordering, and compositions with more similarly sized A- and B-site cations had a lower defect formation energy. Raman spectra revealed differences in the degree of short-range order of the different compositions. Due to the large phase fraction of cotunnite at high pressure for B=Zr compositions, Raman modes for cotunnite could be observed, with more modes recorded for A=Eu than A=Dy. These additional modes are attributed to increased short-to-medium range ordering in the initially pyrochlore structured Eu2Zr2O7 as compared with the initially defect-fluorite structured Dy2Zr2O7.

  20. Sintering and Electrical Characterization of La and Nb Co‐doped SrTiO3 Electrode Materials for Solid Oxide Cell Applications

    DEFF Research Database (Denmark)

    Sudireddy, Bhaskar Reddy; Agersted, Karsten

    2014-01-01

    Single‐phase lanthanum and niobium co‐doped strontium titanate (Sr1–3x/2LaxTi0.9Nb0.1O3; x = 0–0.02) ceramics were prepared. Dilatometry in reducing atmosphere showed an increase in the sintering rate and sintered density with an increase in La amount. Microscopy of fractured surfaces of sintered...... samples showed that the average grain size increased drastically in reducing conditions with increasing La content (and associated A‐site vacancies). By incorporating 2 mol.% La, the electronic conductivity significantly improved from 80 to 135 S cm−1 at 1,000 °C, and even larger improvements were...... observed at lower temperatures. These observations demonstrate the flexibility in tailoring the microstructure and electronic transport properties by doping small amounts of La into the Nb‐doped SrTiO3 and show that Sr1–3x/2LaxTi0.9Nb0.1O3 is a potential electrode material for solid oxide cells....

  1. In-pile test of Li 2TiO 3 pebble bed with neutron pulse operation

    Science.gov (United States)

    Tsuchiya, K.; Nakamichi, M.; Kikukawa, A.; Nagao, Y.; Enoeda, M.; Osaki, T.; Ioki, K.; Kawamura, H.

    2002-12-01

    Lithium titanate (Li 2TiO 3) is one of the candidate materials as tritium breeder in the breeding blanket of fusion reactors, and it is necessary to show the tritium release behavior of Li 2TiO 3 pebble beds. Therefore, a blanket in-pile mockup was developed and in situ tritium release experiments with the Li 2TiO 3 pebble bed were carried out in the Japan Materials Testing Reactor. In this study, the relationship between tritium release behavior from Li 2TiO 3 pebble beds and effects of various parameters were evaluated. The ( R/ G) ratio of tritium release ( R) and tritium generation ( G) was saturated when the temperature at the outside edge of the Li 2TiO 3 pebble bed became 300 °C. The tritium release amount increased cycle by cycle and saturated after about 20 pulse operations.

  2. Supramolecular photocatalyst of RGO-cyclodextrin-TiO2

    International Nuclear Information System (INIS)

    Shen, Jianfeng; Li, Na; Ye, Mingxin

    2013-01-01

    Graphical abstract: Supramolecular photocatalyst of RGO-cyclodextrin-TiO 2 was achieved, which showed high photocatalytic activity and adsorption capacity. Highlights: •Supramolecular photocatalyst of RGO-cyclodextrin-TiO 2 was achieved. •β-CD molecules acted as linkers between RGO and monodisperse TiO 2 nanoparticles. •Reduction of GO and preparation of RGO-cyclodextrin-TiO 2 was simultaneous. •The prepared RGO-cyclodextrin-TiO 2 shows high photocatalytic activity and adsorption capacity. -- Abstract: Reduced graphene oxide (RGO)/β-cyclodextrin (β-CD)/titanium oxide (TiO 2 ) supramolecular photocatalyst was synthesized with a one-pot hydrothermal method. The reducing process was accomplished with the attaching of β-CD and generation of TiO 2 . β-CD acted as a linker between RGO and monodisperse TiO 2 nanoparticles. The structure and composition of the hybrid had been characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermal gravimetric analysis, X-ray diffraction and Transmission electron microscopy. The as-prepared RGO-CD-TiO 2 showed significant enhanced performance for phenol and Cr (VI) removal, due to the effective transfer of photo-generated electron from TiO2 to RGO and improved absorbance performance of the hybrid

  3. Eosin Y-sensitized nanostructured SnO{sup 2}/TiO{sup 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Tai, Weon-Pil [Institute of Advanced Materials, Inha University, Yonghyun-dong, Nam-ku, Inchon 402-751 (South Korea); Inoue, Kozo [National Institute of Advanced Industrial Science and Technology, Tosu, Saga 841-0052 (Japan)

    2003-02-01

    The photoelectrochemical behaviors of eosin Y (organic dye)-sensitized nanostructured SnO{sub 2}/TiO{sub 2} coupled and SnO{sub 2}+TiO{sub 2} composite solar cells were studied. The value of incident photon-to-current conversion efficiency (IPCE) in the coupled system was higher than the composite system. A maximum IPCE value, 63%, was reached at 525 nm wavelength in the coupled cell with 3.5-{mu}m-thick SnO{sub 2} and 7-{mu}m-thick TiO{sub 2}. The IPCE difference in the coupled and composite cells sensitized by eosin Y dye is discussed.

  4. Enhancement of the irreversibility field in bulk MgB2 by TiO2 nanoparticle addition

    DEFF Research Database (Denmark)

    Xu, G.J.; Grivel, Jean-Claude; Abrahamsen, A.B.

    2004-01-01

    MgB2 samples doped with TiO2 nanoparticles were prepared and the effect of TiO2 addition on the superconducting transition temperature (T-c), irreversibility field (H-irr) and critical current density (J(c)) were investigated. It is found that the hexagonal lattice parameters a and c decrease...... with TiO2 doping. Tc decreases gradually from 38.2 to 37.8 K as the TiO2 content increases from 0 to 15 wt%. The H-irr increases at 20 K from 4.3 to 4.9 T as the TiO2 content increases from 0 to 10 wt%, and at the same temperature J(c) increases from 450 to 4250 A/cm(2) at 4.2 T. (C) 2004 Published...

  5. TiO2/Cu2O composite based on TiO2 NTPC photoanode for photoelectrochemical (PEC) water splitting under visible light

    KAUST Repository

    Shi, Le

    2015-01-01

    in practice of water splitting with pure TiO2 material, one of the most popular semiconductor material used for photoelectrochemical water splitting, is still challenging. One dimensional TiO2 nanotubes is highly desired with its less recombination

  6. Highly Efficient Light-Driven TiO2-Au Janus Micromotors.

    Science.gov (United States)

    Dong, Renfeng; Zhang, Qilu; Gao, Wei; Pei, Allen; Ren, Biye

    2016-01-26

    A highly efficient light-driven photocatalytic TiO2-Au Janus micromotor with wireless steering and velocity control is described. Unlike chemically propelled micromotors which commonly require the addition of surfactants or toxic chemical fuels, the fuel-free Janus micromotor (diameter ∼1.0 μm) can be powered in pure water under an extremely low ultraviolet light intensity (2.5 × 10(-3) W/cm(2)), and with 40 × 10(-3) W/cm(2), they can reach a high speed of 25 body length/s, which is comparable to common Pt-based chemically induced self-electrophoretic Janus micromotors. The photocatalytic propulsion can be switched on and off by incident light modulation. In addition, the speed of the photocatalytic TiO2-Au Janus micromotor can be accelerated by increasing the light intensity or by adding low concentrations of chemical fuel H2O2 (i.e., 0.1%). The attractive fuel-free propulsion performance, fast movement triggering response, low light energy requirement, and precise motion control of the TiO2-Au Janus photocatalytic micromotor hold considerable promise for diverse practical applications.

  7. Investigations of structural, morphological and optical properties of Cu:ZnO/TiO2/ZnO and Cu:TiO2/ZnO/TiO2 thin films prepared by spray pyrolysis technique

    Directory of Open Access Journals (Sweden)

    M.I. Khan

    Full Text Available The aim of this research work is presented a comparison study of Cu:ZnO/TiO2/ZnO (Cu:ZTZ and Cu:TiO2/ZnO/TiO2 (Cu:TZT thin films deposited by spray pyrolysis technique on FTO substrates. After deposition, these films are annealed at 500 °C. XRD confirms the anatase phase of TiO2 and Hexagonal wurtzite phase of ZnO. SEM shows that Cu:TZT has more porous surface than Cu:ZTZ and also the root mean square (RMS roughness of Cu:TZT film is 48.96 and Cu:ZTZ film is 32.69. The calculated optical band gaps of Cu:TZT and Cu:ZTZ thin films are 2.65 eV and 2.6 eV respectively, measured by UV–Vis spectrophotometer. This work provides an environment friendly and low cost use of an abundant material for highly efficient dye sensitized solar cells (DSSCs. Keywords: Multilayer films, ZnO, TiO2, Cu

  8. Na2MoO2As2O7

    Directory of Open Access Journals (Sweden)

    Raja Jouini

    2012-12-01

    Full Text Available Disodium molybdenum dioxide diarsenate, Na2MoO2As2O7, has been synthesized by a solid-state reaction. The structure is built up from MoAs2O12 linear units sharing corners to form a three-dimensional framework containing tunnels running along the a-axis direction in which the Na+ cations are located. In this framework, the AsV atoms are tetrahedrally coordinated and form an As2O7 group. The MoVI atom is displaced from the center of an octahedron of O atoms. Two Na+ cations are disordered about inversion centres. Structural relationships between different compounds: A2MoO2As2O7 (A = K, Rb, AMOP2O7 (A = Na, K, Rb; M = Mo, Nb and MoP2O7 are discussed.

  9. μSR investigations of the high temperature superconductors La1.85Sr0.15CuO4 and YBa2Cu3O7

    International Nuclear Information System (INIS)

    Birrer, P.; Gygax, F.N.; Hitti, B.

    1987-01-01

    μSR studies of La 1.85 Sr 0.15 CuO 4 and YBa 2 Cu 3 O 7high temperature superconductors are carried out. The interval magnetic properties of these systems are studied on a microscopic level in the 4 kOe magnetic field and in the temperature range 10 K - 120 K. The magnetic penetration depth λ in this system did not show any significant differences from the two temperature scans (10 K and 120 K) and it destroys a field independence above 1 kOe. For T=OK the authers obtain λ(OK)≅2650 A

  10. TiO{sub 2}/SiO{sub 2} porous composite thin films: Role of TiO{sub 2} areal loading and modification with gold nanospheres on the photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Levchuk, Irina, E-mail: irina.r.levchuk@gmail.com [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Laboratoire de Chimie, ENS Lyon, CNRS, Universite Claude Bernard Lyon 1, Universite de Lyon, UMR 5182, 46 allee d’Italie, 69364 Lyon (France); Sillanpää, Mika [Laboratory of Green Chemistry, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland); Guillard, Chantal [Institut de Recherches sur la Catalyse et l’Environnement, IRCELYON, CNRS—University of Lyon, 69100 (France); Gregori, Damia; Chateau, Denis; Parola, Stephane [Laboratoire de Chimie, ENS Lyon, CNRS, Universite Claude Bernard Lyon 1, Universite de Lyon, UMR 5182, 46 allee d’Italie, 69364 Lyon (France)

    2016-10-15

    Highlights: • Composite TiO{sub 2}/Au/SiO{sub 2} films were prepared by sol-gel. • Size of Au NPs was in range 5–7 nm. • Physico-chemical and photocatalytic properties of TiO{sub 2}/Au/SiO{sub 2} were tested. • After UVC treatment all coatings exhibit super-hydrophilic character. • Photocatalytic activity of thin films was associated with areal loading of TiO{sub 2}. - Abstract: The aim of the work was to study photocatalytic activity of composite TiO{sub 2}/Au/SiO{sub 2} thin films. Coatings were prepared using sol-gel technique. Physicochemical parameters of coatings were characterized using UV–vis spectrometry, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectrometry (XPS), inductively coupled plasma optical emission spectroscopy (ICP-OES), ellipsometry, tactile measurements, goniometry and diffuse reflectance measurements. The photocatalytic activity of the films was tested in batch mode using aqueous solution of formic acid. Changes of formic acid concentration were determined by means of high pressure liquid chromatography (HPLC). Increase of initial degradation rate of formic acid was detected for TiO{sub 2}/Au/SiO{sub 2} films with gold nanoparticle’s load 0.5 wt.% and 1.25 wt.%. However, deeper insights using more detailed characterization of these coatings demonstrated that the improvement of the photocatalytic activity is more probably attributed to an increase in the areal loading of TiO{sub 2}.

  11. Application of UV/TiO2/H2O2 Advanced Oxidation to Remove Naphthalene from Water

    Directory of Open Access Journals (Sweden)

    Behroz Karimi

    2016-11-01

    Full Text Available Naphthalene is released into the environment by burning such organic materials as fossil fuels and wood and in industrial and vehicle exhaust emissions. Naphthalene is used in the manufacture of plastics, resins, fuels, and dyes. The aim of this study was to evaluate the performance of UV/TiO2/H2O2 process to decompose naphthalene in aqueous solutions. For this purpose, the photocatalytic degradation of naphthalene was investigated under UV light irradiation in the presence of TiO2 and H2O2 under a variety of conditions. Photodegradation efficiencies of H2O2/UV, TiO2/UV, and H2O2/TiO2/UV processes were compared in a batch reactor using the low pressure mercury lamp irradiation. The effects of operating parameters such as reaction time (min; solution pH; and initial naphthalene, TiO2, and H2O2 concentrations on photodegradation were examined. In the UV/TiO2/H2O2 system with a naphthalene concentration of 15 mg/L, naphthalene removal efficiencies of 63, 75, 80, 88, 92, 95, 96.5, and 98% were achieved, respectively, for reaction times of 5, 10, 20, 30, 40, 50, 60, 100 and 120 min. This is while removal efficienciesof 50, 59.5, 69, 80, 85, 88, 91, and 95% were obtained in the UV/TiO2 system under the same conditions. For initial pH values of 3, 4, 5, 6, 7,9, 10, and 12, naphthalene removal efficiencies of approximately 96.8, 85.5, 86, 75.5, 68.8, 57.8, and 52.5% were acheived, respectively, with the UV/TiO2/H2O2 system. Thus, it may be claiomed that, compared to either H2O2/UV or TiO2/UV process, the H2O2/TiO2/UV process yielded a far more efficient photodegradation.

  12. High-pressure polymorphs of anatase TiO2

    DEFF Research Database (Denmark)

    Arlt, T.; Bermejo, M.; Blanco, M. A.

    2000-01-01

    The equation of state of anatase TiO2 has been determined experimentally-using polycrystalline as well as single-crystal material-and compared with theoretical calculations using the ab initio perturbed ion model. The results are highly consistent, the zero-pressure bulk modulus being 179(2) GPa ...

  13. Emission analysis of Tb3+ -and Sm3+ -ion-doped (Li2 O/Na2 O/K2 O) and (Li2 O + Na2 O/Li2 O + K2 O/K2 O + Na2 O)-modified borosilicate glasses.

    Science.gov (United States)

    Naveen Kumar Reddy, B; Sailaja, S; Thyagarajan, K; Jho, Young Dahl; Sudhakar Reddy, B

    2018-05-01

    Four series of borosilicate glasses modified by alkali oxides and doped with Tb 3+ and Sm 3+ ions were prepared using the conventional melt quenching technique, with the chemical composition 74.5B 2 O 3 + 10SiO 2 + 5MgO + R + 0.5(Tb 2 O 3 /Sm 2 O 3 ) [where R = 10(Li 2 O /Na 2 O/K 2 O) for series A and C, and R = 5(Li 2 O + Na 2 O/Li 2 O + K 2 O/K 2 O + Na 2 O) for series B and D]. The X-ray diffraction (XRD) patterns of all the prepared glasses indicate their amorphous nature. The spectroscopic properties of the prepared glasses were studied by optical absorption analysis, photoluminescence excitation (PLE) and photoluminescence (PL) analysis. A green emission corresponding to the 5 D 4 → 7 F 5 (543 nm) transition of the Tb 3+ ions was registered under excitation at 379 nm for series A and B glasses. The emission spectra of the Sm 3+ ions with the series C and D glasses showed strong reddish-orange emission at 600 nm ( 4 G 5/2 → 6 H 7/2 ) with an excitation wavelength λ exci = 404 nm ( 6 H 5/2 → 4 F 7/2 ). Furthermore, the change in the luminescence intensity with the addition of an alkali oxide and combinations of these alkali oxides to borosilicate glasses doped with Tb 3+ and Sm 3+ ions was studied to optimize the potential alkali-oxide-modified borosilicate glass. Copyright © 2017 John Wiley & Sons, Ltd.

  14. Efficient H2 production over Au/graphene/TiO2 induced by surface plasmon resonance of Au and band-gap excitation of TiO2

    International Nuclear Information System (INIS)

    Liu, Yang; Yu, Hongtao; Wang, Hua; Chen, Shuo; Quan, Xie

    2014-01-01

    Highlights: • Both surface plasmon resonance and band-gap excitation were used for H 2 production. • Au/Gr/TiO 2 composite photocatalyst was synthesized. • Au/Gr/TiO 2 exhibited enhancement of light absorption and charge separation. • H 2 production rate of Au/Gr/TiO 2 was about 2 times as high as that of Au/TiO 2 . - Abstract: H 2 production over Au/Gr/TiO 2 composite photocatalyst induced by surface plasmon resonance of Au and band-gap excitation of TiO 2 using graphene (Gr) as an electron acceptor has been investigated. Electron paramagnetic resonance study indicated that, in this composite, Gr collected electrons not only from Au with surface plasmon resonance but also from TiO 2 with band-gap excitation. Surface photovoltage and UV–vis absorption measurements revealed that compared with Au/TiO 2 , Au/Gr/TiO 2 displayed more effective photogenerated charge separation and higher optical absorption. Benefiting from these advantages, the H 2 production rate of Au/Gr/TiO 2 composite with Gr content of 1.0 wt% and Au content of 2.0 wt% was about 2 times as high as that of Au/TiO 2 . This work represents an important step toward the efficient application of both surface plasmon resonance and band-gap excitation on the way to converting solar light into chemical energy

  15. Chromate enhanced visible light driven TiO2 photocatalytic mechanism on Acid Orange 7 photodegradation

    International Nuclear Information System (INIS)

    Wang, Yeoung-Sheng; Shen, Jyun-Hong; Horng, Jao-Jia

    2014-01-01

    Highlights: • Photocatalysis of Cr(VI) and TiO 2 were studied by ESR analysis on DMPO-OH signals. • Mechanism of Cr(VI)-enhanced by visible light was different from that by UV. • O 2 adsorbed on TiO 2 surfaces could react with Cr(VI) to lower photoenergy needed. • Even by UV, no TiO 2 photocatalysis was observed without O 2 solution. • Visible light and Cr(VI) redox reaction could activate TiO 2 and would yield ·OH. - Abstract: When hexavalent chromium (Cr(VI)) is added to a TiO 2 photocatalytic reaction, the decolorization and mineralization efficiencies of azo dyes Acid Orange 7 (AO7) are enhanced even though the mechanism is unclear. This study used 5,5-dimethyl-L-pyrroline-N-oxide (DMPO) as the scavenger and the analysis of Electron Spin Resonance (ESR) to investigate this enhancement effect by observing the hydroxyl radical (·OH) generation of the Cr(VI)/TiO 2 system under UV and visible light (Vis) irradiation. With Cr(VI), the decolorization efficiencies were approximately 95% and 62% under UV and Vis, and those efficiencies were 25% less in the absence of Cr(VI). The phenomena of the DMPO-OH signals during the ESR analysis under Vis 405 and 550 nm irradiation were obviously the enhancement effects of Cr(VI) in aerobic conditions. In anoxic conditions, the catalytic effects of Cr(VI) could not be achieved due to the lack of a redox reaction between Cr(VI) and the adsorbed oxygen at the oxygen vacancy sites on the TiO 2 surfaces . The results suggest that by introducing the agents of redox reactions such as chromate ions, we could lower the photoenergy of TiO 2 needed and allow Vis irradiation to activate photocatalysis

  16. Electrical and magnetic behavior of La0.7Ca0.3MnO3/La0.7Sr0.2Ca0.1MnO3 composites

    International Nuclear Information System (INIS)

    Phong, P.T.; Dai, N.V.; Manh, D.H.; Thanh, T.D.; Khiem, N.V.; Hong, L.V.; Phuc, N.X.

    2010-01-01

    The electrical transport properties and the magnetoresistance of La 0.7 Ca 0.3 MnO 3 /La 0.7 Sr 0.2 Ca 0.1 MnO 3 composites are investigated as a function of sintering temperature. On the basis of an analysis by X-ray powder diffraction and scanning electron microscopy we suggest that raising the sintering temperature enhanced the interfacial reaction and creates interfacial phases at the boundaries of the La 0.7 Ca 0.3 MnO 3 and La 0.7 Sr 0.2 Ca 0.1 MnO 3 . Results also show that in 3 kOe, and at the Curie temperature, the magnetoresistance value of 14% was observed for the composite sintered at 1300 o C. Based on the phenomenological equation for conductivity under a percolation approach, which depends on the phase segregation of ferromagnetic metallic clusters and paramagnetic insulating regions, we fitted the experimental resistivity-temperature data from 50-300 K and find that the activation barrier decreases as temperature is increased.

  17. TiO2/Pt/TiO2 Sandwich Nanostructures: Towards Alcohol Sensing and UV Irradiation-Assisted Recovery

    Directory of Open Access Journals (Sweden)

    Rungroj Maolanon

    2017-01-01

    Full Text Available The TiO2/Pt/TiO2 sandwich nanostructures were synthesized by RF magnetron sputtering and demonstrated as an alcohol sensor at room-temperature operation with a fast recovery by UV irradiation. The TiO2/Pt/TiO2 layers on SiO2/Si substrate were confirmed by Auger electron spectroscopy with the interdiffusion of each layer. The TiO2/Pt/TiO2 layers on printed circuit board show the superior sensor response to alcohol in terms of the sensitivity and stability compared to the nonsandwich structure, that is, the only Pt layer or the TiO2/Pt structures. Moreover, the recovery time of the TiO2/Pt/TiO2 was improved by UV irradiation-assisted recovery. The optimum TiO2/Pt/TiO2 with thicknesses of the undermost TiO2 layer, a Pt layer, and the topmost TiO2 layer being 50 nm, 6 nm, and 5 nm, respectively, showed the highest response to ethanol down to 10 ppm. Additionally, TiO2/Pt/TiO2 shows an excellent sensing stability and exhibits different sensing selectivity among ethanol, methanol, and 2-propanol. The sensing mechanism could be attributed to the change of Pt work function during vapor adsorption. The TiO2 layer plays an important role in UV-assisted recovery by photocatalytic activity and the topmost TiO2 acts as protective layer for Pt.

  18. TiO2-TiO2 composite resistive humidity sensor: ethanol crosssensitivity

    International Nuclear Information System (INIS)

    Ghalamboran, Milad; Saedi, Yasin

    2016-01-01

    The fabrication method and characterization results of a TiO 2 -TiO 2 composite bead used for humidity sensing along with its negative cross-sensitivity to ethanol vapor are reported. The bead shaped resistive sample sensors are fabricated by the drop-casting of a TiO 2 slurry on two Pt wire segments. The dried bead is pre-fired at 750°C and subsequently impregnated with a Ti-based sol. The sample is ready for characterization after a thermal annealing at 600°C in air. Structurally, the bead is a composite of the micron-sized TiO 2 crystallites embedded in a matrix of nanometric TiO 2 particle aggregates. The performance of the beads as resistive humidity sensors is recorded at room temperature in standard humidity level chambers. Results evince the wide dynamic range of the sensors fabricated in the low relative humidity range. While the sensor conductance is not sensitive to ethanol vapor in dry air, in humid air, sensor's responses are negatively affected by the contaminant. (paper)

  19. Synthesis and characterization of Ag-doped TiO2 nanotubes on Ti-6Al-4V and Ti-6Al-7Nb alloy

    Science.gov (United States)

    Ulfah, Ika Maria; Bachtiar, Boy M.; Murnandityas, Arnita Rut; Slamet

    2018-05-01

    The present paper is focused on comparative behavior of nanotubes growth on Ti-6Al-4V and Ti-6Al-7Nb alloy using electrochemical anodization method. These alloys were anodized in electrolytes solution containing glycerol, water and 0.5wt.% of NH4F. Silver-doped TiO2 nanotubes were synthesized using photo-assisted deposition (PAD) at various Ag loading concentration in 0.05 M, 0.10 M, and 0.15 M. The phase composition and morphological characteristics were investigated by XRD and FESEM/EDX, respectively. The surface wettability was measured by contact angle meter. The results showed that TiO2 nanotubes can be grown on these surface alloys. XRD profiles revealed crystal formation of anatase, rutile and Ag on these surface alloys. According to FESEM images, the average nanotube diameter of Ti-6Al-4V alloy and Ti-6Al-7Nb alloy are 134 nm and 120 nm, respectively. EDX-Mapping analysis showed that Ag desposited over surface of TiO2 nanotubes. The surface wettability indicated hydrophilicity properties on Ti-4Al-4V alloy and Ti-6Al-7Nb alloy surface. This study may contribute to the development of silver-doped TiO2 nanotubes on Ti-6Al-4V alloy and Ti-6Al-7Nb alloy can be considered in various photocatalytic applications such as biomedical devicesdue to photocatalytic mechanism and antibacterial ability.

  20. Cytocompatibility and early osseointegration of nanoTiO{sub 2}-modified Ti-24 Nb-4 Zr-7.9 Sn surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.H. [Department of Prosthodontics, China Medical University School of Stomatology, Shenyang (China); Wu, L., E-mail: wulin13@163.com [Department of Prosthodontics, China Medical University School of Stomatology, Shenyang (China); Ai, H.J. [Department of Prosthodontics, China Medical University School of Stomatology, Shenyang (China); Han, Y. [State Key laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an (China); Hu, Y. [Department of Prosthodontics, China Medical University School of Stomatology, Shenyang (China)

    2015-03-01

    This study aimed to evaluate the cytocompatibility and early osseointegration of Ti-24 Nb-4 Zr-7.9 Sn (Ti-2448) surfaces that were modified with a nanoscale TiO{sub 2} coating. The coating was fabricated using a hydrothermal synthesis method to generate nanoTiO{sub 2}/Ti-2448. The surface characteristics of the samples were evaluated using scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The cytotoxicity of the fabricated nanoTiO{sub 2}/Ti-2448 was determined using MTT assays. The proliferation and alkaline phosphatase (ALP) activity of MC3T3-E1 osteoblasts cultured on nanoTiO{sub 2}/Ti-2448 were compared with those cultured on Ti-2448. Disk-shaped implants were placed in Wistar rats. The histological sections were stained with haematoxylin and eosin (HE), and the histocompatibility was analysed at 4 and 12 weeks post-implantation. Cylindrical implants were embedded in Japanese white rabbits, and the histological sections were stained with HE and anti-TGF-β1 to evaluate the histocompatibility and early osseointegration at 4, 12 and 26 weeks post-implantation. NanoTiO{sub 2}/Ti-2448 exhibited a rougher surface than did Ti-2448. NanoTiO{sub 2}/Ti-2448 was determined to be non-cytotoxic. More osteoblasts and higher ALP activity were observed for nanoTiO{sub 2}/Ti-2448 than Ti-2448 (p < 0.05). Few inflammatory cells were detected around nanoTiO{sub 2}/Ti-2448, and the expression of TGF-β1 on nanoTiO{sub 2}/Ti-2448 peaked at earlier time than that on Ti-2448. The results indicate that the cytocompatibility and early osseointegration were enhanced by the nanoTiO{sub 2} coating. - Highlights: • The cytocompatibility of nanoTiO2/Ti-2448 is first reported in our work. • The early osseointegration of nanoTiO2/Ti-2448 is first reported in our work. • We evaluate the biocompatibility of nanoTiO2/Ti-2448 by in-vitro and in-vivo tests.