The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Tatsumi Ishihara - One of the best experts on this subject based on the ideXlab platform.
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low temperature operation of a solid oxide fe air rechargeable battery using a la0 9sr0 1ga0 8mg0 2o3 oxide ion Conductor
Journal of Materials Chemistry, 2015Co-Authors: Atsushi Inoishi, Tatsumi Ishihara, Junji Hyodo, Takaaki SakaiAbstract:We investigated a catalyst for oxidation of Fe powder using steam and it was applied to a Fe–air rechargeable battery based on the low temperature operating Solid Oxide Fuel Cells technology. Stable charge–discharge cycling over 20 cycles was achieved at 673 K.
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ni fe ce mn fe o2 cermet anode for rechargeable fe air battery using lagao3 oxide ion Conductor as electrolyte
RSC Advances, 2013Co-Authors: Atsushi Inoishi, Shintaro Ida, Shouichi Uratani, Takayuki Okano, Tatsumi IshiharaAbstract:There is a strong demand for the development of a large capacity rechargeable battery in various fields. Recently, we proposed the combination of solid oxide fuel cell technology with Fe–air battery concepts using H2/H2O as a redox mediator and a LaGaO3-based oxide as an electrolyte. Because large internal resistance and large degradation during charge and discharge cycles were observed on the anode, there is a strong demand for improvements in discharge potential and cycle stability. This study investigates the use of a cermet anode consisting of a Ni–Fe alloy combined with an oxide ion Conductor. It was observed that by using a cermet anode of Ni–Fe combined with Ce0.6Mn0.3Fe0.1O2 (CMF), the observed capacity of the cell was improved to 1163 mAh g−1 Fe−1 at 10 mA cm−2 and 873 K. This is about 97% of the theoretical capacity by assuming the formation of Fe3O4 (1200 mAh g−1 Fe−1). Cycle stability of the cell was also considerably improved with the use of a Ni–Fe–CMF anode compared to a Ni–Fe anode because of the suppressed aggregation provided by the mixing of Ni with CMF.
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intermediate temperature solid oxide fuel cells using a new lagao3 based oxide ion Conductor i doped as a new cathode material
Journal of The Electrochemical Society, 1998Co-Authors: Tatsumi Ishihara, Miho Honda, Takaaki Shibayama, Hiroaki Minami, Hiroyasu Nishiguchi, Yusaku TakitaAbstract:‐based perovskite oxides doped with Sr and Mg exhibit high ionic conductivity over a wide range of oxygen partial pressure. In this study, the stability of ‐based oxide was investigated. The ‐based oxide was found to be very stable in reducing, oxidizing, and atmospheres. Solid oxide fuel cells (SOFCs) using ‐based perovskite‐type oxide as the electrolyte were studied for use in intermediate‐temperature SOFCs. The power‐generation characteristics of cells were strongly affected by the electrodes. Both Ni and (Ln:rare earth) were suitable for use as anode and cathode, respectively. Rare‐earth cations in the Ln site of the Co‐based perovskite cathode also had a significant effect on the power‐generation characteristics. In particular, a high power density could be attained in the temperature range 973–1273 K by using a doped for the cathode. Among the examined alkaline earth cations, Sr‐doped exhibits the smallest cathodic overpotential resulting in the highest power density. The electrical conductivity of increased with increasing Sr doped into the Sm site and attained a maximum at . The cathodic overpotential and internal resistance of the cell exhibited almost the opposite dependence on the amount of doped Sr. Consequently, the power density of the cell was a maximum when was used as the cathode. For this cell, the maximum power density was as high as 0.58 W/cm2 at 1073 K, even though a 0.5 mm thick electrolyte was used. This study revealed that a ‐based oxide for electrolyte and a ‐based oxide for the cathode are promising components for SOFCs operating at intermediate temperature.
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oxygen surface exchange and diffusion in the new perovskite oxide ion Conductor lagao3
Journal of the American Chemical Society, 1997Co-Authors: Tatsumi Ishihara, J A Kilner, And Miho Honda, Yusaku TakitaAbstract:One of the aims of these experiments was to verify that the oxygen ion is the majority carrier in LaGaO{sub 3}-based materials, as they are thought to exhibit p-type conductivity in the high oxygen partial pressure range. Specifically, we have investigated oxygen surface exchange and diffusion in La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-x} by {sup 18}O isotopic exchange and SIMS at high partial pressures of oxygen (0.1 MPa). In conclusion, these results show that bulk oxygen diffusion in LSGM is very rapid. By a comparison of the oxygen self-diffusivity obtained from tracer and ionic conductivity, the electrical conductivity observed is ionic in the temperature range we have measured. The surface exchange coefficients are anomalous when compared to other perovskite oxides. The activation enthalpy for surface exchange is higher than that for self diffusion coefficient, a finding observed for two other solid oxide electrolytes with the fluorite structure. This behavior is thought to originate in the low electron concentrations found in these electrolyte materials, particularly at the lowest temperatures. 13 refs., 2 figs.
Yusaku Takita - One of the best experts on this subject based on the ideXlab platform.
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intermediate temperature solid oxide fuel cells using a new lagao3 based oxide ion Conductor i doped as a new cathode material
Journal of The Electrochemical Society, 1998Co-Authors: Tatsumi Ishihara, Miho Honda, Takaaki Shibayama, Hiroaki Minami, Hiroyasu Nishiguchi, Yusaku TakitaAbstract:‐based perovskite oxides doped with Sr and Mg exhibit high ionic conductivity over a wide range of oxygen partial pressure. In this study, the stability of ‐based oxide was investigated. The ‐based oxide was found to be very stable in reducing, oxidizing, and atmospheres. Solid oxide fuel cells (SOFCs) using ‐based perovskite‐type oxide as the electrolyte were studied for use in intermediate‐temperature SOFCs. The power‐generation characteristics of cells were strongly affected by the electrodes. Both Ni and (Ln:rare earth) were suitable for use as anode and cathode, respectively. Rare‐earth cations in the Ln site of the Co‐based perovskite cathode also had a significant effect on the power‐generation characteristics. In particular, a high power density could be attained in the temperature range 973–1273 K by using a doped for the cathode. Among the examined alkaline earth cations, Sr‐doped exhibits the smallest cathodic overpotential resulting in the highest power density. The electrical conductivity of increased with increasing Sr doped into the Sm site and attained a maximum at . The cathodic overpotential and internal resistance of the cell exhibited almost the opposite dependence on the amount of doped Sr. Consequently, the power density of the cell was a maximum when was used as the cathode. For this cell, the maximum power density was as high as 0.58 W/cm2 at 1073 K, even though a 0.5 mm thick electrolyte was used. This study revealed that a ‐based oxide for electrolyte and a ‐based oxide for the cathode are promising components for SOFCs operating at intermediate temperature.
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oxygen surface exchange and diffusion in the new perovskite oxide ion Conductor lagao3
Journal of the American Chemical Society, 1997Co-Authors: Tatsumi Ishihara, J A Kilner, And Miho Honda, Yusaku TakitaAbstract:One of the aims of these experiments was to verify that the oxygen ion is the majority carrier in LaGaO{sub 3}-based materials, as they are thought to exhibit p-type conductivity in the high oxygen partial pressure range. Specifically, we have investigated oxygen surface exchange and diffusion in La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-x} by {sup 18}O isotopic exchange and SIMS at high partial pressures of oxygen (0.1 MPa). In conclusion, these results show that bulk oxygen diffusion in LSGM is very rapid. By a comparison of the oxygen self-diffusivity obtained from tracer and ionic conductivity, the electrical conductivity observed is ionic in the temperature range we have measured. The surface exchange coefficients are anomalous when compared to other perovskite oxides. The activation enthalpy for surface exchange is higher than that for self diffusion coefficient, a finding observed for two other solid oxide electrolytes with the fluorite structure. This behavior is thought to originate in the low electron concentrations found in these electrolyte materials, particularly at the lowest temperatures. 13 refs., 2 figs.
Ivana Radosavljevic Evans - One of the best experts on this subject based on the ideXlab platform.
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hexagonal perovskite related oxide ion Conductor ba3nbmoo8 5 phase transition temperature evolution of the local structure and properties
Journal of Materials Chemistry, 2019Co-Authors: Matthew S Chambers, John S O Evans, Kirstie S Mccombie, Josie E Auckett, Abbie C Mclaughlin, John T S Irvine, Philip A Chater, Ivana Radosavljevic EvansAbstract:Ba3NbMoO8.5 has recently been demonstrated to exhibit competitive oxide ion conductivity and to be stable under reducing conditions, making it an excellent potential electrolyte for solid oxide fuel cells. We report here the first investigation of the local structure in Ba3NbMoO8.5, carried out using variable-temperature neutron total scattering and pair distribution function (PDF) analysis. This work reveals a significant degree of disorder in the material, even at ambient conditions, in both the cation and the anion arrangements and suggests the prevalence of the five-fold Nb/Mo coordination. In addition, high resolution powder X-ray diffraction data indicate that the temperature-dependent structural changes in Ba3NbMoO8.5 are due to a first order phase transition, and reveal a previously unreported effect of thermal history on the room-temperature form of the material. PDF modelling shows that Ba3NbMoO8.5 has an essentially continuous oxygen distribution in the ab plane at 600 °C which leads to its high Oxide-Ion conductivity.
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brownmillerite type sr2scgao5 oxide ion Conductor local structure phase transition and dynamics
Chemistry of Materials, 2019Co-Authors: Chloe A Fuller, Quentin Berrod, B Frick, Mark R Johnson, S J Clark, John S O Evans, Ivana Radosavljevic EvansAbstract:Brownmillerite-type Sr2ScGaO5 has been investigated by a range of experimental X-ray and neutron scattering techniques (diffraction, total scattering, and spectroscopy) and density functional theory calculations in order to characterize its structure and dynamics. The material undergoes a second-order phase transition on heating during which a rearrangement of the (GaO4/2)∞ tetrahedral chains occurs, such that they change from being essentially fully ordered in a polar structure at room temperature to being orientationally disordered above 400 °C. Pair distribution function analysis carried out using neutron total scattering data suggests that GaO4 tetrahedra remain as fairly rigid units above and below this transition, whereas coordination polyhedra in the (ScO6/2)∞ layers distort more. Inelastic neutron scattering and phonon calculations reveal the particular modes that are associated with this structural change, which may assist ionic conductivity in the material at higher temperatures. On the basis of...
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polymorphism and oxide ion migration pathways in fluorite type bismuth vanadate bi46v8o89
Chemistry of Materials, 2012Co-Authors: Xiaojun Kuang, Mark R Johnson, Julia L Payne, James D Farrell, Ivana Radosavljevic EvansAbstract:We report the synthesis, structural characterization, and ionic conductivity measurements for a new polymorph of bismuth vanadate Bi46V8O89, and an ab initio molecular dynamics study of this oxide ion Conductor. Structure determination was carried out using synchrotron powder X-ray and neutron diffraction data; it was found that β-Bi46V8O89 crystallizes in space group C2/m and that the key differences between this and the previously reported α-form are the distribution of Bi and V cations and the arrangement of the VO4 coordination polyhedra in structure. β-Bi46V8O89 exhibits good oxide ion conductivity, with σ = 0.01–0.1 S/cm between 600 and 850 °C, which is about an order of magnitude higher than yttria stabilized zirconia. The ab initio molecular dynamics simulations suggest that the ion migration pathways include vacancy diffusion through the Bi–O sublattice, as well as the O2– exchanges between the Bi–O and the V–O sublattices, facilitated by the variability of the vanadium coordination environment a...
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oxide ion conductivity phase transitions and phase separation in fluorite based bi38 xmo7 xo78 1 5x
Chemistry of Materials, 2010Co-Authors: Xiaojun Kuang, Chris D Ling, Raymond Withers, Ivana Radosavljevic EvansAbstract:We present, for the first time, the ionic conductivity properties of two different, but closely related, bismuth molybdates: Bi38Mo7O78 and Bi37.5Mo7.5O78.75. Both are good oxide ion Conductors, with the latter being comparable to yttria-stabilized zirconia. We show that the structure of Bi38Mo7O78 is more complex than previously reported, and that this compound is a 5 × 3 × 6 fluorite superstructure with slight monoclinic distortion. In addition to being a good oxide ion Conductor, the material is noncentrosymmetric-polar and second harmonic generation (SHG) active. The second phase, orthorhombic Bi37.5Mo7.5O78.75, reported for the first time, is an excellent oxide ion Conductor. The materials have been characterized by impedance spectroscopy, variable-temperature synchrotron, neutron and laboratory powder X-ray diffraction, electron diffraction, and SHG measurements.
J A Kilner - One of the best experts on this subject based on the ideXlab platform.
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oxygen diffusion and surface exchange in la2 xsrxnio4 δ
Solid State Ionics, 2000Co-Authors: Stephen J Skinner, J A KilnerAbstract:Abstract The compounds La 2− x Sr x NiO 4+ δ , x =0, 0.1, have been prepared with an oxygen excess of up to δ =0.24. The oxygen tracer diffusion coefficient and surface exchange coefficient of the materials have been determined by the isotope exchange depth profile method (IEDP). La 2 NiO 4+ δ was found to have an oxygen diffusivity higher than that of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) and one order of magnitude lower than the best perovskite oxide ion Conductor La 0.3 Sr 0.7 CoO 3 (LSC). The fast oxide ion diffusion of La 2 NiO 4+ δ combined with its thermal stability indicate that this material would be a good candidate for use in ceramic oxygen generators (COGs) and solid oxide fuel cells (SOFCs). Furthermore, optimisation by a combination of donor and/or acceptor doping should improve the properties reported here.
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oxygen surface exchange and diffusion in the new perovskite oxide ion Conductor lagao3
Journal of the American Chemical Society, 1997Co-Authors: Tatsumi Ishihara, J A Kilner, And Miho Honda, Yusaku TakitaAbstract:One of the aims of these experiments was to verify that the oxygen ion is the majority carrier in LaGaO{sub 3}-based materials, as they are thought to exhibit p-type conductivity in the high oxygen partial pressure range. Specifically, we have investigated oxygen surface exchange and diffusion in La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-x} by {sup 18}O isotopic exchange and SIMS at high partial pressures of oxygen (0.1 MPa). In conclusion, these results show that bulk oxygen diffusion in LSGM is very rapid. By a comparison of the oxygen self-diffusivity obtained from tracer and ionic conductivity, the electrical conductivity observed is ionic in the temperature range we have measured. The surface exchange coefficients are anomalous when compared to other perovskite oxides. The activation enthalpy for surface exchange is higher than that for self diffusion coefficient, a finding observed for two other solid oxide electrolytes with the fluorite structure. This behavior is thought to originate in the low electron concentrations found in these electrolyte materials, particularly at the lowest temperatures. 13 refs., 2 figs.
Philippe Lacorre - One of the best experts on this subject based on the ideXlab platform.
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free volume expansion and formation enthalpy of defects as key parameters tuning the oxide ionic conductivity in derivatives of β la2mo2o9
Chemistry of Materials, 2014Co-Authors: Gwenael Corbel, Ania Selmi, E Suard, Philippe LacorreAbstract:The crystal structure of fast Oxide-Ion Conductor β-La1.85Ba0.15Mo2O8.925 and its thermal evolution have been studied using neutron powder diffraction, and compared to those already published [G. Corbel et al., Chem. Mater. 2011, 23, 1288] of a bismuth counterpart in the LAMOX family, β-La1.7Bi0.3Mo2O9. Comparable evolutions have a tendency to suggest that the observed behavior, a specific combination of rotation and distortion of cationic building units, is a common feature of La-substituted β-LAMOX compounds. For the first time in crystallized solids, a quantitative link is made for both compounds between the high-temperature (high-T) conductivity increase relative to Arrhenius behavior and the volume expansion of the voids, through consecutive fits to crystallographic and conductivity data of the Dienes–Macedo–Litovitz (DML) equation. Both the expansion of the “free” volume (VF) and the formation enthalpy of the Frenkel defects (ΔHf) are the key parameters tuning the conductivity of LAMOX compounds abo...
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thermodynamic stability structural and electrical characterization of mixed ionic and electronic Conductor la2mo2o8 96
Dalton Transactions, 2012Co-Authors: Jesus Vegacastillo, Uday K Ravella, Gwenael Corbel, Philippe Lacorre, A CaneiroAbstract:Thermogravimetric analysis (TGA) technique in controlled oxygen partial pressure (pO2) atmospheres has been used to obtain equilibrium oxygen content data as a function of pO2 on the La2Mo2O9−δ system resulting from the partial reduction of fast Oxide-Ion Conductor La2Mo2O9 (LM). Thermodynamic conditions for stabilization of crystalline La7Mo7O30 and amorphous La2Mo2O7−y at 718 °C have been determined and discussed. At 608 °C, the compound reported for the first time La2Mo2O8.96 (LM896) has been found. The crystalline form and transition temperature in LM896 have been identified by X-ray diffraction at room temperature (XRD) and at controlled temperature. Conductivity curves obtained by electrochemical impedance spectroscopy (EIS) as a function of temperature for both LM and LM896 have been compared. The results indicate that LM896 is a mixed ionic and electronic Conductor (MIEC).
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thermal structural and transport properties of the fast oxide ion Conductors la2 xrxmo2o9 r nd gd y
Solid State Ionics, 2003Co-Authors: Samuel Georges, E Suard, Francois Goutenoire, F Altorfer, Denis Sheptyakov, F Fauth, Philippe LacorreAbstract:Abstract The thermal evolution of the crystal structure of the new fast Oxide-Ion Conductor La 2 Mo 2 O 9 across its structural α to β first order transition at 580 °C has been followed using synchrotron X-ray diffraction (XRD). The influence on the transition, structure and Oxide-Ion conductivity of partial substitution by other rare earths (Nd, Gd, Y) is studied. For Nd substitution the monoclinic α form is retained at room temperature in the whole compositional range. For Gd and Y substitutions, above a certain doping level, the suppression of the phase transition and stabilization at room temperature of the cubic β form are achieved. The cubic structures of La 1.9 Y 0.1 Mo 2 O 9 at room temperature and of β-La 2 Mo 2 O 9 at 670 °C (revisited), both refined from neutron powder diffraction patterns, are very similar. Despite the cell volume reduction, lanthanide substitution results above 500 °C in an increase of the anion conductivity compared to that of β-La 2 Mo 2 O 9 , which might result from differences in samples' relative density.
