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Masatomo Yashima - One of the best experts on this subject based on the ideXlab platform.
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high oxide ion conductivity through the Interstitial Oxygen site in ba7nb4moo20 based hexagonal perovskite related oxides
Nature Communications, 2021Co-Authors: Masatomo Yashima, Takafumi Tsujiguchi, Yuichi Sakuda, Yuta Yasui, Yu Zhou, Kotaro Fujii, Shuki Torii, Takashi Kamiyama, Stephen J SkinnerAbstract:Oxide-ion conductors are important in various applications such as solid-oxide fuel cells. Although zirconia-based materials are widely utilized, there remains a strong motivation to discover electrolyte materials with higher conductivity that lowers the working temperature of fuel cells, reducing cost. Oxide-ion conductors with hexagonal perovskite related structures are rare. Herein, we report oxide-ion conductors based on a hexagonal perovskite-related oxide Ba7Nb4MoO20. Ba7Nb3.9Mo1.1O20.05 shows a wide stability range and predominantly oxide-ion conduction in an Oxygen partial pressure range from 2 × 10−26 to 1 atm at 600 °C. Surprisingly, bulk conductivity of Ba7Nb3.9Mo1.1O20.05, 5.8 × 10−4 S cm−1, is remarkably high at 310 °C, and higher than Bi2O3- and zirconia-based materials. The high conductivity of Ba7Nb3.9Mo1.1O20.05 is attributable to the Interstitial-O5 Oxygen site, providing two-dimensional oxide-ion O1−O5 Interstitialcy diffusion through lattice-O1 and Interstitial-O5 sites in the Oxygen-deficient layer, and low activation energy for oxide-ion conductivity. Present findings demonstrate the ability of hexagonal perovskite related oxides as superior oxide-ion conductors. Oxide-ion conductors are important in various applications for clean energy. Here, authors report high oxide-ion conductivity of hexagonal perovskite-related oxide Ba7Nb3.9Mo1.1O20.05, which is ascribed to the Interstitialcy diffusion and low activation energy for oxide-ion conductivity.
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role of ga3 and cu2 in the high Interstitial oxide ion diffusivity of pr2nio4 based oxides design concept of Interstitial ion conductors through the higher valence d10 dopant and jahn teller effect
Chemistry of Materials, 2012Co-Authors: Masatomo Yashima, Hiroki Yamada, Sirikanda Nuansaeng, Tatsumi IshiharaAbstract:We have investigated the crystal structure, nuclear- and electron-density distributions, electronic structure, and Oxygen permeation rate of three K2NiF4-type oxides of Pr2(Ni0.75Cu0.25)0.95Ga0.05O4+δ, Pr2Ni0.75Cu0.25O4+δ, and Sr2Ti0.9Co0.1O4–e, in order to study the role of d10 Ga3+, Jahn–Teller Cu2+, and Interstitial Oxygen O3 in the high Oxygen diffusivity of Pr2(Ni0.75Cu0.25)0.95Ga0.05O4+δ. The composition Pr2(Ni0.75Cu0.25)0.95Ga0.05O4+δ has a larger amount of Interstitial Oxygen O3 atoms (δ = 0.31 at room temperature (RT)) compared with Pr2Ni0.75Cu0.25O4+δ (δ = 0.19 at RT) and the Oxygen deficient Sr2Ti0.9Co0.1O4–e (e = 0.02 at RT). The Interstitial O3 atom is stabilized by (1) the substitution of (Ni,Cu)2+ by higher valence Ga3+, (2) static atomic displacements of the apical O2 Oxygen, and (3) local relaxation near d10 Ga3+. Nuclear-density distributions of Pr2(Ni0.75Cu0.25)0.95Ga0.05O4+δ and Pr2Ni0.75Cu0.25O4+δ at high temperatures have visualized the −O2–O3–O2– diffusional pathway of oxide ions, w...
Stephen J Skinner - One of the best experts on this subject based on the ideXlab platform.
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high oxide ion conductivity through the Interstitial Oxygen site in ba7nb4moo20 based hexagonal perovskite related oxides
Nature Communications, 2021Co-Authors: Masatomo Yashima, Takafumi Tsujiguchi, Yuichi Sakuda, Yuta Yasui, Yu Zhou, Kotaro Fujii, Shuki Torii, Takashi Kamiyama, Stephen J SkinnerAbstract:Oxide-ion conductors are important in various applications such as solid-oxide fuel cells. Although zirconia-based materials are widely utilized, there remains a strong motivation to discover electrolyte materials with higher conductivity that lowers the working temperature of fuel cells, reducing cost. Oxide-ion conductors with hexagonal perovskite related structures are rare. Herein, we report oxide-ion conductors based on a hexagonal perovskite-related oxide Ba7Nb4MoO20. Ba7Nb3.9Mo1.1O20.05 shows a wide stability range and predominantly oxide-ion conduction in an Oxygen partial pressure range from 2 × 10−26 to 1 atm at 600 °C. Surprisingly, bulk conductivity of Ba7Nb3.9Mo1.1O20.05, 5.8 × 10−4 S cm−1, is remarkably high at 310 °C, and higher than Bi2O3- and zirconia-based materials. The high conductivity of Ba7Nb3.9Mo1.1O20.05 is attributable to the Interstitial-O5 Oxygen site, providing two-dimensional oxide-ion O1−O5 Interstitialcy diffusion through lattice-O1 and Interstitial-O5 sites in the Oxygen-deficient layer, and low activation energy for oxide-ion conductivity. Present findings demonstrate the ability of hexagonal perovskite related oxides as superior oxide-ion conductors. Oxide-ion conductors are important in various applications for clean energy. Here, authors report high oxide-ion conductivity of hexagonal perovskite-related oxide Ba7Nb3.9Mo1.1O20.05, which is ascribed to the Interstitialcy diffusion and low activation energy for oxide-ion conductivity.
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characterisation of la2nio4 δ using in situ high temperature neutron powder diffraction
Solid State Sciences, 2003Co-Authors: Stephen J SkinnerAbstract:Abstract La2NiO4+δ, has been studied using in-situ high temperature neutron diffraction over a temperature range of 25–800 °C in vacuum. The behaviour of this material, and in particular the Oxygen Interstitial content, is discussed and quite remarkable bond length changes observed. It is observed that at temperatures above 150 °C La2NiO4+δ transforms to the tetragonal I4/mmm structure and maintains this over the entire temperature range on both heating and cooling. The loss of the Interstitial Oxygen was observed over the low temperature region of the study and significant changes in both lattice constant and bond lengths found to mirror these changes, indicating the structural importance of the Interstitial Oxygen.
Linards Skuja - One of the best experts on this subject based on the ideXlab platform.
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diffusion and reactions of photoinduced Interstitial Oxygen atoms in amorphous sio2 impregnated with 18o labeled Interstitial Oxygen molecules
Journal of Physical Chemistry C, 2014Co-Authors: Koichi Kajihara, Linards Skuja, Hideo HosonoAbstract:Both diffusion and reactions of Interstitial Oxygen atoms (O0) in amorphous SiO2 (a-SiO2) were examined using Oxygen-excess a-SiO2 containing 18O-labeled Interstitial Oxygen molecules (O2) and exposed to F2 laser light (hν = 7.9 eV). Both the F2 laser photolysis of Interstitial O2 at 77 K and subsequent heat treatment at ≳200 °C give rise to Oxygen exchange between residual Interstitial O2 and Oxygen atoms in the a-SiO2 network, and these temperatures are far lower than the temperature at which conventional thermal network-Interstitial Oxygen exchange in unirradiated a-SiO2 occurs (≳700 °C). However, at the initial stage of the low-temperature F2 laser photolysis, an efficient formation of Interstitial ozone molecules (quantum yield ≳0.06) via nearly exchange-free diffusion of photogenerated Interstitial O0 is observed, and this reaction predominates over the network-Interstitial Oxygen exchange.
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diffusion and reactions of Interstitial Oxygen species in amorphous sio2 a review
Journal of Non-crystalline Solids, 2008Co-Authors: Koichi Kajihara, Hayato Kamioka, Masahiro Hirano, Taisuke Miura, Linards Skuja, Akira Aiba, Motoko Uramoto, Yukihiro MorimotoAbstract:This article briefly summarizes the diffusion and reactions of Interstitial Oxygen species in amorphous SiO 2 (a-SiO 2 ). The most common form of Interstitial Oxygen species is Oxygen molecule (O 2 ), which is sensitively detectable via its characteristic infrared photoluminescence (PL) at 1272 nm. The PL observation of Interstitial 0 2 provides key data to verify various processes related to Interstitial Oxygen species: the dominant role of Interstitial O 2 in long-range Oxygen transport in a-SiO 2 ; formation of the Frenkel defect pair (Si-Si bond and Interstitial Oxygen atom, 0°) by dense electronic excitation; efficient photolysis of Interstitial O 2 into O° with F 2 laser light (λ= 157 nm, hv = 7.9 eV); and creation of Interstitial ozone molecule via reaction of Interstitial O 2 with photogenerated O°. The efficient formation of Interstitial 0° by F 2 laser photolysis makes it possible to investigate the mobility, optical absorption, and chemical reactions of Interstitial O°. The observed properties of O° are consistent with the model that O° takes the configuration of Si-O-O-Si bond. Interstitial O 2 and O° react with dangling bonds, Oxygen vacancies, and chloride groups in a-SiO 2 . Reactions of Interstitial Ο 2 and O° with mobile Interstitial hydrogen species produce Interstitial water molecules and hydroperoxy radicals. Interstitial hydroxyl radicals are formed by F 2 laser photolysis of Interstitial water molecules.
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Interstitial Oxygen molecules in amorphous sio2 iii measurements of dissolution kinetics diffusion coefficient and solubility by infrared photoluminescence
Journal of Applied Physics, 2005Co-Authors: Koichi Kajihara, Hayato Kamioka, Masahiro Hirano, Taisuke Miura, Linards Skuja, Hideo HosonoAbstract:Concentration changes of Interstitial Oxygen molecules (O2) in amorphous SiO2(a-SiO2) thermally annealed in Oxygen atmosphere were examined by the O2 photoluminescence at 1272 nm excited with 765-nm light of titanium sapphire laser. This highly sensitive technique allows the time- and temperature-dependent concentration changes of Interstitial O2 due to their incorporation from an Oxygen atmosphere to be directly measured. The data provide the dissolution rate, the diffusion coefficient, and the solubility of Interstitial O2 in a-SiO2 and are able to exclude interferences from other forms of mobile Oxygen species in a-SiO2. These observations confirm that O2 molecules are incorporated into a-SiO2 without separating into monoatomic species, diffuse in a-SiO2 without extensive interaction with the a-SiO2 network, and play a primary role in the thermal oxidation of silicon.
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role of mobile Interstitial Oxygen atoms in defect processes in oxides interconversion between Oxygen associated defects in sio 2 glass
Physical Review Letters, 2004Co-Authors: Koichi Kajihara, Masahiro Hirano, Linards Skuja, Hideo HosonoAbstract:The role of mobile Interstitial Oxygen atoms (O(0)) in defect processes in oxides is demonstrated by interconversion between the Oxygen dangling bond and the peroxy radical (POR) in SiO2 glass. Superstoichiometric O(0) was created by F2 laser photolysis of the Interstitial O2. On annealing above 300 degrees C, O(0) migrated and converted the Oxygen dangling bond to POR. Exposure to 5.0 eV light converted POR back to a pair of the Oxygen dangling bond and O(0) (quantum yield: approximately 0.1). These findings suggest that various defect processes typically occurring in SiO2 glass at approximately 300-500 degrees C are related to migration of O(0), which exists in the glass network in the peroxy linkage form.
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infrared photoluminescence of preexisting or irradiation induced Interstitial Oxygen molecules in glassy sio 2 and α quartz
Physical Review B, 1998Co-Authors: Linards Skuja, B Guttler, D Schiel, A R SilinAbstract:A sensitive technique for detecting Interstitial ${\mathrm{O}}_{2}$ molecules in ${\mathrm{SiO}}_{2}$ is demonstrated by measuring their infrared $\stackrel{\ensuremath{\rightarrow}}{a}X$ luminescence at 1272.2 nm under a Ti-sapphire laser excitation into the ${\mathrm{O}}_{2}\stackrel{\ensuremath{\rightarrow}}{X}b$ absorption band at 765 nm. Contrary to the case of ${\mathrm{O}}_{2}$ trapped in inert gas matrices, the visible emission of ${\mathrm{O}}_{2}$ corresponding to the direct $\stackrel{\ensuremath{\rightarrow}}{b}X$ transition is not found. Examination of different neutron- and gamma-irradiated glassy ${\mathrm{SiO}}_{2}$ and \ensuremath{\alpha}-quartz samples reveals radiation-induced Interstitial Oxygen molecules in concentrations between ${10}^{14}$ and ${10}^{16}{\mathrm{m}\mathrm{o}\mathrm{l}\mathrm{e}\mathrm{c}\mathrm{u}\mathrm{l}\mathrm{e}\mathrm{s}/\mathrm{c}\mathrm{m}}^{3}.$ The radiolytic ${\mathrm{O}}_{2}$ molecules in \ensuremath{\alpha}-quartz and glassy ${\mathrm{SiO}}_{2}$ experience different structural environments.
Hideo Hosono - One of the best experts on this subject based on the ideXlab platform.
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diffusion and reactions of photoinduced Interstitial Oxygen atoms in amorphous sio2 impregnated with 18o labeled Interstitial Oxygen molecules
Journal of Physical Chemistry C, 2014Co-Authors: Koichi Kajihara, Linards Skuja, Hideo HosonoAbstract:Both diffusion and reactions of Interstitial Oxygen atoms (O0) in amorphous SiO2 (a-SiO2) were examined using Oxygen-excess a-SiO2 containing 18O-labeled Interstitial Oxygen molecules (O2) and exposed to F2 laser light (hν = 7.9 eV). Both the F2 laser photolysis of Interstitial O2 at 77 K and subsequent heat treatment at ≳200 °C give rise to Oxygen exchange between residual Interstitial O2 and Oxygen atoms in the a-SiO2 network, and these temperatures are far lower than the temperature at which conventional thermal network-Interstitial Oxygen exchange in unirradiated a-SiO2 occurs (≳700 °C). However, at the initial stage of the low-temperature F2 laser photolysis, an efficient formation of Interstitial ozone molecules (quantum yield ≳0.06) via nearly exchange-free diffusion of photogenerated Interstitial O0 is observed, and this reaction predominates over the network-Interstitial Oxygen exchange.
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Interstitial Oxygen molecules in amorphous sio2 iii measurements of dissolution kinetics diffusion coefficient and solubility by infrared photoluminescence
Journal of Applied Physics, 2005Co-Authors: Koichi Kajihara, Hayato Kamioka, Masahiro Hirano, Taisuke Miura, Linards Skuja, Hideo HosonoAbstract:Concentration changes of Interstitial Oxygen molecules (O2) in amorphous SiO2(a-SiO2) thermally annealed in Oxygen atmosphere were examined by the O2 photoluminescence at 1272 nm excited with 765-nm light of titanium sapphire laser. This highly sensitive technique allows the time- and temperature-dependent concentration changes of Interstitial O2 due to their incorporation from an Oxygen atmosphere to be directly measured. The data provide the dissolution rate, the diffusion coefficient, and the solubility of Interstitial O2 in a-SiO2 and are able to exclude interferences from other forms of mobile Oxygen species in a-SiO2. These observations confirm that O2 molecules are incorporated into a-SiO2 without separating into monoatomic species, diffuse in a-SiO2 without extensive interaction with the a-SiO2 network, and play a primary role in the thermal oxidation of silicon.
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role of mobile Interstitial Oxygen atoms in defect processes in oxides interconversion between Oxygen associated defects in sio 2 glass
Physical Review Letters, 2004Co-Authors: Koichi Kajihara, Masahiro Hirano, Linards Skuja, Hideo HosonoAbstract:The role of mobile Interstitial Oxygen atoms (O(0)) in defect processes in oxides is demonstrated by interconversion between the Oxygen dangling bond and the peroxy radical (POR) in SiO2 glass. Superstoichiometric O(0) was created by F2 laser photolysis of the Interstitial O2. On annealing above 300 degrees C, O(0) migrated and converted the Oxygen dangling bond to POR. Exposure to 5.0 eV light converted POR back to a pair of the Oxygen dangling bond and O(0) (quantum yield: approximately 0.1). These findings suggest that various defect processes typically occurring in SiO2 glass at approximately 300-500 degrees C are related to migration of O(0), which exists in the glass network in the peroxy linkage form.
Seonggi Kim - One of the best experts on this subject based on the ideXlab platform.
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Effect of hyperoxia, hypercapnia and hypoxia on cerebral Interstitial Oxygen tension and cerebral blood flow in the rat brain: an 19F/1H study. Magn Reson Med 2001;45:61–70
2015Co-Authors: Timothy Q Duong, Costantino Iadecola, Seonggi KimAbstract:The assessment of cerebral Interstitial Oxygen tension (piO2) can provide valuable information regarding cerebrovascular physiology and brain function. Compartment-specific cerebral piO2 was measured by 19F NMR following the infusion of an Oxygen-sensitive perfluorocarbon directly into the Interstitial and ventricular space of the in vivo rat brain. 19F T1 measure-ments were made and cerebral piO2 were obtained through in vitro calibrations. The effects of graded hyperoxia, hypercapnia, and hypoxia on piO2 and cerebral blood flow (CBF) were inves-tigated. Under normoxia (arterial pO2; 120 mm Hg), piO2 was;30 mm Hg and jugular venous pO2 was;50 mm Hg. During hyperoxia (arterial pO2 5 90–300 mm Hg), piO2 increased lin-early with the arterial pO2. Following hypercapnia (arterial pCO2 5 20–60 mm Hg), the piO2 increased sigmoidally with increasing CBF. With hypoxia (arterial pO2 5 30–40 mm Hg), CBF increased;56 % and piO2 decreased to;15 mm Hg. The hypoxia-induced CBF increase was effective to some extent in compensating for the reduced piO2. This methodology may prove useful for investigating cerebral piO2 under pathologically or functionally altered conditions. Magn Reson Med 45:61–70
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effect of hyperoxia hypercapnia and hypoxia on cerebral Interstitial Oxygen tension and cerebral blood flow
Magnetic Resonance in Medicine, 2001Co-Authors: Timothy Q Duong, Costantino Iadecola, Seonggi KimAbstract:The assessment of cerebral Interstitial Oxygen tension (piO(2)) can provide valuable information regarding cerebrovascular physiology and brain function. Compartment-specific cerebral piO(2) was measured by (19)F NMR following the infusion of an Oxygen-sensitive perfluorocarbon directly into the Interstitial and ventricular space of the in vivo rat brain. (19)F T(1) measurements were made and cerebral piO(2) were obtained through in vitro calibrations. The effects of graded hyperoxia, hypercapnia, and hypoxia on piO(2) and cerebral blood flow (CBF) were investigated. Under normoxia (arterial pO(2) approximately 120 mm Hg), piO(2) was approximately 30 mm Hg and jugular venous pO(2) was approximately 50 mm Hg. During hyperoxia (arterial pO(2) = 90-300 mm Hg), piO(2) increased linearly with the arterial pO(2). Following hypercapnia (arterial pCO(2) = 20-60 mm Hg), the piO(2) increased sigmoidally with increasing CBF. With hypoxia (arterial pO(2) = 30-40 mm Hg), CBF increased approximately 56% and piO(2) decreased to approximately 15 mm Hg. The hypoxia-induced CBF increase was effective to some extent in compensating for the reduced piO(2). This methodology may prove useful for investigating cerebral piO(2) under pathologically or functionally altered conditions. Magn Reson Med 45:61-70, 2001.
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effect of hyperoxia hypercapnia and hypoxia on cerebral Interstitial Oxygen tension and cerebral blood flow
Magnetic Resonance in Medicine, 2001Co-Authors: Timothy Q Duong, Costantino Iadecola, Seonggi KimAbstract:ments were made and cerebral piO2 were obtained through in vitro calibrations. The effects of graded hyperoxia, hypercapnia, and hypoxia on piO2 and cerebral blood flow (CBF) were investigated. Under normoxia (arterial pO2 ; 120 mm Hg), piO2 was ;30 mm Hg and jugular venous pO2 was ;50 mm Hg. During hyperoxia (arterial pO2 5 90 ‐300 mm Hg), piO2 increased linearly with the arterial pO2. Following hypercapnia (arterial pCO2 5 20 ‐ 60 mm Hg), the piO2 increased sigmoidally with increasing CBF. With hypoxia (arterial pO2 5 30 ‐ 40 mm Hg), CBF increased ;56% and piO2 decreased to ;15 mm Hg. The hypoxia-induced CBF increase was effective to some extent in compensating for the reduced piO2. This methodology may prove useful for investigating cerebral piO2 under pathologically or functionally altered conditions. Magn Reson Med 45:61‐70, 2001. © 2001 Wiley-Liss, Inc.
