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上原 章寛*; 秋山 大輔*; 池田 篤史; 沼子 千弥*; 寺田 靖子*; 新田 清文*; 伊奈 稔哲*; 武田 志乃*; 桐島 陽*; 佐藤 修彰*
Journal of Nuclear Materials, 559, p.153422_1 - 153422_11, 2022/02
被引用回数:2 パーセンタイル:56.43(Materials Science, Multidisciplinary)The reaction products were analysed by a combination of powder X-ray diffraction (PXRD) and X-ray absorption spectroscopic measurements of the U L- and Zr K-edges. Under an oxidizing atmosphere, the formation of UO and UZrO was observed in equilibrium with UO, monoclinic-ZrO, and tetragonal-ZrO. However, when O gas was purged through the reaction tube during the cooling process to room temperature, pentavalent U in ZrUO was produced by the oxidation of solid solution UO formed at 1774 K during the temperature dropped at 1473 K. Under the inert atmosphere, mixed oxides of uranium were found to form at 1673 K due to a low concentration of O impurity with the Ar gas. This study can pave the way for understanding the interaction between the nuclear fuels and the cladding materials in damaged reactors enabling further simulation of possible decontamination procedures.
浅野 駿*; 石井 賢司*; 松村 大樹; 辻 卓也; 伊奈 稔哲*; 鈴木 謙介*; 藤田 全基*
Journal of the Physical Society of Japan, 87(9), p.094710_1 - 094710_5, 2018/09
被引用回数:11 パーセンタイル:65.34(Physics, Multidisciplinary)We investigated the Ce substitution and reduction annealing effects on the electronic states at copper sites by Cu -edge X-ray absorption near-edge structure measurements in PrCeCuO (PCCO) with varying and (amount of oxygen loss during annealing). Absorption near-edge spectra were modified by Ce substitution and reduction annealing similarly with increasing and . Considering electron doping by Ce substitution, this similarity indicates an increase in electron number at the copper sites due to annealing (). Furthermore, quantitative analyses of the spectra clarified that the number of Cu sites, corresponding to the induced electron number by Ce substitution increases linearly with in the as-sintered PCCO, whereas is not exactly equal to 2. For each -fixed sample, tends to exceed 2 with increasing , suggesting the emergence of two types of carrier due to annealing.
浅野 駿*; 鈴木 謙介*; 松村 大樹; 石井 賢司*; 伊奈 稔哲*; 藤田 全基*
Journal of Physics; Conference Series, 969, p.012051_1 - 012051_5, 2018/04
被引用回数:3 パーセンタイル:82.43Reduction and oxidation annealing effects on the electronic states around the copper sites for PrCeCuO and NdCeCuO with = 0 and = 0.15 were investigated by Cu -edge X-ray absorption measurements. Cu near-edge spectra were changed by the reduction annealing in a manner similar to the case of Ce substitution for both = 0 and = 0.15. This means an increase of electron density at the copper sites, indicating the aspect of electron doping in the reduction annealing. This reduction annealing effect on the near-edge spectra are reverted by the additional oxidation annealing. The amount of electron density around the copper sites is varied by the reduction and oxidation annealing, reversibly, corresponding to the reversible variation of the physical property from insulating to superconductivity.
Wang, H.*; 磯部 仁*; 清水 剛志*; 松村 大樹; 伊奈 稔哲*; 吉川 浩史*
Journal of Power Sources, 360, p.150 - 156, 2017/08
被引用回数:12 パーセンタイル:41.69(Chemistry, Physical)-phase LiVO, which shows superior electrochemical performance as cathode material in Li-ion batteries, was prepared by annealing the polyoxovanadate cluster Li[VO(CO)]. The reaction mechanism was studied using X-ray absorption fine structure (XAFS), powder X-ray diffraction (PXRD), and X-ray photoelectron spectroscopy (XPS) analyses. The X-ray absorption near edge structure (XANES) and XPS results reveal that -LiVO undergoes two-electron redox reaction per VO pyramid unit, resulting in a large reversible capacity of 260 Ah/kg. The extended X-ray absorption fine structure (EXAFS) and PXRD analyses also suggest that the V-V distance slightly increases, due to the reduction of V to V during Li ion intercalation as the material structure is maintained. As a result, -LiVO shows highly reversible electrochemical reaction with x = 0.1-1.9.