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Machida, Akihiko; Honda, Mitsunori; Hattori, Takanori; Sano, Asami; Watanuki, Tetsu; Katayama, Yoshinori; Aoki, Katsutoshi; Komatsu, Kazuki*; Arima, Hiroshi; Oshita, Hidetoshi*; et al.
no journal, ,
Formation of an NaCl-type mono-deuteride LaD has been found by neutron diffraction experiments at high pressure. The NaCl-type structure has been reported for alkaline hydrides and transition metal hydrides, but not for rare-earth metal hydrides. The NaCl-type mono-hydride is formed in rare-earth metals for the first time. Lanthanum mono-deuteride is formed as a result of the phase separation of the di-deuteride under high pressure. This result suggests that the three different hydrides, mono-, di-, and tri-hydrides, with the fcc metal lattice are realized. The hydrogen atoms occupy only O-sites, only T-sites and both O-sites and T-sites in the mono-, di-, and tri-hydrides, respectively. Hence, it is expected that the H-M bonding nature is different for each hydride.
Kamakura, Nozomu; Takeda, Yukiharu; Okane, Tetsuo; Fujimori, Shinichi; Saito, Yuji; Yamagami, Hiroshi; Miyaoka, Hiroki*; Tsubota, Masami*; Ichikawa, Takayuki*; Kojima, Yoshitsugu*; et al.
no journal, ,
no abstracts in English
Matsumura, Daiju; Okajima, Yuka*; Nishihata, Yasuo; Mizuki, Junichiro
no journal, ,
Structural change of Pd nanoparticles on aluminum oxide during hydrogen absorption reaction was directly observed by X-ray absorption fine structure spectroscopy with dispersive optics. Mean particle size dependence of reaction kinetics was also studied. As the mean particle size decreases, the amount of absorbed hydrogen atoms decreases but the reaction rate increases. Determined reaction order implies that the rate of the hydrogen absorption reaction is limited by the surface dissociative adsorption step. Debye-Waller factor of Pd-Pd interatomic distance shows large value only while the hydrogen absorption reaction proceeds. This means that longer interatomic distance in hydride phase coexists with shorter interatomic distance in solid-solution phase in the Pd nanoparticle as the intermediate state of the hydrogen absorption reaction.