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Kume, Tetsuji*; Machida, Akihiko; Aoki, Katsutoshi; Sasaki, Shigeo*; Shimizu, Hiroyasu*
Koatsuryoku No Kagaku To Gijutsu, 21(3), p.184 - 189, 2011/09
Raman and visible absorption spectra of rare earth trihydrides have been measured at high pressures, in order to investigate the structural and electronic phase transitions. The successive phase transitions of hcp-intermediatefcc phase were confirmed by Raman measurements. From the visible absorption experiments, the band gap energy was estimated. The gap closure was found to occur on the transition from the intermediate to the fcc phase.
; Raman, infrared, and visible absorption spectroscopyKume, Tetsuji*; Oura, Hiroyuki*; Takeichi, Tomoo*; Omura, Ayako*; Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi; Sasaki, Shigeo*; Shimizu, Hiroyasu*; Takemura, Kenichi*
Physical Review B, 84(6), p.064132_1 - 064132_7, 2011/08
Times Cited Count：19 Percentile：61.3(Materials Science, Multidisciplinary)Raman, IR, and visible absorption spectra of scandium trihydride (ScH) have been measured at high pressures up to 50 GPa at room temperature. The structural and electronic phase transitions were investigated. Successive hcp-intermediate-fcc phase transitions took place at 25 and 46 GPa. It was suggested that the intermediate phase of ScH has the same structure as that of YH. The energy gap of ScH is 1.7 eV at the ambient condition and is closed around 50 GPa, at which the crystal structure transforms to fcc.
by Raman and visible absorption spectroscopyKume, Tetsuji*; Oura, Hiroyuki*; Sasaki, Shigeo*; Shimizu, Hiroyasu*; Omura, Ayako*; Machida, Akihiko; Watanuki, Tetsu; Aoki, Katsutoshi; Takemura, Kenichi*
Physical Review B, 76(2), p.024107_1 - 024107_5, 2007/07
Times Cited Count：38 Percentile：79.32(Materials Science, Multidisciplinary)Raman and visible absorption spectra of YH were measured at high pressures, in order to clarify the structural and electronic phase transitions. The Raman results revealed the presence of an intermediate phase at 9-24 GPa between the low-pressure hexagonal and high-pressure fcc phases. The Y-framework structure and the positions of interstitial H atoms are changed on the transition to the intermediate phase. The results of the absorption measurements demonstrate that the optical band gap begins to close in response to the phase transition.
Shimizu, Hiroyasu*; Utsumi, Wataru; Kume, Tetsuji*; Kondo, Tadashi*; Shimizu, Katsuya*; Sotani, Tomohiro*; Taniguchi, Takashi*; Nakamura, Kazutaka*
Koatsuryoku No Kagaku To Gijutsu, 11(4), p.334 - 338, 2001/12
no abstracts in English
