Structural transition in rare-earth hydride under pressure

希土類水素化物の高圧下の構造転移

青木 勝敏; 町田 晃彦; 大村 彩子*; 綿貫 徹; 竹村 謙一*

Aoki, Katsutoshi; Machida, Akihiko; Omura, Ayako*; Watanuki, Tetsu; Takemura, Kenichi*

ダイヤモンドアンビルセル(DAC)を用いて、流体水素と金属の高圧反応による水素化物の合成と放射光X線回折による高圧結晶構造測定を、Sc,Y, Laを対象に室温下、50GPaまでの圧力領域で行った。YHはhcp-fccの構造相転移を、さらに高圧fcc相はバンドギャップクロジャーを起すことが観測された。

Structural investigation on metal hydrides provides an insight into the interactions between hydrogen atoms occupying the interstitial spaces of a metal lattice. The hydrogen atoms are often negatively ionized due to the charge transfer from the host metal lattice and the electrostatic forces play a dominant role in structural stabilization or transition. Synchrotron X-ray diffraction measurements were made for di-hydrides and tri-hydrides of rare-earth metals (Sc, Y, La) at pressures up to 50 GPa and at ambient pressure at SPring-8.