金属水素化物の高圧研究のフロンティア

Frontier of high pressure research on metal hydrides

青木 勝敏; 町田 晃彦; 大村 彩子*; 綿貫 徹

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

構造相転移と電子転移を探索するために金属水素化物の高密度状態の観測を行った。水素原子は金属格子内で変位や移動をして転移を引き起こす。絶縁体-金属転移ではサイト内の変位が、フォトクロミック現象ではサイト間の移動が現象発現を担っていると考えられる。

The highly compressed state of metal hydride has been investigated to explore structural and electronic transitions characteristic to hydride. The hydrogen atoms play the lead in the transitions, showing displacement in or transfer between the interstitial sites of a metal lattice. One example is the band gap closing observed for a long period lattice of yttrium tri-hydride, appearing at pressures above 12 GPa. Another example is photochromic event observed again for yttrium hydride. The former is likely accompanied by the in-site displacement of hydrogen atoms and the latter by the site-to-site transfer.