Journal Article The role of π-blocking hydride ligands in a pressure-induced insulator-to-metal phase transition in SrVO2H

Yamamoto, Takafumi  ,  Zeng, Dihao  ,  Kawakami, Takateru  ,  Arcisauskaite, Vaida  ,  Yata, Kanami  ,  Patino, Midori Amano  ,  Izumo, Nana  ,  McGrady, John E.  ,  Kageyama, Hiroshi  ,  Hayward, Michael A.

82017-10-31 , Springer Nature
負電荷をもつ水素の新たな性質を発見 --圧縮しやすく、金属原子間の相互作用をブロック--. 京都大学プレスリリース. 2017-11-01.
Transition-metal oxyhydrides are of considerable current interest due to the unique features of the hydride anion, most notably the absence of valence p orbitals. This feature distinguishes hydrides from all other anions, and gives rise to unprecedented properties in this new class of materials. Here we show via a high-pressure study of anion-ordered strontium vanadium oxyhydride SrVO2H that H− is extraordinarily compressible, and that pressure drives a transition from a Mott insulator to a metal at ~ 50 GPa. Density functional theory suggests that the band gap in the insulating state is reduced by pressure as a result of increased dispersion in the ab-plane due to enhanced Vdπ-Opπ-Vdπ overlap. Remarkably, dispersion along c is limited by the orthogonal Vdπ-H1s-Vdπ arrangement despite the greater c-axis compressibility, suggesting that the hydride anions act as π-blockers. The wider family of oxyhydrides may therefore give access to dimensionally reduced structures with novel electronic properties.

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