Department of Energy and Hydrocarbon Chemistry, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto, 615-8510, Japan.
Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK.
Nat Commun. 2017 Oct 31;8(1):1217. doi: 10.1038/s41467-017-01301-0.
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 SrVOH 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 V-O-V overlap. Remarkably, dispersion along c is limited by the orthogonal V-H-V 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.
过渡金属氧氢化物由于氢阴离子的独特性质而受到极大的关注，特别是其没有价 p 轨道。这一特征使氢化物与所有其他阴离子区别开来，并使这一新类材料具有前所未有的性质。在这里，我们通过对阴离子有序锶钒氧氢化物 SrVOH 的高压研究表明，H 是非常可压缩的，并且在约 50GPa 时压力驱动从莫特绝缘体到金属的转变。密度泛函理论表明，在绝缘状态下的带隙随着 ab 平面中由于增强的 V-O-V 重叠而导致的分散度的增加而减小。值得注意的是，尽管 c 轴的压缩性更大，但由于垂直的 V-H-V 排列，沿 c 轴的分散度受到限制，这表明氢阴离子作为π阻断剂。因此，更广泛的氧氢化物家族可能会获得具有新型电子性质的维度降低的结构。
