Peña-Alvarez Miriam, Binns Jack, Martinez-Canales Miguel, Monserrat Bartomeu, Ackland Graeme J, Dalladay-Simpson Philip, Howie Ross T, Pickard Chris J, Gregoryanz Eugene
Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH8 8AQ, U.K.
Center for High Pressure Science and Technology Advanced Research, Shanghai 100094, P.R. China.
J Phys Chem Lett. 2021 May 27;12(20):4910-4916. doi: 10.1021/acs.jpclett.1c00826. Epub 2021 May 19.
By combining pressures up to 50 GPa and temperatures of 1200 K, we synthesize the novel barium hydride, BaH, stable down to 27 GPa. We use Raman spectroscopy, X-ray diffraction, and first-principles calculations to determine that this compound adopts a highly symmetric structure with an unusual 5:1 hydrogen-to-barium ratio. This singular stoichiometry corresponds to the well-defined type-I clathrate geometry. This clathrate consists of a Weaire-Phelan hydrogen structure with the barium atoms forming a topologically close-packed phase. In particular, the structure is formed by H and H clathrate cages showing substantially weakened H-H interactions. Density functional theory (DFT) demonstrates that cubic BaH requires dynamical effects to stabilize the H and H clathrate cages.
通过结合高达50吉帕斯卡的压力和1200开尔文的温度，我们合成了新型氢化钡BaH，它在27吉帕斯卡的压力下仍保持稳定。我们使用拉曼光谱、X射线衍射和第一性原理计算来确定该化合物采用了高度对称的结构，具有不寻常的5:1氢钡比。这种独特的化学计量比对应于明确的I型笼状结构几何形状。这种笼状结构由韦尔-费伦氢结构组成，钡原子形成拓扑密堆积相。特别地，该结构由H和H笼状结构形成，显示出显著减弱的H-H相互作用。密度泛函理论（DFT）表明，立方BaH需要动力学效应来稳定H和H笼状结构。
