Synthesis of BaSiH 6 Hydridosilicate at High Pressures─A Bridge to BaSiH 8 Polyhydride

作者：Doreen Beyer, Kristina Spektor, Olga Yu. Vekilova, Jêkabs Grîns, Paulo H. B. Brant Carvalho, Logan J. Leinbach, Michael Sannemo-Targama, Shrikant Bhat, Volodymyr Baran, Martin Etter, Asami Sano‐Furukawa, Takanori Hattori, Holger Kohlmann, S. I. Simak, Ulrich Häußermann · 发表于：ACS Omega · 年份：2025 · DOI：10.1021/acsomega.4c10502 · 被引用次数：4 · 研究领域：Hydrogen Storage and Materials、High-pressure geophysics and materials、Superconductivity in MgB2 and Alloys

High Resolution Image Download MS PowerPoint Slide Hydridosilicates featuring SiH 6 octahedral moieties represent a rather new class of compounds with potential properties relating to hydrogen storage and hydride ion conductivity. Here, we report on the new representative BaSiH 6 which was obtained from reacting the Zintl phase hydride BaSiH ∼1.8 with H 2 fluid at pressures above 4 GPa and subsequent decompression to ambient pressure. Its monoclinic crystal structure ( C 2/ c, a = 8.5976(3) Å, b = 4.8548(2) Å, c = 8.7330(4) Å, β = 107.92(1)°, Z = 4) was characterized by a combination of synchrotron radiation powder X-ray diffraction, neutron powder diffraction, and DFT calculations. It consists of complex SiH 6 2– ions ( d Si–H ≈ 1.61 Å), which are octahedrally coordinated by Ba 2+ counterions. The arrangement of Ba and Si atoms deviates only slightly from an ideal fcc NaCl structure with a ≈ 7 Å. IR and Raman spectroscopy showed SiH 6 2– bending and stretching modes in the ranges 800–1200 and 1400–1800 cm –1, respectively, in agreement with a hypervalent Si–H bonding situation. BaSiH 6 is thermally stable up to 95 °C above which decomposition into BaH 2 and Si takes place. DFT calculations indicated a direct band gap of 2.5 eV and confirmed that at ambient pressure BaSiH 6 is a thermodynamically stable compound in the ternary Ba–Si–H system. The discovery of BaSiH 6 consolidates the compound class of hydridosilicates, accessible from hydrogenations of silicides at gigapascal...