TY  - JOUR
AU  - Beyer, Doreen C.
AU  - Spektor, Kristina
AU  - Vekilova, Olga Yu
AU  - Grins, Jekabs
AU  - Barros Brant Carvalho, Paulo H.
AU  - Leinbach, Logan J.
AU  - Sannemo-Targama, Michael
AU  - Bhat, Shrikant
AU  - Baran, Volodymyr
AU  - Etter, Martin
AU  - Sano-Furukawa, Asami
AU  - Hattori, Takanori
AU  - Kohlmann, Holger
AU  - Simak, Sergei I.
AU  - Häussermann, Ulrich
TI  - Synthesis of BaSiH<sub>6</sub> Hydridosilicate at High Pressures─A Bridge to BaSiH<sub>8</sub> Polyhydride
JO  - ACS omega
VL  - 10
IS  - 15
SN  - 2470-1343
CY  - Washington, DC
PB  - ACS Publications
M1  - PUBDB-2025-01505
SP  - 15029 - 15035
PY  - 2025
AB  - Hydridosilicates featuring SiH<sub>6</sub> 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<sub>6</sub> which was obtained from reacting the Zintl phase hydride BaSiH∼<sub>1.8</sub> with H<sub>2</sub> fluid at pressures above 4 GPa and subsequent decompression to ambient pressure. Its monoclinic crystal structure (C2/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<sub>6</sub><sup>2–</sup> ions (d<sub>Si–H</sub> ≈ 1.61 Å), which are octahedrally coordinated by Ba2+ 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<sub>6</sub><sup>2–</sup> bending and stretching modes in the ranges 800–1200 and 1400–1800 cm<sup>–1</sup>, respectively, in agreement with a hypervalent Si–H bonding situation. BaSiH<sub>6</sub> is thermally stable up to 95 °C above which decomposition into BaH<sub>2</sub> and Si takes place. DFT calculations indicated a direct band gap of 2.5 eV and confirmed that at ambient pressure BaSiH<sub>6</sub> is a thermodynamically stable compound in the ternary Ba–Si–H system. The discovery of BaSiH<sub>6</sub> consolidates the compound class of hydridosilicates, accessible from hydrogenations of silicides at gigapascal pressures (<10 GPa). The structural properties of BaSiH<sub>6</sub> suggest that it presents an intermediate (or precursor) for further hydrogenation at considerably higher pressures to the predicted superconducting polyhydride BaSiH<sub>8</sub> [Lucrezi, R.; et al. npj Comput. Mater. 2022, 8, 119] whose structure is also based on a NaCl arrangement of Ba and Si atoms but with Si in a cubic environment of H.
LB  - PUB:(DE-HGF)16
C6  - pmid:40290916
UR  - <Go to ISI:>//WOS:001461833900001
DO  - DOI:10.1021/acsomega.4c10502
UR  - https://bib-pubdb1.desy.de/record/626708
ER  -