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@ARTICLE{Beyer:626708,
author = {Beyer, Doreen C. and Spektor, Kristina and Vekilova, Olga
Yu and Grins, Jekabs and Barros Brant Carvalho, Paulo H. and
Leinbach, Logan J. and Sannemo-Targama, Michael and Bhat,
Shrikant and Baran, Volodymyr and Etter, Martin and
Sano-Furukawa, Asami and Hattori, Takanori and Kohlmann,
Holger and Simak, Sergei I. and Häussermann, Ulrich},
title = {{S}ynthesis of {B}a{S}i{H}$_6$ {H}ydridosilicate at {H}igh
{P}ressures─{A} {B}ridge to {B}a{S}i{H}$_8$ {P}olyhydride},
journal = {ACS omega},
volume = {10},
number = {15},
issn = {2470-1343},
address = {Washington, DC},
publisher = {ACS Publications},
reportid = {PUBDB-2025-01505},
pages = {15029 - 15035},
year = {2025},
abstract = {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 (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$_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 pressures (<10 GPa). The structural
properties of BaSiH$_6$ suggest that it presents an
intermediate (or precursor) for further hydrogenation at
considerably higher pressures to the predicted
superconducting polyhydride BaSiH$_8$ [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.},
cin = {FS DOOR-User / FS-PETRA-D},
ddc = {660},
cid = {$I:(DE-H253)FS_DOOR-User-20241023$ /
I:(DE-H253)FS-PETRA-D-20210408},
pnm = {631 - Matter – Dynamics, Mechanisms and Control
(POF4-631) / 6G3 - PETRA III (DESY) (POF4-6G3) / FASTCORR -
Ultrafast dynamics of correlated electrons in solids
(854843) / FS-Proposal: I-20210167 EC (I-20210167-EC)},
pid = {G:(DE-HGF)POF4-631 / G:(DE-HGF)POF4-6G3 /
G:(EU-Grant)854843 / G:(DE-H253)I-20210167-EC},
experiment = {EXP:(DE-H253)P-P61.2-20150101 /
EXP:(DE-H253)P-P02.1-20150101},
typ = {PUB:(DE-HGF)16},
pubmed = {pmid:40290916},
UT = {WOS:001461833900001},
doi = {10.1021/acsomega.4c10502},
url = {https://bib-pubdb1.desy.de/record/626708},
}