posted on 2022-01-28, 15:12authored byAnastasiia Poltarak, Pavel Poltarak, Andrey Enyashin, Vladislav Komarov, Sofya Artemkina, Vladimir Fedorov
The binary niobium sulfide NbS4 was synthesized as a
crystalline phase. We showed that NbS4 can be formed from
Nb metal, from defect niobium sulfide Nb1.14S2, or from some other niobium dichalcogenides in reactions with excess
sulfur in an evacuated ampule at 440 °C. The crystal structure
of NbS4 (monoclinic space group C2/c, a = 13.126(2) Å, b = 10.454(1) Å, c = 6.951(1) Å, β
= 111.939(5)°) is a packing of infinite chains {NbS4}1∞, analogous to VS4. In the chains,
Nb atoms are in a tetragonal-antiprismatic coordination of sulfur
atoms of disulfide groups (S2)2–; short
Nb···Nb contacts (2.896 Å) alternating with longer
ones (3.278 Å) appear within the chains at 150 K. According to
density functional theory calculations, NbS4 is a thermodynamically
stable compound, a nonmagnetic semiconductor. NbS4 is a
new member of the family of quazi-one-dimensional compounds, group
5 metal polychalcogenides, well-known for their interesting electrophysical
properties. The synthesis and crystal structure as well as the thermal
stability and lattice dynamics of NbS4 are discussed here.