Crystal structure,electronic structure and electrical conductivity of the antimony selenide BaLaSb2Se6

BaLaSb₂S₆ and BaLaSb₂Se₆ were prepared by heating the elements in the stoichiometric ratio under exclusion of air at 850 °C. Both chalcogenides adopt the KThSb₆Se₆ structure type, crystallizing in the space group P2₁/c (Z = 4) with a = 4.324(3) Å, b = 14.7057(16) Å, c = 15.910(2) Å, β = 92.741(3)°, Z = 4 for the sulfide and a = 4.4173(3) Å, b = 15.333(1) Å, c = 16.816(1) Å, β = 92.545(2)°, Z = 4 for the selenide. The structure of BaLaSb₂Se₆ is composed of ribbons of distorted SbSe₆ octahedra and Se₂^2? pairs. Electronic structure calculations show that the selenide is a semiconductor, in accord with the electrical conductivity measurement.