LiSbS2-mC16: Structure Determination from X-ray Powder Diffraction Data

Monoclinic LiSbS2-mC(16) was synthesized by solid-state reaction of Li2S, Sb, and S in the ratio 1: 2: 5 at a temperature of 900 degrees C. The excess of sulfur serves as a kind of flux and is not incorporated in the structure. The product is air and moisture sensitive. The crystal structure of the dark red product was determined from X-ray powder diffraction data at 293 K. LiSbS2-mC(16) crystallizes in the space group C2/c (no. 15) with a = 8.0205(8) angstrom, b = 7.9243(8) angstrom, c = 6.6987(7) angstrom, beta = 126.303(6)degrees, V = 343.11(7) angstrom(3), and Z = 4. It forms an ordered NaCl type superstructure, which shows two different sites for the cations, whereas the cubic high temperature modification cF8 exhibits only one position with a mixed occupation by lithium and antimony. Lithium has a slightly distorted octahedral coordination by sulfur. The distortion of the octahedral coordination polyhedron is much stronger in the case of antimony. Therefore it is better described as a 2 + 2 + 2 coordination mode.