Crystal structure, electronic structure and thermoelectric properties of Cu 4Sn 7S 16

Abstract

Single crystals of Cu 4Sn 7S 16 have been prepared by direct reaction of the elements at 850 °C. The crystal structure was re-determined using single-crystal X-ray diffraction data. Cu 4Sn 7S 16 crystallizes in the rhombohedral space group R 3 ¯ m (No. 166) with cell dimensions of a = 7.3788(2) Å, c = 36.032(2) Å, V = 1699(1) Å 3 ( Z = 3). The three-dimensional structure of this compound contains (in part severely distorted) CuS 6 and SnS 6 octahedra, CuS 4 tetrahedra, and CuS 4 trigonal pyramids. Electrical conductivity and Seebeck coefficient measurements show (n-type) semiconducting behavior, in agreement with the electronic band structure calculations.