Tetrahedral quaternary chalcogenides of the type Cu 2IIIVS 4(Se 4)

Abstract

A survey is given on lattice data and structure types of 40 compounds of the type Cu 2IIIVS 4(Se 4) with II = Mn, Fe, Co, Ni, Zn, Cd, Hg and IV = Si, Ge, Sn. Of the 42 possible compounds, 22 had been known. The missing ones have been synthesized and characterized by x-ray powder methods. Three tetrahedral structure types, differing in symmetry and unit cell size exist: 1) The stannite structure (tetragonal superstructure of sphalerite with a tetr≈a Sph, c tetr≈2a Sph). 2) An orthorhombic superstructure of wurtzite (a or≈2a W, b or≈a W√3, c or≈c W). 3) A hitherto unknown structure type based on slightly distorted, sphalerite-sized cells of tetragonal, orthorhombic or monoclinic symmetry.