Crystal structure and cation distribution in the solid solution series 2(ZnX)–CuInX 2 (X=S, Se, Te)

Abstract

The solid solution series (2ZnX) x (CuInX 2) 1− x (X=S, Se, Te) were studied by the combination of laboratory and synchrotron X-ray and by neutron powder diffraction. Within the homologous series the tetragonal distortion ¼-u increases in the sequence S→Se→Te whereas the tetragonal deformation η= c/2 a decreases. Besides that, with increasing 2ZnX content in CuInX 2 the anion position parameter u increases as expected. The cation site occupancy in the chalcopyrite type phase of single phase tetragonal samples was obtained by Rietveld analysis of the neutron diffraction data. A non-statistic Zn distribution could be deduced for all three systems. The high temperature in situ diffraction experiments with synchrotron radiation on CuInX 2 powder samples revealed the Cu–In anti-site occupation as the driving force of the temperature dependent phase transition from the chalcopyrite to the zinc-blende type structure.