Crystal structure of the ternary semiconductor Cu2In14/3□4/3Se8determined by X-ray powder diffraction data

Abstract

The crystal structure of the partially ordered vacancy compound Cu2In14/3□4/3Se8, belonging to the system I3-III7-□2-VI12, was analyzed using X-ray powder diffraction data. Several structural models were derived from the structure of the selenium-rich phaseβ-Cu0.39In1.2Se2by permuting the cations in the available Wyckoff positions. The refinement of the best model by the Rietveld method in the tetragonal space groupP$\overline 4 $2c(No 112), with unit-cell parametersa= 5.7487(3) Å,c= 11.5106(6) Å,V= 380.40(3) Å3, led toRp= 9.0%,Rwp= 9.9%,Rexp= 7.2%,S= 1.4 for 134 independent reflections. This model has the following Wyckoff site atomic distribution: Cu in 2e(0,0,0); In in 2b(½,0,¼), 2d(0,½,¼), and 2f(½,½,0);□ in 2f(½,½,0); Se in 8n(x,y,z).