Crystal structure of the ternary semiconductor Cu_2In_(14/3□4/3)Se_8 determined by X-ray powder diffraction data

摘要

The crystal structure of the partially ordered vacancy compound Cu2In4/3 square Se-4/3(8), belonging to the system I-3-III7-square-VI12, was analyzed using X-ray powder diffraction data. Several structural models were derived from the structure of the selenium-rich phase beta-Cu0.39In1.2Se2 by permuting the cations in the available Wyckoff positions. The refinement of the best model by the Rietveld method in the tetragonal space group P (4) over bar 2c (No 112), with unit-cell parameters a = 5.7487(3) angstrom. c = 11.5106(6) angstrom. V= 380.40(3) angstrom(3), led to R-p = 9.0%, R-wp = 9.9%, R-exp = 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 (1/2,0,1/4), 2d (0,1/2,1/4), and 2f(1/2,1/2,0);square] in 2f (1/2,1/2,0); Se in 8n (x,y,z) (C) 2018 International Centre for Diffraction Data.