Rietveld refinement for CuInSe2 and CuIn3Se5

Rietveld refinements for copper indium selenides CuInSe2 and CuIn3Se5 and their mixture were performed using data collected at a Bragg-Brentano diffractometer. The values of lattice parameters, axial ratio and positional parameters are discussed and compared to available literature data for single crystals and polycrystals. Results for CuInSe2 give a(0) = 5.78149(1) Angstrom and c(0) = 11.61879(4) Angstrom. The positional parameter x is determined to be equal 0.2271(4). Refinements for CuIn3Se5 give an indication concerning the choice of a structural model for this compound. Namely, the best fit is obtained for a model based on 1 (4) over bar 2m space group, yielding a composition close to the experimental one and the lattice parameters a(0) = 5.75812(2) Angstrom and c(0) = 11.53593(7) Angstrom. Parameters of this model are discussed. (C) 2003 Elsevier B.V. All rights reserved.