A structural study on the CuGaSe2-related copper-poor materials CuGa3Se5 and CuGa5Se8: thin-film vs. bulk material



Polycrystalline samples of CuGaSe2-related defect compounds (DC) have been prepared by Chemical Close-Spaced Vapour Transport (CCSVT) (thin films) and elemental synthesis (powder) respectively. In the latter case a homogenisation step was introduced during the preparation, including mechanical intermixing and adjacent-heat treatment after the main reaction. Following this route we assured conditions “close to” thermodynamic equilibrium. The influence of the annealing temperature on the lattice parameters a0 and c0, as well as the cation distribution, was investigated. By means of X-ray and neutron diffraction analysis the structural properties of the Cu–Ga–Se based DCs have been determined and a new structural model has been derived. Finally the structural parameters of CCSVT-grown thin-film material were correlated with findings for bulk material samples which were intentionally prepared off-equilibrium. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)