In this work a series of stoichiometric Cu 2 ZnSnS 4 (CZTS) samples annealed at different temperatures in the range of 473 -623 K were investigated. The temperature dependence of the Cu/Zn-orderdisorder behavior was analyzed by neutron powder diffraction measurements. Cu fully occupies the 2a and Sn the 2b position within the whole temperature range. For Zn and the remaining Cu on sites 2d and 2c, a clear change from ordered to disordered kesterite structure is found. The critical temperature T c for this Landau-type second order transition was determined as 552 ± 2 K. It was found that in Cu 2 ZnSnS 4 very long annealing times are necessary to reach equilibrium at low temperatures.

With respect to absorber materials in solar cells, Cu 2 ZnSnS 4 (CZTS) has been a focus of interest in recent years. In this work, a new route leading to single phase CZTS powders is presented. For structural characterization X-ray and neutron powder diffraction measurements were performed. Further structural and compositional analysis of the CZTS powder was carried out by means of X-ray absorption near edge spectroscopy (XANES) and wavelengthdispersive X-ray spectroscopy (WDS). The obtained CZTS powder with an actual composition of Cu 2.00(4) Zn 1.02(2) Sn 0.99(2) S 4.00(8) adopts the kesterite-type structure. A detailed cation distribution analysis using the average neutron scattering length method revealed a partial disorder of copper and zinc on the (2c) and (2d) sites.

We have investigated the high-pressure structural and vibrational behavior of the ordered kesterite-type Cu 2 ZnSnS 4 compound. Our investigations have revealed two structural transitions: a kesterite-to-disordered kesterite transition was observed between 7 and 9 GPa, which involves a Zn/Cu disorder within the respective cationic sublattice, whereas a rocksalt-type structure was realized at $15 GPa. The latter transition is accompanied by a cationic coordination increase from fourfold-to-sixfold with respect to the sulfur anions. The predicted kesterite-to-stannite transition was not detected. Furthermore, our high-pressure Raman studies have shown that the aforementioned Zn/Cu cationic disorder will always be present in Cu 2 ZnSnS 4 under relatively moderate compression. Published by AIP Publishing. [http://dx