High-pressure induced phase formation in the CuGaS2-CuGaO2 chalcopyrite-delafossite system

Abstract

Phase formation under high pressure int he chalcopyrite-delafossite system has been studied at 5 GPa and 500-1000 degrees C. The parent chalcopyrite composition used in this study was slightly Cu-deficient, corresponding to the chemical formula (Cu,Ga)(0.905)GaS2. It was revealed that under high-pressure and high-temperature conditions, a mixture of the parent phases partly decomposes to form Cu2S and Ga2O3. The defect chalcopyrite (Cu,Ga)(0.905)GaS2 splits into a near-stoichiometric CuGaS2 and Cu-deficient subic (sphalerite-like) phase of the (Cu,Ga)(0.8)S composition. Such a phenomenon has been considered in terms of characteristic features of chalcopyrite and sphalerite crystal structures. Delafossite CuGaO2 at 5 GPa and 1000 degrees C was found to recrystallize entirely, which results in the disappearance of the stacking faults in its layered structure. [GRAPHICS] (C) 2014 WILEY-VCH Verlag GmbH \& Co. KGaA, Weinheim