Phase diagrams of the coper(I) bromide-lead bromide and copper (I) iodide-lead iodide systems and the ionic conductivity of CuPb3Br7

Abstract

Abstract The phase diagrams of the systems CuBrPbBr2 and CuiPbI2 have been determined by the use of differential thermal analysis and X-ray diffraction analysis. A new compound CuPb3Br7 has been found in the CuBrPbBr2 system. This compound is stable between its incongruent melting point (300°C) and 160°C, and below 160°C disproportionates to CuBr and PbBr2. It has a relatively high ionic conductivity of 3 × 10−2 (ohm-cm)−1 at 200°C and a low activation energy for conduction of 22 kJ/mole. The transport number measurement with Tubandt's method shows that the copper ions must be considered as the only charge carriers. No intermediate compound has been found in the CuIPbI2 system.