Pogodin A. The Cu2S-CuBr(I)-"P2S5" system: phase equilibrium, obtaining and properties of intermediate phases

Phase equilibriums in quasibinary sections Cu2S - CuBr(I), Cu2S - Cu6PS5Br(I), CuBr(I) - Cu6PS5Br(I), Cu7PS6 - Cu6PS5Br(I) of quasiternary systems Cu2S-CuBr(I)-P2S5 were investigated by methods of differential-thermal, X-ray diffraction analysis, phase diagrams have been built. The eutectic type of interaction was established in the systems Cu2S - CuBr, Cu2S - Cu6PS5Br(I), CuBr(I) - Cu6PS5Br(I), Cu7PS6 - Cu6PS5I. Refinement of physico - chemical interaction in Cu2S - CuI system shows a wide homogeneous region based on CuI compound. In the Cu7PS6 - Cu6PS5Br system nonlimited solid solution based on high temperature modifications is formed. Projections of liquidus surfaces and space diagrams of ternary systems CuBr - Cu2S - Cu6PS5Br, Cu2S - Cu7PS6 - Cu6PS5Br, CuI - Cu2S - Cu6PS5I, Cu2S - Cu7PS6 - Cu6PS5I have been constructed using the mathematic simulation method. The optimum technological conditions for growing of single crystals of Cu7PS6, Cu6PS5Br, Cu6PS5I compounds by the directional crystallization method and solid solutions by the vertical zone crystallization method have been developed. Crystal structure of Cu7PS6 was calculated using Rietveld refinement methods. Mechanism of formation of solid solutions in Cu7PS6 - Cu6PS5Br and Cu7PS6 - Cu6PS5I systems has been established. The heterovalent isomorphism Br?S with the charge compensation of copper atoms have been observed during formation of the solid solutions. The copper - selective electrodes constructed from grown crystals were tested in the model solutions. The working range of pH, the range of detection, the obstructive ions to the metrology characteristics of the sensors have been measured in the ammonia-chloride (pH 9.8), glycine (pH 9.8) and ammonia-acetate buffer solutions.