Influence of cation substitution on the polymorphic transformation in Ag_2–#0445#Cu_#0445#S (#0445# = 0.45, 0.8, and 1.07) crystals

The influence of the concentration substitution of Ag ions for Cu ions in the structure of Ag_2–хCu_хS (х = 0.45, 0.8, and 1.07) solid solutions on the temperature of polymorphic phase transitions is demonstrated. The phase composition of Ag_2–хCu_хS (х = 0.45, 0.8, and 1.07) solid solutions has been investigated by X-ray diffraction at different temperatures. It is shown that the structure of the polymorphic modification of Ag_0.93Cu_1.07S composition and the phase transition temperature correspond to the structure and parameters of AgCuS single crystal. The structures of the modifications of compositions with a high silver concentration (Ag_1.55Cu_0.45S and Ag_1.2Cu_0.8S) and the phase transitions temperatures differ from the structure and corresponding parameters of AgCuS single crystal.