Thermodynamic Study of Copper Antimonides by the EMF Method with the Cu4RbCl3I2 Solid Electrolyte

Copper antimonides and phases based on them are of great interest as environmentally friendly functional materials for potential application in various areas of industry and technology. Present work demonstrates the results of thermodynamic study of Cu4Sb and two polymorphic modifications of Cu2Sb by low temperature electromotive force method (EMF) with a Cu+ conducting solid electrolyte RbCu4Cl3I2 in 300–480 K temperatures range. Measurements were performed using equilibrium samples from the Cu2Sb + Sb and Cu4Sb + Cu2Sb phase regions of the system. Phase compositions of samples were controlled using the powder X-ray diffraction (PXRD) method. Partial molar thermodynamic functions of copper in alloys, as well as, thermodynamic functions of formation and the absolute entropies of the RT–Cu2Sb, HT–Cu2Sb, and Cu4Sb compounds were calculated. The enthalpy and entropy of the polymorph transition of Cu2Sb were calculated based on the EMF data. A comparative analysis of obtained results with literature data was performed.