THERMODYNAMIC STUDY OF COPPER ARSENIDES BY THE EMF METHOD WITH THE Cu4RbCl3I2 SOLID ELECTROLYTE

The present work demonstrates the thermodynamic study of copper arsenides using electromotive force measurements with a solid Cu⁺ conductive electrolyte, Cu₄RbCl₃I₂, within the temperature range of 300440 K. Measurements were performed using the equilibrium samples from the Cu₃As + As, Cu₃As + Cu₈As, and Cu₈As + (Cu) two-phase regions of the Cu-As system. The phase compositions of all samples were controlled using the powder X-ray diffraction method. The partial molar functions of copper in alloys, as well as the standard thermodynamic functions of formation and standard entropies of the Cu₃As, Cu₈As compounds, as well as, the Cu₀.₉₄As₀.₀₆ solid solutions based on copper, were calculated. A thermodynamic study of the Cu₈As compound and the Cu₀.₉₄As₀.₀₆ solid solution has been carried out for the first time in the current contribution. Thermodynamic properties for the Cu₃As compound obtained in this work have been analyzed compared with the available literature data.