Thermodynamic stability of AuSe at temperature from (400 to 700) K by a solid state galvanic cell

Highlights: • Experimental data on AuSe were obtained from T = (400 to 700) K. • Superionic conductor AgI was used as the solid electrolyte. • EMF accuracy was improved by advanced cell design. -- Abstract: The numerical values on the standard thermodynamic functions of AuSe were determined by the electromotive force (EMF) method in a solid-state galvanic cell with a superionic conductor AgI as the solid electrolyte. According to the experimental data on the EMF vs. temperature, the analytical equations for Gibbs free energy, enthalpy and entropy were obtained for the single stable polymorphic form of AuSe. The temperature-dependent relationships of Gibbs free energy of formation of AuSe and the standard thermodynamic functions of compounds within the temperature range (400 to 700) K were also evaluated. No α–β transformation was identified in the gold saturation and β-form is a metastable modification of AuSe