Thermodynamic properties of ternary phases in the Cu-Tl-Se system

The Cu-Tl-Se system has been studied at temperatures from 300 to 420 K using emf measurements with Cu₄RbCl₃I₂ as a Cu+ ion conducting solid electrolyte. The emf data have been used to map out the subsolidus phase diagram of the Cu-Tl-Se system in the composition region Tl₂Se-CuTlSe-CuSe-Se. We have calculated the partial molar thermodynamic functions of the copper in the alloys and the standard thermodynamic functions of formation and standard entropies of the ternary compounds CuTlSe₂, CuTlSe, and Cu₂TlSe₂. The results confirm that the thermodynamic properties of copper-containing ternary systems can be studied using the approach in question even when they contain an element (thallium in this study) located to the left of copper in the electrochemical series.