The energy functions of the components were determined based on additional studies intended to determine the values of total pressure and vapor composition over liquid solutions of the selenium-tellurium system: entropy, enthalpy, Gibbs energy, and heat capacity change in the existence field of alloys in the state diagram. The liquid-vapor phase transition was calculated to determine the upper boundary of existence of melts - their boiling point. The boiling point of selenium-tellurium liquid solutions corresponds to the dependence: \(t_{boiling} [^\circ C] = 478x_{Se}^{3} - 764x_{Se}^{2} - 31x_{Se} + 989\) , where \({x}_{Se}\) – atomic fraction of selenium in the alloy. The formation of azeotropic mixtures was found when the pressure was lowered less than 67.08 kPa (0.66 atm.) in the system and its absence of at atmospheric pressure. The line connecting the points of azeotropic mixtures corresponds to a linear relationship: \(t_{azeotropes} [^\circ C] = - 2285.7x_{Se} + 945.42\) . The energy characteristics of the molten system can be used for thermal engineering and technological calculations when the selenium- and tellurium-based products are obtained. The shape of the boundaries of the melt and vapor coexistence fields at atmospheric pressure and in vacuum, as well as the presence of azeotropic mixtures, indicate the impossibility of direct distillation separation of the system into elements.
