Siberian Federal University

In this work, the standard enthalpy of formation, the standard entropy, and temperature dependence of the heat capacity of compounds with a garnet-like structure Ca₃R₂Ge₃O₁₂ (R = Y, Er – Lu) were determined by various calculation methods. Based on the obtained data, the changes in the Gibbs energy of synthesis reactions these germanates in the range of 273–1800 K were calculated: a) from initial oxides, b) from calcium carbonate and initial GeO₂ and R₂O₃, c) from initial oxides and pseudobinary compounds. It is shown that the solid-phase synthesis of Ca₃R₂Ge₃O₁₂ garnets is the most thermodynamically advantageous using initial oxides or a mixture of R2O₃ and CaGeO₃