Formation enthalpies and thermodynamic stability of the Sm1+xBa2–xCu3Oy solid solutions

Enthalpies of solution of Sm2O3, BaCO3, CuO, Sm2BaCuO5, and Sm1+xBa2–xCu3Oy solid solutions (x = 0.1, 0.7) were measured by solution calorimetry using 2 N HCl solvent at 323 K. The obtained values were used to give thermodynamic data for reactions of formation of Sm2BaCuO5, Sm1.1Ba1.9Cu3O6.95, Sm1.7Ba1.3Cu3O7.24 from the mixture including BaCO3. The enthalpies of reactions were determined as +185 ± 3 kJ/mol for Sm2BaCuO5, +357 ± 5 kJ/mol for Sm1.1Ba1.9Cu3O6.95, +216 ± 5 kJ/mol for Sm1.7Ba1.3Cu3O7.24. The data obtained showed that the above mentioned phases were thermodynamically stable with respect to mixture with BaCuO2, Sm2O3, CuO.