Thermodynamics of Ba2Sm2/3UO6

The standard enthalpy of formation of crystalline Ba2Sm2/3UO6 at 298.15 K, −3040.0±7.5 kJ mol−1, was determined by reaction calorimetry. The heat capacity of the compound in the range 80–300 K was measured by adiabatic vacuum calorimetry, and its thermodynamic functions were calculated. Its standard entropy of formation at 298.15 K is −592.5±1.0 J mol−1 K−1, and the Gibbs energy of formation at 298.15 K, −2863.5±8.0 kJ mol−1. The standard thermodynamic functions of the reactions of the Ba2Sm2/3UO6 synthesis were calculated and discussed.