Abstract
The partial molar free energies of thorium in ThC-UC solid solutions were measured from 700 to 950°C by means of the solid state galvanic cells of the type Th, ThF4/CaF2/ThF4, Th1−xUxC. The following results were obtained:
(1) The partial molar free energy of thorium in ThC-UC solid solution increases negatively with decreasing thorium content, and the absolute value of partial molar entropy of thorium shows the maximum near Th0.5U0.5C. (2) As the ThC-UC solid solution is assumed to be a quasi-binary system of thorium and uranium, the partial molar free energy of uranium was calculated from that of thorium, and the free energy of mixing was estimated. (3) The interaction energy between thorium and uranium in Th-U-C system was calculated according to a model of the strictly regular solution. The interaction between thorium and uranium is attractive and its temperature dependence corresponds fairly well with partial molar entropy of thorium in ThC-UC solid solution.
