Thermodynamic properties of cerium dioxide in the condensed state

As part of the further development of the IVTANTERMO information and reference system, the entire set of experimental data on the thermodynamic properties of cerium dioxide available in the literature was critically analyzed and processed. An equation was obtained that approximates the temperature dependence of the heat capacity of crystalline $\rm CeO_2$ in the interval $298.15$–$3083$ K. There are no experimental data for liquid cerium dioxide in the literature. The missing thermodynamic quantities (enthalpy of melting, heat capacity of the liquid phase) are obtained by estimation. Particular attention is paid to the transition between the oxidized and reduced forms of cerium $\rm Ce^{4+} \rightleftarrows \rm Ce^{3+}$, as a result of which in the $\rm CeO_2$–$\rm CeO_{1.5}$ system, a number of intermediate oxides are formed.