Thermodynamic modeling of the cerium–yttrium–oxygen system

The published data for the thermochemical properties and phase relationships of the cerium–yttrium–oxygen system have been critically examined. The thermodynamic properties of the phases are described using “compound energy formalism” for the various solid phases and an associate solution model for liquid phase. The model parameters have been optimized by least-squares fit to the selected experimental information of different kind (phase diagram data, calorimetric data, and equilibrium oxygen pressures) using the CALPHAD method. A self-consistent set of Gibbs energy functions describing the Ce–Y–O system has been obtained for the first time. The models are simple to be compatible with the standard Gibbs energy minimization procedure, but provide enough flexibility to account for the crystal structure, defect chemistry, and thermodynamic properties of phases in the Ce–Y–O system. The backward compatibility of the refined parameters with experimental data has been demonstrated by calculation of phase and property diagrams.