Two optimal sets of thermodynamic functions for the ZrO2-LaO1.5 system are obtained by coupling the CALPHAD (CALculation of PHAse Diagrams) technique, the regularity between thermodynamic properties and crystal structure parameters within the family of rare earth oxides, and the Van't Hoff equation. The phases are modelled with the substitutional solution model (liquid, cubic, tetragonal, monoclinic, and hexagonal solid solutions), as the stoichiometric compounds (Zr19La42O101, Zr2La2O7), and with the sublattice model (Zr2La2O7). Two optimizations are performed. In the first optimization, the Zr2La2O7 phase is treated as a stoichiometric compound, while in the second one it is described by the Wagner-Schottky model. The eutectoid reaction, high-temperature hexagonal LaO1.5 solid solution low-temperature hexagonal LaO1.5 solid solution + Zr2La2O7, is predicted from the calculation. The calculated phase diagrams and thermodynamic quantities agree well with the experimental data.
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry