Heat capacity measurements of the δ-phase Mg2Zr4.2Ti0.8O12 and thermodynamic modelling of the ZrO2–TiO2–MgO System

Abstract Phase equilibria in the ZrO2–TiO2–MgO system have been studied experimentally using powder X-ray diffraction. Isothermal sections were constructed at 1475 and 1555 K. The eutectoid reaction of δ-phase ↔ Mg2TiO4+T-ZrO2+MgO and the solid transition reaction of δ-phase + MgTiO3 ↔ Mg2TiO4 + T-ZrO2 were determined at temperatures 1503 and 1535 K, respectively. Heat capacity measurements for the δ-phase have been obtained in the temperature range from 210 to 1370 K. Debye temperature of the δ-phase was estimated. Standard entropy for the δ-phase was evaluated. Based on the obtained experimental data, a self-consistent thermodynamic description of the ZrO2–TiO2–MgO system has been developed.