Thermochemistry of the ZrO₂–SrO System: From enthalpies of formation and heat capacities of the compounds to the phase diagram

Abstract

The thermodynamics of the ZrO2–SrO system is of interest for the optimization of synthesis and applications of functional materials and high‐temperature structural ceramics. Earlier data on phase relationships and thermodynamic properties of the system are unfortunately scattered and inconsistent. In this study, the compounds Srn+1ZrnO3n+1 (n = 3, 2, and 1) were prepared by solid‐state reaction. Their heat capacities from 573 to 1273 K were measured by differential scanning calorimetry and their enthalpies of formation from component oxides at 298 K were determined by high‐temperature oxide melt solution calorimetry. The CALPHAD method was used to assess the ZrO2–SrO system, using both available literature data and our new measurements. A self‐consistent thermodynamic database and the calculated phase diagram of the ZrO2–SrO system are provided. This work is a prerequisite for accurate predictions of the relationships among the composition, temperature, and microstructure of complex functional and structural materials containing ZrO2 and SrO.