Thermodynamic descriptions of the Al ₂ O ₃ ‒ZrO ₂ , Na ₂ O‒ZrO ₂ , and Al ₂ O ₃ ‒Na ₂ O‒ZrO ₂ systems

Abstract Understanding the thermodynamic equilibria in the Al 2 O 3 ‒Na 2 O‒ZrO 2 system is essential for the design of refractory and ceramic materials. Using reliable phase diagram and thermodynamic property data, thermodynamic optimizations of the Al 2 O 3 ‒ZrO 2 , Na 2 O‒ZrO 2 , and Al 2 O 3 ‒Na 2 O‒ZrO 2 systems were performed using the Calculation of Phase Diagrams (CALPHAD) method. The liquid phase was described by using the ionic two‐sublattice model with the formulation (Al +3 , Na +1 , Zr +4 ) P (O −2 , AlO 2 −1 ) Q . The species AlO 2 −1 was introduced to model pure liquid Al 2 O 3 , ensuring compatibility with the latest thermodynamic optimization of the Al 2 O 3 ‒Na 2 O‒SiO 2 system. A new set of self‐consistent thermodynamic parameters for the Al 2 O 3 ‒Na 2 O‒ZrO 2 ternary system was obtained. Comprehensive comparisons between calculated results and experimental data demonstrate that the present thermodynamic descriptions accurately reproduce the experimental data.