Effect of point defects on heat capacity of yttria-stabilized zirconia

First-principles calculation and anharmonic dynamical theory were used in sequence to explain a large excess heat capacity observed in yttria-stabilized zirconia in comparison with the additive rule value. It is found that the excessive shape of heat capacity decays gradually with the Y$_{2}$O$_{3}$ doping when the number of environmentally different O sites falls to its zero value at 33 mol % Y$_{2}$O$_{3}$-ZrO$_2$ due to the Y atoms adjacent. The model and results presented in this work provide a key insight into the complex behaviour and characterization of fast-ion conductors.