Anisotropy in elasticity, sound velocities and minimum thermal conductivity of zirconia from first-principles calculations

The anisotropies of mechanics and thermodynamics properties of zirconia with three zero-pressure polymorphs were studied by using first-principles calculations. It has been shown that Young's moduli of three phases strongly depend on directions. The sound velocities of faster mixed mode (v+) is much larger than that of slower mixed mode (v−) and pure transverse mode (vt) in monoclinic phase. For both tetragonal phase and the cubic phase, most pure longitudinal mode (vl) have the greatest sound velocity among the three acoustic modes. According to the Clarke's model, three zero-pressure polymorphs zirconia also have pronounced anisotropic minimum thermal conductivity.