The structural phase transition and elastic properties of zirconia under high pressure from first-principles calculations

The structural phase transition and elastic properties of monoclinic, orthoI and orthoII zirconium dioxide (ZrO₂) are investigated by using pseudopotential plane-wave methods within the Perdew-Burke-Ernzerhof (PBE) form of generalized gradient approximation (GGA). Our calculated equilibrium structural parameters of ZrO₂ are in good agreement with the available experimental data. On the basis of enthalpy versus pressure data obtained from our theoretical calculations for high pressure, we find that phase transition pressure from monoclinic to orthoI and orthoI to orthoII are ca. 7.94 GPa and 11.58 GPa, respectively, which are in good agreement with the experimental observations. Especially, the elastic properties of orthoII ZrO₂ under high pressure are studied for the first time. We note that the elastic constants, bulk moduli, shear moduli, compressional and shear wave velocities as well as Debye temperature of orthoII ZrO₂ increase monotonically with increasing pressure. By analyzing G/B, the brittle-ductile behavior of ZrO₂ is assessed. In addition, polycrystalline elastic properties are also obtained successfully for a complete description of elastic properties.