Mechanical and thermodynamic properties of ZrO2 under high-pressure phase transition: A first-principles study

The pressure-dependence behaviors of phase stability, mechanical and thermodynamic properties of ZrO2 in the second-order phase transition procedure (P2(1)/c --> Pbca --> Pnma) were systematically investigated for the first time by using density functional theory (DFT) calculations. We found that the phase transformation, P2(1)/c --> Pbca --> Pnma, occurs at around 9.09 GPa and 12.68 GPa from the Gibbs free energy calculations, respectively. Furthermore, the ground state properties, such as the lattice parameter and elastic constants of ZrO2 were also calculated which yield good agreement with previous work available. From the theoretical calculations, the elastic constants (C-ij), bulk modulus (B), shear modulus (G), Young's modulus (E), Poisson's ratio (m), elastic anisotropy (A(U)), brittle/ductile characteristic (B/G), hardness (H-V) and Debye temperature (Theta) of ZrO2 almost all experience different degrees of changes with the increasing pressure from 0 GPa to 20 GPa. Additionally, the related phases of ZrO2 keep thermodynamic and mechanical stability in the corresponding range of pressure during the procedure. Overall, this study presents insight on the quantitative theoretical prediction of mechanical and thermodynamic properties of ZrO2 and may provide references data for the future theoretical calculations and experimental results. (C) 2014 Elsevier B. V. All rights reserved.