First-principles calculations of mechanical and thermodynamic properties of YAlO3

First-principles calculations are performed to investigate the crystal structure, electronic properties, the elastic properties, hardness and thermodynamic properties of YAlO3. The calculated ground-state quantities such as lattice parameter, bulk modulus and its pressure derivative, the band structure and densities of states were in favorable agreement with previous works and the existing experimental data. The elastic constants C-ij, the aggregate elastic moduli (B, G, E), the Poisson's ratio, and the elastic anisotropy have been investigated. YAlO3 exhibits a slight elastic anisotropy according to the universal elastic anisotropy index A(U) = 0.24. The estimated hardness for YAlO3 is consistent with the experimental value, and Al-O bond in AlO6 octahedra plays an important role in the high hardness. The Y-O bonds in YO12 polyhedra exhibit different characteristic. Using the quasi-harmonic Debye model considering the phonon effects, the temperature and pressure dependencies of bulk modulus, heat capacity and thermal expansion coefficient are investigated systematically in the ranges of 0-20 GPa and 0-1300 K. (C) 2011 Elsevier B.V. All rights reserved.