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 Cij, 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 AU = 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.

► This paper systematically studied the mechanical and thermodynamic properties of YAlO3 from first-principles calculations.
► YAlO3 is mechanically stable and it is brittle for B/G < 1.75.
► The universal elastic anisotropy index AU for YAlO3 is 0.24, so YAlO3 is slightly anisotropic.
► The high hardness of YAlO3 is mainly due to the existence of Al–O bonds. Y–O bands in YO12 polyhedra exhibit different characters.