LAUSR

Abstract The structural, mechanical, and thermodynamic properties of cubic Y 2 O 3 crystals at different hydrostatic pressures and temperatures are systematically investigated based on density functional theory within the generalized gradient approximation. The calculated ground state properties, such as equilibrium lattice parameter a 0 , the bulk modulus B 0 , and its pressure derivative B 0 ′ are in favorable agreement with the experimental and available theoretical values. The pressure dependence of a / a 0 and V / V 0 are also investigated. Furthermore, the elastic constants C ij , bulk modulus B , shear modulus G , Young's modulus E , the ductile or brittle ( B / G ), Vickers hardness H v , isotropic wave velocities and sound velocities are calculated in detail in a pressure range from 0 to 14 GPa. It was found that the Debye temperature decreases monotonically with an increase in pressure, the calculated elastic anisotropic factors indicate that Y 2 O 3 has low anisotropy at zero pressure, and that its elastic anisotropy increases as the pressure increases. Finally, the thermodynamic properties of Y 2 O 3 , such as the dependence of the heat capacities C V and C P , the thermal expansion coefficient α , the isothermal bulk modulus, and the Gruneisen parameter γ on temperature and pressure, are discussed from 0 to 2000 K and from 0 to 14 GPa, respectively, applying the non-empirical Debye model in the quasi-harmonic approximation.