FP-LAPW study of the structural, elastic and thermodynamic properties of spinel oxides ZnX2O4 (X = Al, Ga, In)

We have performed density functional self-consistent calculations based on the full-potential augmented plane wave plus local orbital method with the local density approximation to investigate the structural, elastic and thermal properties of three spinel oxides: ZnAl2O4, ZnGa2O4 and ZnIn2O4. The computed ground state structural parameters, i.e. lattice constant, free internal parameter, bulk modulus and its pressure derivative, are in good agreement with the available theoretical an experimental works. Single and polycrystalline elastic parameters and their pressure dependence are calculated and compared with the previous theoretical results. Thermal and pressure effects on some macroscopic properties of ZnAl2O4, ZnGa2O4 and ZnIn2O4 are predicted using the quasi-harmonic Debye model in which the lattice vibrations are taken into account. We have computed the variations of the lattice constant, bulk modulus, volume expansion coefficient, heat capacities and Debye temperature with pressure and temperature in the ranges of 0–30 GPa and 0–1600 K.