First-principles study of structural, electronic, elastic and phonon properties of AB2O4 (A = Ge, Si; B = Mg, Zn, Cd) spinel oxides

The structural, electronic, elastic and phonon properties of the cubic spinels AB(2)O(4) (A = Ge, Si; B = Mg, Zn, Cd) compounds at zero pressure are investigated via density functional theory (DFT) using the Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional. It has been shown that the predicted values of the structural parameters (a(0) and u), bulk modulus (B), elastic constants (C-ij), shear modulus G and B/G ratio are in good agreement with the previously reported results. The phonon dispersion curves of the AB(2)O(4) (A = Ge, Si; B = Mg, Zn, Cd) are calculated for the first time using the direct method. The estimated phonon spectra indicate that GeMg2O4, GeZn2O4, GeCd2O4, SiMg2O4 and SiZn2O4 are dynamically stable in the cubic spinel structure.