Structural, electronic and optical properties of spinel oxides ZnAl2O4, ZnGa2O4 and ZnIn2O4

We report the systematic trends for structural, band structure, total density of states, dielectric function, reflectivity, refractive index and loss function for the family of spinel oxides ZnB2O4 depending on the type of B element (B are Al, Ga and In). The full-potential augmented plane wave plus local orbitals method based on the density functional theory is used within the generalized gradient approximation (GGA). Moreover, the alternative form of GGA proposed by Engel and Vosko (GGA-EV) is also used for the band structure calculations. The optimized zero pressure geometrical parameters: the unit cell length a, the internal coordinate u, the bulk modulus B and the pressure derivative of the bulk modulus B' are in agreement with the available experimental data. Results obtained for the band structure using GGA-EV show a significant improvement over other theoretical works and are closer to the experimental data. Calculations of optical spectra have been performed for the energy range 0-35 eV. The peaks and structures in the optical spectra are assigned to interband transitions. Pressure dependence of the band gaps, static dielectric constant and static refractive index are also investigated. (C) 2011 Elsevier Masson SAS. All rights reserved.