Investigation of electronic and optical properties of rare earths oxides: AB initio method

In this thesis electronic properties of Eu2O3 and Tb2O3 crystals which have cubic and monoclinic structure, was calculated with the ABINIT program that uses density functional theory for the first time. Volumetric optimizations of Eu2O3 and Tb2O3 of crystals were made and lattice parameters were found to be in agreement with the experimental results in literature. Total state density (DOS) of Eu2O3 and Tb2O3 crystals were calculated and plotted. Variation of DOS with energy exchange were examined. Electronic band structure of Eu2O3 and Tb2O3 crystals in the direction of high symmetry was calculated and optical transitions were determined. Direct band gap for Eu2O3 and Tb2O3 crystals was observed. Direct band gap for Eu2O3 and Tb2O3 crystals in the monoclinic structure were detected as 0,172 eV and 0,197 eV respectively. Calculated energy band gaps are found close to experimental values. All optical functions of Eu2O3 and Tb2O3 crystals, i.e., real and imaginary components of linear dielectric tensor depending to photon energy, the energy loss function, refractive index, extinction coefficient, reflection coefficient and the absorption coefficient, effective number of valance electrons and the effective optical dielectric constant were calculated and interpreted. Keywords: Eu2O3 , Tb2O3, electronic band structure, optical functions, density functional theory, ABINIT