A combined ab initio and experimental study of lanthanides and/or transition metal doped oxides

Ab initio modelling techniques have produced a notable contribution in analysing semiconductor metal oxides properties by use of first principles. These techniques have transformed to a high level of accuracy, owing to the development in algorithms and improved computational ability. In the study of structural, electronic and optical properties of metal oxides, ab initio techniques have been used with a lot of success to illustrate these properties. Ab initio studies therefore can complement experimental findings or even provide reliable results on properties which have not yet been experimentally investigated. Properties which can be calculated with the use of density functional theory (DFT) include spectroscopic, energetic, electronic and geometric properties. In this combined experimental and ab initio work on metal oxides doped with transition metals, the used of local density approximation with the Hubbard U correlation to compute the structural, electronic and optical properties of ZnA12O4 and Cu2+:ZnA12O4 was used. The powders of doped and undoped ZnA12O4 were effectively synthesized by use of the sol-gel technique. The X-ray diffraction (XRD) pattern for ZnA12O4 displayed crystalline peaks corresponding to cubic structure and phase dissociation was not observed. It also showed negligible lattice distortion and a slight shift to higher angles with increase of Cu2+ percentage doping. Energy dispersive X-rays spectroscopy (EDS) confirmed pure samples of ZnA12O4 components. Scanning electron microscopy (SEM) micrographs showed a uniform, well distributed and spherical morphology. The high resolution transmission electron microscopy (HRTEM) showed the influence of varying Cu2+ concentration on the particle agglomeration as well as on the crystallite sizes. The average crystallite sizes of ZnA12O4 powders almost remained constant with the increase of Cu2+ doping concentration. The lattice spacing approximated from selected area electron diffraction (SAED) was 0.24