Synthesis and characterization of ZnGa2O4:Cr3+Ge3+ compounds with tunable photoluminescence properties

Abstract

Pure and doped (Cr and Ge) ZnGa2O4 compounds are prepared using solid-state reaction method. Single-phase nature of pure and doped ZnGa2O4 compounds is investigated using X-ray diffraction (XRD). XRD results indicate lower theta angle shifting, decrease in particle size and tensile strain in the doped samples. A granular morphology of amalgamated particles is seen in the SEM images. EDS results convey, practically, the same concentrations (atm%) of doped elements as used during the preparation. X-ray absorption near-edge structure (XANES) results helped to determine the valence state of elements. O K-edge XANES shows a significant orbital hybridization of O 2p shells with the d shells of doped atoms (i.e., Cr and Ge). Broad PL bands, of nearly the white-light emission, are observed in all of the samples. Modification in the PL intensity and emitted wavelengths, upon doping of Cr3+ and Ge3+ ions, are discussed through the energy transfer mechanisms and defects in the compounds.