Defect luminescence and lattice strain in Mn2+ doped ZnGa2O4

Undoped and Mn2+ doped ZnGa2O4 phosphors were prepared by solution combustion method and characterized by XRD, SEM, luminescence and electron paramagnetic resonance (EPR) techniques. Based on XRD results, it is inferred that, strain in ZnGa2O4 host lattice increases with incorporation of Mn2+ ions in the lattice. Mn2+ doping at concentration levels investigated, lead to significant reduction in the defect emission and this has been attributed to the formation of higher oxidation states of Mn ions in the lattice. Electron Paramagnetic Resonance studies confirmed that majority of Mn ions exist as Mn2+ species and they occupy tetrahedral Zn2+ site in ZnGa2O4 lattice with an average hyperfine coupling constant, Aiso∼82 G.