Citrate-gel synthesis and luminescent properties of ZnGa_2O_4 doped with Mn~(2+) and Eu~(3+)

摘要

By using inorganic salts as raw materials and citric acid as complexing agent, spinel oxide ZnGa_2O_4 and Mn~(2+), Eu~(3+)-doped ZnGa_2O_4 phosphor powders were prepared by a citrate-gel process. X-ray diffraction (XRD), TG-DTA, FT-IR and luminescence excitation and emission spectra were used to characterize the resulting products. The results of XRD reveal that the powders begin to crystallize at 500 deg C and pure ZnGa_2O_4 phase is obtained at 700 deg C, which agrees well with the results of TG-DTA and FT-IR. In the crystalline ZnGa_2O_4, the Eu~(3+) shows its characteristic red (615 nm, ~5D_0-~7F_2) emission with a quenching concentration of 5 mol percent (of Ga~(3+)), and the Mn~(2+) shows green emission (505 nm, ~4T_1-~6A_1) with a quenching concentration of 0.1 mol percent (of Zn~(2+)). The luminescence mechanism of ZnGa_2O_4:Mn~(2+)/Eu~(3+) is presented.