Synthesis and Luminescence Properties of Rare-Earth Doped Gadolinium Silicon Oxynitride with Cuspidine Structure

The luminescence properties of rare-earth doped Gd4Si2O7N2 with cuspidine structure were examined. The Gd4Si2O7N2 powder, i.e., a host material, was prepared by mechanically mixing a-Si3N4, SiO2, Gd2O3 and rare-earth oxide (activator) powders (in the stoichiometric ratio Si3N4 : SiO2 : Gd2O3 = 1 : 1: 4) by heating the mixtures at 1700ºC for 2 h in N2 atmosphere. When Ce3+ was doped to Gd4Si2O7N2, the emission peak of (Gd0.98Ce0.02)4Si2O7N2 appeared at 457 nm (excitation wavelength: 393 nm) where the blue light was emitted (the relative emission intensity = 0.11 against the standard substance: YAG: Ce3+ (P46-Y3)). When Tb3+ was doped to Gd4Si2O7N2, the emission peak of (Gd0.98Tb0.02)4Si2O7N2 appeared at 545 nm (excitation wavelength: 266 nm) where the green light was emitted (the relative emission intensity = 1.01 against the standard substance: YAG: Ce3+ (P46-Y3)). When both Ce3+ and Tb3+ were co-doped to Gd4Si2O7N2, the emission peak of (Gd0.79Ce0.01Tb0.20)4Si2O7N2 appeared at 545 nm (excitation wavelength: 393 nm) where the greenish yellow light was emitted (the relative emission intensity = 0.95). Such emitting behavior was discussed based upon the energy transfer from Ce3+ and Tb3+.