Luminescence properties of Eu3+ doped La3Ga5GeO14 and effect of Bi3+ co-doping

Red-emitting phosphors La3Ga5GeO14: Eu3+, Bi3+ were prepared by high temperature solid state reactions. The structure and luminescence properties of these phosphors were investigated in detail. The X-ray diffraction study shows the phase formation of La3Ga5GeO14: Eu3+, Bi3+ phosphors. Scanning electronic microscope observation proves that the size of obtained samples is approximately 1-2 mu m. The band gap of La3Ga5GeO14 is calculated to be 5.234 eV based on obtained diffuse reflectance spectrum. Under the near ultraviolet excitation, Eu3+ doped samples can emit bright red light corresponding to the electric dipole transition (D-5(0) -> F-7(2) transition). The dipole-dipole interaction is dominating mechanism for the concentration quenching. The introduction of Bi3+ enhances the luminescence intensity of Eu3+. It also results in the red shift of charge transfer band of O-2- Eu3+. The effect of the co-doping of Bi3+ on the luminescence properties of Eu3+ is discussed in detail. The CIE chromaticity coordinates of typical La3Ga5GeO14: Eu3+, Bi3+ phosphor is close to red-emitting phosphor Y2O2S: Eu3+. Present research indicates that La3Ga5GeO14: Eu3+, Bi3+ is a promising candidate of red-emitting phosphor for white light-emitting diodes.