Preparation and Luminescent Properties of Eu3+ Doped B2O3-CaO Luminescent Materials

The high pure B2O3-CaO:Eu3+ phosphor is prepared by sol-gel method. The structures of samples obtained at different annealing temperatures are characterized by XRD and IR. It is found that the borate matrix with different structures can be formed with the change of annealing temperature. Based on the analysis of the excitation spectrum, emission spectrum and fluorescence decay curves of borate phosphors with different structures, the luminescent properties and luminescent mechanism of the phosphors are investigated. The result indicate that Eu3+ ions occupy no inversion symmetry site with the dominant electric dipole transition in borate matrix of the different structure, and these phosphors give off red light under ultraviolet excitation. The high pure CaB2O4 matrix obtained by annealing at 900 degrees C is most favorable for luminescence and the B2O3-CaO:Eu3+ phosphor have the longest fluorescence decay time. These are attributed to the fact that Eu3+ in the matrix is more likely to replace Ca2+ to form relatively large numbers of p-n junctions and traps.