| Abstract: | A series of YAG:Ce,Tb phosphors were synthesized by vacuum sintering method.Moreover,their spectral properties,thermal quenching behaviors and color rendering properties were investigated systematically.The photoluminescence emission spectra of YAG:Ce,Tb show a great red shift compared with that of YAG:Ce.Direct energy transfer from Tb~(3+) to Ce~(3+) ions is verified based on the analysis of different photoluminescence spectra.The quenching temperature for Tb~(3+)-doped YAG:Ce phosphors is about 490 K.The thermal activation energy is estimated to be 0.18 and 0.291 eV for Tb~(3+)-doped YAG:Ce and YAG:Ce phosphors,respectively.The smaller activation energy for Tb~(3+)-doped YAG:Ce means a more rapid nonradiative transition from 5d to 4f state,thus resulting in the lower quenching temperature.In addition,white LEDs with improved color rendering properties are achieved by using modified YAG:Ce,Tb phosphors. |
