An attempt has been made to synthesize the Eu 3+-activated Ca 9R(VO 4) 7 (R=Bi, La, Gd, and Y) red emitting phosphors by a modified sol-gel process. The phase formation processes of these samples have been characterized by thermogravimetric analysis (TGA) and x-ray diffraction (XRD). The optical excitation spectra of Ca 9R(VO 4) 7 samples showed an intense charge transfer band (CTB) along with a group of typical sharp lines from Eu 3+, and the emission spectra have been dominated by the electric dipole 5D 0- 7F 2 transition peaked at 614 nm. The parameters for the synthesis of these phosphors including their annealing temperature and concentration of Eu 3+ ions have also been optimized. No concentration quenching is found in this class of samples, and the Ca 9Eu(VO 4) 7 phosphor shows the strong red light. In addition, the thermal stability of phosphor Ca 9Eu(VO 4) 7 was also investigated, and the results indicate that this class of phosphors can be served as a potential red emitting phosphor candidate for LEDs.
- Red emission