In this study, the long photoluminescence phosphor, SrAl2O4 : Eu2+,Dy3+ was synthesized by a coprecipitation method in which metal salts of Sr(NO3)2, Al(NO3)3 ·9H2O, were dissolved in a (NH4)2CO3 solution with Eu(NO3)3 ·5H2O and Dy(NO3)3 ·5H2O added as an activator and co-activator, respectively. The coprecipitated products were separated from the solution, washed, dried in a vacuum and heated at 800-1400 oC for 3 h under a reducing ambient atmosphere of 95%Ar +5%H2. For the synthesized SrAl2O4 : Eu2+,Dy3+ , the properties of photoluminescence such as emission, excitation and decay time were examined. Monitored at 520 nm, the excitation spectrum showed a maximum peak intensity at 313 nm with a broad band from 200-500 nm. The shift of main peaks of excitation toward shorter wavelengths for the phosphors prepared by the coprecipitation method occurred due to the quantum size effect of the nano-sized particles, compared with those produced by the solid-state reaction method. The emission intensity increased as the annealing temperature increased and showed a maximum peak intensity at 510 nm with a broad band from 400-650 nm. The decay time of SrAl2O4 : Eu2+,Dy3+ increased as the heat treatment temperature increased.

Keywords: Photoluminescence, Long phosphorescence phosphor, Decay time.