A self-activated MgGa2O4 for persistent luminescence phosphor

The spinel compound MgGa2O4 synthesized by a high temperature solid state reaction method exhibits a long and bright blue persistent luminescence with UV source excitation. The blue afterglow can be observed by naked eyes in the dark for at least 10 min. The photoluminescence spectra of the MgGa2O4 host reveal a broad emission band in the range of 325–650 nm with the main peak at 424 nm and the secondary weaker peak at 480 nm under 265 nm excitation. The thermoluminescence curve disclosed a broad distribution of the traps existent in the MgGa2O4 host. In addition, a systematic investigation about the photoluminescence and the thermoluminescence of Mn2+ or Cr3+ single doped MgGa2O4 was also conducted to examine the doping effect. It is found that the distribution of traps responsible for thermoluminescence was disturbed significantly by different doping. A mechanism of the emission and the persistent luminescence is proposed in the light of the comparison of the results of the undoped host and the doped samples. The results indicate that the various vacancy defects in the MgGa2O4 host play an important role in its persistent luminescence.