The effect of annealing on spectral characteristics of the Ti doped MgAl2O4 crystal

Abstract The prepared Ti:MgAl2O4 crystal samples were annealed at different temperature for 24 hours in an air atmosphere, and then the transmission spectra, emission spectra, excitation spectra and photoluminescence decay curve were recorded. Furthermore, electron spin resonance of annealed samples were measured at 130 K. It is found that the absorption bands disappeared and the fluorescence intensity increased after annealed at 1200 °C. And when the annealing temperature is up to 1400 °C, the intensity of fluorescence emission was reduced significantly. These results are related to the oxidation of Ti3+ to Ti4+ and the increase of the disorder of cations. The shortening of fluorescence lifetime of the annealed samples may be related to the decrease or disappearance of oxygen vacancies.