Effect of annealing treatment on the persistent luminescence of Y3Al2Ga3O12:Ce3+,Cr3+,Pr3+ ceramics

The Y3Al2Ga3O12:Ce3+,Cr3+,Pr3+ (YAGG) persistent luminescent ceramics were sintered in static air (without airflow) and followed by hot isostatic pressing (HIP) treatment. The low aggregated and relatively narrow particle-size distributed starting powders, with the particle size of about 50 nm, were synthesized by using Pechini method and then annealed at 900 °C for 16 h in static air. Compared to nano-phosphors, the ceramics exhibited more intense and longer persistent luminescence (PersL). The photoluminescence and PersL spectra were found to have a similar shape, indicating that the emitting centers for photoluminescence and PersL processes were same. The intense Ce3+ and Cr3+ bands, as well as weak Pr3+ narrow peaks, were observed under and after blue light irradiation, due to energy transfer from donor (Ce3+) to emitting centers (Cr3+ and Pr3+). The annealing treatment in static air significantly decreased the intensity and shortened the duration of the PersL of the ceramic, due to the elimination of oxygen vacancies, which played an important role of energy traps during PersL process.