Energy transfer and excitation wavelength dependent long-lasting phosphorescence in Pr3+ activated Y3Al5O12

Long-lasting phosphorescence (LLP) was observed in Pr3+-doped Y3Al5O12 (YAG:Pr) after it was excited by 240 or 290 nm light. The photoluminescence (PL) and LLP properties were studied. It is interesting that the PL and LLP spectra were different. In the PL emission spectra both the emissions of d–f and f–f transitions of Pr3+ ions were observed. However, in the LLP spectra of YAG:Pr the emissions of d–f transition were absent. It is deduced that the differences were due to the energy transfer process between traps and emission centers. On the other hand, significant differences were observed between the two LLP spectra after the sample was excited by 240 and 290 nm lights, respectively. The thermoluminescence (TL) properties were also studied. It is suggested that these studies will be significant for understanding the mechanism of LLP phenomenon.