Thermoluminescence and persistence luminescence of barium aluminate (BaAl₂O₄) and Eu doped BaAl₂O₄ phosphors: a preliminary study

Thermoluminescence (TL) and persistence luminescence (PerL) are two luminescence emission phenomena associated with trapping and subsequent release of charge carriers in various point defects in a crystal. We report preliminary results of TL and PerL of an undoped BaAl₂O₄ and a 2% Eu doped BaAl₂O₄ phosphor synthesized using a solution combustion method. Surface morphological analysis suggests that the average grain size of the undoped sample is ~ 60.67 nm whereas that of the doped sample is ~ 53.45 nm. A TL glow curve of the undoped sample recorded at 1 ^oC/s following 260 nm UV-C irradiation for 15 min shows a weak TL glow peak at ~ 102 ^oC. On the other hand, the doped sample under identical measurement conditions shows a high intensity glow peak at ~ 184 ^oC. For both samples, the peak intensity was found to increase sublinearly with irradiation time. Under the UV-C irradiation, both samples show PerL for more than 1 h. The intensity of PerL of the undoped sample is found to be weaker than that of the doped one. This study reveals that the undoped BaAl₂O₄ sample has intrinsic electron traps which help to persist luminescence in BaAl₂O₄. This preliminary study also reveals that the intensities of TL and PerL in BaAl₂O₄ can be enhanced by doping of Eu.