Dose effects on the long persistent luminescence properties of beta irradiated SrAl2O4:Eu2+, Dy3+ phosphor

The SrAl2O4:Eu2+, Dy3+ is a phosphor characterized by a long persistent luminescence (PLUM) when it is excited with UV-VIS light and ionizing radiation. In this paper, we study the PLUM behavior as a function of beta irradiation dose in the 0-650 Gy range with a fixed dose rate of 5 Gy/min. The PLUM intensity showed a complex decay behavior, exhibiting a near linear response in the 0-1.7 Gy low dose range and gradually increasing up to 160 Gy. The PLUM reached the saturation for higher doses (>275 Gy) with a slight decrease in the range of 300-650 Gy. In addition, a systematic PLUM enhancement was produced after a thermal cleaning procedure and irradiation at RT in a series of 10 cycles. The observed phenomenon may be related to a radiation-induced process of charge trapping accumulation, which is triggered by thermal stimulation during the irradiation stage. It improves the luminescent characteristics of SrAl2O4:Eu2+, Dy3+ phosphors rendering them suitable for permanent display and illumination devices. (C) 2009 Elsevier Ltd. All rights reserved.