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SrAl2O4:Eu2+, Dy3+ is a phosphor characterized by a long persistent luminescence (PLUM) when excited with UV–vis light and ionizing radiation exhibiting intensity variation in the 10–320 K temperature range and maximum intensity around 320 K. In this work, we study the PLUM behavior of SrAl2O4:Eu2+, Dy3+ as a function of temperature from room temperature to 670 K in samples exposed to β irradiation. The room-temperature irradiation followed by PLUM readout revealed an integrated PLUM maximum at 323 K decreasing later. In contrast, irradiation and PLUM readout at temperatures above room temperatures produced integrated PLUM intensities maxima around 425 and 625 K. Successive cycles of preheating followed by irradiation and PLUM readout produced an increasing of the PLUM intensity as a function of cycle number. The observed phenomenon was ascribed to trapped electrons at the multiple trapping states related to the 425 and 625 K defects levels and electron transfer from one trap to another (electron hopping). Eventually, there is a return to the 5d level of Eu3+ cations with the characteristic PLUM emission by thermal energy supplied at room temperature (lattice vibrations) or by a preheating–irradiation-readout cycle. This property may allow keeping up the PLUM properties of SrAl2O4:Eu2+, Dy3+ phosphors through background radiation self exposure and adequate heating processes.

Current radiation dosimetry methods involve the release of trapped charge carriers in the form of electrons–holes pairs generated by irradiation exposure of the dosimetric materials. Thermal and optical stimulations of the irradiated material freed the trapped charges that eventually recombine with interband centers producing the emission of light. The integrated intensity of the emitted light is proportional to the radiation dose exposure. In this work, we present an UV radiation dosimetry technique based on the characteristic persistence luminescence (PLUM) 4f65d1→4f7 electronic transition of Eu2+ ions in SrAl2O4:Eu2+, Dy3+. The dose assessment is carried out by measuring the PLUM signal integrated during a certain time. The PLUM performance of SrAl2O4:Eu2+, Dy3+ phosphor exhibited a linear behavior for the first 50 s of UV irradiation. For higher UV time exposure the behavior is sublinear with no apparent saturation during a 10 min period. The PLUM dosimetry response was performed at 400 nm that corresponds to the main band component of the PLUM excitation spectrum in the 250–500 nm range. The main advantage of a dosimeter device based on the PLUM of SrAl2O4:Eu2+, Dy3+ is that neither thermal nor optical stimulation is required, avoiding the need of cumbersome electronic photo/thermal stimulation equipment. Due to the highly efficient 250–500 nm PLUM response of SrAl2O4:Eu2+, Dy3+, it could have potential application as UV radiation dosimeter in the UV range of grate human health concerns caused by UV solar radiation.

The SrAl 2 O 4 :Eu 2+ , Dy 3+ 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 SrAl 2 O 4 :Eu 2+ , Dy 3+ phosphors rendering them suitable for permanent display and illumination devices.

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