Persistent luminescence, TL and OSL characterization of beta irradiated SrAl₂O₄:Eu²⁺, Dy³⁺ combustion synthesized phosphor

The persistent luminescence (PLUM), thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of strontium aluminates co-doped with Eu⁺² and Dy⁺³ exposed to beta radiation is reported. The phosphor was synthesized by the combustion synthesis method employing a highly exothermic redox reaction between the metal nitrates [Al(NO₃)₃, Sr(NO₃)₂, Eu(NO₃)₃ and Dy(NO₃)₃] and organic fuel carbohydrazide (CH₆N₄O). The long decay PLUM emission, TL and OSL were measured as a function of beta radiation dose. A wide emission band centered at 510 nm (green) related to Eu²⁺ ions and lattice defects were observed for the synthesized samples. The presence of a variety of defects and aggregates were responsible for the observed broad 100 °C peaked TL glow curve of the irradiated sample which is composed of several overlapped TL peaks. The existence of multiple trapping levels, with different trapping/detrapping probabilities, is behind the particular features for the PLUM, TL and OSL emissions. We conclude that in the SrAl₂O₄:Eu²⁺, Dy³⁺ phosphors, the low temperature TL peaked around 30-75°C is responsible for the PLUM emission and those around 100°C were related to very stable trapping states which provide suitable radiation storage properties to be used as a PLUM/TL/OSL radiation phosphor.