On the photo and thermally stimulated luminescence properties of U doped SrBPO₅

Highlights: • Synthesis of SrBPO₅:U phosphor by solid state route. • Confirmed the stabilization of uranium as UO₂²⁺. • Evaluation of order of kinetics and trap parameters of the system. • ESR-TSL correlation of the observed glow peak. • Probable mechanism proposed for the TSL glow peak. - Abstract: Un-doped and uranium doped SrBPO₅ samples were synthesized using solid-state reaction route and investigated for their photo and luminescence properties. Photoluminescence (PL) spectrum of uranium doped sample showed five peaks at 502, 524, 547, 569 and 597 nm. The average frequency of symmetric stretching of O=U=O in the ground electronic state was found to be about 757 cm⁻¹. PL decay time measurements on the system confirmed the stabilization of uranium as UO₂²⁺ in the matrix. Thermally stimulated luminescence (TSL) measurements carried out on gamma irradiated SrBPO₅:U sample showed a glow peak at 390 °K, whose spectral characteristics was found to be typical of UO₂²⁺. The trap parameters were evaluated using different heating rate method. Room temperature EPR data suggested the formation of borate and oxygen based radical centers in the gamma-irradiated sample. Detailed EPR-TSL correlation studies confirmed the destruction of the oxygen radical to be responsible for the observed glow peak