TL, OSL, EPR, and defect centers in Tb-doped strontium silicate phosphor synthesized by a solid-state reaction method

Strong thermoluminescence (TL) was observed in Tb-doped strontium silicate phosphor prepared by the solidstate reaction method. Two glow peaks are observed at 100 and 190 degrees C. TL emission spectra indicate three recombination centers. The number of peaks and the kinetic parameters associated with the TL glow peaks of Tbdoped Sr2SiO4 phosphor after gamma irradiation were analyzed by Tm-Tstop and deconvolution methods. A study of defect centers induced by gamma-irradiation and identification of defect centers responsible for the observed TL glow peaks has been carried out using the electron paramagnetic resonance (EPR) technique. The observed spectrum at room temperature is a superposition of at least three defect centers. Center I is characterized by an axially symmetric g-tensor with principal values g|| = 2.019, and g perpendicular to = 2.0013 and is ascribed to a O2  ion. Center II has a rhombic g-tensor with principal values 2.0072, 2.0024, and 1.995 and is assigned to an F+ center (singly ionized oxygen vacancy) and correlates with the 190 degrees C TL peak. The third center (center III) has an isotropic g value of 1.991 and is identified as an F+ center.

Automated summary

The thermoluminescent properties and defect centers induced by gamma irradiation in Tb-doped strontium silicate phosphor were studied. The number of TL glow peaks and the kinetic parameters were analyzed using Tm-Tstop and deconvolution methods. The electron paramagnetic resonance technique was used to identify the defect centers responsible for the observed TL glow peaks.