Synthesis, structural characterization, and luminescence behavior of Tb-doped Zn2SiO4 phosphor: Insights into radiation-induced defect formation using the EPR technique

In this study, Tb-doped Zn 2 SiO 4 phosphor synthesized by the solid-state reaction method was examined. The thermoluminescence (TL) results of the phosphor doped with 0.03 mol% Tb and calcined at 1250 °C showed an intense peak centered at 265 °C, as well as other low-intensity peaks between 70 and 200 °C. The main peak, centered at 265 °C, shows a linear response for the dose range from 60 to 5000 mGy. In addition, the intensity of continuously optically stimulated luminescence (CW-OSL) was investigated as a function of dose, showing linear behavior for doses between 80 and 4000 mGy. On the other hand, EPR studies have been carried out on Zn 2 SiO 4 :Tb phosphor to determine the defect centers related to the TL process. Four defect centers have been identified. Center I is identified as the O − ion, characterized by the principal values g || = 2.0035 and g ⊥ = 2.018. This center was associated with the TL peak at 142 °C. Center II, with an isotropic g value of 2.012, is attributed to an O - ion. Center III is characterized by a g value equal to 2.0069 and was attributed to an F + center (single ionized oxygen vacancy). Center IV was also assigned to an F + center.