Thermo-luminescence kinetic parameters of γ-irradiated Sr4Al14O25:Eu2+, Dy3+ phosphors

In this paper, we present a detailed investigation of the thermo-luminescence (TL) kinetics of the long afterglow phosphor, Sr4Al14O25:Eu2+,Dy3+, synthesized by the combustion method. Kinetic parameters such as the activation energy (E), the frequency factor (s) and the order of kinetics (b) were calculated using Chen's formulism. The crystalline structure of the phosphor was examined using X-ray powder diffraction and transmission electron microscopy. The average particle size was found to be in the range of 45-52nm. The optimum dopant concentrations were Eu (1mol%) and that of Dy (2mol%). The TL response of the phosphor was monitored after the samples were irradiated with a -dose using a Co-60 source in the 20-800Gy range. A broad TL peak, (stretching from 328 to 410K) with a maximum at 368K was observed. With increasing irradiation dose, the main peak shifts toward higher temperatures. Symmetry factor calculations show that the main TL glow peak obeys second-order kinetics, which could be attributed to the creation of deep level traps. This means that -ray irradiation greatly affects the distribution of traps in the Sr4Al14O25:Eu2+,Dy3+ phosphor. The phosphor showed a linear response with -dose.