Investigation of thermoluminescence characteristics of CaSrS: Ce nanophosphors

Thermoluminescence characteristics of Ca0.75Sr0.25S: Ce nanophosphors exposed to UV radiations have been investigated. Solid state diffusion method was employed to synthesize the nanophosphors. The confirmation for the formation of the mixed lattice was done by XRD. The particles formed were found to have 45 nm size as calculated by the Debye Scherrer formula. TEM results were in close agreement with the XRD as the nanoparticles formed possess capsule like structure with an average diameter of 50 nm. TL glow curves for the low doses (110-1680 mJ/cm2) of UV show a main peak around 381 K and another peak of very low intensity around 570 K. The TL intensity increases up to 450 mJ/cm2 of UV exposure. At higher doses (3.5-80 J/cm2) the peak position varies slightly but the high temperature peak becomes more intense. Thermoluminescence characteristics of UV irradiated Ca1-xSrxS: Ce as a function of x (0.25, 0.50, and 0.75) have also been investigated. TL glow curves of Ca1-xSrxS: Ce (0.25, 0.50, and 0.75) recorded after 450 mJ/cm2 of exposure of UV radiations show almost similar structure except slight variation in the peak position. Ca0.25Sr0.75S: Ce and Ca0.50Sr0.50S: Ce have single peak at 373 and 367 K, respectively, while Ca0.75Sr0.25S: Ce has a main peak at 381 K and a less intense peak at 570 K. Ca0.75Sr0.25S: Ce shows the most intense TL peak. The trap parameters namely, activation energy (E), order of kinetics (b), and frequency factor (s) of Ca0.75Sr0.25S: Ce have been determined using Chen's peak shape method and GCD function suggested by Kitis for second order kinetics.