TL behavior of Ca0.5Sr0.5S:Ce nanophosphors

Ca0.50Sr0.50S:Ce nanophosphors were synthesized via solid state diffusion method. XRD shows a single cubic phase of Ca0.50Sr0.50S:Ce with an average size of 31 nm. TEM shows rod like structures of diameter in the range 20-30 nm and having length of several nanometers. The thermoluminescence behavior of Ca0.50Sr0.50S:Ce nanophosphors have been investigated in the low (0.1-126 Gy) and high dose (1-6 kGy) range of gamma rays from 60Co source at a heating rate of 10 K/s. The TL glow curves show a main peak at 382 K with a shoulder at 470 K and a peak of very low intensity at 573 K in low dose region. In high dose range the peak position of the 382 K peak remains unchanged while the peak at 573 K shifted to 554 K and the shoulder at 470 K has turned into a peak at 456 K. The intensities of all the three peaks have increased while moving from low to high dose region but the rise in the intensities of 554 K and 456 K peaks is so rapid that these overshoot the intensity of 382 K peak in the high dose region. The effect of different heating rates (5 K/s, 10 K/s and 15 K/s) on the TL glow curve has been investigated for the samples exposed to a dose of 1 kGy. All the samples with different Sr and Ca concentrations show different TL glow curves. The PL emission spectrum has a main peak at 496 nm with a shoulder at 551 nm which may be due to the transition among 5d-4f levels of Ce in the mixed lattice.