TL behavior of Ca 0.5Sr 0.5S:Ce nanophosphors

Abstract

Ca 0.50Sr 0.50S:Ce nanophosphors were synthesized via solid state diffusion method. XRD shows a single cubic phase of Ca 0.50Sr 0.50S: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 Ca 0.50Sr 0.50S: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.