Variation of trap depth by dopant/codopant and heating rate in CaWO4 phosphors

Abstract

This paper deals with comparative investigation on the thermoluminescence (TL) properties as well as trapping parameters of undoped, Dy3+ doped and K+ codoped CaWO4 phosphors. The glow curves of phosphors were recorded after exposure to γ-rays in the dose range 1–5 kGy at a heating rate of 5 °C/s. The glow curves of undoped, doped and codoped phosphors show single prominent glow peak at 100, 135 and 130 °C respectively. In order to investigate the effect of heating rate, TL glow curves were also recorded by varying the heating rates to 3 and 7 °C/s. The TL glow curves were analyzed in order to get the trapping parameters such as trap depth (E), order of kinetics (b) and frequency factor (s). The obtained trapping parameters confirm the presence of second order kinetics. The codoped phosphor show better linear TL response compared to other phosphors indicating their suitability in radiation dosimetry.