Photo transfer thermoluminescence in CASO 4:Dy — grain size dependence

Abstract

The grain size dependence of PTTL (photo transfer TL) and RTL (residual TL) in CaSO 4: Dy TL phosphor has been studied. For unground phosphor the PTTL was found to decrease as a function of grain size and for 53–37 μm grain size range the PTTL was found to be higher by a factor of 7.5 compared to the phosphor of grain size range 840–420 μm. When this unground phosphor in different grain size ranges were ground separately to 53–37 μm grain size, the PTTL in each case was found to increase. However, this increased PTTL was always less than that of the unground phosphor of 53–37 μm grain size but increased with the decrease in the original grain size range from which it was obtained. The residual glow curves of smaller grain size phosphor have an additional glow peak at 520 ° C which has been also found to contribute to the PTTL besides the 420 ° C glow peak. The PTTL was found to increase with Dy-concentration initially upto 0.05 mole %, thereafter it steadily decreased with the Dy-concentration.