Thermally stimulated luminescence and electron paramagnetic resonance studies of 147Pm doped K3Na(SO4)2

Rare earth and actinide doped alkali and alkaline earth sulphates, exhibit a variety of point defects stabilized due to the charge imbalance/self-irradiation and they play an important role in luminescence properties. In this paper, we report the point defects formed in the mixed sulphate K3Na(SO4)(2) on doping with the radio-active rare earth element Pm-147 as studied by TSL and EPR techniques. EPR studies on self and gamma irradiated samples showed the signal due to the radical pair, SO4--SO3- in addition to the signals from SO4-, SO3- and O-2(-) ions. However EPR spectra of electron beam irradiated (undoped) K3Na(SO4)(2) samples did not show the presence of the radical pair SO4--SO3-, indicating the importance of dopant per se, in stabilizing the radical pair. EPR studies of Pm-147 doped samples annealed at different temperatures after gamma irradiation showed that SO4--SO3- radical pair gets destroyed around 550 K, whereas SO4- ion gets annealed in the temperature range 375-450 K. SO3- ion was found to be stable upto 600 K. From TSL-EPR correlation, it is inferred that the release of trapped hole at SO4- ion on heating leads to the formation of SO42- * and energy transfer to Pm3+ ion, results in the glow peak at 415 K. (C) 2003 Published by Elsevier Science Ltd.