Correlated ESR, PL and TL studies on K3Na(SO4)(2): Eu thermoluminescence dosimetry phosphor

Abstract

Strong thermoluminescence (TL) was observed in K3Na(SO4)(2):Eu phosphor in the Eu doped K2SO4-Na2SO4 system. The defect centres formed in this TL phosphor are studied using the technique of electron spin resonance. Two glow peaks at 423 and 475 K are observed in K3Na(SO4)(2):Eu phosphor prepared by the melt method. The peak 475 K is shown to be at least thrice as sensitive as the conventional CaSO4: Dy phosphor used in the TL dosimetry of ionizing radiations. Two centres, assigned to SO4- and SO3-, are observed at room temperature in the melt prepared phosphor. Step annealing measurements showed a connection between these centres and the observed TL glow peaks. Three TL glow peaks at 360, 423 and 453 K are observed in the K3Na(SO4)(2):Eu phosphor prepared by the evaporation method. A SOS centre and two different SO4- centres are observed in this phosphor. TL and photoluminescence emission spectra indicate that the europium ion is in the divalent state in K3Na(SO4)(2):Eu phosphor. (C) 2001 .