Energy transfer process in CaSO4 : Tb,Ce phosphor

Thermoluminescence (TL) and photoluminescence studies have been carried out on CaSO4:Tb, CaSO4:Ce, and, CaSO4:Tb,Ce phosphors with,the aim of studying energy transfer process in the CaSO4:Tb,Ce phosphor. (CaSO4Tb)-Tb-.,Ce shows TL peaks at 150, 220, 320 and 400degreesC. Changes in Tb and Ce concentrations influence the relative heights of these glow peaks. Co-doping with 0.1 mol% of Ce in CaSO4:Tb enhances the sensitivity of 320degreesC TL peak by a factor of 15. Fluorescence results show that there is energy transfer from Ce to Tb ion. The defect centres formed in CaSO4:Tb,Ce phosphor are studied using electron spin resonance technique. The 320degreesC glow peak correlates with a centre (SO3- radical) with g-values: g(parallel to) = 2.0061 and g(perpendicular to) = 2.0026. (C) 200