Thermally stimulated luminescence of alkaline earth sulphide phosphors doped with cerium and samarium impurities

Alkaline earth sulphide phosphors (CaS, SrS, and BaS) doped with rare earth ion (Sm and Ce) impurities were prepared by carbon reduction of pure sulphates of Ca, Sr, and Ba in a N2 atmosphere and using NaCl as flux. The thermally stimulated luminescence of these phosphors was studied by excitation with ultraviolet-, γ-, and X-rays. Intense glow maxima in the temperature range from 60 to 85°C were exhibited by most of the phosphors under the three methods of excitation. Some results on thermally stimulated conductivity and photoluminescence relevant in this context are also reported. Considering all these results, the trapping centres responsible for the energy storage in this system of phosphors were identified as Sm and Ce and their complexes involving native defects.MST/405