Mechano and Thermoluminescence of Gamma-irradiated CaSO4:Dy Phosphor

In order to have a better idea of the interaction of the defect centres produced by gamma-irradiation with dislocation in the processes of deformation destruction, mechanoluminescence (ML) and thermoluminescence (TL) of gamma-irradiated CaSO4:Dy, these phoshors have been investigated. CaSO4:Dy phosphors were prepared by dissolving CaSO4.2H2O in sulphuric acid and evaporating the excess acid around 300 oC. ML was excited impulsively by dropping a load on to the sample. Two peaks have been observed in the ML intensity against time curve. The total light output, i.e. integrated ML intensity, increases with concentration of dopant, strain rate and with irradiation doses. The TL glow curves of CaSO4:Dy phosphors at different concentrations of dopant and irradiation doses were also recorded. Studies of the influence of post-irradiation annealing on the ML of CaSO4:Dy show that with the removal of the TL dosimetric peak (~210 oC) the ML intensity decreases markedly. A spectroscopic study of ML and TL has also been carried out to elucidate the mechanism of ML. Correlation between ML and TL has also been found.