Mechanoluminescence and thermoluminescence characterization of Tb3+ doped CaAl2O4: a theoretical and experimental study
Abstract
Mechanoluminescence and thermoluminescence of Tb in CaAl2O4 prepared by a solution combustion method has been reported. Phase purity, formation of a phosphor and surface morphology were confirmed by XRD and SEM techniques. The resulting phosphors were characterized by photoluminescence (PL) to detect incorporation of the dopant. When a gamma-irradiated Tb-doped CaAl2O4 crystal is impulsively deformed, two peaks appear in the ML intensity versus time curve, whereby the first ML peak is found in the deformation region and the second in the post deformation region of the crystals. The energy levels and hence trapping and detrapping mechanism of charge carriers can be explained using ML. The Tb-doped CaAl2O4 phosphor can be used in the dosimetric applications for ionizing radiation. The TL characteristics of CaAl2O4 may be useful for high radiation doses. Thermoluminescence (TL) materials have wide applications in the dosimetry of ionizing radiation, scintillators, X-ray laser materials, etc. The samples were irradiated using a 60Co gamma-ray source at a dose of 0.930 kGy h−1 and the heating rate used for TL measurements was 5 °C s−1. The samples show good TL peaks for 0.2 mol% (urea), 0.2 mol% (hydrazine) and 0.2 mol% (carbohydrazide) doping concentrations of Tb3+ ions. We also report a more detailed theoretical understanding of the mechanism of TL and ML. All TL glow curves obey the second-order kinetics with a single glow peak, which reveals that only one set of trapping parameters is set for a particular temperature. The TL sensitivity was found to depend upon the annealing temperature and Tb3+ doping concentration. The prepared sample may be useful in TL dosimetry.
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