Evaluation of trapping parameters of γ-rays irradiated Dy3+ -doped LaPO4 phosphors

Thermoluminescence (TL) materials are widely used in radiation measurements. The best-known applications of TL materials are in the dosimetry of ionizing radiation, and in CTV screen phosphors, scintillators, X-ray laser materials, etc. The TL glow curve and its kinetic parameters for annealed LaPO4 at different constant temperatures and for Dy(3+) -doped LaPO4 phosphors irradiated by gamma-rays are reported here. The samples were irradiated using a (60) Co gamma-ray source at a dose of 10 Gy and the heating rate used for TL measurements was 5 ºC/s. The samples were characterized using X-ray diffraction (XRD), Fourier transform infrared, transmission electron microscopy and TL techniques. The XRD pattern shows that the prepared phosphor has a good crystalline structure with an average crystallite size of ~ 18 nm. The samples show good TL peaks for 0.05, 0.1 and 0.2 mole % doping concentrations of Dy(3+) ions and anneal above 400 ºC. The TL glow curve characteristics of annealed LaPO4 and Dy(3+) -doped LaPO4 were analyzed and trapping parameters calculated using various methods. All TL glow curves obey the second-order kinetics with a single glow peak, which reveals that only one set of trapping parameter is set for a particular temperature. The TL sensitivity was found to depend upon the annealing temperature and Dy(3+) doping concentration. The prepared sample may be a new nano phosphor and be useful in TL dosimetry.