Study of the thermoluminescence properties of γ and UV-C irradiated Li3PO4: Dy synthesized by solid state diffusion method

This paper reports the thermoluminescence (TL) properties of Li ₃PO ₄ doped with rare earth Dy ³⁺ ions. The solid state diffusion method is used to synthesize phosphors with varying concentrations of the dopant (0.1, 0.2, 0.3, 0.4 and 0.5 mol%). Characterization of the samples is performed using X-ray diffraction (XRD), Fourier Transform Infrared-Attenuated Total Reflection spectroscopy (FTIR-ATR) and Scanning Electron Microscopy (SEM). Samples are irradiated with γ rays in the dose range of 10 Gy to 6 kGy and by UV-C rays (254 nm) for exposure duration ranging from 0.5 to 5 h. Maximum TL intensity in both cases is observed for the phosphor doped with 0.2 mol% Dy ³⁺. While a linear TL response is found for the entire duration of UV-C irradiation, the dose response for γ irradiation stays linear upto 3 kGy for the high temperature peak at 335 ^∘C. Appreciable repeatability values are found (for both γ and UV-C irradiated samples) and significantly low fading (for the UV-C irradiated phosphor) is reported. The computerized glow curve deconvolution has been done using an R-package, “tgcd: Thermoluminescence Glow Curve Deconvolution” by assuming the Kitis general order kinetics model. Chen’s peak shape method is utilized to extract trapping parameters such as the order of kinetics ( b), shape factor ( μ _g), frequency factor ( s ), activation energy ( E) and trap density ( n ₀ ). Various promising properties of this material are found suggesting that it could be used as a TL dosimeter.