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

Abstract

This paper reports the thermoluminescence (TL) properties of Li3PO4 doped with rare earth Dy3+ 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% Dy3+. 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 (μg), frequency factor (s), activation energy (E) and trap density (n0). Various promising properties of this material are found suggesting that it could be used as a TL dosimeter.