Thermoluminescence dose and heating rate dependence and kinetic analysis of ZnB_2O_4:0.05Dy~(3+) phosphor

摘要

The intention of this study is to explore the thermoluminescence (TL) behavior of beta irradiated 5% Dy~(3+) doped zinc borate (Zn(BO_2)_2:0.05Dy~(3+)) phosphor prepared using the nitric acid method. The TL glow curve corresponding from 1 Gy to 80 Gy beta irradiation (preheated at 140 ℃) shows a maxima at c.a. 180 ℃. The dependence of heating rate was tested and found out that thermal quenching effect was dominating on TL glow curves as the heating rate increases. The dose response of the phosphor material exposed to beta radiation was investigated. Deconvolution was applied using the peak fit method on the glow curve for optimized conditions. Also peak shape (PS), various heating rates (VHR) and computerized glow curve deconvolution (CGCD) methods were used to evaluate the trapping level parameters, namely trap depth (E), frequency factor (s) and order of kinetics (b) associated with the main glow curve in Zn(BO_2)_2:0.05Dy~(3+) phosphor after beta irradiation of 20 Gy. The values of trap depth corresponding with the TL glow peak at 180 ℃ were found to be 0.93 eV, 0.92 ± 0.05 and 1.05 ± 0.02 respectively. Furthermore Wand c parameters characterizing thermal quenching based on the Mott-Seitz theory were determined as 0.31 ± 0.04 eV and 162.55. The TL mechanism appears more likely to get second order kinetics, suggesting the probability of re-trapping of charge carriers by emptied traps.