Dose-response and trap kinetics of Dy3+-doped LiCa4O(BO3)3 for thermoluminescence dosimetry

Abstract

LiCa4O(BO3)3:Dy3+ (0.5 wt%) phosphors were investigated as potential thermoluminescent (TL) dosimeters under β irradiation. Following preheating at 155 ◦C for 10 s and readout at 2 ◦C s − 1 , the material exhibits a wellresolved main dosimetric peak at ~185 ◦C whose maximum temperature remains essentially independent of dose between 1.4 and 150.1 Gy. The integrated TL signal and peak intensity follow a power-law dose dependence (I ∝Db ) with exponents b ≈ 1.07–1.16, indicating an extended quasi-linear response with slight supralinearity at higher doses. Variable heating rate analyses using the Hoogenstraaten and Booth–Bohun–Parfianovitch formalisms yield consistent activation energies of E ≈ 0.86–1.6 eV and frequency factors on the order of 1013 s − 1, supporting the presence of a relatively deep and thermally stable dosimetric trap. Tm–Tstop and E–Tstop analyses reveal a mixed trap hierarchy with stepwise quasi-stable energy intervals, indicative of thermally grouped shallow, intermediate and deep trapping regions. Computerized glow-curve deconvolution resolves the composite glow curve into ten general-order components (≈0.85–1.65 eV) prior to preheating, which reduce to five deeper components (≈1.44–1.67 eV) after thermal cleaning, consistent with the suppression of shallow traps and the dominance of stable dosimetric levels. Post-irradiation storage exhibits a two-stage temporal evolution of the ~185 ◦C peak, characterized by early intensity build-up followed by long-term fading while Tm remains constant, behaviour consistent with charge redistribution within a mixed-trap framework. Overall, the results indicate that LiCa4O(BO3)3:Dy3+ combines a thermally robust main peak, extended quasi-linear dose response, and low effective atomic number, supporting its potential for tissue-equivalent TL dosimetry