Synthesis and low dose response of Li 2 B 4 O 7 :Ag phosphor for radiation dosimetry

Li2B4O7:Ag phosphor was synthesized using a modified solid-state reaction with sequential heating steps. The structural and morphological characteristics were analyzed through X-ray diffraction (XRD) and Scanning Electronic Microscope (SEM). The elemental composition of the materials was confirmed through Energy Dispersive X-Ray Analysis (EDX). Photoluminescence studies revealed an emission peak at 346 nm under 331 nm excitation. Thermoluminescence (TL) glow curve exhibits multiple overlapping peaks in the temperature range of 50–400 °C. TL glow curve was deconvoluted and the kinetic parameters, such as activation energy and frequency factor, were evaluated by the TL glow curve deconvolution method. The phosphor exhibited an approximately linear TL dose response over the investigated dose range of 1 mGy to 30 Gy, while the OSL dose response was also nearly linear over most of this range, with some sublinearity observed at higher doses. The CW-OSL decay curve was successfully resolved into three exponential components (fast, medium and slow), associated with differences in photoionization probability and optical cross-sections of the trapping centers. The Li2B4O7:Ag phosphor demonstrated OSL sensitivity 0.82 times that of α-Al2O3:C phosphor, with a minimum detectable dose (MDD) of ∼60 µGy. The effective atomic number of Li2B4O7:Ag phosphor (Zeff = 7.4) is tissue equivalent. The stable OSL output signal over 20 cycles confirms good reusability and fading of the OSL signal was found to be about 50% in 1 day, stabilizing thereafter with no further loss.