Rare Earth Doped Lithium Tetraborate for Optically/Thermally Stimulated Luminescence Dosimetry

Radiometry materials tested from optically stimulated luminescence (OSL) and thermally stimulated luminescence (TL) are widely used in environmental radiation monitoring, nuclear medicine and space exploration. Li₂B₄O₇ (LTB, Lithium tetraborate) with similar equivalent atomic number to that of human tissue, which can improve the absorbed dose accuracy and broaden the radiation dosimetry range with rare earth elements regulation. LTB ceramic compacts by different Er ions doping were prepared by the hydrothermal method, then their morphological features, crystal structures, and compositional components were systematically characterized. The characteristic luminescence spectra and concentration quenching effects at different doping levels were investigated using UV-vis absorption and photoluminescence (PL) spectroscopy, complemented by analysis of elemental oxidation states, binding energies, and impurity-induced energy levels. It was found that the LTBE: Er(0.5 mol.%) sample exhibited the highest luminescence intensity. However, as the doping concentration decreased, the luminescence lifetime shortened from 6.13 ms to 3.98 ms. For OSL/TL performance evaluation, their repeatability and reproducibility were investigated, and the precise deconvolution of the luminescence curves enables rigorous quantification of trap parameters with activation energy and frequency factor through kinetic analysis. The correlation between time-dependent luminescence decay behavior and trap distribution is revealed, and we elucidate how competing electron retrapping processes and radiation-induced defect configurations collectively govern the photo-stimulated charge transfer dynamics. The optimized sample demonstrated excellent OSL dose–response characteristics, showing good linearity over a range of 0.05–250 Gy. The precise doping of rare earth elements provides atomic-level modulation for optimizing the OSL/TL performance of LTBE as radiation dosimetry.