Witherite-Modified Lithium Tetraborate Glasses: A Promising Candidate for Gamma-Ray and Fast Neutron Shielding Applications

Abstract

In this study, a series of lithium tetraborate (Li2B4O7) based glasses were synthesized by incorporating different amounts of witherite (BaCO3) ranging from 0 to 20 wt% via the conventional melt-quenching method. The amorphous nature of all prepared samples was confirmed by X-ray diffraction (XRD), showing a broad humb without any crystalline peaks. The density of the glasses increased from 2.26 g/cm3 (pure LB) to 2.54 g/cm3 with 20 wt% BaCO3 addition, due to the high atomic weight of barium. Gamma-ray attenuation properties were evaluated using a Ba-133 radioactive source (3 Ci) and a high-purity germanium (Ultra Ge) detector, across photon energies of 81, 276, 302, 356, and 383 keV. The linear attenuation coefficient (LAC) at 81 keV increased significantly from 0.382 cm-1 (0 wt%) to 1.956 cm-1 (20 wt%), while the mass attenuation coefficient (MAC) rose from 0.169 cm2/g to 0.771 cm2/g in the same range. The half-value layer (HVL) was reduced from 1.814 cm to 0.354 cm at 81 keV, indicating enhanced shielding with increasing BaCO3 content. The effective atomic number also increased as BaCO3 content increased. Buildup factor analyses (EBF and EABF), calculated over the 0.015-15 MeV range, demonstrated that 20 wt% BaCO3-doped samples exhibited lower buildup values than undoped glass across all photon energies and mean free path (mfp) values. Fast neutron attenuation was evaluated by calculating the effective removal cross section (Sigma R) with values ranging from 0.10957 to 0.10991 cm-1 for glass samples. In addition, experimental neutron dose measurements confirmed a clear improvement in dose absorption capacity, with the 20 wt% BaCO3 glass absorbing up to 30.45 % of the incident neutron dose. In conclusion, the incorporation of witherite significantly enhances gamma-ray attenuation due to increased density and effective atomic number, while maintaining effective fast neutron shielding from the LB matrix. The developed Li2B4O7-BaCO3 glasses represent a promising dual-function, lead-free shielding material for future radiation protection technologies.