Optical, structural, and gamma shielding characteristics of bismuth-doped lithium borosilicate glass composite

This study investigates the optical, structural, and gamma radiation shielding properties of bismuth-doped lithium borosilicate glass composites. Glasses containing 0-20 mol% Bi₂O₃ were synthesized and analyzed using XRD, FTIR, density measurements, and UV-Vis spectroscopy. All samples exhibited an amorphous structure. The density increased markedly from 2.31 g/cm³ (0 mol% Bi₂O₃) to 4.59 g/cm³ (20 mol% Bi₂O₃), accompanied by a molar volume expansion from 27.33 to 31.02 cm³/mol. Optical studies revealed a progressive reduction in the band gap energy from 3.44 eV to 2.39 eV, while the Urbach energy increased from 0.216 eV to 0.488 eV, indicating enhanced structural disorder with Bi₂O₃ incorporation. Gamma attenuation analysis showed a significant improvement in shielding efficiency: at 0.662 MeV, the mass attenuation coefficient reached 9.83 × 10⁻² cm²/g with an effective atomic number up to 22.24, compared to only 7.76 × 10⁻² cm²/g for Portland concrete. Moreover, the half-value layer decreased with Bi₂O₃ loading, confirming improved attenuation performance. These results highlight that bismuth-doped lithium borosilicate glasses are promising lead-free materials for medical and nuclear radiation shielding applications.