Lead fluoride as a multifunctional modifier in bismuth gadolinium borate glasses: Optical, structural, and radiation attenuation characterization

This study systematically evaluates the role of PbF₂ in altering the optical and radiation shielding properties of bismuth gadolinium borate glasses with compositions 30Bi₂O₃–Gd₂O₃-xPbF₂-(70-x)B₂O₃, for x ranging from 0 to 40 mol. %. The introduction of PbF₂ significantly modified the absorbance profile, exhibiting distinct absorption peaks at 3.45, 4.15, and 4.69 eV, shifting from a flat curve in the undoped sample to well-defined peaks with increasing PbF₂ content. Crucially, a reduction in both the direct and indirect optical band gaps was observed as the PbF₂ content increased, indicating changes in the electronic structure of the glasses. Photon and neutron shielding capabilities were analyzed, revealing that the linear attenuation coefficient (μ), half-value layer (T_0.5), and effective atomic number (Z_eff) were enhanced with PbF₂ additions. Notably, the BGPB5 sample contained 40 mol. % PbF₂ outperformed other compositions, offering the highest attenuation efficiency, which surpassed some conventional glasses and concretes. Simultaneously, an inversely proportional relationship was found between PbF₂ concentration and the effective removal cross-section for fast neutrons (Σ_R), demonstrating the BGPB1 sample's superiority as a neutron shield. The incorporation of PbF₂ in the glass matrix not only improved gamma radiation shielding but also tuned the optical properties, marking these glasses as potential candidates for multifunctional radiation shielding applications.