Lead Fluoride as a Multifunctional Modifier in Bismuth Gadolinium Borate Glasses: Optical, Structural, and Radiation Attenuation Characterization

Abstract

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 (T0.5), and effective atomic number (Zeff) 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 (ΣR), 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.