Enhanced gamma radiation shielding and attenuation behavior of Eu3+-Modified bismuth phosphate glasses

Radiological protection requires advanced, lead-free shielding materials for medical, industrial, and nuclear applications; however, the role of Eu 2 O 3 doping in determining the gamma-ray attenuation characteristics of bismuth-barium-phosphate glasses over the entire energy range has not yet been fully clarified. In this study, the composition-dependent shielding performance of xEu 2 O 3 –20Bi 2 O 3 –1.5Al 2 O 3 –20BaO–(58.5−x)P 2 O 5 glasses (x = 0, 5, 10, and 15 mol%) was investigated from 0.015 to 15 MeV by combining Geant4 Monte Carlo simulations with Phy-X/PSD theoretical calculations. The two approaches showed very close agreement, thereby validating the results. The mass attenuation coefficients, effective atomic numbers, half-value layers, and radiation protection efficiency were calculated as functions of Eu 2 O 3 content, showing that increasing Eu 2 O 3 to 15 mol% raised the bulk density to 5.13 g/cm 3 and produced an 18.1% improvement in the linear attenuation coefficient across the entire investigated energy range. At low energies, photoelectric absorption is dominant, whereas in the Compton range, weighting by volumetric density decreases the required tenth-value layer thickness by as much as 22% near 3 MeV. Moreover, the closely coupled absorption edges of the high atomic-number constituents mitigate the pronounced attenuation decreases and yield a local increase of more than 19% in radiation shielding efficiency. The optimized formulation with 15 mol% achieves a lead-equivalent thickness of 1.13 mm, which practically satisfies the highly toxic commercial specifications, and it demonstrates improved broad-spectrum photon attenuation with reduced HVL and increased RPE. This work identifies Eu2O3-doped bismuth-barium-phosphate glasses as lead-free candidates for compact, transparent shielding and provides a new design framework for advanced radiological shielding materials for diagnostic and clinical applications.