Radiation shielding efficiency and optical properties of Pr3+-doped borate glasses

Abstract

Zinc bismuth borate glasses were doped with varying concentrations of praseodymium ions (Pr³⁺) using the compositional formula [(65−x)B₂O₃–30Bi₂O₃–5ZnO−xPr₆O₁₁], where x = 0.0, 0.5, 1.0, and 5.0 mol%. The glasses were synthesized via a conventional melt-quenching technique. X-ray diffraction (XRD) patterns confirmed the amorphous nature of the samples. Fourier-transform infrared (FTIR) spectroscopy revealed that the glass matrix comprises BO₃, BO₄, ZnO₄, BiO₃, and BiO₆ structural units. The observed changes in density and molar volume with increasing Pr₆O₁₁ content were attributed to structural modifications within the glass network. Optical absorption spectra of the Pr³⁺-doped glasses exhibited characteristic absorption bands, indicating significant alterations in optical properties due to Pr³⁺ incorporation. The gamma radiation shielding performance of the glasses was assessed by measuring its attenuation parameters, including the mass attenuation coefficient (MAC), half-value layer (HVL), mean free path (MFP), effective atomic number (Z_eff), and effective electron density (N_eff). Experimental results were compared with theoretical predictions from XCOM and EpiXS (based on the ENDF/B-VIII library). For MAC, the experimental data agreed well with EpiXS, while a slight deviation (1.7–4 %) occurred at low energies compared to XCOM. The HVL, evaluated for photon energies (0.081–1.408 MeV), decreased with higher Pr₆O₁₁ content, following the trend: BPr-0.0 < BPr-0.5 < BPr-1.0 < BPr-5.0 (where BPr-5.0 contains 5 mol% Pr₆O₁₁). The MFP results were benchmarked against ordinary concrete, barite concrete, and commercial glass (RS 360). The BPr-5.0 sample demonstrated the lowest MFP across all energies, surpassing all reference materials. Notably, even a modest Pr₆O₁₁ doping (5 mol%) increased Z_eff by ∼14 %, significantly enhancing gamma shielding efficiency. In conclusion, the developed Pr₆O₁₁-doped zinc bismuth borate glasses combine tunable optical properties (via Pr³⁺ absorption bands) and superior γ-radiation shielding, with the 5 mol% composition outperforming conventional shielding materials.