Improved physical, optical, and radiation shielding characteristics of SrO-doped borate glasses: Insights from experiments and machine learning

This study investigates the influence of Strontium oxide (SrO) doping on the physical, structural, optical, and radiation shielding characteristics of borate glass systems with the composition (69-x)B₂O₃-6Na₂O-6CaO-6K₂O-6BaTiO₃-6ZnO-1Sb₂O₃-xSrO (x = 0, 1.25, 2.5 mol%, encoded AY100, AY101 and AY102). Utilizing the melt-quenching technique, glasses were synthesized and systematically characterized to evaluate their physical, optical, and nuclear radiation shielding capabilities. Experimental techniques such as XRD, FTIR spectroscopy, UV–Vis spectroscopy, and Vickers hardness tests provided insights into the influence of SrO content on glass properties. To predict glass densities, we utilized a suite of machine learning models, including Linear Regression, Bayesian Regression, Support Vector Regression, Extreme Gradient Boosting, CatBoost, and Light Gradient Boosting Machine. Among these, the XGBoost model demonstrated exceptional performance, achieving an R2 score of 0.97. Experimental measurements using Archimedes' principle confirmed that the density of the synthesized glasses increased with the addition of the SrO. The observed density increase of the 2.5 % additive glass (from 2.755 to 2.805 g/cm³) aligns with the predictions of our machine learning models. Increasing the amount of SrO doping increased the refractive index and band gap energies. Direct band gap values increased from 3.01 to 3.12 eV. The substitution of lighter B₂O₃ with heavier SrO significantly enhanced density and refractive index. The incorporation of 2.5 mol% SrO into glass led to a substantial improvement in its mechanical performance, as evidenced by a 12.5 % increase in hardness and a 13.11 % increase in yield strength. The radiation shielding performance of the glasses, another critical focus of this work, was assessed for gamma rays and fast neutrons. SrO-doped glasses demonstrated superior gamma-ray attenuation properties, with increased MAC and Zeff values, as well as reduced HVL values. The MAC values of AY100 and AY102 glasses vary between 0.597 and 0.610 cm2/g at 81 keV. Among the samples, glass with 2.5 mol% SrO exhibited the highest shielding efficiency, attributed to its enhanced density and effective atomic number. Neutron shielding effectiveness also improved, as evidenced by a higher neutron removal cross-section and absorbed dose rates. As a result of the experimental measurements, the equivalent absorbed dose rate increased from 31.36 to 34.16 % for AY100 and AY102 glasses. This comprehensive study underscores the potential of SrO-doped borate glasses as multifunctional materials for optical and radiation shielding applications.