Tungsten-Doped Borosilicate Glasses for Radiation Shielding

In this study, a series of glasses in the 25 Na₂O- 15 B₂O₃- (60-x)SiO₂- xWO₃ system (with x up to 2 mol%) was developed by a melt-quench route. To evaluate their potential applications as novel lead-free transparent shielding materials in nuclear medicine, the impact of tungsten trioxide (WO₃) addition on glass formation, structure, properties, and radiation shielding effectiveness of the produced glasses was also investigated. The glass forming ability was found to be restricted, and high-transparency homogeneous bulk glasses containing WO₃ up to 1.5 mol% could only be achieved, as verified by XRD measurements. FTIR spectroscopy revealed the network modifications caused by the incorporation of various WO₃ concentrations into the glass system. This was further supported by thermal and mechanical investigation, which demonstrated that increasing WO₃ content increased both glass transition temperature (T_g) and Vickers hardness (H_v) values. The increases in T_g and H_v could be attributed to tungsten's participation in the formation of new strong W-O connections. Furthermore, the radiation shielding performance of the glasses, such as the half-value layer (HVL), the mean free path (MFP) and the lead equivalent thickness (LEV), as determined by means of a NaI(Tl) scintillation detector in a narrow beam geometry setup using ¹³⁷Cs, ¹³³Ba and ⁵⁷Co as the radiation sources, were compared to that of commercial lead glass and found to be improved with higher WO₃ content. The findings provide sufficient data to indicate that our tungsten-doped borosilicate glasses, especially the sample containing 1.5 mol% WO_3, could be potential candidates for alternative lead-free, high-transparency radiation shielding materials in nuclear medicine applications.