ZnO-modified magnesium lead borate glasses: Optical, mechanical, and radiation shielding characteristics

This study presents a comprehensive investigation of the optical, mechanical, and gamma-ray shielding properties of ZnO-modified magnesium lead borate (ZPMB) glasses with the composition (60-x)B 2 O 3 -20PbO-10MgO-xZnO (x = 0, 10, 20, 30 mol%), synthesized via the conventional melt-quenching technique. X-ray diffraction (XRD) analysis confirmed the amorphous nature of all glass samples. A progressive increase in density from 3.802 g/cm 3 (Z0) to 4.230 g/cm 3 (Z30), along with a reduction in molar volume, indicates enhanced structural compactness with ZnO incorporation. Optical absorption studies revealed a redshift in the absorption edge from 247 nm to 333 nm (Z10), followed by a gradual blueshift with further ZnO addition. Correspondingly, the optical band gap exhibited a non-monotonic trend: it decreased initially to 2.905 eV (Z10) due to the formation of non-bridging oxygen sites, then increased with further ZnO content, reflecting structural reorganization and increased bridging oxygen content. Urbach energy analysis supported these observations, indicating changes in structural disorder. Differential scanning calorimetry (DSC) showed a decrease in glass transition temperature (Tg) from 340 °C (Z0) to 319 °C (Z10), followed by a rise to 333 °C (Z30), suggesting an initial reduction and subsequent reinforcement of the glass network connectivity. Mechanical properties, evaluated using the Makishima–Mackenzie model, showed improvement with ZnO content, attributed to increased mean bond strength and network rigidity. Gamma-ray attenuation measurements demonstrated that ZPMB glasses possess superior shielding efficiency compared to conventional materials such as RS-253-G1 and concrete. Notably, the half-value layer values, while slightly exceeding RS-520, remain highly competitive, particularly at 0.662 MeV, emphasizing the potential of ZPMB glasses for advanced radiation shielding applications.