Gamma-Ray Shielding Performance of Ho ₂ O ₃ –Doped Borate Glasses: Influence of ZnO and CaO Substitution

Lead-free transparent materials that effectively attenuate gamma radiation as alternatives to traditional shielding are being explored in medical, industrial, and nuclear sectors; there is increasing interest in using new materials. There are a variety of studies available on the performance of borate glasses for radiation shielding that have explored the addition of various rare earth elements and different network modifiers to achieve radiation attenuation. However, no comprehensive study has been done on how to use both zinc oxide (ZnO) and calcium oxide (CaO) as co-substituents for holmium oxide (Ho2O3)–doped borate glass in order to improve gamma-ray attenuation properties.To fill this gap in knowledge, four different glass compositions made from a system of B2O3, Na2O, ZnO, CaO, and Ho2O3 were produced using traditional melt-quenching methods. The density of each glass sample was measured using the Archimedes method. The gamma-ray attenuation properties of the samples were evaluated using a NaI(Tl) scintillation detector and standard radioactive sources (241Am, 137Cs, and 60Co), with gamma-ray photon energies ranging between 0.059 MeV and 1.332 MeV.The experimental linear attenuation coefficients (LAC) were compared to the theoretical LACs calculated with Phy-X/PSD. Additional shielding properties, such as the half-value layer (HVL), mean free path (MFP), tenth-value layer (TVL), transmission factor (TF in percent), and radiation shielding efficiency (RSE in percent), were also evaluated.The fabricated glass density increased from 2.98 to 3.29 g/cm3 as the composition was modified gradually through the series. The experimental LAC measurements supported the theoretical values with only a few percent difference between the two (software showing < 6% deviation). The highest attenuation of all the samples was exhibited by Zn20Ho1 with LAC values of 3.531 cm−1 at 0.059 MeV and 0.169 cm−1 at 1.332 MeV and also the lowest HVL, MFP, and TVL values. The results for TF and RSE further supported the excellent shielding of the higher density compositions throughout this energy range.When compared to previously studied glass and concrete shielding materials, the fabricated glasses had competitive mass attenuation coefficients. The enhancement of the observed shielded materials can be attributed to the modification of the material composition, resulting in changes to the ZnO and CaO contents and density simultaneously. Therefore, the investigated glasses containing Ho2O3 show good promise as gamma-ray attenuating materials and present an exciting new environmentally friendly shielding option for use in protecting against radiation.