Effects of energy deposition on mechanical properties of sodium borosilicate glass irradiated by three heavy ions: P, Kr, and Xe

Sodium borosilicate glasses are candidate materials for high-level radioactive waste vitrification; therefore, understanding the irradiation effects in model borosilicate glass is crucial. Effects of electronic energy deposition and nuclear energy deposition induced by the impact of heavy ions on the hardness and Young’s modulus of sodium borosilicate glass were investigated. The work concentrates on sodium borosilicate glasses, henceforth termed NBS1 (60.0% SiO2, 15.0% B2O3, and 25.0% Na2O in mol%). The NBS1 glasses were irradiated by P, Kr, and Xe ions with 0.3 MeV, 4 MeV, and 5 MeV, respectively. The hardness and Young’s modulus of ion-irradiated NBS1 glasses were measured by nanoindentation tests. The relationships between the evolution of the hardness, the change in the Young’s modulus of the NBS1 glasses, and the energy deposition were investigated. With the increase in the nuclear energy deposition, both the hardness and Young’s modulus of NBS1 glasses dropped exponentially and then saturated. Regardless of the ion species, the nuclear energy depositions required for the saturation of hardness and Young’s modulus were apparent at approximately 1.2 × 1020 keV/cm3 and 1.8 × 1020 keV/cm3, respectively. The dose dependency of the hardness and Young’s modulus of NBS1 glasses was consistent with previous studies by Peuget et al. Moreover, the electronic energy loss is less than 4 keV/nm, and the electronic energy deposition is less than 3.0 × 1022 keV/cm3 in this work. Therefore, the evolution of hardness and Young’s modulus could have been primarily induced by nuclear energy deposition.