Effect of 10B(n, α)7Li irradiation on the structure of a sodium borosilicate glass

Abstract

The effects of the nuclear reaction 10B(n, α)7Li on the properties and structure of a sodium borosilicate glass were analysed by density, hardness and fracture toughness measurements, Raman and Nuclear Magnetic Resonance spectroscopy and Transmission Electronic Microscopy (TEM) characterization. The TEM observations showed a homogeneous irradiated glass structure up to the nanometer scale. Modifications of the local order around the main cations were noticed, mainly a slight decrease of the mean boron coordination number and an increase of non-bridging oxygen concentrations. At the glass medium range order, the appearance of the D2 Raman band and a modification of the Si–O–Si angle distribution were also observed after irradiation.A comparison with other irradiation conditions with Swift Heavy Ions (Kr with 74MeV) and Gold irradiation (with energies ranging from 1 to 7MeV) is presented. Raman spectroscopy showed a similar final structure for irradiation conditions under which the glass evolutions are controlled by electronic energy loss in the ion tracks formation regime or nuclear energy loss. Despite important differences in energy deposition regimes, the similarities observed between the final glass structures suggest that structural evolutions are controlled by the glass relaxation mechanisms during the high quenching rate step that follows the energy deposition step.