Effects of temperature and flux on oxygen bubble formation in Li borosilicate glass under electron beam irradiation

Oxygen bubble formation and evolution under a 300 keV electron beam are analyzed in a Li borosilicate glass under different irradiation conditions: temperature, flux, and dose. Oxygen bubbles are observed to form in a delimited flux and temperature region with a threshold requirement. This region ranges between 100 and 300°C for the temperatures and between 1019 and 1021 e m-2 s-1 for the electron fluxes. In situ transmission electron microscopy allows the bubble evolution kinetics to be described as a four-step process. An incubation step is followed by a growth phase of sigmoid type. For high values of temperature and/or flux the saturation growth and the subsequent dissolution of the bubbles are also observed. The bubble evolution kinetics can be explained by considering the production and diffusion mechanisms of the molecular oxygen O2 as a function of the temperature and the electron flux.