Sodium diffusion in glasses during electron irradiation

Sodium migration in glasses during electron probe microanalysis is investigated. We observe the change in x-ray emission as a fnction of time andfor various incident electron doses. A specific protocol is used in this study: independently drawn from a multivariate statistical analysis of the data and from an a priori simple model, an exponential decay of the Na signal is clearly established. Thismodel for Na^+ migration is only basedon an electric field with a linear decrease behavior as a function of depth and it acconts for themain expermental results with no evidence of an incubation time prior to ion migration. The electron densities and the fracton of incident electrons remaining trapped into the glass are deduced from an estimate of ion mobility. The maximum electric field values at the coating/glass interface are also given.

Jbara, O. Cazaux, J.