Sodium diffusion in glasses during electron irradiation

Abstract

Sodium migration in glasses during electron probe microanalysis is investigated. We observe the change in x-ray emission as a function of time and for 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. This model for Na+ migration is only based on an electric field with a linear decrease behavior as a function of depth and it accounts for the main experimental results with no evidence of an incubation time prior to ion migration. The electron densities and the fraction 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.

Resolving Problems of EPMA-derived Water Contents of Melt Inclusions

“…Our results imply that a maximum electric field strength on the order of 0.01-0.1 V·nm -1 reproduces the observed overestimation of WBD (Fig. 1b), which is similar to values that have been experimentally measured in glasses previously [12].The effects of sub-surface charging cannot currently be included in matrix corrections, as this would require measuring the magnitude of sub-surface charging during analysis which is very difficult. Standards which experience the same magnitude of charging could be used for all elements analysed but as it is not possible to know the amount of charging the sample and unknown have experienced, picking appropriate standards would be impossible.…”

Viscosity and diffusion of barium and fluoride in Na2O/K2O/Al2O3/SiO2/BaF2 glasses

“…In Ref. [17] the fast sodium diffusion in glasses induced by the electron beam and the effect on changed X-ray emission with time is reported. Moreover, sodium on the surface is excited by the incoming electrons and reconstructs to a foreign phase in the glassy network [18].…”

Electron Probe Microanalysis of Insulating Oxides: Monte Carlo Simulations

“…Among the reasons for our choice is the fact that this simple model has been successfully used to explain some experimental results involving ion migration in electron-irradiated insulators. 4,5 The same model of electric Ðeld has also been used for suggesting an analytical expression for the compression of the '(oz) function1 [and one goal of the present paper is to compare the '(oz) distortion obtained by the present numerical (MC) approach for the same postulated electric Ðeld].…”