On the disintegration of copper electrodes and the transport of Cu+ ions in a sodium potassium borosilicate glass

Abstract

The disintegration of a copper electrode and the subsequent transport of Cu+ ions into a borosilicate glass has been qualitatively observed in a recent electron charge attachment induced transport (e-CAIT) experiment [SSI, 339 (2019) 114997]. This work reports the quantitative analysis of the transport coefficients of Cu+ and two native alkali ions in the glass. Electron attachment to the front side of the sample generates a negative surface potential inducing transport of mobile native alkali ions towards the front side. At the backside of the sample, in contact with a copper electrode, the electric field increases as a result of the alkali ion transport. Under these conditions, Cu+ ions become ejected from the electrode and enter into the glass. The concentration depth profiles of all mobile species in the glass have been quantitatively analyzed by means of the Nernst-Planck-Poisson theory. As the result of the analysis we arrive at a diffusion coefficient for Cu+ ions in the borosilicate glass at 160 °C of D(Cu+) = (5.2 ± 1) · 10−20 m2/s.to be published in Solid State Ionics.