Glasses with the base mol% composition xNa2O·10CaO·(90−x)SiO2 with x=10, 16,

20 and 26 were investigated at high temperatures using square-wave voltammetry.

The recorded voltammograms exhibit two peaks. That at less negative or

(depending on temperature and glass composition) even positive potential was

attributed to the reduction of Cu2+ to Cu+, while that observed at more negative

potential was caused by the reduction of Cu+ to metallic copper. For both redox

steps, the peak potentials decreased linearly with temperature. Those of the

composition with 10mol% Na2O showed the most negative values. The diffusion

coefficients can be fitted to Arrhenius equation. If referenced to the same viscosity,

the diffusion coefficients decreased with increasing Na2O-concentration. The effect

of composition on the thermodynamics as well as on diffusivities was explained by

the incorporation of the copper ions into the melt structure.

Redox Behaviour and Diffusion of Copper in Soda-Lime-Silica Melts. J.Kaufmann,

C.Rüssel: Journal of Non-Crystalline Solids, 2008, 354[40-41], 4614-9