Diffusivity Of Tin In Some Soda-Silica And Soda-Lime-Silica Melts

Glasses with the compositions xNa2O.(100x)SiO2(x=15,20,26 & 33) and xNa2O.10CaO.(90-x)SiO2(x=10,16,20 & 26) all doped with 0.25 mol% SnO2 were studied by square wave voltammetry. All curves exhibited a pronounced peak attributed to the reduction of Sn4+ to Sn2+. From the respective peak currents, the self diffusion coefficients of tin were calculated. The temperature dependence of the self diffusion coefficients could be fitted to Arrhenius equation. Diffusion coefficients referenced to the same viscosity decreased with increasing Na2O concentration, due to a stronger incorporation of tin into the silicate network.