Incorporation of tin in soda-lime and alumosilicates

Square-wave voltammetric and Mössbauer measurements have been carried out in soda-lime and alumosilicates doped with 0.25–3.0 mol% SnO2. The Na2O and Al2O3 concentrations have been varied. Only Sn2+ and Sn4+ have been detected. In soda-lime-silicates, with increasing Na2O concentration Sn4+ is successively favored and the covalent character of the Sn2+–O bonds increases. By contrast, in alumosilicates the incorporation of Sn2+ is favored with increasing Al2O3 concentration. Here, the s-electron density increases. Sn2+ possesses a fourfold coordination. Sn4+ is incorporated in octahedral positions. Changes in the Al2O3 concentration have the largest effect on the incorporation of tin in the investigated glasses.