The effect of oxygen diffusion from the atmosphere on tin depth profile in the bottom face of a soda-lime-silica float glass at temps above Tg was investigated. The sheet glass samples were heat-treated in O2/N2 atmosphere, resulting in the formation of a tin-enriched layer near the surface region. It was found that the tin was supplied from the region shallower than the "hump" which is commonly observed in the tin depth profile of a commercial soda-lime-silica float glass. No significant change in the tin depth profile was observed for the glass heat-treated in Ar atmosphere. The results indicate that diffusion into the glass, which causes the change in valence of tin from Sn2+ to Sn4+, induces the diffusion of tin. The precipitation of crystalline Sn02 particles with a diameter of ~1nm was clearly recognised in the tin-enriched layer.
