Effect of tin on the relationship between composition, structure, and properties of soda-lime-silicate glasses

The effect of tin on the properties of soda-lime-silicate glass was investigated using laboratory and commercial glasses. The commercial materials were float glasses, while the model glasses with nominal soda-lime-silicate commercial compositions were synthesized in the laboratory with tin concentrations ranging from 0--3 mol%. In one set of the modeled glasses, melt processing was used to drive the tin into the reduced state. Mossbauer spectroscopy was used to determine the presence and relative amounts of Sn2+ and Sn4+ in the glasses. The glasses were also examined using nuclear magnetic resonance (NMR) to gain insight into the effect of substituting tin for sodium on the number of silica Q4 species present in the glass structure.; Dilatometry experiments revealed the effects of tin on the coefficient of thermal expansion, dilatometric softening temperature, and glass transition temperature. Beam-bending viscosity experiments were used to measure the viscosity as a function of tin, and from the viscosity curves, strain and annealing temperatures were determined. Sonic resonance, ultrasonic pulse, and nanoindentation experiments were performed to determine the role of tin on elastic modulus of the glass. The results of these experiments, along with the NMR and Mossbauer experiments, suggested that the substitution of tin for sodium results in an increase in the network connectivity of the glass structure. This increased network connectivity correlated with an increased in the ratio of Sn 4+/Sn2+ suggesting that Sn4+ plays a direct role in cross-linking the silicate structure.