Heats of Mixing in Mixed Alkali Silicate Glasses

⊿H≒-1~-2kcal/mol SiO2 The model proposed for the heats of mixing in fused salts mixtures containing a common anion was used for explanation of the mixed alkali effect in these glasses. In the mixed system, Li2ONa2O, the calculated results by using the model were in general agreement with the experimental results. On the other hand, the mixed alkali effect could not be observed on the volume per mol SiO2. It is concluded from these results that the interaction between unlike ions is a more important factor than the geometrical factor in explaining the mixed alkali effect. (Received Aug. 27, 1976)