Application of the modified quasichemical model to solutions with strong short-range ordering

The present study is concerned with analysis of a specific feature of the modified quasichemical solution model (MQSM). The analyzed feature is typical for binary solutions with very strong short-range ordering. As demonstrated, a solid compound whose composition coincides with that of maximum ordering in the liquid is required for reasonable representation of phase equilibria in such a system. The limiting slopes of the liquidus curve of the compound are calculated. As a demonstrational example, the thermodynamic model for the system K2O–SiO2 with the MQSM for the liquid phase is re-optimized. The new parameters of the thermodynamic model fit the available experimental data and represents reasonable phase relations for the entire compositional range.