Thermodynamic evaluation and optimization of the Li, Na, K, Mg, Ca//F, CI reciprocal system using the modified quasi-chemical model

A complete critical evaluation of all available ternary reciprocal phase diagram data has been performed for all condensed phases of the LiF-LiCl-NaF-NaCl-KF-KCl-MgF2-MgCl2-CaF2-CaCl2 system and optimized model parameters have been found. The model parameters obtained for ternary reciprocal subsystems can be used to predict thermodynamic properties and phase equilibria for the multicomponent reciprocal system. The modified quasi-chemical model in the quadruplet approximation was used for the molten salt phase. This model takes into account, simultaneously, both first-nearest-neighbor (FNN) and second-nearest-neighbor (SNN) short-range-ordering (SRO) and the coupling between them. The predictions are significantly better than those obtained with previous models.