Revealing the Effect of Local Structure on Phase Equilibria in Binary Molten Salts

Abstract

Liquidus curves for LiF-KF and LiF-KCl mixtures are calculated from the two-phase technique in the framework of molecular dynamics simulation. The calculated topology of the solid-liquid equilibria is in excellent correspondence with the experimental data. The local structures in liquid LiF-KF and LiF-KCl mixtures are analyzed by the partial structure factors (PSFs) calculations. For the reciprocal mixture LiF-KCl of equimolar composition, the appearance of a significant intensity peak in the region of small k and only a decrease in the height of the principal peaks of the PSFs for lithium-lithium, fluorine-fluorine, and lithium-fluorine pairs is observed. An intermediate range ordering appears for the Li+ and F– ions, which is associated with clustering of these species and is reflected in the s-shape form for the liquidus curve for LiF-KCl mixture.