Molecular dynamics simulations and thermodynamic modeling of NaCl–KCl–ZnCl2 ternary system

• Modeled NaCl–KCl–ZnCl2 system by combining molecular dynamics simulation with CALPHAD.
• We characterized the structure of the liquid employing molecular dynamics simulations.
• Molecular dynamics simulations predicted the enthalpies of mixing of the liquid.
• A two-sublattice Ionic Liquid model informed by MD simulations was chosen for liquid.
• The calculated phase diagrams are in good agreement with the experimental data.

The NaCl–KCl–ZnCl2 ternary system is examined and modeled using the CALPHAD methodology in conjunction with molecular dynamics (MD) simulations. In particular, MD simulations are used for calculating liquid enthalpies of mixing as a function of composition for the ternary and its binary sub-systems. In addition, key structural features are obtained from MD that is then used for informing the employed two-sublattice ionic liquid model (Na+1, K+1: Cl−1, ZnCl2), which describes the ternary liquid phase. The structure of the simulated liquid systems show that Zn+2 cations primarily exhibit 4-fold coordination in addition to a smaller percentage of 5-fold followed by 3-fold coordination; in contrast, the coordination of both Na+ and K+ cations are distributed between 2- and 4-fold states. The optimized self-consistent thermodynamic model parameters show good agreement with MD data obtained in this work and available experimental literature data.