MD Study on the Thermal Conductivity of Molten Alkali Halides: Effect of Ionic Mass Difference

A definition suitable for the average ionic mass used for two kinds of expressions of the thermal conductivity for molten alkali halides has been explored from the viewpoint of the difference in anion and cation masses. One is the scaling equation, lambda proportional to m(-1/2) (N/V)(2/3), where m is the average ionic mass between the anion and cation and N/V is the number density, which was previously obtained from molecular dynamics (MD) simulation. The other is the equation used in the corresponding-states (CS) analysis which has been applied to the thermal conductivities calculated by the MD simulation. Among some representative definitions, it turned out that a simple arithmetic average is best for the equation. As an estimation method of the thermal conductivity, it was shown that both equations have comparable precision. It was indicated that considering the difference in ionic masses between the anion and cation is important for building a more precise correlation in the CS analysis.