Molecular dynamics study of the transport properties and local structures of molten alkali metal chlorides. Part III. Four binary systems LiCl-RbCl, LiCl-CsCl, NaCl-RbCl and NaCl-CsCl

The effects of LiCl and NaCl on the local structures and transport properties as the self-diffusion coefficients, viscosities and ionic conductivities of molten RbCl and CsCl have been calculated and analyzed in detail at 1100 K across the full composition range by molecular dynamics simulations. For molten RbCl or CsCl, with the gradual addition of a smaller cation (Li+ or Na+), the densities of the mixed salts decrease monotonously, besides, the cationic-anionic interactions and the interactions between cations become weaker, while the corresponding atomic close packing gets a promotion respectively. Influenced by the local structures and interatomic forces simultaneously, the shear viscosities of molten LiCl-RbCl, LiCl-CsCl, NaCl-RbCl and NaCl-CsCl decrease firstly and then present slightly fluctuated variations as the contents of LiCl or NaCl are increased, being in consonance with the available experimental results. In addition, the ionic diffusivity and ionic conductivity of each system present positive composition dependences along with the increase of LiCl or NaCl concentration. Besides, the effects of LiCl on the local structures and transport properties of RbCl and CsCl are more pronounced than those of NaCl.