An Arrhenius Argument to Explain Electrical Conductivity Maxima versus Temperature

The existence of conductivity maxima in pure molten salt was interpreted by Grantham and Yosim to be due to ion association at low densities. Todheide used a chloride-transfer shifting-equilibrium hypothesis to explain ion association in the case of bismuth trichloride. We have performed density-functional-theory based molecular dynamics simulations of the molten chlorides of Bi(III), Sn(II), and Hg(II), and Todheide's hypothesis is not supported. Instead, the simulations imply a hopping barrier for ions between counterions, and we develop this concept into a density-dependent Arrhenius equation to explain the conductivity maxima.