A MODEL FOR THE METAL-NONMETAL TRANSITION IN METAL MOLTEN-SALT SOLUTIONS

We outline a theory for the metal-non-metal transition occurring in so lutions of alkali metals in molten alkali halides as governed by a bal ance between the binding of ionic clusters by localized electrons and the excess free energy of an ionic assembly screened by metallic elect rons. In the model the transition is driven by the composition depende nce of the screening length. The theory is amenable to an analytic sol ution within the mean spherical approximation when Thomas-Fermi screen ing is used and the ions are described by charged hard spheres.