Ionic-metallic transition in gold-based liquid alkali metal alloys

Abstract

The authors have calculated the density of states and conductivity of a series of gold-based liquid alkali metal alloys using a tight-binding model that includes short-range order and charge transfer in a self-consistent way. They take account of the variation of the alkali band widths, electronegativities and Coulomb interactions. The model can account for the diversity of conductivities observed at the equiatomic concentrations which range from metallic values for LiAu to ionic values for CsAu and RbAu. The calculations show that the difference of electronegativity between the alloy components is not the essential factor giving rise to the ionic to metallic transition in this series of liquid alloys, but rather it is the variations in the band widths and the interatomic Coulomb interactions that are the dominant factors.