Transport Properties of Mercury Vapor

Mercury has the lowest critical temperature of any fluid metals.Therefore, it has been investigated experimentally with accurate measurements in the critical region. These measurements involve its magnetic, electrical, structural, optical, and thermophysical properties with optimal control of temperature in the critical region [1]. The fundamental difficulty in dealing with fluid metals is that the electronic structures of liquid and gas phases are completely different. The electronic structure of mercury (and other molten metals) at low temperatures can be well approximated by the structure of the solid metals, and thus the thermodynamic properties of metals can be obtained by the same cohesion mechanism of the solid metals. Experimental data clearly represent that mercury near its triple point (at densities larger than 11 g/cm3) follows the nearly free electron theory of metals that considers the nuclei completely shielded by delocalized electrons [2]. At lower densities (8-9 g/cm3), the cohesion mechanism of its atoms will be suppressed by a partial localization of electrons and the metallic character is changed to a nonmetal kind and a gradual metal-nonmetal transition (M-NMT) occurs and consequently density-dependent equation of state was presented [3]. Therefore, the accuracy of theoretical studies on the transport properties of liquid metals is subjected to the accuracy of pair potential function describing the intermolecular interaction of these metals.