The liquid–vapour phase transition in fluid metals

Fluid metals are typical examples of materials whose electronic structures depend strongly on the thermodynamic state of the system. The most striking manifestation of this state dependence is the metal–non–metal transition which occurs when the dense liquid evaporates to the dilute vapour or when the fluid is expanded by heating to its liquid–vapour critical point.The main emphasis of the paper is on the intimate interplay between the changes in interparticle forces and the changes in the electronic structure associated with the metal–non–metal transition. The most significant experiments relevant to this question are those on the liquid–vapour coexistence curves, the static– and dynamic–structure factors S(Q) and S(Q,ω), the electrical properties and interfacial features in the liquid vapour–critical region. For example, reflectivity experiments on mercury against sapphire reveal clearly the existence of a prewetting transition. The transition line starts at the wetting transition temperature Tw. Tw lies in the metal–non–metal transition region.