Critical point and metal-nonmetal transition in expanded liquid metals

For most metals the two phases of the liquid-gas transition are metallic in a region around the critical point. A method for determining the critical data of expanded liquid metals under such conditions has been published rec ently. Mercury, however, is a well-known exception with the metal-nonmetal transition inside the liquid phase. Mercury is no longer a metal at the cri tical point. The metal-nonmetal transtion of the metallic elements has been considered in view of this problem. It is shown that a group of metals (Mg ; Zn, Cd; As, Sb; Se, Te), including semi-metals as well, should also have the metal-nonmetal transition completely inside the liquid phase. Thus, the above mentioned method is not applicable in this group. A comparison of th e measured electrical conductivity of Al, W, Zn, and Hg with a theoretical approach supports this conclusion.