Liquid metal coexistence properties from corresponding states and third law

Abstract

An empirical procedure is introduced to describe equilibrium thermodynamic properties of metals from the experimentally covered region (0.2Tc≲T≲0.4Tc) over a very large temperature interval up to near the critical point (0.4Tc≲T≲Tc). The method uses arguments of corresponding states for the extrapolation of the interphase properties, like vapor pressure, heat of vaporization, or coexistence volumes, whereas the liquid properties, entropy, or specific heat, are determined from the gas side applying a third-law technique. Resulting high-temperature data may be used for practical description of two-phase processes as well as for estimation of basic liquid properties. two-phase processes as well as for estimation of basic liquid properties. Special application to a set of different metals (Li, Na, Sr, Ba, Pb, U, Fe, Eu), as an example, gave information about large-scale deviations of the liquid specific heat from quadratic temperature dependence (especially transition metals), and about the size of the critical compressibility Zc=pcVc/RTc, which seems to be much closer to a common value of about 0.4 than previously assumed.