Critical parameters and equation of state for heavy liquid metals

Heavy liquid metals (HLM), such as mercury (Hg), lead (Pb), bismuth (Bi) and lead–bismuth eutectic (Pb–Bi), have been studying in several countries as potential materials for spallation neutron sources. However, experimental data on their thermal properties in the temperature range of interest are rare. In this case, an equation of state (EOS) developed on the basis of the fundamental thermodynamics and limited experimental data can play a very important role. Different approaches to construction of EOS are considered in the present work: the generalized van der Waals equation, the Redlich–Kwong equation and the concept of internal pressure of liquids. The results of calculation of the critical temperature, the critical pressure and the critical density of Hg, Pb, Bi and Pb–Bi obtained with these models and available experimental data on thermal properties of these HLM at lower temperatures and normal pressure are presented and discussed. An EOS is proposed which allows to estimate densities of liquid and vapour phases of HLM at high temperatures and pressures.