Corresponding states theory and transport coefficients of liquid metals

Abstract

A study of the applicability of CST towards predicting transport coefficients in liquid metals has been undertaken with particular emphasis on alkali metals. Characteristic parameters were obtained from six different first principles calculations of inter-ionic potentials of simple metals reported in the literature. A wide variation was observed in the characteristic parameters as reported by various authors. Among these, the potential parameters of Shyu et al. provided the best correlation of experimental diffusivity and viscosity data for alkali metals over moderate temperature ranges. However, use of the Goldschmidt diameter as the characteristic distance parameter and k_BT_m, where T_m is the melting temperature, as the characteristic energy parameter gave as good, if not better, results for alkali metals. This parameter set was not found to be satisfactory when non-alkali metals were also included. Chapman's characteristic parameters, obtained from a fit to the viscosity data, provided a reasonable correlation of the diffusivity data to most, but not all metals studied. Fundamental issues associated with attempting to group all liquid metals under a single corresponding states theory as well with the conventional use of the potential well-depth and the distance at which the potential becomes zero as characteristic parameters for liquid metals have been pointed out. A preliminary statistical analysis has been performed to assess the reliability of our predictions in view of the experimental uncertainties in viscosity and diffusivity data.