Electrical and thermal conductivity of metallic potassium, over its entire liquid range, i.e., from the melting point (336·4°K) to the critical point (2450°K)

Abstract

The thermal and electrical conductivities of metallic potassium are presented, both as a liquid and as saturated vapour, over its entire liquid temperature range, i.e., from the melting point (336·4°K) to the critical point (2450°K). Experimental data are now available up to ≅1450°K. Kinetic theory of dense gases permits one to estimate the critical thermal conductivity and from this estimate and the Wiedemann-Franz law (or the experimental Lorenz number) the electrical conductivity at the critical point can be derived. Using these two values as anchor points, coupled with the knowledge from the free-electron theory of metals that the critical values of both properties should be practically zero at the critical point, both the thermal and electrical conductivities are interpolated from the end of the experimental range to the critical point. Both γ therm, vs T and κ vs. T form smooth, slightly concave curves from the melting point to the critical point, as shown in Figs. 1 and 2.