Internal mobilities in the molten ternary system (Li,K,Cs)NO3 of the eutectic composition

The epsilon values in the internal cation mobilities of (Li,K,Cs)NO3 of the eutectic composition (35.2-39.8-25.0 mol%) in the temperature range from 4 53 to 673 K were measured by Klemm's countercurrent electromigration method , where epsilon is defined as (b(i)-b(j))/b(a); b(a) is the average interna l cation mobility and the subscripts i and j refer to any two out of these three cations. The conductivity was measured by a direct current method. Fr om these data and the molar volume calculated from those of the pure salts on the assumption of additivity, the internal cation mobilities, b(Li), b(K ) and b(Cs), have been calculated. The b(Li) is well expressed by the empir ical equation presented for binary alkali nitrates; the negative deviation for b(K) and b(Cs) may be accounted for on the assumption of the tranquiliz ation effect of Li+. The orders of those internal cation mobilities are b(C s)<b(K)<b(Li) at 453-473 K, b(Cs)<b(Li)< b(K) at 473-583 K, and b(Li)<b(Cs) <b(K) at 583-673 K. These orders can be interpreted in terms of the dynamic dissociation model previously presented.