Internal Cation Mobilities and their Isotope Effects in the Molten System (Li, K)Cl

Abstract

With the Klemm method, the internal m obility ratios of the Li and K. 6Li and 7Li, and 39K and 41K have been measured for melts o f the system (Li. K)Cl near the eutectic composition (ca. 56% Li) in the range 729 -976 K. Under all these conditions the Chemla effect occurs, i.e. bLi<bK. (b- internal mobility). In the region near the anode the com position becomes that corresponding to the Chemla crossing point, which shifts with temperature toward higher concentration of Li+. Both bLi and bK have been found to be well expressed by the equation b = [A/( V - V0)] exp ( - E/RT ) (V: molar volum e. A and E: constants depending on the respective cation. V0: a parameter depending on the respective cation and temperature), which is also valid for the mobilities in alkali nitrates when the C oulom bic attraction plays a dominant role. The isotope effects o f both cations seem to be similar to those in pure LiCl and KCl and slightly increase with temperature.