Self-diffusion of Ag⁺ and Na⁺ in molten Ca(NO₃)₂-KNO₃

Abstract

In order to explore the behaviour of diffusing ionic species in a molten salt in which non-Arrhenius behaviour of other transport properties is established, the diffusivities in dilute solution of Ag+ and Na+ in 38.1 mol% Ca(NO₃)²⁺ 61.9 mol% KNO₃ have been measured. For both ions limited radio-tracer diffusion coefficients, determined using a diffusion-out-of-capillary method, are reported. D(Ag⁺) has also been measured by chronopotentiometry, by which means the range and reliability of the measurements were considerably extended. Chronopotentiometric and tracer data agree within expected errors of measurement. Both ionic diffusivities show a non-Arrhenius temperature dependence which is indistinguishable in magnitude from that of the electrical conductance of the solvent melt.