By repeated grinding, and X-ray diffraction analysis of the removed powder, an investigation was made of the interdiffusion of couples. It was found that the Matano interface always moved towards the KCl, and the concentration of KCl at the Matano interface was 46mol%. The standard deviation of the diffusion coefficient was 10% for intermediate concentrations, and was up to 18% for extreme concentrations (table 75). The concentration dependence of the chemical diffusion coefficient could be deduced from self-diffusion data, but the activation energies in the intermediate concentration range were considerably higher than the calculated values.

Chemical Diffusion Coefficient of the KCl-RbCl Couple. M.Kantola, R.Lindström: Annales Academiae Scientiarum Fennicae A, 1967, 6, 11

Figure 18

Diffusion of Br in the KCl-KBr System