Self-Diffusion in Potassium

The self-diffusion of ${}_{}{}^{42}{}_{}{}^{}\mathrm{K}$ in potassium has been measured over the temperature range - 52.2 ± + 61.8°C. The temperature dependence of the diffusion coefficient can be described by $D=0.\mathrm{}16\pm 0.01 e^{-\frac{(9360\mathrm{}\pm 50)}{\mathrm{RT}}}$. However the deviations of the individual points from this Arrhenius line suggest that diffusion could be occurring by two mechanisms.