Thermal diffusion of potassium on the modified iron surface

The diffusion of potassium on the polycrystalline iron surface modified by adsorbed oxygen and nitrogen has been studied by means of AES. The migration of potassium atoms has been observed independently on the constitution of the iron surface in the temperature range between 300 and 450 °C. The final concentration of potassium on the iron surface increases with temperature from 300 to 400 °C, irrespective of what atoms accompany potassium on the surface. At 450 °C, the final level of potassium concentration is decreased. The profiles of the concentration on the surface along the line crossing the source of potassium were also acquired. Applying the diffusion model of finite source, the diffusion coefficient of potassium for oxygen-covered and nitrogen-covered surfaces were evaluated.