Surface Self-Diffusion at High Temperatures

Abstract

The first evidence that atoms diffuse much more rapidly over the surface than through the lattice was presented in 1921 by Volmer and Estermann [¹], who studied the rate of growth of mercury whiskers from a mercury vapor and found that they could explain their results only if they assumed that atoms hitting the shank of the whisker diffused over the surface to the tip before becoming incorporated in the lattice. In the intervening 35 years, there were many observations that indicated that atoms could diffuse along surfaces much more rapidly than through the lattice. However, these were primarily qualitative observations; the quantitative work was performed after 1955. Some of the work has been done with the field emission technique, for example, work on the spreading of adsorbed gases on tungsten tips [²]. This topic is not discussed here; what is exclusively considered is the diffusion of metal atoms over their own surfaces.