Surface Self-Diffusion on a Face Centered Crystal: An Atomic View.
ILLINOIS UNIV URBANA COORDINATED SCIENCE LAB
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Migration of individual atoms self-adsorbed on different low-index planes of a face-centered cubic metal has been studied. Diffusion coefficients and activation energies for the motion of rhodium on perfect planes of the rhodium lattice, in the absence of high fields, have been derived from direct observation of atomic positions, using a field ion microscope. Correlation effects, due to interactions with other rhodium atoms, are observed even at interatomic distances greater than 7.5 A. All diffusion parameters have therefore been derived from experiments with only a single atom on a plane. Estimates have been made of both the activation energy and entropy, based on a simple model involving pair potentials. These give good account of the behavior observed on rhodium, but not of previous measurements on tungsten. No simple relationship is found for diffusion on similarly structured planes of the two metals.
- Physical Chemistry
- Solid State Physics