The migration of interstitial atoms in gold I. experimental

Abstract

Direct information about the migration energy of single interstitial atoms in gold was obtained using a combination of low energy ion bombardment and transmission electron microscope techniques. Both annealed and quenched gold foils, containing vacancy tetrahedra, were bombarded with 200 ev argon ions inside an electron microscope at temperatures between -130°c and 30°c. The foils were observed both at the bombardment temperature and during subsequent annealing. The bombardment produced focused replacement sequences which deposited interstitials about 100 Å beneath the incident surface. The observations of the formation of interstitial clusters and of the removal of vacancy tetrahedra as a function of temperature and foil thickness give strong support to the hypothesis that a type of single interstitial is produced which migrates over distances of several hundred angstroms only above 0°c. On this model the energy of migration of this interstitial is not less than 0·7 ev.