THE FORMATION OF VACANCY-TYPE DEFECT CLUSTERS BY ION-BOMBARDMENT - A PROBLEM REVISITED BY MOLECULAR-DYNAMICS

In 1969 Professor Balluffi and students L. E. Thomas and T. Schober pr esented a series of three papers on the nature of defects produced by keV Au irradiation of Au [Thomas et al., Radiat. Effects 1, 257, 269, 279 (1969)]. They noted that vacancy clusters were produced with high efficiencies but could not find evidence for interstitial clusters. Th e authors interpreted their data on the basis of replacement collision sequences carrying interstitial atoms beyond the cascade core, leavin g behind a vacancy rich depleted zone which subsequently collapsed int o a visible dislocation loop. We have simulated this experiment by mol ecular dynamics and can now predict much of what these authors reporte d in 1969. However, 25 years later we offer a new. explanation for the creation of vacancy clusters based on viscous flow of liquid metal th rough the irradiated surface.