Influences of thermal spikes in ion beam mixing

Guided by the results of molecular dynamics simulations, we develop a thermal spike model for the relaxation of collision cascades in which the hot zone has mobile, reacting defects and cools by thermal diffusion. Marker atoms within such spikes are taken to migrate by radiation enhanced diffusion which is governed by the locally transient temperatures and defect concentrations. The atomic mixing associated with such motions is examined, on the basis of the model, for a variety of ion-target systems. The dependences of spike mixing on diffusion mechanism, irradiation ion and energy, and sample temperature are discussed.