Ion-beam mixing in energetic collision cascades: Thermal-spike model and experiments

Abstract

A phenomenological model of ion-beam mixing during energetic collision cascades is developed, based on the concept of a thermal spike, to correctly predict that the mixing rate Dt depends linearly on nuclear stopping power (instead of a power-law dependence), and is correlated with a heat of mixing (analogous to Darken's relation). Previous ion-beam mixing experiments from 25 different metallic bilayers agree well with the model's predictions: mixing rates (Dt)/(ion-dose) ∼ 1 nm4, and an activation enthalpy of approximately 1 eV for atomic diffusion in liquid-like cascades.