Ion irradiation of gold inclusions in SiO2: Experimental evidence for inverse Ostwald ripening

When sub mm size gold inclusions in SiO2 are irradiated with MeV gold ions, a ring of nanometer-size clusters is formed in their immediate vicinity. T he size, density and radial distribution of these nanoclusters were determi ned, Our observations are in agreement with a recent prediction that in a d riven system, under appropriate ion beam and temperature conditions, the st eady-state solute concentration's dependence on precipitate size may be opp osite to that expected from the equilibrium Gibbs-Thomson relation, Kinetic Monte-Carlo simulations account for additional experimental results: the i rradiation-induced increase in solute concentration can promote nucleation of additional precipitates around the first ring. The latter finding contra dicts the usual assumption that ion beam mixing hinders nucleation. (C) 200 1 Elsevier Science B.V. All rights reserved.