Inverse Ostwald ripening under ion irradiation

The steady-state behavior of plain interfaces and nanoclusters (NCs) under
ion irradiation has been studied analytically as well as by kinetic
Monte-Carlo (MC) simulations. In the two-phase system mixing of A-type atoms
into phase B region leads to a strong increase of the solute concentration
at low irradiation temperatures. For NCs the ion irradiation induced
elevated solute concentration depends on their sizes. The analytical form of
this size dependence is identical to that of NCs in equilibrium, i.e. it is
given by the Gibbs-Thomson relation. However, in contrast to equilibrium,
small NCs have a lower increase in solute concentration than larger ones.
This may result in a dramatically change of the evolution of NC ensembles:
The driven system can get a negative capillarity length for its interfaces
with the consequence of mass transport from large NCs to smaller ones, i.e.
inverse Ostwald ripening is observed. Thus, it is predicted theoretically
that a broad size distribution can be made narrow by ion irradiation. At
conditions not being too far from equilibrium this behavior has been proven
by a computer experiment. The MC simulations predict in addition to the
analytical result that at very high fluxes or low temperatures large NCs can
disintegrate due to the formation of smaller ones by nucleation.