PACS number(s): 82.70.Gg, 82.70.RrWe present results from a detailed numerical study of the kinetics of phase transformations in a model
two-dimensional depletion-driven colloidal system. Transition from a single, dispersed phase to a two-phase
coexistence of monomers and clusters is obtained as the depth of the interaction potential among the colloidal
particles is changed. Increasing the well depth further, fractal clusters are observed in the simulation. These
fractal clusters have a hybrid structure in the sense that they show hexagonal closed-packed crystalline ordering
at short length scales and a ramified fractal nature at larger length scales. For sufficiently deep potential wells,
the diffusion-limited cluster-cluster aggregation model is recovered in terms of the large-scale fractal dimension Df
of the clusters, the kinetic exponent z, and the scaling form of the cluster size distribution. For
shallower well depths inside the two-phase coexistence region, simulation results for the kinetics of cluster
growth are compared with intermediate-stage phase separation in binary mixtures. In the single-phase region,
growth kinetics agree well with a mean-field aggregation-fragmentation model of Sorensen, Zhang, and Taylor.J.J.C. and T.S. acknowledge financial support from the
Spanish MCyT through Grant No. BMF2001-0341-C02-01.
A.C. and C.S.were supported by NASA through Grant No.
NAG 3-2360Peer reviewe
