PERIODIC AND APERIODIC MACROSCOPIC PATTERNING IN 2 PRECIPITATE POST-NUCLEATION SYSTEMS

Precipitating systems are transiently out of equilibrium. The kinetics of a first order phase transition is typically nonlinear. Thus, precipitating systems meet two necessary conditions for self-organization. Earlier work has shown that these systems can self-organize macroscopically even without the presence of cross gradients of coprecipitates and attendant nucleation feedback as suggested by Ostwald for Liesegang systems. Rather a surface tension mediated competitive particle growth (CPG) mechanism can be the feedback process leading to pattern formation. Here a two precipitate (A and B) model is presented and studied via the CPG theory. A correlated per-iodic pattern (with overlap of A and B bands) and an anti-correlated periodic pattern (with alternation of A and B bands) are shown to exist depending on the choice of model parameters. It is also found that the system can manifest aperiodic banding characterized by highly complex undulatory non-repetitive patterns which are extremely sensitive to variations of initial data.