Ostwaldripening

Ostwaldripening is a term used in materials science to describe a diffusion-driven coarsening process in colloidal dispersions where larger particles grow at the expense of smaller ones. The mechanism is essentially the same as Ostwald ripening, but the term is sometimes used to emphasize its origin in Wilhelm Ostwald’s early work or to denote specific experimental conditions.

The driving force is curvature-dependent solubility: smaller particles have higher solubility due to the Gibbs-Thomson effect, dissolving into the surrounding medium and redepositing on larger particles. Mass transfer is usually diffusion-controlled in a supersaturated system. Over time, small particles vanish and the average size increases, often broadening the size distribution.

LSW theory provides a framework for diffusion-controlled ripening in dilute suspensions, predicting that the average radius grows roughly with time to the one-third power and particle number density declines. Real systems may show deviations due to coalescence, nonuniform environments, or interactions between particles.

Applications include nanoparticle synthesis, pigments, ceramics, and stabilization of emulsions. Observations use transmission electron microscopy, dynamic light scattering, or small-angle scattering to track size distributions.

Nomenclature: Ostwaldripening is not widely used in standard literature; most authors refer to Ostwald ripening. When encountered, it may reflect historical emphasis or regional naming.