Revision of the classical nucleation theory for supersaturated solutions

TL;DR

This paper revises classical nucleation theory by incorporating the effects of diffusion flux near the cluster-solution interface, significantly improving the accuracy of nucleation rate predictions in diffusion-limited regimes.

Contribution

It introduces a new approach that accounts for local concentration changes affecting nucleation kinetics, which were neglected in classical theory.

Findings

Discrepancies with classical theory are significant in diffusion-limited regimes.

The revised model aligns with classical results in interface-limited cases.

Total solubility and nucleation rates are quantitatively affected by the new approach.

Abstract

During the processes of nucleation and growth of a precipitate cluster from a supersaturated solution, the diffusion flux between the cluster and the solution changes the solute concentration near the cluster-solution interface from its average bulk value. This feature affects the rates of attachment and detachment of solute atoms at the interface and, therefore, alters the entire nucleation kinetics. Unless quite obvious, this effect has been ignored in the classical nucleation theory. To illustrate the results of this new approach, for the case of homogeneous nucleation, we calculate the total solubility (including the contribution from heterophase fluctuations) and the nucleation rate as functions of two parameters of the model and compare these results to the classical ones. One can conclude that discrepancies with the classical nucleation theory are great in the diffusion-limited regime, when the bulk diffusion mobility of solute atoms is small compared to the interfacial one, while in the opposite interface-limited case they vanish.