Phase formation — Stability and nucleation kinetics of small clusters

Abstract

The properties of small particles and clusters have proved significant for a number of physical and chemical phenomena such as catalysis, adsorption, electrochemical deposition, etc. The formation of nuclei in a supersaturated phase is the basic process described by the theory of phase formation. It allows the evaluation of the nucleation work, the size of the critical nuclei and its dependence on supersaturation. The energetics of clusters and therefore any phenomenon dependent on their energetic state can be elucidated by studying the phase formation process. The theory of phase formation so far developed relies on two different approaches. The classical theory is based on thermodynamic considerations and its consequences are restricted to clusters consisting of a significant number of atoms, allowing the use of thermodynamic magnitudes and functions. In many cases, however, the critical nuclei have been found to contain only a few atoms. For such cases the so-called atomistic approach has been developed. It has been shown that there is a full continuity in the results deduced by both approaches. Published experimental work is reviewed, making use of either of them.