Metastable zone width of different solute-solvent systems during cooling crystallization: Experimental observations and their interpretation

• Experimental observations of metastable zone width (MSZW) of various solute−solvent systems obtained by cooling crystallization are reviewed. • MSZW data are interpreted from the standpoint of deterministic theoretical models based on the classical three-dimensional (3D) nucleation theory (CNT). • Solid−solvent interfacial energy γ eff and preexponential factor A for 3D nucleation are two parameters of CNT. • General trends of variations of the nucleation parameters as functions of solution temperature and additive concentration are discussed. • Dimensions of 3D nuclei formed during MSZW of different systems are discussed. Experimental observations of metastable zone width (MSZW) of various solute−solvent systems obtained by cooling crystallization at controlled rates R L are reviewed and interpreted from the standpoint of deterministic theoretical models based on the classical three-dimensional (3D) nucleation theory containing two nucleation parameters: effective solid−solvent interfacial energy γ eff and preexponential factor A for nucleation. After a brief introduction to the parameters F and F 1 of the models in terms of nucleation parameters of the classical nucleation theory and the effects of additives contained in the solution on the nucleation parameters A and γ eff , typical experimental data of MSZW for selected solute−solvent systems are described and discussed according to the models to observe general trends of variations of γ eff and A as functions of solution saturation temperature T 0 and concentration c i of additives contained in the saturated solutions of different systems. Thereafter the observed general trends of variations of γ eff and A as functions of solution saturation temperature T 0 , solvent and concentration c i of additives contained in the saturated solutions of different systems are discussed. The dimensions of 3D nuclei formed during MSZW of different systems and the limitations and applicability of deterministic models in crystallization processes are then presented and discussed. Finally, a summary of the contents of the review is given.