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

Abstract

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 F₁ 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 T₀ 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 T₀, 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.