Speculations on a New Mechanism of Crystal Growth from Aqueous Solutions

Abstract

AbstractThe activity of lead ions to form heterogeneous nuclei in supersaturated KCl solutions was shown (in previous publications) to account quantitatively for the effect of these ions on the limit of stability of the supersaturated solutions, the rate of crystallization, and the co‐precipitation of the lead ions with the crystallizing salt. Hence the process of crystal growth is described as the deposition of subcolloidal sized nuclei on the crystal seed. Many otherwise perplexing phenomena recorded in the literature, and observed in studies of various aspects related to the crystallization of KCl and NaCl, prove to be a direct consequence of this mechanism of crystallization. Other examples indicate that heteronucleation and a similar growth mechanism may be prevalent in the crystallization of several salts from their aqueous solutions. Some implications and possible applications of the proposed growth mechanism are also discussed.