Nucleation and Growth of Crystals at High Supersaturation

Homogeneous nucleation followed by diffusion controlled crystal growth was observed in highly supersaturated solutions of BaSO4, BaCrO4, BaMoO4, BaWO4, BaCO3, PbSO4, PbCrO4, PbCO3, SrSO4, and CaWO4. In the range of concentrations where the number of homogeneously nucleated particles is larger than the number of heteronuclei the induction period decreases from 1 to 10−4 sec, and the number of particles found per cm3 increases from 107 to 1012 with increasing concentration. Theoretical maps showing the rate determining mechanisms of crystal growth are drawn for different values of the physical parameters, primarily crystal size, supersaturation ratio, and interfacial tension. The techniques used for rapid mixing and for film recording are described.