Colloidal interactions during the precipitation of uniform submicrometre particles

Mechanisms of nucleation and growth of uniform micrometre and submicrometre inorganic particles are discussed. Precipitation reactions involving the hydrolysis and condensation of silicon and titanium alkoxides are studied and evidence is presented that the short nucleation time model of LaMer fails to describe the unniformity of the resulting precipitates. Drawing on analogies with emulsion and dispersion polymerization, a model is postulated where aggregation plays a central role in determining final number densities. Results of numerical calculations where growth is assumed to occur solely by aggregation are described.