HETEROGENEOUS NUCLEATION ON DEVELOPING SUBSTRATE PARTICLES

A simple model is used to describe the heterogeneous nucleation process which assumes that the substrate particle must grow to a critical size prior to its effectiveness as a nucleating agent. Also, multiple impurity site nucleation events are not permitted. The results obtained from solutions of the governing equations are applied to discuss some recent findings concerning the Raman spectra of heated lithium glass. It is shown that the anomalous maximum in the ratio of scattering intensities at 950 and 1080 cm-1 cannot be taken as evidence for the heterogeneous nucleation of lithium disilicate crystals upon metastably formed lithium silicate crystals. This conclusion is reached by an analysis of the time dependences of the substrate and heterogeneously nucleating particle number densities.