Solid State Nucleation Processes and Models

Let us now examine how the nucleation of particles occurs during the initial stages of a solid state reaction. In general, the rate of solid state nucleation is similar to the classical rate of chemical reaction, and is given by  

We will examine heterogeneous nucleation first and homogeneous nucleation (no outside influences) later. We do this because the former is easier to understand and forms a basis for understanding the latter. 

If we are interested in the solid state nucleation process to form a particle prior to completing the reaction, we can distinguish between surface and volume nucleation of the particle. Such cases are shown in 3.1.12. on the next page as follows. 

Starting with a particle, we can transform it either to a gas, a liquid, or a solid. Model A is determined by a phase transformation wherein the initial solid is transformed to afluid (melting) or agas (sublimation), i.e.- 

An example of this reaction is A1(N03)3 9 H2O which dissolves in its own water of hydration, i.e.- When heated, the salt loses water at slightly less than 100 °C. The water does not evaporate but begins to dissolve the 

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