Kinetics stable nuclei

This may continue until eventually the cluster is large enough to be thermodynamically stable (i.e., will not redissolve). However, if the cluster is smaller than the critical nucleus size, then there is the possibility that the nucleus will redissolve. The lifetime of the nucleus will then depend on its size and also on the temperature lower temperatures will slow the redissolution step. Thus lower temperature increases the chance that a subcritical nucleus will eventually grow to a stable size rather than redissolve. This kinetic stabilization of small nuclei results in a greater total density of nuclei and therefore smaller crystal size, since the total quantities of reactants are fixed. 

Generally, nucleation is a kinetic process where a small number of atoms form a stable cluster of atoms arranged closely to the structure of the new phase or phases, named nucleus, within the old phase. This nucleus subsequently operates as the primary construction block for a growing grain (see Figure 3.1). 

D nucleus, building blocks just adsorb on the faces and then diffuse together and cluster. Once the nucleus has reached critical size, it becomes stable and exhibits some class K faces, where growth units can be incorporated that convert the class K face to class S. The process continues until all the K faces are filled the S sites then begin to fill, resulting in a perfect crystal that has all F faces. The kinetics of the growth is typically diffusion-controlled at the rate R ... 

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