Stages of Crystal Growth

Whether or not this latter process occurs will depend on the relative energies of the binding at a particular site at which first attachment occurs to the energy of binding at an adjacent site. 

Whilst this analysis is appropriate for solution growth, similar situations will be developed in the melt, except the growing entity will often be a cluster of molecules. In both situations the formation of the step is a critical step in determining the final morphology of the material. 

The process of crystal growth occurs in the following stages  

Diffusion along a step, vi. Integration into the crystal at a kink. 

Diffusion of coordination shell of solvent molecules away from crystal surface, 

Liberation of heat of crystallization and its transport away from crystal. 

11 schematically presents these processes along with the energetics of each step [35]. 

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In most carbon and graphite processes, the initial polymerization reactions occur in the Hquid state. The subsequent stages of crystal growth, heteroatom elimination, and molecular ordering occur in the soHd phase. The result is the development of a three-dimensional graphite stmcture. 

Figure 7 A conceptual model that takes into account recent experimental data. It shows that siibcritical nuclei should always be associated with a nucleating surface and that after nucleation, a variety of structures may result. The metastable structures, likely including kinetic products, will eventually convert to the thermodynamically stable product. The arrows underneath show where additives for inhibition are active. The Kinetic inhibitors may interfere with both micleation and growth at any stage of crystal growth.

The importance of kinetic factors in isomer crystallization highlights the role played by the crystal-medium interface, particularly during the early stages of crystal growth when crystals are small and surface interactions dominate relative to lattice energy. Chemical variation in the crystallization medium can be achieved by modification of solvent, counterions, and pH, among other factors. 

It is clear that the rigorous requirements of some physical property measurements can only be met by introducing SSE into the crystal growth route, whether on its own or in combination with another technique. In the latter case, it is usual for SSE to be the final stage of crystal growth or improvement in crystallinity, but in some instances it has been used as a precursor to another... 

The solutions required consist of BEDT-TTF (0.012 g, 0.03 mmol) in purified (see Section A) TCE (5mL), and [CH3(CH2)3]4NFS03 (0.512 g, 1.5 mmol) in purifled TCE (10 mL). The crystals are grown using a current of 1.0 and harvested after 2 weeks (when color changes may occur) or at any desired stage of crystal growth. 

Patil. N.. Balzano, L., Portale, G., and Rastogi. S. (2009) Influence of nanopartides on the rheological behaviour and initial stages of crystal growth in linear polyethylene. Macromolecular Chemistry and Physics,... 

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