Interface kinetics lateral growth

X3 is also metastable but is far less stable kinetically than is X2. X3 is transformed into XI not X2) simply on standing at room temperature for a period of 1-2 months (relative humidity about 35%). This transformation occurs much more rapidly if X3 is contacted with liquid water (as in a DIT cell). During DIT studies, X3 initially swells to form metastable liquid and liquid crystal phases (see later), but the growth of XI crystals from the X3/ lamellar liquid crystal interface was observed. The X3 —> XI transformation is also accelerated by exposing the X3 phase to an atmosphere of 90% relative humidity (RH) under these conditions the reaction is complete within about 2 weeks. Whether by reaction with liquid water or with water vapor, the path of the X3 —> XI transformation probably involves dissolution of X3 (to form a fluid liquid or liquid crystal phase), followed by the nucleation and growth of XI crystals. These data suggest that the free energies of these three crystal phases decrease in the order X3 > X2 > XL... 

Figure 6.6 Myelins formed at the interface between surfactant C12E3 and water, (a) Diffusive growth in early stages, (b) Coiling in later stage. [Reprinted from P. B. Warren et al, Curr. Opin. Colloid Interface ScL, 6, Kinetics of... , 287, 293. Copyright (2001), with permission from Elsevier]...

Fig. 3.1 Sketch of intrinsic point-defect kinetics of an AB compound at atomically flat melt/solid interface propagating by a step-growth mechanism (Rjt - lateral step-growth rate).

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