Crystal defect formation locations

Formation and Growth of Nnclei Nuclei form at specific points of the reactant crystal lattice. These points are located in regions with disordered structure, for instance, where dislocations emerge onto the surface, at vacancies, at interstitial-ion or impurity clusters. At these points of the lattice the molecules of the original substance may not be as fully coordinated as on an ideal (defect-free) surface and this makes them more susceptible to decomposition. 

In the simplest form of the double twist cylinder, two helices are formed with their axes perpendicular to one another in the plane at right angles to the direction of the long axis of the molecule [26]. Expanding this structure in two dimensions, the two helices can intersect to form a 2-D lattice. However, the helices cannot fill space uniformly and completely, and hence defects are formed. As helices are periodic structures, the locations of the defects created by their inability to fill space uniformly are also periodic. Thus a 2-D lattice of defects is created. This inability to pack molecules uniformly can be extended to three dimensions to give various cubic arrays of defects [27]. The different lattices of defects provide the structural network required for the formation of a range of novel liquid crystal phases that are called blue phases. In prin-... 

A crystal represents a complex quantum mechanical system with an enormous amount of particles with a strong interaction between them. If all the particles are located in space strictly ordered with the formation of an ideal three-dimensional crystal structure, then such a system possesses minimal free energy. In a real crystal, however, the ideal periodicity is often broken due to inevitable thermal fluctuations some atoms break periodic array, abandon their ideal position and produce a defect. The frequency and amount of fluctuations are defined by the Boltzmann factor, i.e., they depend on temperature and binding strength or, in other words, on the depth of the potential well corresponding to the regular position of atoms. 

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