Coincidence boundary

Figure 5.9 A coincidence boundary (001) in Zeolite L. The top part of the crystal is rotated by 32.2° with respect to the bottom part thereby generating a coincidence boundary. (From Terasaki et ai, 1984.)...

Fig. 9.42. Frequency of various coincident boundaries as a function of the E number (adapted from Watanabe (1989)). The data are for a fully annealed Fe-6.5 wt%Si alloy. The two distributions (different color histograms) correspond to samples with different textures.

Similar expressions are valid also for the concentration of vacancies in the boundary layer. The binding energy of atoms in coinciding boundary sites is somewhat lower on the average than in the LRC volume. Therefore the vacancies concentration in coincident sites is higher than in the LRC body. If one accounts for the fact that on the boundaries the concentration of nonthermal partial vacancies is high, then we may state that the diffusion of atoms by the vacancy mechanism on the boundaries is considerably higher than in LRC. 

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