Electron microscopy
 
Effect of Screw Axis on Electron Diffraction Patterns
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Figure 1444 shows electron diffraction patterns of the Al64Cu22Co14 DQC (decagonal quasicrystal, see page1453) taken with the incident beam parallel to three primary axes. The diffraction patterns taken along directions q and p indicate that the structure includes two layers along the ten-fold axis and thus has centrosymmetry. The reflections marked by the arrows in Figure 1444 (c) disappear due to the existence of a 105 screw axis in the space group of P105/mmc.

Al64Cu22Co14 decagonal quasicrystal (DQC) diffraction

Figure 1444. Electron diffraction patterns of the Al64Cu22Co14 DQC (space group: P105/mmc): (a) In ten-fold symmetry, (b) Along direction q and (b) Along direction p. [2]

 

 

 

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