Practical Electron Microscopy and Database

Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix

Effect of Screw Axis on Electron Diffraction Patterns

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. 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]