2mm Symmetry  Practical Electron Microscopy and Database   An Online Book  

Microanalysis  EM Book https://www.globalsino.com/EM/  


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Figure 2999a shows the wholepattern symmetry and projectiondiffraction symmetry of the [1100] CBED patterns of T1 (Al_{2}CuLi) crystals. [2] The symmetries of both patterns are 2mm. The projectiondiffraction symmetry in Figures 2999a(b) does not show perfect 2mm symmetry due to slight misalignment of the second condenser aperture.
Figure 2999b shows an electron diffraction pattern obtained from Zr_{41}Ti_{14}Cu_{12.5}Ni_{10}Be_{22.5} in [100] zone axis. This crystal system belongs to space group I4/mmm and the diffraction pattern have 2mm Symmetry. Figure 2999b. Electron diffraction pattern obtained from Zr_{41}Ti_{14}Cu_{12.5}Ni_{10}Be_{22.5} in [100] zone axis. The lattice parameters are a = 0.34 nm, and c = 1.137 nm. [1]
[1] Q. Wei, N. Wanderka, P. SchubertBischoff, and MP. Macht, S. Friedrich, Crystallization phases of the Zr_{41}Ti_{14}Cu_{12.5}Ni_{10}Be_{22.5} alloy after slow solidification, J. Mater. Res., 15 (8) 1729, (2000).


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