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- Bravais lattice (1)
- EBSD (1)
- Electron backscatter diffraction (1)
- Kikuchi pattern (1)
- Lattice parameter determination (1)
- Lattice parameters (1)
Organisationseinheit der BAM
A typical electron backscatter diffraction (EBSD) pattern usually contains more than a hundred of Kikuchi poles that formed by intersecting dozens of visible Kikuchi bands. The poles correspond to zone axes in real space or lattice planes in reciprocal space. The band widths are inversely proportional to the interplanar spacings of diffracting lattice planes, and the angle formed by the beam source and two band center-lines approximately corresponds to angle between two lattice planes. However, EBSD patterns always suffer from gnomic distortions. In addition, the band width measurement has a relative error of 5-20% due to the complex profile. Thus, an EBSD pattern always provides abundant crystallographic information but disappointingly low accuracy.
The Bravais lattices and their lattice parameters are blindly determined using electron backscatter diffraction (EBSD) patterns of materials with cubic or tetragonal crystal structures. Since the geometric relationships in a single EBSD pattern are overdetermined, the relative errors of determining the lattice parameters as well as the axial ratios are confined to about 0.7 ± 0.4% and 0.07 ± 0.03%, respectively, for ideal simulated EBSD patterns. The accuracy of the crystal orientation determination reaches about 0.06 ± 0.03°. With careful manual band detection, the accuracy of determining lattice parameters from experimental patterns can be as good as from simulated patterns, although the results from simulated patterns are often better than expermental patterns, which are lower quality and contain uncertain systematic errors. The reasonably high accuracy is obtained primarily because the detection of the diffracting-plane traces and zone axes is relatively accurate. The results here demonstrate that the developed procedure based on the EBSD technique presents a reliable tool for crystallographic characterization of the Bravais lattices of unknown phases.