scholarly journals Reflector Selection for the Indexing of Electron Backscatter Diffraction Patterns

2019 ◽  
Vol 25 (3) ◽  
pp. 675-681 ◽  
Author(s):  
Stuart I. Wright ◽  
Saransh Singh ◽  
Marc De Graef

AbstractWe propose a new methodology for ranking the reflectors used in traditional Hough-based indexing of electron backscatter diffraction (EBSD) patterns. Instead of kinematic X-ray or electron structure factors (Fhkl) currently utilized, we propose the integrated Kikuchi band intensity parameter (βhkl) based on integrated dynamical electron backscatter intensities. The proposed parameter is compared with the traditional kinematical intensity, $I_{hkl}^{{\rm kin}} $, as well as the average Hough transform peak intensity, $I_{hkl}^{{\rm HSP}} $ and used to index EBSD patterns for a number of different material systems of varying unit cell complexities including nickel, silicon, rutile, and forsterite. For elemental structures, βhkl closely follows the kinematical ranking. However, significant ranking differences arise for more complex unit cells, with the βhkl parameter showing a better correlation with the integrated Hough intensities. Finally, Hough-based indexing of a simulated forsterite data set showed an appreciable improvement in the median confidence index (0.15 to 0.35) when βhkl is used instead of $I_{hkl}^{{\rm kin}} $ for ranking the reflectors.

2021 ◽  
Vol 54 (2) ◽  
pp. 513-522
Author(s):  
Edward L. Pang ◽  
Christopher A. Schuh

Accurately indexing pseudosymmetric materials has long proven challenging for electron backscatter diffraction. The recent emergence of intensity-based indexing approaches promises an enhanced ability to resolve pseudosymmetry compared with traditional Hough-based indexing approaches. However, little work has been done to understand the effects of sample position and orientation on the ability to resolve pseudosymmetry, especially for intensity-based indexing approaches. Thus, in this work the effects of crystal orientation and detector distance in a model tetragonal ZrO2 (c/a = 1.0185) material are quantitatively investigated. The orientations that are easiest and most difficult to correctly index are identified, the effect of detector distance on indexing confidence is characterized, and these trends are analyzed on the basis of the appearance of specific zone axes in the diffraction patterns. The findings also point to the clear benefit of shorter detector distances for resolving pseudosymmetry using intensity-based indexing approaches.


2015 ◽  
Vol 48 (3) ◽  
pp. 797-813 ◽  
Author(s):  
Farangis Ram ◽  
Stefan Zaefferer ◽  
Tom Jäpel ◽  
Dierk Raabe

The fidelity – that is, the error, precision and accuracy – of the crystallographic orientations and disorientations obtained by the classical two-dimensional Hough-transform-based analysis of electron backscatter diffraction patterns (EBSPs) is studied. Using EBSPs simulated based on the dynamical electron diffraction theory, the fidelity analysis that has been previously performed using the patterns simulated based on the theory of kinematic electron diffraction is improved. Using the same patterns, the efficacy of a Fisher-distribution-based analytical accuracy measure for orientation and disorientation is verified.


2020 ◽  
Vol 53 (4) ◽  
pp. 1060-1072 ◽  
Author(s):  
Edward L. Pang ◽  
Peter M. Larsen ◽  
Christopher A. Schuh

Resolving pseudosymmetry has long presented a challenge for electron backscatter diffraction and has been notoriously challenging in the case of tetragonal ZrO2 in particular. In this work, a method is proposed to resolve pseudosymmetry by building upon the dictionary indexing method and augmenting it with the application of global optimization to fit accurate pattern centers, clustering of the Hough-indexed orientations to focus the dictionary in orientation space and interpolation to improve the accuracy of the indexed solution. The proposed method is demonstrated to resolve pseudosymmetry with 100% accuracy in simulated patterns of tetragonal ZrO2, even with high degrees of binning and noise. The method is then used to index an experimental data set, which confirms its ability to efficiently and accurately resolve pseudosymmetry in these materials. The present method can be applied to resolve pseudosymmetry in a wide range of materials, possibly even some more challenging than tetragonal ZrO2. Source code for this implementation is available online.


2007 ◽  
Vol 107 (4-5) ◽  
pp. 414-421 ◽  
Author(s):  
Aimo Winkelmann ◽  
Carol Trager-Cowan ◽  
Francis Sweeney ◽  
Austin P. Day ◽  
Peter Parbrook

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