Error analysis of the crystal orientations obtained by the dictionary approach to EBSD indexing

Ram, Farangis; Wright, Stuart I.; Singh, Saransh; Graef, Marc De

doi:10.1016/j.ultramic.2017.04.016

Cited by 63 publications

(46 citation statements)

References 19 publications

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“…An accurate pattern center is necessary to obtain accurate orientation data using intensity-based indexing methods (Ram et al, 2017;Tanaka & Wilkinson, 2019;Pang et al, 2020). In pseudosymmetric materials, this is even more important since crystallographically distinct orientations can give rise to virtually identical patterns, as previously reported (Zambaldi et al, 2009;Jackson et al, 2018;De Graef et al, 2019) and seen in Fig.…”

Section: Fitting the Pattern Centermentioning

confidence: 87%

Resolving pseudosymmetry in tetragonal ZrO₂ using electron backscatter diffraction with a modified dictionary indexing approach

2020

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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.

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Section: Fitting the Pattern Centermentioning

confidence: 87%

Resolving pseudosymmetry in tetragonal ZrO₂ using electron backscatter diffraction with a modified dictionary indexing approach

2020

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“…For our approach to be widely attractive, we require high quality dynamical simulations and we are fortunate to have these now courtesy of the work of Winkelmann [2,14,35,37,38] and the commercial DynamicS package. Similar simulations capability has also been implemented by de Graef and co-workers [10,11,24] and are available within EMSoft). The master pattern approach ignores significant instrument variation (e.g.…”

Section: Discussionmentioning

confidence: 97%

Indexing electron backscatter diffraction patterns with a refined template matching approach

et al. 2019

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Graphical AbstractAbstract Electron backscatter diffraction (EBSD) is a well-established method of characterisation for crystalline materials. Using this technique, we can rapidly acquire and index diffraction patterns to provide phase and orientation information about the crystals on the material surface. The conventional analysis method uses signal processing based on a Hough/Radon transform to index each diffraction pattern. This method is limited to the analysis of simple geometric features and ignores subtle characteristics of diffraction patterns, such as variations in relative band intensities. A second method, developed to address the shortcomings of the Hough/Radon transform, is based on template matching of a test experimental pattern with a large library of potential patterns. In the present work, the template matching approach has been refined with a new cross correlation function that allows for a smaller library and enables a dramatic speed up in pattern indexing. Refinement of the indexed orientation is performed with a follow-up step to allow for small alterations to the best match from the library search. The refined template matching approach is shown to be comparable in accuracy, precision and sensitivity to the Hough based method, even exceeding it in some cases, via the use of simulations and experimental data collected from a silicon single crystal and a deformed α-iron sample. The speed up and pattern refinement approaches should increase the widespread utility of pattern matching approaches.

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“…Instead, in standard EBSD, indexing is based on Hough‐transforms of the pattern for indexing and in most scenarios only the indexing is saved and the original data, namely the Kikuchi patterns, are discarded. From that perspective, SPED performed with ASTAR can be compared to the Dictionary Indexing approach for EBSD indexing, which also saves all patterns and performs image matching for indexing against a library of precomputed patterns (Marquardt et al, ; Ram et al, ; Singh & De Graef, , ). If reliable results in terms of angular resolution (HR‐EBSD or HR‐KAM, cf.…”

Section: Methodsmentioning

confidence: 99%

Characterization by Scanning Precession Electron Diffraction of an Aggregate of Bridgmanite and Ferropericlase Deformed at HP‐HT

Nzogang

Bouquerel

Mussi

et al. 2018

Geochem Geophys Geosyst

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Scanning precession electron diffraction is an emerging promising technique for mapping phases and crystal orientations with short acquisition times (10–20 ms/pixel) in a transmission electron microscope similarly to the Electron Backscattered Diffraction (EBSD) or Transmission Kikuchi Diffraction (TKD) techniques in a scanning electron microscope. In this study, we apply this technique to the characterization of deformation microstructures in an aggregate of bridgmanite and ferropericlase deformed at 27 GPa and 2,130 K. Such a sample is challenging for microstructural characterization for two reasons: (i) the bridgmanite is very unstable under electron irradiation, (ii) under high stress conditions, the dislocation density is so large that standard characterization by diffraction contrast are limited, or impossible. Here we show that detailed analysis of intracrystalline misorientations sheds some light on the deformation mechanisms of both phases. In bridgmanite, deformation is accommodated by localized, amorphous, shear deformation lamellae whereas ferropericlase undergoes large strains leading to grain elongation in response to intense dislocation activity with no evidence for recrystallization. Plastic strain in ferropericlase can be semiquantitatively assessed by following kernel average misorientation distributions.

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Error analysis of the crystal orientations obtained by the dictionary approach to EBSD indexing

Cited by 63 publications

References 19 publications

Resolving pseudosymmetry in tetragonal ZrO₂ using electron backscatter diffraction with a modified dictionary indexing approach

Resolving pseudosymmetry in tetragonal ZrO₂ using electron backscatter diffraction with a modified dictionary indexing approach

Indexing electron backscatter diffraction patterns with a refined template matching approach

Characterization by Scanning Precession Electron Diffraction of an Aggregate of Bridgmanite and Ferropericlase Deformed at HP‐HT

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Error analysis of the crystal orientations obtained by the dictionary approach to EBSD indexing

Cited by 63 publications

References 19 publications

Resolving pseudosymmetry in tetragonal ZrO2 using electron backscatter diffraction with a modified dictionary indexing approach

Resolving pseudosymmetry in tetragonal ZrO2 using electron backscatter diffraction with a modified dictionary indexing approach

Indexing electron backscatter diffraction patterns with a refined template matching approach

Characterization by Scanning Precession Electron Diffraction of an Aggregate of Bridgmanite and Ferropericlase Deformed at HP‐HT

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Resolving pseudosymmetry in tetragonal ZrO₂ using electron backscatter diffraction with a modified dictionary indexing approach

Resolving pseudosymmetry in tetragonal ZrO₂ using electron backscatter diffraction with a modified dictionary indexing approach