Accurate determination of low-symmetry Bravais unit cells by EBSD

Han, Ming; Zhao, Guangming; Zhu, Ye

doi:10.1016/j.ultramic.2018.08.024

Cited by 3 publications

(3 citation statements)

References 36 publications

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“…Similar to ab-initio analysis on diffraction patterns developed for convergent beam electron diffraction (CBED) (Ayer, 1989; Page, 1992), phase identification using just EBSD patterns (Michael & Goehner, 1999; Michael & Eades, 2000; Dingley & Wright, 2009; Li et al, 2014; Li & Han, 2015; Han et al, 2018 a ; Kaufmann et al, 2019), chemical-sensitive holography (Lühr et al, 2016), or combinations with EDS data (Small & Michael, 2001; Nowell & Wright, 2004) have also been extensively studied to compete with the more traditional XRD method. Due to the inherent nature of diffuse scattering, the accuracy of any electron diffraction-based method to measure lattice parameters is unlikely to reach that of XRD without a sophisticated band localization algorithm (Ram et al, 2014), although correct classification of the Bravais lattice with a reasonably accurate lattice parameter is already possible (Michael & Goehner, 1999, 2000; Han et al, 2018 a , 2018 b ). In order to determine the symmetry elements from EBSPs (e.g., rotation axes, diads, triads, etc.…”

Section: Resultsmentioning

confidence: 99%

Automated Reconstruction of Spherical Kikuchi Maps

2019

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An automated approach to reconstruct spherical Kikuchi maps from experimentally collected electron backscatter diffraction patterns and overlay each pattern onto its corresponding position on a simulated Kikuchi sphere is presented in this study. This work demonstrates the feasibility of warping any Kikuchi pattern onto its corresponding location of a simulated Kikuchi sphere and reconstructing a spherical Kikuchi map of a known phase based on any set of experimental patterns. This method consists of the following steps after pattern collection: 1) pattern selection based on multiple threshold values; 2) extraction of multiple scan parameters and phase information; 3) generation of a kinematically simulated Kikuchi sphere as the 'skeleton' of the spherical Kikuchi map; and 4) overlaying the inverse gnomonic projection of multiple selected patterns after appropriate pattern center calibration and refinement. In the case study of pure aluminum, up to 90% of the Kikuchi sphere could be reconstructed with just seven experimentally collected patterns. The proposed method is the first automated approach to reconstructing spherical Kikuchi maps from experimental Kikuchi patterns. It potentially enables 2 more accurate orientation calculation, new pattern center refinement methods, improved dictionary-based pattern matching, and phase identification in the future.

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Section: Resultsmentioning

confidence: 99%

Automated Reconstruction of Spherical Kikuchi Maps

2019

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“…But when the calculation error of the interplanar spacing is large, although this approach (the reciprocal vector length is proportional to the bandwidth) will introduce additional errors, it seems that there is no better way. Most previous methods used the naked eye to determine the position and width of Kikuchi bands 16–18 . Relying on visual recognition is not only time consuming due to the generally manual definition of band positions and widths, but also has low accuracy.…”

Section: Introductionmentioning

confidence: 99%

Identifying rotational symmetry axes in Kikuchi patterns by reciprocal vectors

Peng

Zhang

et al. 2021

Journal of Microscopy

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Symmetry analysis of the Kikuchi pattern is helpful to determine the crystal structure, and can significantly reduce the screening range of phase identification, thereby improving the accuracy and reliability of phase identification in electron backscatter diffraction (EBSD). Accurately identifying the symmetry axis from the Kikuchi pattern is the primary task of symmetry analysis. In this study, a new method was proposed to identify symmetry axes in Kikuchi patterns with the aid of reciprocal vectors. Taking the Kikuchi patterns of single‐crystal silicon as a typical example, a method for drawing reciprocal vectors after strict projection correction is introduced. The complex task of identifying the symmetry axis is transformed into an intuitive judgment of the geometric relationship between reciprocal vectors, thus greatly simplifying the process. This method successfully elucidated information on six Kikuchi poles in three single‐crystal silicon Kikuchi patterns, including 3‐fold axes, 4‐fold axes and asymmetric axes. The method can also distinguish between a 3‐fold axis and an analogous 3‐fold axis despite their only slight differences.

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“…电子背散射衍射(EBSD)作为一种相对较新的显微结构分析手段，可以在较大范围内提供材料的取向、织构、相鉴定及含量分布等晶体学统计性信息 [1][2][3][4] ，为无机材料制备工艺的改善、微结构调控及性能优化提供了可靠的科学依据。Fang 等 [5] 通过 EBSD 技术对梯度纳米(GNG)金属铜进行表征，为解释其拉伸变形的机理提供了重要显微结构证据。 EBSD 还是研究涂层内部残余应力分布的最佳显微结构分析手段，为研究热障涂层的服役失效行为提供了重要支撑。EBSD 提供的所有晶体学信息都依赖对菊池衍射花样的分析 [6] ，菊池花样直观反映材料内部微观结构，其中，菊池带对应不同指数的晶面，菊池带的交点即菊池极代表晶带轴 [4] [7] 尝试利用对称性进行相鉴定，但因为晶面间距计算误差较大，只能依靠肉眼在菊池花样中识别对称轴，容易误判。通过菊池带宽度计算晶面间距的误差通常较大(5%~20%) [7][8] ，这是用菊池花样进行对称性分析的最大难点。我们前期工作对晶面间距进行了准确测量，平均相对误差为 2.6% [9] ，为准确识别对称轴奠定了基础，还可区分非对称轴。对 Si 单晶菊池花样的分析发现了类似三次轴的非对称轴，计算晶面间距发现，菊池带并不属于同一晶面族，不满足三次轴的条件，这是肉眼识别很容易误判的。晶面夹角可通过三维空间矢量计算获得 [10]…”

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Method of Crystal Structure Identification by Using Kikuchi Diffraction Patterns

Fan¹,

Zeng²

2021

Journal of Inorganic Materials

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Electron backscatter diffraction (EBSD) is an important microstructure analysis method in the field of inorganic materials research. The Kikuchi pattern obtained through EBSD is an intuitive reflection of the internal microscopic crystal structure of the material. In this paper, a method of crystal symmetry analysis and crystal structure identification by using Kikuchi patterns was proposed by recognizing the symmetry axis though Kikuchi patterns and using the law of crystal symmetry. The symmetry and crystal structure of three unknown samples were successfully determined by this method. One of the samples was identified to which crystal system it belongs, and the other two were fixed on some certain point groups. Through the determination of crystal system and point group, some phase identification results that do not conform to symmetry were excluded. It is indicated that the symmetry analysis of Kikuchi patterns is an effective way to identify the crystal structure and can significantly filter the phase database. Compared with the existing methods, this method greatly reduces the retrieval range of phase identification, and significantly improves the accuracy and reliability of phase identification. It is a promising indexing technique for the new generation of EBSD devices.

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Accurate determination of low-symmetry Bravais unit cells by EBSD

Cited by 3 publications

References 36 publications

Automated Reconstruction of Spherical Kikuchi Maps

Automated Reconstruction of Spherical Kikuchi Maps

Identifying rotational symmetry axes in Kikuchi patterns by reciprocal vectors

Method of Crystal Structure Identification by Using Kikuchi Diffraction Patterns

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