Kikuchi pattern simulations of backscattered and transmitted electrons

Abstract

We discuss a refined simulation approach which treats Kikuchi diffraction patterns in electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). The model considers the result of two combined mechanisms: (a) the dynamical diffraction of electrons emitted coherently from point sources in a crystal and (b) diffraction effects on incoherent diffuse intensity distributions. Using suitable parameter settings, the refined simulation model allows to reproduce various thickness‐ and energy‐dependent features which are observed in experimental Kikuchi diffraction patterns. Excess‐deficiency features are treated by the effect of gradients in the incoherent background intensity. Based on the analytical two‐beam approximation to dynamical electron diffraction, a phenomenological model of excess‐deficiency features is derived, which can be used for pattern matching applications. The model allows to approximate the effect of the incident beam geometry as a correction signal for template patterns which can be reprojected from pre‐calculated reference data. As an application, we find that the accuracy of fitted projection centre coordinates in EBSD and TKD can be affected by changes in the order of 10−3–10−2 if excess‐deficiency features are not considered in the theoretical model underlying a best‐fit pattern matching approach. Correspondingly, the absolute accuracy of simulation‐based EBSD strain determination can suffer from biases of a similar order of magnitude if excess‐deficiency effects are neglected in the simulation model.

Improved high-resolution EBSD analyses by correcting radial distortion of electron diffraction patterns

“…This effect is due to the intuitively anisotropic diffracted electron distribution, a phenomenon well illustrated in Ref. [29] and partly solved recently [30]. The assessment and rectification of these secondary effects improves the EBSD indexation accuracy significantly.…”

Structure Analysis Using Time-of-Flight Momentum Microscopy with Hard X-rays: Status and Prospects

“…This contribution increases with temperature and energy, and leads to excessdeficiency Kikuchi lines in the general case of an anisotropic angular intensity distribution, even for a totally incoherent electron distribution. 78) The above-mentioned quantitative estimation indicates that the prominent features in Figs. 1(b)-1(d) and 2(e)-2(g) originate from Bragg reflection under shallow impact angles; in other words, from near-forward scattering.…”

Use of electron backscatter diffraction patterns to determine the crystal lattice. Part 1. Where is the Bragg angle?

“…The influence of the PC is a well discussed problem in all high-precision electron backscatter diffraction (EBSD) techniques and it is therefore a recurring topic in the literature [see e.g. Britton et al (2010), Maurice et al (2011), Basinger et al (2011), Alkorta (2013), , Pang et al (2019), Winkelmann et al (2020Winkelmann et al ( , 2021, Zhong et al (2021) and Shi et al (2021)]. The PC is only exactly known for a projection of simulated BKD patterns, so this error is just as irrelevant as that for trace positions.…”