Mapping the full lattice strain tensor of a single dislocation by high angular resolution transmission Kikuchi diffraction (HR-TKD)

Yu, Hongbing; Liu, Junliang; Karamched, Phani; Wilkinson, Angus J.; Hofmann, Felix

doi:10.1016/j.scriptamat.2018.12.039

Cited by 42 publications

(35 citation statements)

References 44 publications

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“…The strain tensor calculation from the diffraction pattern of transmission electron microscopy is described in the previous research . The components of the strain tensor ( ɛ xy ) of the high‐resolution image at any position are obtained by differentiation of the small displacements

ε_{x y} = \frac{1}{2} (\frac{\partial u_{x}}{\partial y} + \frac{\partial u_{y}}{\partial x})

…”

Section: Methodsmentioning

confidence: 99%

Heterogeneous Supersaturation in Mixed Perovskites

et al. 2020

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Thin‐film solar cells based on hybrid lead halide perovskites have achieved certified power conversion efficiencies exceeding 24%, approaching those of crystalline silicon. This motivates deeper studies of the mechanisms that determine their performance. Twin defect sites have been proposed as a source of traps in perovskites, yet their origin and influence on photovoltaic performance remain unclear. It is found that twin defects—observed herein via both transmission electron microscopy and X‐ray diffraction—are correlated with the amount of antisolvent added to the perovskite and that twin defects in the highest‐performing perovskite photovoltaics are suppressed. Heterogeneous supersaturation nucleation is discussed as a contributor to efficient perovskite‐based optoelectronic devices.

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ε_{x y} = \frac{1}{2} (\frac{\partial u_{x}}{\partial y} + \frac{\partial u_{y}}{\partial x})

…”

Section: Methodsmentioning

confidence: 99%

Heterogeneous Supersaturation in Mixed Perovskites

et al. 2020

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“…The HR-EBSD technique measures lattice rotation and elastic strain with an accuracy up to 10 À4 (0,006°) on single crystals such as GaN and SiGe [26] or silicon subjected to four-point bending [27]. It was also applied for the first time to "off-axis" TKD [28] in 2018 to map the strain field in the vicinity of a single dislocation in tungsten or more recently to "on-axis" TKD [29]. In the HR-EBSD method, at least four non-collinear regions of interest (ROI) are picked up across two highresolution EDP (typically 1000 £ 1000 pixels), one reference EDP and one target EDP.…”

Section: Introductionmentioning

confidence: 99%

Global DIC approach guided by a cross-correlation based initial guess for HR-EBSD and on-axis HR-TKD

et al. 2020

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Digital image correlation (DIC) techniques usually performed on deforming speckle patterns are applied here on electron diffraction patterns (EDP) in order to map disorientations with high angular resolution, as well as geometrically necessary dislocation densities and elastic strains. The proposed approach relies on a DIC analysis which is conducted independently from the microscope calibration. It registers EDP as a whole through a single and large region of interest whose relative deformation with respect to a reference EDP is described by a first-order homography. Subpixel registration is performed iteratively in the spatial domain using an inverse-compositional Gauss-Newton (IC-GN) algorithm which integrates the correction of the optical distortions. Its robustness against large orientation changes as well as its computational efficiency are improved by mean of an automated and path-independent initial guess which fairly captures the effects of large rotations on the EDP. Using successive Fourier-Mellin and Fourier transforms based cross-correlation techniques, the initial guess measures the in-plane rotation and translation between the reference and the target EDP, respectively. The performances of the technique are illustrated in markedly plastically deformed steels using two electron diffraction techniques in the scanning electron microscope. A 15% deformed interstitial free steel is investigated by means of electron backscattered diffraction (EBSD) while a quenched and tempered oxide dispersed strengthened steel subjected to martensitic transformation is characterized using a recently developed on-axis Transmission Kikuchi Diffraction (TKD) configuration.

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“…The spatial resolution of about 100 nm is consistent with observations for Tungsten as discussed in Tripathi & Zaefferer (2019). We observe that the orientation precision of the FPM method presented here approaches the level of HR transmission Kikuchi (TKD) measurements on the strain field of single dislocations (Yu et al ., 2019), where the spatial resolution of TKD is about an order of magnitude better than EBSD. The possibility to resolve fine orientational features by the FPM method demonstrated here suggests future investigations of additional strain effects via aprojective pattern matching approach that has been used for mapping the local tetragonality in martensite using low‐resolution patterns (Winkelmann et al ., 2018).…”

Section: Discussionmentioning

confidence: 99%

Improving EBSD precision by orientation refinement with full pattern matching

Winkelmann

Jablon

Tong

et al. 2020

Journal of Microscopy

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Summary We present a comparison of the precision of different approaches for orientation imaging using electron backscatter diffraction (EBSD) in the scanning electron microscope. We have used EBSD to image the internal structure of WC grains, which contain features due to dislocations and subgrains. We compare the conventional, Hough‐transform based orientation results from the EBSD system software with results of a high‐precision orientation refinement using simulated pattern matching at the full available detector resolution of 640 × 480 pixels. Electron channelling contrast imaging (ECCI) is used to verify the correspondence of qualitative ECCI features with the quantitative orientation data from pattern matching. For the investigated sample, this leads to an estimated pattern matching sensitivity of about 0.5 mrad (0.03°) and a spatial feature resolution of about 100 nm. In order to investigate the alternative approach of postprocessing noisy orientation data, we analyse the effects of two different types of orientation filters. Using reference features in the high‐precision pattern matching results for comparison, we find that denoising of orientation data can reduce the spatial resolution, and can lead to the creation of orientation artefacts for crystallographic features near the spatial and orientational resolution limits of EBSD.

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Mapping the full lattice strain tensor of a single dislocation by high angular resolution transmission Kikuchi diffraction (HR-TKD)

Cited by 42 publications

References 44 publications

Heterogeneous Supersaturation in Mixed Perovskites

Heterogeneous Supersaturation in Mixed Perovskites

Global DIC approach guided by a cross-correlation based initial guess for HR-EBSD and on-axis HR-TKD

Improving EBSD precision by orientation refinement with full pattern matching

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