Subset geometric phase analysis method for deformation evaluation of HRTEM images

Zhang, Hongye; Liu, Zhanwei; Wen, Hu; Xie, Huimin; Liu, Chao

doi:10.1016/j.ultramic.2016.08.019

Cited by 35 publications

(25 citation statements)

References 28 publications

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“…To obtain the local variations in wavelength λ(x) of the original wave, shown on the bottom, one calculates the derivative of the local phase. Spatial lock-in algorithms like this have been used previously in electron microscopy studies (known as geometric phase analysis) (28)(29)(30) and optical metrology (31). In the context of STM, the most wellknown application is known as the Lawler-Fujita algorithm (32).…”

Section: Arxiv:200813766v1 [Cond-matmes-hall] 31 Aug 2020mentioning

confidence: 99%

Measuring local moiré lattice heterogeneity of twisted bilayer graphene

Benschop

Jong

Stepanov

et al. 2021

Phys. Rev. Research

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We introduce a new method to continuously map inhomogeneities of a moiré lattice and apply it to open-device twisted bilayer graphene (TBG). We show that the variation in the twist angle, which is frequently conjectured to be the reason for differences between devices with a supposed similar twist angle, is about 0.04° over areas of several hundred nm, comparable to devices encapsulated between hBN slabs. We distinguish between an effective twist angle and local anisotropy and relate the latter to heterostrain. Our results suggest that the lack of evidence for superconductivity in open devices is not a consequence of higher heterogeneity in the twist angle, but possibly due to the absence of interaction with a top hBN layer. Furthermore, our results imply that for our devices, twist angle heterogeneity has a roughly equal effect to the electronic structure as local strain. The method introduced here is applicable to results from different imaging techniques, and on different moiré materials.

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Section: Arxiv:200813766v1 [Cond-matmes-hall] 31 Aug 2020mentioning

confidence: 99%

Measuring local moiré lattice heterogeneity of twisted bilayer graphene

Benschop

Jong

Stepanov

et al. 2021

Phys. Rev. Research

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“…GPA is a widely used method to map the strain field from high resolution TEM images based on Fourier‐space‐based data processing, [ 25–31 ] and has been applied for various materials. [ 32–42 ] However, GPA method can be difficult to be directly applied to STEM images, as low‐sampled STEM images often lose detailed information at atomic scale, in addition to other artifacts such as scanning noise and scanning distortions etc.…”

Section: Theory and Developmentsmentioning

confidence: 99%

Moiré Fringe Method via Scanning Transmission Electron Microscopy

Zhang

Zhao

et al. 2021

Small Methods

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Moiré fringe, originated from the beating of two sets of lattices, is a commonly observed phenomenon in physics, optics, and materials science. Recently, a new method of creating moiré fringe via scanning transmission electron microscopy (STEM) has been developed to image materials’ structures at a large field of view. Moreover, this method shows great advantages in studying atomic structures of beam sensitive materials by significantly reduced electron dose. Here, the development of the STEM moiré fringe (STEM‐MF) method is reviewed. The authors first introduce the theory of STEM‐MF and then discuss the advances of this technique in combination with geometric phase analysis, annular bright field imaging, energy dispersive X‐ray spectroscopy, and electron energy loss spectroscopy. Applications of STEM‐MF on strain, defects, 2D materials, and beam‐sensitive materials are further summarized. Finally, the authors′ perspectives on the future directions of STEM‐MF are presented.

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“…Similarly, the relative deformation when the strain gauge value was 0 was also obtained. Finally, the actual deformation distributions, including the 2D displacements (Figure 2d), the 2D normal strains, and the shear strain (Figure 2e), were measured using equations (5) and (6).…”

Section: A) Deformation Measurement Of Cfrp #1mentioning

confidence: 99%

“…Since optical techniques are non-contact, full-field, and non-destructive, various optical methods have been developed for deformation measurement during the last few decades. In recent years, the micro/nano-scale deformation measurement techniques mainly include the moiré methods 1,2,3,4 , geometric phase analysis (GPA) 5,6 , Fourier transformation (FT), digital image correlation (DIC), and electronic speckle pattern interferometry (ESPI). Among these techniques, GPA and FT are not well suited for complex deformation measurements because multiple frequencies exist.…”

Section: Introductionmentioning

confidence: 99%

Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes

Wang

Tsuda

2017

JoVE

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This work describes the measurement procedure and principles of a sampling moiré technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moiré method or the spatial phase-shifting sampling moiré method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moiré fringes are generated to reconstruct a multiplication moiré pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moiré method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moiré fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moiré techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

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Subset geometric phase analysis method for deformation evaluation of HRTEM images

Cited by 35 publications

References 28 publications

Measuring local moiré lattice heterogeneity of twisted bilayer graphene

Measuring local moiré lattice heterogeneity of twisted bilayer graphene

Moiré Fringe Method via Scanning Transmission Electron Microscopy

Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes

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Subset geometric phase analysis method for deformation evaluation of HRTEM images

Cited by 35 publications

References 28 publications

Measuring local moiré lattice heterogeneity of twisted bilayer graphene

Measuring local moiré lattice heterogeneity of twisted bilayer graphene

Moiré Fringe Method via Scanning Transmission Electron Microscopy

Micro/Nano-scale Strain Distribution Measurement from Sampling Moir&#233; Fringes

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Resources

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Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes