Direct Visualization of Large‐Scale Intrinsic Atomic Lattice Structure and Its Collective Anisotropy in Air‐Sensitive Monolayer 1T’‐ WTe₂

Abstract

Probing large-scale intrinsic structure of air-sensitive 2D materials with atomic resolution is so far challenging due to their rapid oxidization and contamination. Here, by keeping the whole experiment including growth, transfer, and characterizations in an interconnected atmosphere-control environment, the large-scale intact lattice structure of air-sensitive monolayer 1T'-WTe 2 is directly visualized by atom-resolved scanning transmission electron microscopy. Benefit from the large-scale atomic mapping, collective lattice distortions are further unveiled due to the presence of anisotropic rippling, which propagates perpendicular to only one of the preferential lattice planes in the same WTe 2 monolayer. Such anisotropic lattice rippling modulates the intrinsic point defect (Te vacancy) distribution, in which they aggregate at the constrictive inner side of the undulating structure, presumably due to the ripple-induced asymmetric strain as elaborated by density functional theory. The results pave the way for atomic characterizations and defect engineering of air-sensitive 2D layered materials.

Atomic-scale insights on hydrogen trapping and exclusion at incoherent interfaces of nanoprecipitates in martensitic steels

“…6 ). Note that the CalAtom software employs a multiple-ellipse fitting algorithm to determine the positions of the atomic columns with high precision, which has been widely applied in literatures 39 , 40 . Following the strain analysis method in the literature 41 , atomic strain maps are generated by comparing the nearest-neighbor distances in two crystallographic directions (namely and [110]) separately to their reference values.…”

A small-dataset-trained deep learning framework for identifying atoms on transmission electron microscopy images

“…In order to make the AP-GANs better to predict the probability map for the experimental images, experimental input-output pairs must be included in the training set, since their features are directly related to the images to be analyzed. In this paper, only about 30 experimental images of 256*256 pixels 2 are used in the training set, and the total pixel area of all the training set is small, only equaling to the half pixel area of one image of 2048*2048 pixels 2 . The application on graphene has proven that the AP-GANs are more reliable than the existing networks, especially when only 70% of the pixels are reserved.…”

“…To highlight the atomic columns and depress intrinsic noise in experimental images, the loss functions of the generator model are deliberate and composed of three parts with different weights (see Supplementary Eqs. (1)(2)(3)(4)(5)(6)(7) and Supplementary Table S1 for hyperparameters of network training), which are the adversarial loss of the generator model and the discriminator model, the loss of the structural similarity (SSIM) 32 , and the loss of the peak signal-to-noise ratio (PSNR) 32 . The adversarial loss is an inherent loss to compel the generator model for outputting high-quality fake images to deceive the discriminator model.…”

One-Step Growth of Bilayer 2H–1T′ MoTe2 van der Waals Heterostructures with Interlayer-Coupled Resonant Phonon Vibration

“…Even though the bilayer 2H–1T′ vdWHs can be constructed, they are also sensitive in the ambient conditions and degrade quickly. So a well-protected atmosphere from growth to characterization is needed to probe the intrinsic structure and the interfacial properties of the bilayer 2H–1T′ vdWHs …”

“…So a well-protected atmosphere from growth to characterization is needed to probe the intrinsic structure and the interfacial properties of the bilayer 2H−1T′ vdWHs. 27 Here, we demonstrated the synthesis of the bilayer 2H−1T′ MoTe 2 vdWHs in a one-step CVD growth method, which was realized by precisely manipulating the metal oxides/NaCl ratio and the reaction temperature to cover the small growth window that is overlapped for the two phases. Noteworthy, our home-built glovebox interconnection system (GIS) provides inert atmosphere protection in all subsequent characterizations.…”