TEM nano-Moiré evaluation for an invisible lattice structure near the grain interface

Abstract

Moiré technique is a powerful, important and effective tool for scientific research, from the nano-scale to the macro-scale, which is essentially the interference between two or more periodic structures with a similar frequency. In this study, an inverse transmission electron microscopy (TEM) nano-Moiré method has been proposed, for the first time, to reconstruct an invisible lattice structure near the grain interface, where only one kind of lattice structure and Moiré fringe were visible in a high resolution TEM (HRTEM) image simultaneously. The inversion process was performed in detail. Three rules were put forward to ensure the uniqueness of the inversion result. The HRTEM image of a top-coat/thermally grown oxide interface in a thermal barrier coating (TBC) structure was observed with coexisting visible lattice and Moiré fringes. Using the inverse TEM nano-Moiré method, the invisible lower layer lattice was inversed and a 3-dimensional structure near the interface was also reconstructed to some degree. The real strain field of oriented invisible and visible lattices and the relative strain field of the Moiré fringe in the grain and near the grain boundary were obtained simultaneously through the subset geometric phase analysis method. The possible failure mechanism and position of the TBC spallation from the nano-scale to the micro-scale were discussed.

Reversed Phase Transformation of β→α-Sn at Elevated Temperatures towards Quantum Material Integration on Silicon

“…[33][34][35] Panels (d) and (e) show an α-Sn(111) inter-planar spacing of d=(0.367 ± 0.03) nm, in good agreement with the expected value of 0.370 nm for 4.2 at.% Ge and -0.63% in-plane compressive strain measured by XRD. Moiré patterns 46,47 are also observed in some regions (see Panel (f)-(h)) due to the vertical overlapping of the predominant α-Sn(111) planes with β-Sn(200) planes at an angle of ∼11.5°. In contrast, panels (i)-(k) shows a pure β-Sn microdot with its (101) planes almost parallel to the surface of the Si substrate.…”

TEM Nano-Moiré Pattern Analysis of a Copper/Single Walled Carbon Nanotube Nanocomposite Synthesized by Laser Surface Implanting

“…Moiré patterns or fringes are produced when two similar patterns are overlapped with different spacings or orientations. In a nanostructure, moiré fringes could be due to the overlapping of two different materials with slightly different lattice spacings at the interface [10][11][12], of two differently oriented lattices of the same materials from different grains [13], of two lattices under stresses and strains [14,15], of two lattices with defects or dislocations or due to a slanted grain interface along the depth direction of the sample [16], or of two lattices with not perfectly repeatable atom arrangements under various conditions and configurations, such as those found in graphene [17][18][19][20][21]. In [22], moiré fringes are used to identify the existence of palladium clusters deposited on γ-Al 2 O 3 /NiAl{110}.…”

Evaluation of interfacial misfit strain field of heterostructures using STEM nano secondary moiré method

“…Due to the mismatch of the crystal lattice at the interface of the two materials, a certain strain is often generated, 3,4 which is sometimes an effective way to design or improve the properties of nanomaterials. 5,6 In addition, the lattice mismatch can also cause dislocations at the interface, 7,8 which will break the symmetry of the crystal structure, change the local bandgap structure, 9 and seriously affect the photoelectric performance of the heterostructure. Therefore, analyzing the strain field of the heterostructure interface is of great significance for improving material properties.…”