Electron tomography imaging methods with diffraction contrast for materials research.

Daisuke Hirakami,Hideharu Nakashima,Hikaru Saito,Hiromitsu Furukawa,Hiroya Miyazaki,Katsumi Kawamoto,Ken-Ichi Ikeda,Kosuke Kimura,Masashi Sakamoto,Masatoshi Mitsuhara,Mitsu Mitsuhiro Murayama,Noritaka Horii,Satoshi Hata,Shigeto Yamasaki,Shinsuke Miyazaki,Syo Matsumura,Takashi Gondo

doi:10.1093/jmicro/dfaa002

Abstract

ABSTRACTTransmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM) enable the visualization of three-dimensional (3D) microstructures ranging from atomic to micrometer scales using 3D reconstruction techniques based on computed tomography algorithms. This 3D microscopy method is called electron tomography (ET) and has been utilized in the fields of materials science and engineering for more than two decades. Although atomic resolution is one of the current topics in ET research, the development and deployment of intermediate-resolution (non-atomic-resolution) ET imaging methods have garnered considerable attention from researchers. This research trend is probably not irrelevant due to the fact that the spatial resolution and functionality of 3D imaging methods of scanning electron microscopy (SEM) and X-ray microscopy have come to overlap with those of ET. In other words, there may be multiple ways to carry out 3D visualization using different microscopy methods for nanometer-scale objects in materials. From the above standpoint, this review paper aims to (i) describe the current status and issues of intermediate-resolution ET with regard to enhancing the effectiveness of TEM/STEM imaging and (ii) discuss promising applications of state-of-the-art intermediate-resolution ET for materials research with a particular focus on diffraction contrast ET for crystalline microstructures (superlattice domains and dislocations) including a demonstration of in situ dislocation tomography.

Highlights

Electron tomography (ET) is a three-dimensional (3D) imaging method based on transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM)
The small changes in diffraction contrast, denoted with arrows (Fig. 14(a)) and circles (Fig. 14(b)) suggest movement of the dislocations with the specimen straining. We found that such slight movements of the dislocations are more clearly recognized in the 3D reconstructions than in the original 2D images
The current status and issues of intermediate-resolution electron tomography (ET) for materials research were discussed with a particular focus on diffraction contrast ET of crystalline materials

Summary

Introduction

Electron tomography (ET) is a three-dimensional (3D) imaging method based on transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). Spectroscopic ET methods with energy-dispersive X-ray spectroscopy (EDXS) [20,21,22,23,24,25,26,27] or electron energy-loss spectroscopy (EELS) [20, 28,29,30,31,32,33,34,35,36] have become promising methods for visualizing 3D morphologies and various properties of objects in three dimensions The use of these advanced ET methods is closely related with recent significant developments in 3D reconstruction methods that can reduce artifacts caused by various kinds of missing information in tilt-series projection data sets. Applications of STEM to in situ ET have been reported recently [19, 44]

Objectives

Conclusion