Electron Tomography: A Three‐Dimensional Analytic Tool for Hard and Soft Materials Research

Abstract

Three-dimensional (3D) structural analysis is essential to understand the relationship between the structure and function of an object. Many analytical techniques, such as X-ray diffraction, neutron spectroscopy, and electron microscopy imaging, are used to provide structural information. Transmission electron microscopy (TEM), one of the most popular analytic tools, has been widely used for structural analysis in both physical and biological sciences for many decades, in which 3D objects are projected into two-dimensional (2D) images. In many cases, 2D-projection images are insufficient to understand the relationship between the 3D structure and the function of nanoscale objects. Electron tomography (ET) is a technique that retrieves 3D structural information from a tilt series of 2D projections, and is gradually becoming a mature technology with sub-nanometer resolution. Distinct methods to overcome sample-based limitations have been separately developed in both physical and biological science, although they share some basic concepts of ET. This review discusses the common basis for 3D characterization, and specifies difficulties and solutions regarding both hard and soft materials research. It is hoped that novel solutions based on current state-of-the-art techniques for advanced applications in hybrid matter systems can be motivated.

Electron Tomography: A Unique Tool Solving Intricate Hollow Nanostructures

“…[1][2][3] To endow with versatile functions, these hollow nanoparticles are engineered with an increasing structural complexity. [20,23] In this regard, the high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) mode is usually employed to minimize the contribution of diffracted electrons by crystalline structures. Thus, the ET acquisition mode should be specified according to the characteristics of target materials.…”

“…TEM projects both surface and inner nanostructures along the electron beam, however at the same time renders the 3D spatial information overlapped on a 2D image. [20] By retrieving the integrated information of these electron projections, delicate features no matter where they locate, inside or on the outmost surface, can be clearly distinguished via reconstruction of the nanomaterials. Unfortunately, their spatial discrimination is rather limited, since the slicing thickness is normally in the range of several tens of nanometers, [18,19] which in some cases is larger than the 3D features of interest.…”

“…[20] By retrieving the integrated information of these electron projections, delicate features no matter where they locate, inside or on the outmost surface, can be clearly distinguished via reconstruction of the nanomaterials. [20] By retrieving the integrated information of these electron projections, delicate features no matter where they locate, inside or on the outmost surface, can be clearly distinguished via reconstruction of the nanomaterials.…”

Advanced method for the accurate measurement of tilt angle in a transmission electron microscopy goniometer

“…In particular, structural information such as specimen shape, size, and distribution can be analyzed from the directly obtained images (Mühlfeld et al 2007). However, projected twodimensional (2D) images acquired from threedimensional (3D) nanostructured materials can provide limited information, and sometimes, information is missing; the development of nanotechnology requires the relationship between the 3D structure and properties of the material to be characterized on the nanometer scale (Ercius et al 2015). In order to overcome the lack of information provided by 2D images, the electron tomography (ED) technique has been employed to produce reconstructed 3D images.…”

Advanced tomography techniques for inorganic, organic, and biological materials

“…This requires similar multiscale three-dimensional (3D) imaging approaches as those needed in materials science to link atomic-structure defects to crack propagation and component failure in jet engines or to understand mechanistic details of how chemical changes affect the nanoscale morphology of solid phases leading to reduced capacity of battery systems or activity and selectivity loss in catalysts. The ability to visualize the whole system intact with low resolution, such as with x-ray microcomputed tomography, and then sequentially zoom in with increasing spatial resolution and narrower fi eld-ofview using x-ray nanotomography 1 or electron tomography approaches, 2 promises new paradigms for interrogating not only static systems, but also systems perturbed or evolving over time.…”