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Experimental methods in chemical engineering: Transmission electron microscopy—TEM
Author(s) -
Braidy Nadi,
Béchu Aude,
Souza Terra Júlio C.,
Patience Gregory S.
Publication year - 2020
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.23692
Subject(s) - materials science , transmission electron microscopy , optics , energy filtered transmission electron microscopy , resolution (logic) , crystallinity , thin film , synchrotron , reflection high energy electron diffraction , acceleration voltage , electron diffraction , electron microscope , scanning electron microscope , electron , cathode ray , scanning transmission electron microscopy , diffraction , nanotechnology , physics , composite material , computer science , quantum mechanics , artificial intelligence
Thanks to an accelerating voltage in the range of 30 to 300 kV, an electron beam can pass through a thin specimen and form an image with sub‐Ångström spatial resolution. When impinging on a thin crystalline specimen, the fast electrons scatter and diffract. The transmitted electron pattern depends on the local thickness, density, crystal structure, and chemical nature of the sample. The transmission electron microscope (TEM) shapes the incoming electron beam using magnetic lenses onto the specimen and, using a different set of magnetic lenses, focuses the projected electron pattern to a camera. The final image magnification and contrast are controlled using the parameters from the electron gun, apertures positioned along the optical path, and magnetic lenses. With this combination of lens and aperture, TEM offers two possible modes of operation: (a) imaging, including high‐resolution electron microscopy to reveal the size, shape, crystallinity, and morphology of materials; and (b) diffraction, to determine the crystalline nature of a region of interest of a thin film, particle, or collection of particles. Chemical engineers have taken advantage of both of these modes to analyze their samples and inform their research. A bibliometric study conducted using the WoS database places TEM as one of the preferred microscopy tools to study advanced materials such as thin films, nanomaterials, and composites used in particular for the development of applications related to energy storage and conversion (catalysis, photocatalysis, electrochemistry, and batteries) and environment (adsorption, waste‐water treatment, and filtration).