Nanocharacterisation (Rsc Nanoscience & Nanotechnology, 37, Band 37) - Hardcover

Hardcover

ISBN 10: 184973805X ISBN 13: 9781849738057

Verlag: Royal Society of Chemistry, 2015

Inhaltsangabe

Following on from the success of the first edition, this new edition has been fully revised and updated to reflect the recent developments in instrumental characterisation methods used to study nanostructured materials. With contributions from internationally recognised experts, each chapter focuses on a different technique to characterise nanomaterials providing experimental procedures and applications. This indispensable resource will appeal to academics, professionals and anyone working fields related to the research and development of nanocharacterisation and nanotechnology.

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Über die Autorin bzw. den Autor

A I Kirkland is Professor of Materials at Oxford University and the author of over 170 refereed papers. He was awarded "best materials paper" of 2005 by the Microscopy Society of America. Since 2000 he has also been involved in the characterisation of CCD cameras for TEM. His most recent work involves the development of approaches to complex phase extension and diffractive imaging to further improve resolution.

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Nanocharacterisation provides an overview of the main characterisation techniques that are currently used to study nanostructured materials. Following on from the success of the first edition, this new edition has been fully revised and updated to reflect the recent developments in instrumental characterisation methods. With contributions from internationally recognised experts, each chapter focuses on a different technique to characterise nanomaterials providing experimental procedures and applications. State of the art characterisation methods covered include Transmission Electron Microscopy, Scanning Transmission Electron Microscopy, Scanning Probe Microscopy, Electron Energy Loss Spectroscopy and Energy Dispersive X-ray Analysis, 3D Characterisation, Scanning Electron and Ion Microscopy and In situ Microscopy. Essentially a handbook to all working in the field this indispensable resource will appeal to academics, professionals and anyone working fields related to the research and development of nanocharacterisation and nanotechnology.

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Nanocharacterisation

By Angus I. Kirkland, Sarah J. Haigh

The Royal Society of Chemistry

Copyright © 2015 The Royal Society of Chemistry
All rights reserved.

ISBN: 978-1-84973-805-7

Contents

Chapter 1 Characterization of Nanomaterials Using Transmission Electron Microscopy David J. Smith, 1, 
Chapter 2 Scanning Transmission Electron Microscopy A. R. Lupini, S. N. Rashkeev, M. Varela, A. Y. Borisevich, M. P. Oxley, K. van Benthem, Y. Peng, N. de Jonge, G. M. Veith, T. J. Pennycook, W. Zhou, R. Ishikawa, M. F. Chisholm, S. T. Pantelides and S. J. Pennycook, 30, 
Chapter 3 Scanning Tunnelling Microscopy of Surfaces and Nanostructures Martin R. Castell, 80, 
Chapter 4 Electron Energy-loss Spectroscopy and Energy-dispersive X-ray Analysis M. B. Ward, N. Hondow, A. P. Brown and R. Brydson, 108, 
Chapter 5 Electron Holography of Nanostructured Materials Rafal E Dunin-Borkowski, Takeshi Kasama and Richard J Harrison, 158, 
Chapter 6 Electron Tomography Matthew Weyland and Paul A. Midgley, 211, 
Chapter 7 Scanning Electron and Ion Microscopy of Nanostructures Natasha Erdman and David C. Bell, 300, 
Subject Index, 351, 

CHAPTER 1

Characterization of Nanomaterials Using Transmission Electron Microscopy

DAVID J. SMITH

Department of Physics, Arizona State University, Tempe, AZ 85287, USA Email: david.smith@asu.edu

1.1 Introduction

The transmission electron microscope (TEM) has evolved over many years into a highly sophisticated instrument that has found widespread application across many scientific disciplines. Because the TEM has an unparalleled ability to provide structural and chemical information over a range of length scales down to the level of atomic dimensions, it has developed into an indispensable tool for scientists who are interested in understanding the properties of nanostructured materials and manipulating their behavior.

The resolution of the optical microscope is restricted by the wavelength of visible light, which thus precludes atomic-scale imaging. In contrast, an energetic or fast-moving electron has a wavelength of much less than 1 Å (where 1 Å = 10-10 m), so that an enormous improvement in resolution can be achieved, at least in principle, by using an electron beam for imaging. A suitable combination of (magnetic) electron lenses is required, both for focusing the electron beam onto the object and also for providing an enlarged image. Maximum magnifications of the conventional, fixed-beam TEM are typically close to or exceeding one million times, so that key structural features of nanoscale objects are easily visualized on the final viewing screen or recording medium. Moreover, recent scanning TEMs can provide much larger magnifications, up to 50 million times or more, making feature visibility even easier.

Image formation in the TEM is more complicated in practice than is the case for the optical microscope. Strong magnetic fields are needed for focusing the electron beam, and these cause electrons to take a spiral trajectory through the lens field. In addition, a major restriction on ultimate microscope performance results from unavoidable aberrations of the electron lenses. Primarily due to the need for a compromise between small-angle diffraction effects and wide-angle spherical aberration limits, the resolution d can be roughly expressed by an equation of the form

d = A CS¼ λ¾ (1.1)

where CS is the spherical aberration coefficient of the objective lens, λ is the electron wavelength, and A is a constant with a value ranging from 0.43 to 0.7 depending on the type of imaging (coherent, incoherent, or phase contrast). Values of d typically range from about 3.0 Å down to 1.0 Å as electron energies are increased from 100 to 1250 keV. Modern-day TEMs operating at 200 or 300 keV have resolution limits well below 2.0 Å, which is comparable to the spacing between atoms. Individual columns of atoms can then be resolved in crystalline materials, which must first however be oriented so that the incident electron beam is aligned along some major crystallographic zone axis of the sample. In some special cases, such as along the edges of catalyst particles or in single-layered, two-dimensional sheets, isolated single atoms can even be imaged.

The power of the electron microscope is illustrated by the simple example in Figure 1.1, which shows the boundary region between two Al crystals, both of which are oriented so that the electron beam is parallel with a [001]-type zone axis. Each black spot in the image marks the position of a column of Al metal atoms viewed in an end-on geometry. It is obviously straightforward to visualize the periodic array of misfit dislocations (arrowed) which accommodate the angular misfit of 6º between the two crystals, and further analysis would enable the detailed atomic structure around the dislocation core to be determined.

This chapter begins by providing a brief introduction to the TEM and some of the key aspects of high-resolution imaging. The recent emergence of aberration-corrected instruments is also briefly mentioned. Applications to nanostructured materials are then described in greater detail, and some emerging trends and problems are discussed. For further information about microscope operation and more details about applications to a broader range of materials, the interested reader is referred to the review articles and monographs listed at the end of the chapter.

1.2 Imaging

1.2.1 Transmission Electron Microscopy: Standard Operating Mode

In the standard TEM operating mode, which is commonly referred to as amplitude or diffraction-contrast imaging, only a small fraction of those electrons which have passed through the sample are used to form the highly magnified final image. Most of the scattered (or diffracted) electrons are prevented from reaching the image plane by positioning a small objective aperture located in the back focal plane of the objective lens. This aperture thus serves to determine the image contrast. For crystalline samples, the electron diffraction pattern (EDP) is used to ensure that the orientation of the specimen relative to the direction of the incident electron beam will satisfy a strongly diffracting condition. Many common structural defects have a highly characteristic appearance under such diffraction-contrast conditions. The spacings and angles between crystal lattice planes can also be determined if the EDP is first calibrated using a known material. In addition, the availability of a crystalline substrate or support can provide a convenient method for sample orientation during observation. By using the substrate EDP for reference purposes, internal interfaces can be aligned perpendicular to the electron beam direction so that any changes in the microstructure of thin films and multilayers can then be determined as a function of film thickness. As an example, Figure 1.2 shows a multilayered magnetic tunneling transistor (MTT) deposited directly on the native oxide of a Si substrate. The individual layers of the MTT can be clearly recognized, and their thickness uniformity is easily confirmed. Finally, it should be appreciated that preparing such complex samples for examination with the TEM can represent a serious challenge to the electron microscopist. Because of considerable differences in thinning rates, it will often be difficult to prepare samples that are electron-transparent across the entire region of interest simultaneously. Descriptions of standard approaches...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 2015
• Sprache: Englisch
• ISBN 10: 184973805X
• ISBN 13: 9781849738057
• Einband: Gebundene Ausgabe
• Auflage: 2
• Anzahl der Seiten: 358
• Herausgeber: Kirkland Angus I, Haigh Sarah J
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: gpsr@libri.de; gpsr@libri.de; ; Friedensallee 273; Hamburg; 22763; Deutschland