Transmission Electron Microscopy C. Barry Carter · David B. Williams (Eds.)

Transmission Electron Microscopy

Diffraction, Imaging, and Spectrometry Editors C. Barry Carter David B. Williams University of Connecticut The Ohio State University Storrs, USA Columbus, USA

ISBN 978-3-319-26649-7 ISBN 978-3-319-26651-0 (eBook) DOI 10.1007/978-3-319-26651-0

Library of Congress Control Number: 2016945257

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Dedicated to Bryony Carter and Margie Williams Foreword by Sir John Thomas of the Companion to Williams and Carter’s book on TEM

Ever since 1996, when the first edition ofTransmission Electron Microscopy: A Textbook for Materials Science (by David Williams and Barry Carter) appeared, this became the favoured and standard text for all those interested in mastering the electron microscopic examination of materials. It was, and remains, the vade mecum of choice. With its massive repository of highly relevant information and advice, teem- ing with attractive pedagogical accoutrements, this text gained almost instant, worldwide popularity.

The second edition, published in 2009, contained many new features, prompted primarily by the growth of the subject and the arrival of a range of powerful additional variants of transmission electron micros- copy (TEM). It had become fully apparent at that time that TEM is not just a widely useful investigative tool, but also, in its most modern form, a near complete chemical and structural laboratory, from which a multitude of properties pertaining to condensed matter may be extracted.

In the intervening years it has become possible to add yet further, powerful variants for identification and characterization of both solids and, increasingly of liquids and surfaces, at evermore impressive resolutions – spatial, spectral and temporal. For example, modern scanning transmission electron mi- croscopes (STEM), used principally for the retrieval of energy-dispersive X-rays (EDX) and electron energy loss (EEL), as may be gleaned from Chap. 11 of this Companion, can routinely generate spectra of images in which behind every image pixel lies a complete (EDX or EEL) spectrum. Moreover, by recording a tilt series of such spectrum images, 4D ‘spectrum tomograms’ produce spectral (and have chemical) information at every real space voxel.

One of the most dramatic advances made since the second edition of W&C appeared is the vast im- provement (by nearly ten orders of magnitude) in temporal resolution that has been accomplished, largely through the innovative work of Zewail and colleagues in California. Up until less than a decade ago, electron microscopists recorded dynamic changes of specimens in TEMs at around millisecond resolution. Nowadays, sub-picosecond resolutions can be attained, thereby uncovering a whole host of new condensed-matter phenomena.

The emergence of major new advances such as this, along with those in tomography, holography, EELS and in ‘aberration corrected’ imaging, has, inter alia, persuaded W&C to enlist a collection of world-renowned experts to expatiate their knowledge following the same admirable pedagogic approach of the progenitor text. Nowadays, thanks to modern versions of electron microscopes, the structure and composition of matter in all realms can be elucidated at unprecedented resolution in both space and time; one can ‘see’ individual atoms, and follow the acts of bond formation and rupture. All this opens up ways, outlined by contributors to this admirable Companion, to even greater insights and informa- tion in the years to come. It is reassuring to learn that W&C intend to produce further editions of this Companion when the time is ripe to do so.

When I decided to turn to TEM as an investigative tool, more than fifty years ago, other chemists re- garded my decision with incredulity and perplexity. ‘Of what possible use could TEM be to the chem- ist?’ was the refrain I heard. That was in the era when chemists believed that only X-ray crystallography could enlighten chemists about the nature of solids. It was fondly believed by most chemists of that generation that all crystals were, in effect, a paradise of faultless regularity. But I had already discovered that the reactivity of solids, as well as their electronic and excitonic behaviour, is intimately associated with crystalline defects, and TEM, in its numerous variants, could answer most of my questions. These

vii viii Foreword by Sir John Thomas of the Companion to Williams and Carter’s book on TEM

days, no self-respecting Department of Chemistry anywhere in the world can function properly with- out an . Indeed, nanoscience and nanotechnology, which are of importance to all physical and biological sciences, are impossible to pursue without a TEM. Today, such is the power of direct-detection cameras (described in Chap. 2), that many X-ray crystallographers have now turned to the TEM to solve very complicated biologically significant structures like large ribosomal subunits from human mitochondria. It is most gratifying that this Companion text is likely to satisfy the scientific appetites of all complexions of investigators of condensed matter.

I warmly commend this Companion and, in particular, the way in which it follows the ethos of the original W&C volumes by posing two different levels of questions (Q and T), and the use “traffic light” boxes.

Sir Hon. Professor at the Department of Materials Science and Metallurgy, , and Former Director of the Royal Institution of G.B., London Transmission Electron Microscopy: , Imaging, and Spectrometry

Preface

In the prefaces to the first and second editions of Williams & Carter, we asked the same question: “How is this book different from the many other TEM books on the market?” Our answer was, in essence, that these volumes are true textbooks, written to be studied by undergraduates and graduates, constructed in lecture-size segments and (in the softbound versions) able to be used at the console of the microscope. Perhaps the most distinguishing feature of the books was that, unlike all previous TEM texts, we wrote them as we taught in the classroom: in an informal style, interspersed with side comments and the occa- sional attempted joke – which rendered translation into other languages too challenging. Around 20,000 hard copies have been printed to date, and hundreds of thousands of chapters have been downloaded.

So why do we need a Companion Volume, and why do we refer to it as the Companion Volume? The answer requires recounting a little history, which, as we’ve indicated in prior prefaces, is something we enjoy. We see this book as filling a need that is really a reflection on what has happened to the TEM field in the decades since Williams first suggested the need for such a book to Carter in the living room of the Carter home in Ithaca, NY, one cold spring morning in 1985, and which is why Carter proposed that it should be W&C. Buoyed by excess coffee (see Section 34.2 of the second edition) we decided to go ahead and write. At first, we decided that a group of four complementary experts could cover the principal aspects of the TEM field at that time (hence the division of the book into four parts). Such a team was assembled. However, we found that textbook writing was not for the faint of heart. Soon after we started putting fingers to the keyboards of our $2,500(!) Apple Macintoshes and mailing floppy disks to each other containing our initial attempts, we were reduced to just W&C.

Despite our lack of expertise in certain key areas of the TEM field, we managed, by 1996, to complete W&CI. Then, no doubt due to the same excesses of caffeine, we decided in 2003 to rewrite the text, and so W&CII was born in 2009. When starting W&CII we recognized that there was not much in W&CI that we could omit! But it was already a macrotome. We also realized that writing another full book on all the new things that were happening in TEM was not what we had time to do – it would take another 10 years at least. (It did.) So we invited a few of our long-time friends and colleagues who were won- derfully qualified to write particular chapters; the ones whose photos you see in these pages are still our friends, we hope. So the Companion Volume was conceived as a collection of chapters that would be written by world experts on topics that are either perennially important or really new and fascinating, and that we could keep current without sacrificing material in W&C. It may not all be conventional wisdom but we decided that this volume would be CW, or C&W for consistency.

Our own careers have mirrored the rapid evolution of TEM. If you have nothing better to do than read the previous prefaces to our texts, you’ll know that W&C have both evolved from our professorial positions at Lehigh and Cornell back in 1985. We have both taken on roles that required us (like all TEM operators) to broaden our skills and face more challenging responsibilities. We have each moved on to (two) different universities. Our children of the 1970 s and 80 s are now independent adults with their own twenty-first-century families. Our parents (to whom W&C is dedicated) have all passed on. Yet, particularly important to us, our wives remain with us. Without them, none of this would ever have happened. Thousands of successful TEM students owe their thanks to Bryony and Margie, as do we.

So, taking a leaf out of previous prefaces, we ask anew, why is this Companion Volume different from the many multi-author TEM review texts that are published at regular intervals? First, it builds directly

ix x Preface

on W&C, which is extensively referenced throughout. Second, we have taken the high-quality writing of our friends and attempted to give it a W&C flavor, by changing it into informal script where possible. We apologize to all of them when, in doing so, we have destroyed some of their brilliant phraseology. Nevertheless, we believe that, compared to similar texts, we have managed to bring a greater degree of homogeneity to the writings of multiple authors from many different countries. We apologize that a few of the chapters require two or three (or four) lectures and that the 17 chapters will take a full semester to cover. A consequence of this approach is that, except in the About the Authors pages, rather than ascribe individual chapters to individual author(s), we simply acknowledge all our friends up front. If, or when, you are well versed in the TEM field, it should not be difficult to work out who wrote what! Perhaps a good exercise for all you students who are relatively new to TEM would be to search the literature and come to your own conclusions.

We’ll mention a few idiosyncrasies that you’ll find in the text. One of us has a thing about hyphens and loves Lynne Truss’s book about the panda. In spite of this, we have tried to omit all punctuation when writing equations: punctuation is supposed to help, not confuse. We’ve used our traffic-light boxes again: if it’s red, be sure to stop for a moment; if it’s amber – you’ve been warned; if it’s green, take note but move on.

While we may not have succeeded in making this Companion Volume as comprehensive and uniform as we made the original W&C editions, we do hope that all you students who enjoyed those first volumes will find this one to be equally valuable. It has been one heck of a ride, and this text is the technical apex of both our professional careers, opening doors that we never dreamed of 30 years ago. TEM continues to grow as a discipline and as an instrument: it is the essential tool for studying nanomaterials. What happens on the nanoscale determines what happens, period, and only the TEM can tell us about structure and composition with accuracy and precision at the nanoscale.

Finally, we thank our friend Sir John Thomas for writing the Foreword to this volume and remember our friend the late Gareth Thomas who wrote the Foreword to W&C.

Albuquerque, Storrs and Columbus, September 2015 Thanks to Our Friends

Most of the authors have discussed their chapters with colleagues, received suggestions and crit- icisms, and then updated and improved their chapters. As you will appreciate from our ‘People’ sections, we also recognize that we are all building on the contributions of earlier writers and re- searchers. The editors and authors have been privileged to know many of them personally – this is still a young field. Here we recognize those who specifically helped us in writing these chapters.

Alwyn Eades thanks Jean-Paul Morniroli, Mike Kaufman, and John Spence, who read an early version of his chapter; each of them made suggestions that resulted in important improvements.

Pieter Kruit chapter is based on knowledge that was acquired when he and his then PhD student Merijn Bronsgeest worked closely with Greg Schwind and Lyn Swanson of FEI Beamtech.

Katie Jungjohann and CBC acknowledge the Center for Integrated Nanotechnologies (CINT), a DOE-BES supported national user facility located at both Sandia and Los Alamos National Laboratories. Sandia, where KJ is personally located, is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s (DOE) National Nuclear Security Adminis- tration (NNSA) under contract DE-AC0494AL85000. They thank Matt Janish, Yang Liu, Jiangwei Wang, Joseph Grogan, Madeline Dukes, Paul Kotula, Joe Michael, Bill Mook, Khalid Hattar, Blythe Clark, Katie Harrison, Andrew Leenheer, Eric Stach, Dave Mitlin, Grant Norton, Jessica Vanderburg, Kevin Zavadil, Neal Shinn, Sean Hearne, and Charles Barbour for their support and their help in so many ways.

Grace Burke would like to thank her many colleagues and collaborators over the years, especially Tom Nuhfer (Carnegie-Mellon University) and Ram Bajaj (Bettis) for their long-time collaborations and friendship, and to Joven Lim (University of Manchester). The examples used in this chapter relied on the excellent TEM specimens prepared by Jim Haugh (retired) of Westinghouse, whose expertise and friendship have been so important over the years. She would also like to thank Mike for his patience and proof-reading.

xi xii Thanks to Our Friends Stephen J. Pennycook

is very grateful to all his collaborators in the work described in his chapter: E. Abe, B. Alen, L. J. Allen, H. S. Baik, B. Beaumont, P. F. Becher, A. Y. Borisevich, N. D. Browning, M. F. Chisholm, A. J. D’Al- fonso, N. Dellby, S. Doh, G. Duscher, M. M. Erwin, J. P. Faurie, L. C. Feldman, A. G. Ferridge, S. D. Findlay, D. Fuster, P. L. Galindo, P. Gibart, M. V. Glazoff, L. Gonzalez, Y. Gonzalez, T. R. Gosnell, J.-C. Idrobo, D. E. Jesson, A. V. Kadavanich, M. Kim, T. C. Kippeny, O. L. Krivanek, J. H. Lee, J. T. Luck, A. R. Lupini, J. R. McBride, A. J. McGibbon, M. M. McGibbon, S. I. Molina, M. F. Murfitt, P. D. Nellist, P. D. Nellist, F. Omnes, M. P. Oxley, G. S. Painter, S. T. Pantelides, Y. Peng, R. C. Puetter, S. N. Rashkeev, K. G. Roberts, S. J. Rosenthal, D. L. Sales, M. J. Seddon, W. A. Shelton, N. Shibata, W. H. Sides, S. Sivananthan, K. Sohlberg, Z. S. Szilagyi, M. Tanaka, M. Terauchi, J. Treadway, A. P. Tsai, K. van Benthem, M. Varela, L. G. Wang, S. W. Wang, Y. Xin, A. Yahil, Y. F. Yan.

Paul Midgley

thanks all his collaborators, past and present, for their contributions to the work described in the chapters.

Matthew Weyland

thanks Chris Boothroyd, Owen Saxton, Ron Broom, Rafal Dunin-Borkowski, and Sir John Meurig Thomas for their critical input to the early development of electron tomography in materials science.

Paul Kotula

thanks Peter Duncumb for pioneering X-ray mapping, Legge and Hammond for developing true spectral imaging, and Rick Mott and the late John Friel for bringing modern spectral imaging to the microanalysis community. He would like to thank Michael Rye of Sandia for the preparation of most of the FIB specimens presented here. As we all know, the specimen preparation can be the most critical part of any materials analysis. He would also like to thank Michael Keenan (retired) and Mark van Benthem from Sandia National Laboratories for critical insight and helpful discussions about MSA over the years. Thanks also to Chad Parish (Oak Ridge National Laboratory), Josh Sugar (Sandia), Katie Jungjohann (Sandia), Yang Liu (North Carolina State University), Shreyas Rajasekhara (Intel) for insightful comments that improved this chapter. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States National Nuclear Security Administration, part of the Department of Energy (DOE), under contract DE-AC04 94AL85000.

Masashi Watanabe

wishes to thank Prof. David Williams for his thoughtful supervision for many years. In collaboration with Prof. Williams, the ζ-factor method and MSA plug-ins were developed. In addition, the author would like to thank Prof. Christopher Kiely, Mr. David Ackland, Mr. Bill Mushock, Dr. Rob Keyse and colleagues at Lehigh, Prof. Zenji Horita at Kyushu University, Prof. Ray Egerton at University of Alberta, Dr. Kazuo Ishizuka at HREM Research Inc., Dr. Hidetaka Sawada, Mr. Eiji Okunishi and Mr. Masahiko Kanno at JEOL, Mr. Shintaro Yazuka, Mr. Toshihiro Aoki, Mr. Toshihiro Nomura, Dr. Masahiro Kawasaki and Dr. Tom Isabell at JEOL USA, Dr. Toshie Yaguchi at Hitachi Hitechnologies, and Dr. Nestor Zaluzec at Algonne National Laboratory for their collaboration. List of Contributors

C. Barry Carter Editor and Chapter 2 University of Connecticut C. Barry Carter is the Editor-in-Chief of the Journal of Materials [email protected] Science and a CINT Distinguished Affiliate Scientist. He ist the Past President of the International Federation of Societies for Microscopy. He teaches at UConn.

David B. Williams Editor The Ohio State University, David B. Williams is the Monte Ahuja Endowed Dean’s Chair, College of Engineering Executive Dean of The Professional Colleges and Dean of the College [email protected] of Engineering at The Ohio State University.

Pieter Kruit Chapter 1 Delft University of Technology, Pieter Kruit is Professor of Physics at Delft University of Faculty of Applied Sciences Technology in the Netherlands and has 30 years of experience [email protected] in developing novel electron- and ion-optical instruments for microscopy and lithography.

Katie Jungjohann Chapter 2 CINT, Katie Jungjohann is the TEM Research Leader at CINT, Sandia/LANL. Sandia National Her research is focused on the development and use of operando TEM Laboratories techniques to understand the structural/chemical changes to nanomate- [email protected] rials, especially in the electrochemical cell discovery platform.

Grace Burke Chapter 3 University of Manchester, Grace Burke is a Professor in the School of Materials at the School of Materials University of Manchester, having spent many years in industry, [email protected] where her research involved microstructural characterization applied to understanding materials behavior. She is Director of both the Materials Performance Centre and the Electron Microscopy Centre.

xiii xiv List of Contributors

Alwyn Eades Chapter 4 Lehigh University, Alwyn Eades worked on electron microscopy and, especially, Department of Materials electron diffraction for more than half a century and now enjoys Science & Engineering retirement. [email protected]

John Spence Chapter 5 Arizona State University, John Spence FRS (ForMem) is the Richard Snell Professor of Physics Department of Physics at Arizona State University, author of ‘High Resolution Electron [email protected] Microscopy’, recipient of the Cowley and Buerger Medals, and Director of Science for the NSF BioXFEL Science and Technology Center.

Bernhard Schaffer Chapter 6 Gatan Inc. Bernhard Schaffer did his PhD in developing EFTEM SI [email protected] techniques at FELMI/ZFE Graz before working with Cs corrected STEM at SuperSTEM Daresbury/UK. He is currently working as application developer at Gatan Inc.

Michael Lehmann Chapters 7 and 8 TU Berlin, Michael Lehmann studied physics in Tübingen, was Postdoc at the Institute for Optics Triebenberg Lab, and is now full professor at TU Berlin. and Atomic Physics lehmann@physik. tu-­berlin.de

Hannes Lichte Chapters 7 and 8 TU Dresden, Hannes Lichte studied physics at Kiel and Tübingen universities, Triebenberg Laboratory where he finished the Dr.rer.nat. in 1977 under supervision [email protected] of Gottfried Möllenstedt. He pioneered holographic imaging mainly of atomic structures. Since 1994 he has been professor at the Technische Universität Dresden and founder and director of the Triebenberg Laboratory.

Andreas Thust Chapter 9 Forschungszentrum Andreas Thust is an Austrian physicist working at Forschungszentrum Jülich GmbH, Jülich, Germany. In 2005 he was awarded together with Wim Coene Ernst Ruska-Centre the internationally prestigious Ernst Ruska Price for their outstanding [email protected] achievements in the field of focal-series reconstruction. List of Contributors xv

Sandra Van Aert Chapter 10 University of Antwerp, Sandra Van Aert is a Senior Lecturer at the University of Electron Microscopy for Antwerp (Belgium). Within the Electron Microscopy for Materials Science (EMAT) Materials Research (EMAT) group, her research focuses on new [email protected] developments in the field of model-based electron microscopy aiming at quantitative measurements of atomic positions, atomic types, and chemical concentrations with the highest possible precision.

Dirk Van Dyck Chapter 10 University of Antwerp, Dirk Van Dyck is Emeritus Professor in Physics of the University of Electron Microscopy Antwerp. He is known for his pioneering work in dynamical electron for Materials Science diffraction, exit wave reconstruction, electron channeling, and electron (EMAT) tomography. dirk.vandyck@ uantwerpen.be

Stephen J. Pennycook Chapter 11 National University Stephen J. Pennycook is a Professor in the Materials Science of Singapore, and Engineering Department, National University of Singapore, Department of Materials an adjunct Professor at the University of Tennessee, USA, and Science & Engineering an adjoint Professor at Vanderbilt University, USA. [email protected]

Paul Midgley Chapters 12 and 13 University of Cambridge, Paul Midgley is Professor of Materials Science at the Department of Department of Materials Materials Science and Metallurgy at the University of Cambridge and a Science and Metallurgy Professorial Fellow at Peterhouse. [email protected]

Matthew Weyland Chapter 12 Monash University, Matthew Weyland is an Associate Professor at the Monash Department of Materials Centre for Electron Microscopy and in the Department of Science and Engineering Materials Science and Engineering at Monash University, [email protected] Melbourne.

Paul Thomas Chapter 13 Gatan Inc. Paul Thomas graduated with a PhD in EFTEM Technique Development [email protected] from the University of Cambridge in 2000. Ever since he has worked for Gatan, where he is passionate about software for analytical EM. xvi List of Contributors

Vicki Keast Chapter 14 The University of Newcastle, Vicki Keast is currently Associate Professor in the School School of Mathematical of Mathematical and Physical Science at The University of and Physical Science Newcastle, Australia. [email protected]

Ian Jones Chapter 15 University Ian Jones is an electron microscopist and Professor of Physical Metal- of Birmingham, lurgy at the University of Birmingham, UK. School of Metallurgy and Materials [email protected]

Paul Kotula Chapter 16 Sandia National Laboratories, Paul Kotula is a staff member in the Materials Characteri- Materials Characterization zation Department at Sandia National Laboratories on the Department Albuquerque, NM campus. His research involves analytical [email protected] electron microscopy, and in particular acquisition and statistical analysis of X-ray and electron energy-loss spectral images.

Masashi Watanabe Chapter 17 Lehigh University, Masashi Watanabe is an Associate Professor of Materials Science and Materials Science Engineering at Lehigh University. Masashi’s research emphasizes and Engineering materials characterization using AEMs. masashi.watanabe@ lehigh.edu List of Initials and Acronyms

The field of TEM is a rich source of initials and acronyms (these are words formed by the initials), behind which we hide both simple and esoteric concepts. While the generation of new initials and acronyms can be a source of original thinking (e.g., see ALCHEMl), it undoubtedly makes for easier communication in many cases and certainly reduces the length of voluminous textbooks. You have to master this strange language before being accepted into the community of microscopists, so we present a comprehensive listing that you should memorize.

ABF annular bright field ABLAD all-beam large-angle diffraction ACF absorption-correction factor ACT automated crystallography for TEM ACTF amplitude contrast transfer function A/D analog to digital (converter) ADF annular dark field AEM analytical electron microscope/microscopy AES Auger electron spectrometer/ AFF aberration-free focus AFM atomic force microscope/microscopy ALCHEMI atom location by channeling-enhanced microanalysis ALS alternating least squares ANL Argonne National Laboratory AOs atomic-like orbitals APB anti-phase (domain) boundary APFIM atom-probe field ion microscope/microscopy APW augmented plane wave ART algebraic reconstruction technique ASW augmented spherical wave ATW atmospheric thin window AWG arbitrary waveform generator AXSIA automated expert spectral image analysis BF bright field BFP back-focal plane BGPL beam-gas path length BSE backscattered electron BZB Brillouin-zone boundary C1,2 condenser 1,2, etc., lens CASTEP Cambridge Serial Total Energy Package CAT computerized axial tomography CB coherent bremsstrahlung CBED convergent-beam electron diffraction CBIM convergent-beam imaging CCD charged-coupled device CCF cross-correlation function CCM charge-collection microscopy CDF centered dark field CF coherent Fresnel/Foucault CFE cold field emission

xvii xviii List of Initials and Acronyms

CL cathodoluminescence CNTs carbon nanotubes cps counts per second CRT cathode-ray tube CS crystallographic shear CSET compressed sensing electron tomography CSL coincident-site lattice CSTEM confocal scanning transmission electron microscopy CV cyclic voltammetry CVD chemical vapor deposition DADF displaced-aperture dark field DART discrete algebraic reconstruction technique DC direct current DDF diffuse dark field DF dark field DFT density-functional theory DOS density of states DP diffraction pattern DQE detection quantum efficiency DSTEM dedicated scanning transmission electron microscope/microscopy DTEM dynamical TEM DTSA desktop spectrum analyzer EBD electron beam deposition EBIC electron beam-induced current/conductivity EBSD electron-backscatter diffraction EDS energy dispersive spectroscopy EDX energy dispersive X-ray EELS electron energy-loss spectrometry EFI energy-filtered imaging EFTEM energy filtered transmission electron microscopy ELNES energy-loss near-edge structure ELP™ energy-loss program (Gatan) EMMA electron microscope microanalyzer EMS electron microscope image simulation (E)MSA (Electron) Microscopy Society of America EPMA electron-probe microanalyzer ESCA electron spectroscopy for chemical analysis ESI electron-spectroscopic imaging EST equally-sloped tomography ETEM controlled environment TEM EXAFS extended X-ray-absorption fine structure EXELFS extended energy-loss fine structure FEFF ab-initio multiple scattering software FEG field-emission gun FET field-effect transistor FFP front-focal plane FFT fast Fourier transform FIB focused-ion beam FIM field ion microscopy FLAPW full-potential linearized augmented plane wave FOLZ first-order Laue zone FTP file-transfer protocol FTs Fourier transformations FWHM full width at half maximum FWTM full width at tenth maximum GB grain boundary GGA generalized gradient approximation GIF Gatan Image Filter™ GIGO garbage in garbage out List of Initials and Acronyms xix

GM Lines Gjonnes–Moodie lines GMS Gatan Microscopy Suite™ GOS generalized oscillator strength GS lines “glide and screw” lines HAADF high-angle annular dark-field HOLZ higher-order Laue zone HPGe high-purity germanium HREELS high-resolution electron energy-loss spectrometer/spectrometry HRTEM high resolution transmission electron microscopy HV high vacuum HVEM high-voltage electron microscope/microscopy IBD ion-beam deposition IBF incoherent bright field ICC incomplete charge collection ICDD International Center for Diffraction Data ICP incoherent channeling patterns ID identification (of peaks in spectrum) IDB inversion domain boundary IEEE International Electronics and Electrical Engineering IG intrinsic Ge IHC inverse hole-count ITRS International Technology Roadmap for Semiconductors IVEM intermediate-voltage electron microscope/microscopy K-M Kossel–Möllenstedt KKR Korringa–Kohn–Rostoker LACBED large-angle convergent-beam electron diffraction LCAO linear combination of atomic orbitals LCD liquid-crystal display LDA local-density approximation LEED low-energy electron diffraction LKKR layered Korringa–Kohn–Rostoker LSDA local spin density approximation MAC mass absorption coefficient MAS Microanalysis Society MBE molecular-beam epitaxy MC minimum contrast MCA multichannel analyzer MCDF multi-configuration Dirac–Fock MCR multivariate curve resolution MDA minimum detectable atoms MDM minimum detectable mass MEMS microelectromechanical systems MLLS multiple linear least squares MMF minimum mass fraction MO molecular orbital MRS Materials Research Society MS multiple scattering MSA multivariate statistical analysis MT muffin tin MTF modulation transfer function MV megavolt NCEMSS National Center for Electron Microscopy simulation system NIH National Institutes of Health NIST National Institute of Standards and Technology NPL National Physical Laboratory OIM orientation-imaging microscopy OR orientation relationship OTL ordering tie line PARODI parallel recording of dark-field images xx List of Initials and Acronyms

PAW projector augmented wave PB phase boundary P/B peak to background ratio PCA principal component analysis PCTF phase contrast transfer function PDA photo-diode array PEELS parallel electron energy-loss spectrometer/spectrometry PIPS Precision Ion-Polishing System™ PIXE proton-induced X-ray emission PM photomultiplier POA phase-object approximation ppb/m parts per billion/million PSF point spread function PTS position-tagged spectrometry QCBED quantitative convergent-beam method QHRTEM quantitative high-resolution transmission electron microscopy RB translation boundary (yes, it does!) RDF radial distribution function REM reflection electron microscope/microscopy RGA residual gas analyzer RHEED reflection high-energy electron diffraction ROI region of interest RPA random phase approximation SACT small-angle cleaving technique SAD(P) selected area diffraction (pattern) SCF self-consistent field SDD silicon-drift detector SDK software development kit SE secondary electron SEELS serial electron energy-loss spectrometer/spectrometry SEM scanning electron microscope/microscopy SESAMe sub-eV sub-Å microscope SF stacking fault SHRLI simulated high-resolution lattice images SI spectrum imaging SI Système Internationale SIGMAK K-edge quantification software SIGMAL L-edge quantification software SIMS secondary ion mass spectroscopy SIRT simultaneous iterative reconstructive techniques S/N signal-to-noise ratio SOLZ second-order Laue zone SRM standard reference material STEM scanning transmission electron microscope STM scanning tunneling microscope/microscopy TB twin boundary TCC transmission-cross coefficient TED transmission electron diffraction TEM transmission electron microscope/microscopy TFE thermal field emission UEM ultrafast electron microscopes UHV ultra high vacuum URL uniform resource locator UTW ultra-thin window V/F voltage to frequency (converter) VLM visible-light microscope/microscopy VUV vacuum ultra violet WB weak beam WBDF weak-beam dark field List of Initials and Acronyms xxi

WDS wavelength-dispersive spectrometer/spectrometry WP whole pattern WPOA weak phase-object approximation XANES X-ray absorption near-edge structure XEDS X-ray energy-dispersive spectrometer/spectrometry XPS X-ray photoelectron spectrometer/spectrometry XRD/F X-ray diffraction/fluorescence YAG yttrium-aluminum garnet YBCO yttrium-barium-copper oxide YSZ yttria-stabilized zirconia ZAF atomic number/absorption/fluorescence correction ZAP zone-axis pattern ZLP zero-loss peak ZOLZ zero-order Laue zone Contents

1 Electron Sources 1 1.1 Introduction and Definitions of Parameters 2 1.2 Schottky Sources 4 1.2.1 Emission Theory 4 1.2.2 Coulomb Interactions 6 1.2.3 Practical Aspects 7 1.3 Field Emission Sources 8 1.3.1 Emission Theory 8 1.3.2 Practical Aspects 10 1.4 Photo-Emission Sources 10 1.5 Effect of the Electron Source Parameters on Resolution in STEM 11 1.5.1 Contributions to the Probe Size 11 1.5.2 Current in a Probe 12 Appendix 14 References 15 2 In situ and Operando 17 2.1 General Principles 18 2.2 Some history 18 2.3 The Possibilities 19 2.3.1 Post-Mortem Characterization 20 2.3.2 Statistics 20 2.4 Time 22 2.4.1 Recording the Data 22 2.4.2 The CCD Camera 22 2.4.3 Direct-Detection Cameras 22 2.4.4 Software and Data Handling 23 2.4.5 Drift Correction 24 2.4.6 Ultrafast Electron Microscopy 25 2.5 The Environment 29

xxiii xxiv Contents

2.5.1 Ultrahigh Vacuum 36 2.5.2 Working in a Gas Cell 37 2.5.3 Working in a Liquid Cell 39 2.6 The Temperature 41 2.6.1 Temperature Measurement 41 2.6.2 Heating 42 2.6.3 Cooling 46 2.7 Other Stimuli 48 2.7.1 Deformation 48 2.7.2 Magnetic Fields 55 2.7.3 Electric Fields 56 2.7.4 Photons 64 2.8 Adding or Removing Material 67 2.8.1 Depositing Layers/Particles 67 2.8.2 Deposition Energy: Electron and Ion Irradiation 68 2.9 The Future 73 Appendix 75 References 76 3 Electr on Diffraction and Phase Identification 81 3.1 Introduction 82 3.2 Spinodal Alloys 83 3.2.1 Example: Ordered FeBe Phases and A2 Matrix 83 3.3 Superalloys with Ordered Precipitates 85 3.3.1 Example: γ″ and γ′ Precipitation in Alloy 718 87

3.3.2 Example: D0a-Ordered δ Precipitation in Alloy 718 89 3.4 Carbide Precipitation in fcc Alloys 93

3.4.1 Example: M23C6 Precipitation in a Ni–Base Alloy 93 3.4.2 Example: MC Carbides in a Ni–Base Alloy 94 3.5 Ferritic Steels 96 3.5.1 Relationships Between Austenite and Ferrite, Austenite and Martensite (fcc/bcc) 96

3.5.2 Relationship Between Cementite (Orthorhombic Fe3C or

M3C) and Ferrite/Tempered Martensite 97 3.5.3 Relationships Between Alloy Carbides and Ferrite 97 3.5.4 Precipitation in Ferritic Structures 98

3.6 Epitaxial Oxide on Metal: Presence of Fe3O4 on Steel Foils 99 Appendix 101 References 102 Contents xxv

4 Convergent-Beam Electron Diffraction: Symmetry and Large-Angle Patterns 103 4.1 Symmetry 104 4.2 Point-Group Determination 104 4.3 Space-Group Determination 109 4.3.1 Forbidden Reflections 109 4.3.2 Black Crosses 111 4.3.3 Complete Procedure for Space-Group Determination 113

4.4 Ni3Mo – A Worked Example 114

4.4.1 Ni3Mo – a Worked Example, Part I: Point Group 114 4.4.2 Qualifications 118

4.4.3 Ni3Mo – a Worked Example, Part II: Space Group 119 4.5 Additional and Alternative Symmetry Methods 120 4.5.1 Symmetry Determination from Off-Axis Patterns 120 4.5.2 Symmetry from Precession Patterns 122 4.6 More on Glide Planes 123 4.6.1 GM Lines in HOLZ Reflections 124 4.6.2 Glide Planes Normal to the Beam 124 4.7 Beyond Symmetry 124 4.7.1 Enantiomorphous Pairs: Handedness 126 4.7.2 Polarity 126 4.7.3 Coherent Convergent-Beam Diffraction 127 4.8 Tanaka Methods 127 4.9 LACBED 127 4.9.1 The Nature of LACBED Patterns 129 4.9.2 Obtaining LACBED Patterns in Practice 130 4.9.3 Choosing the Parameters 131 4.10 Spherical Aberration and LACBED 132 4.11 Crystal Defects in LACBED Patterns: Dislocations 132 4.12 Crystal Defects in LACBED Patterns: Stacking Faults and Antiphase Boundaries 134 4.13 Other Tanaka Methods 134 4.13.1 Bright- and Dark-Field LACBED 134 4.13.2 Convergent-Beam Imaging (CBIM) 136 4.13.3 Rastering Techniques 137 Appendix 141 References 142 xxvi Contents

5 Electron Crystallography, Charge-Density Mapping, and Nanodiffraction 145 5.1 Can We Quantify Electron Diffraction Data? 146 5.2 Quantitative CBED for Charge-Density Mapping 147 5.3 Strain Mapping, High Voltage, Lattice Parameters Measured by QCBED 153 5.4 Spot Patterns – Solving Crystal Structures 155 5.5 The Precession Method 157 5.6 Diffuse Scattering, Defects, Phonons, and Phase Transitions 158 5.7 Diffractive Imaging, Ptychography, STEM Holography, Ronchigrams, and All That 159 5.8 Equipment for Quantitative Electron Diffraction 162 Appendix 163 References 164 6 DigitalMicrograph 167 6.1 Introduction 168 6.1.1 What Is DigitalMicrograph? 168 6.1.2 Installing DigitalMicrograph Offline 168 6.1.3 A (Very) Quick Overview 168 6.2 Understanding Data 170 6.2.1 What is an Image? 170 6.2.2 Image Display 171 6.2.3 Number Formats 173 6.2.4 Image Calibration and Image Tags 178 6.2.5 Some Simple Tools 180 6.2.6 Extracting Subsets of Data 181 6.3 Digital Image Processing 183 6.3.1 Image ‘Filters’ 185 6.3.2 Fourier Transformation in Images 187 6.3.3 Fourier Filtering 189 6.3.4 Coordinate Transformations 192 6.4 Scripting and Plugins 193 Appendix 195 References 195 7 Electron Waves, Interference, and Coherence 197 7.1 Introduction 198 7.2 Description of Waves 198 7.2.1 Plane Wave 199 Contents xxvii

7.2.2 Spherical Wave 199 7.2.3 Modulated Wave 199 7.3 Interference 200 7.4 Modulation of a Wave by an Object 201 7.5 Propagation of Waves 201 7.5.1 Fresnel Approximation in the Near-Field of the Object 202 7.5.2 Fraunhofer Approximation in the Far-Field of the Object 202 7.6 Imaging: Formation of the Image Wave 203 7.6.1 Fourier Transform of the Object Exit Wave 203 7.6.2 Building the Image Wave by Inverse Fourier Transform of the Fourier Spectrum 203 7.7 Electron Wave Function 204 7.8 Electron Interference 205 7.9 Findings 206 7.10 Interpretation 207 7.11 Coherence 207 7.11.1 Spatial Coherence 208 7.11.2 Coherent Current 210 7.11.3 Temporal Coherence 211 7.11.4 Total Degree of Coherence 211 7.11.5 A Generalization 211 7.11.6 Coherence at Inelastic Interaction 211 Appendix 213 References 213 8 Electron Holography 215 8.1 Big Problem with TEM: Phase Contrast 216 8.2 Wave Modulation and Conventional Imaging 216 8.2.1 Amplitude Modulation 216 8.2.2 Phase Modulation 217 8.2.3 What Do We See in an Electron Image? 218 8.3 Principle of Image-Plane Off-Axis Holography 219 8.3.1 Recording a Hologram 219 8.3.2 Reconstructing the Object Exit-Wave 220 8.3.3 What Have We Achieved so Far? 223 8.4 Properties of the Reconstructed Object Exit-Wave 223 8.5 Requirements of Holography 224 8.6 Quality Criteria 224 xxviii Contents

8.7 Application to Electric Potentials on Nanometer Scale 225 8.7.1 Phase Shift Due to Electrostatic Potentials 225 8.7.2 Experimental Considerations 226 8.7.3 Application Example: p–n Junctions 227 8.8 Further Derivatives of Electron Holography 227 8.8.1 Holographic Tomography 227 8.8.2 Dark-Field Holography 228 Appendix 230 References 230 9 Focal-Series Reconstruction 233 9.1 Motivation: Why the Effort? 234 9.2 Quick Walk Through Electron Diffraction 235 9.3 From the Wavefunction to the Image 237 9.3.1 Imaging with a ‘Neutral’ Microscope 238 9.3.2 Linear Imaging with a Constant-Phase-Shift Microscope 240 9.3.3 Linear Imaging with a Real Microscope 241 9.3.4 From Oscillations to Windings: an Integral View on Linear Imaging 247 9.4 From the Images to the Wavefunction 249 9.4.1 Tomographic Interpretation of Focal Series 249 9.4.2 Fundamental Properties of Focal Series 250 9.4.3 An Explicit Solution to the Linear Inversion Problem 253 9.4.4 Nonlinear Reconstruction 255 9.4.5 Numerical Correction of Residual Aberrations 256 9.5 Application Examples 257

9.5.1 Twin Boundaries in BaTiO3 258 9.5.2 Stacking Fault in GaAs 260 Appendix 263 References 264 10 Direct Methods for Image Interpretation 267 10.1 Introduction 268 10.2 Basics of Image Formation 268 10.2.1 Real imaging 268 10.2.2 Successive Imaging Steps 269 10.2.3 Coherent Imaging 269 10.2.4 High-Resolution Imaging in the TEM 270 10.3 Focal-Series Reconstruction of the Exit Wave 271 Contents xxix

10.4 Interpretation of the Reconstructed Exit Wave 271 10.4.1 Electron Channeling 272 10.4.2 Argand Plot 273 10.5 Quantitative Structure Refinement 274 10.5.1 Precision Versus Resolution 276 10.5.2 Quantitative Model-Based Structure Determination 276 Appendix 280 References 280 11 Imaging in STEM 283 11.1 Z-Contrast STEM: an Introduction 284 11.1.1 Independent Scatterers 284 11.1.2 An Array of Scatterers 284 11.1.3 As the Crystal Thickens 284 11.1.4 Inside and Outside 286 11.1.5 The Effect of Defects 287 11.1.6 Quasicrystals 288 11.2 An Electron’s Eye View of STEM 288 11.2.1 Plane Waves and Probes 291 11.2.2 Rayleigh, Airy and Resolution 292 11.3 Lens Aberrations for STEM 293 11.3.1 The Benefits of Aberration Correction 295 11.3.2 Resolution in the Third Dimension – Depth Resolution 300 11.4 Spatial and Temporal Incoherence 305 11.4.1 Spatial Incoherence 305 11.4.2 Temporal Incoherence 306 11.4.3 “How Do I Know if I Have a Coherent Probe?” The Ronchigram 306 11.5 Coherent or Incoherent Imaging 310 11.5.1 A Point Detector; Coherent Imaging 311 11.5.2 An Infinite Detector: Incoherent Imaging 312 11.5.3 An Annular Detector: Incoherent Dark-Field or Bright-Field Imaging 314 11.5.4 Atoms Are Smaller in HAADF STEM 315 11.5.5 Transverse Coherence 316 11.5.6 The Origin of Contrast in the Scanned Image 317 11.5.7 Transfer Function and Damping Function ...... 318 11.5.8 Longitudinal Coherence 319 xxx Contents

11.6 Dynamical Diffraction 323 11.7 Other Sources of Image Contrast 326 11.8 Image Processing 329 11.9 Image Simulation 332 11.9.1 Bloch Waves 333 11.9.2 Multislice 333 11.9.3 Bloch Waves with Absorption 333 11.9.4 There Is No Stobb’s Factor in HAADF 334 11.10 Future Directions 335 Appendix 337 References 338 12 Electron Tomography 343 12.1 Theory of Projection 344 12.2 Back-Projection 346 12.3 Constrained Reconstruction 347 12.3.1 Constraint by Projection Consistency 347 12.3.2 Constraint by Discrete Methods ...... 348 12.3.3 Constraint by Symmetry 348 12.3.4 Metric-Based Constraint 348 12.4 Other Reconstruction Approaches 350 12.5 Meeting the Projection Requirement 350 12.6 STEM Tomography 351 12.7 Element-Selected Tomography 354 12.8 Dark-Field TEM Tomography 356 12.9 Holographic Tomography 358 12.10 Atomistic Tomography 359 12.11 Experimental Limitations 360 12.12 Beam Damage and Contamination 364 12.13 Automated Acquisition 365 12.14 Tilt-Series Alignment 366 12.15 Visualization of Three-Dimensional Datasets 368 12.16 Segmentation 369 12.17 Quantitative Analysis of Volumetric Data 371 Appendix 373 References 373 13 EFTEM 377 13.1 Introduction 378 13.2 Why Use EFTEM? 378 Contents xxxi

13.3 Instrumentation for EFTEM 379 13.3.1 General TEM Considerations 379 13.3.2 The Imaging Filter 379 13.3.3 Detector Considerations 380 13.4 Limitations and Artefacts 381 13.4.1 Spatial Resolution in EFTEM Images 381 13.4.2 Non-Isochromaticity 383 13.4.3 Sample Drift 383 13.4.4 Diffraction Contrast 384 13.4.5 Illumination Convergence 384 13.5 Application of EFTEM 385 13.5.1 Zero-Loss Imaging and Diffraction 385 13.5.2 Measuring Relative Thickness (t/λ Mapping) 386 13.6 Core-Loss Elemental Mapping 387 13.6.1 Elemental Mapping (Three-Window Method) 387 13.6.2 Jump-Ratio Mapping (Two-Window Method) 388 13.7 EFTEM Spectrum-Imaging 389 13.8 Low-Loss Imaging 392 13.9 Alternative Imaging Techniques for Biological Specimens 393 13.10 Quantitative Elemental Mapping 394 13.11 Chemical State Mapping Using ELNES 396 13.12 Hybrid EFTEM Modes (ω-q, Line Spectrum EFTEM) 397 13.13 EFTEM Tomography 398 Appendix 401 References 401 14 Calculating EELS 405 14.1 Introduction 406 14.2 Density Functional Theory (DFT) 407 14.2.1 Introduction to DFT 407 14.2.2 The Exchange Correlation Potential 409 14.2.3 Approximations to the Potential 409 14.2.4 Basis Sets 410 14.2.5 The Korringa–Kohn–Rostoker (KKR) Method 412 14.3 Calculations of the ELNES 412 14.3.1 ELNES Theory 412 14.3.2 The Core Hole 414 14.3.3 Multiplet Theory 415 14.3.4 Multiple Scattering (MS) Methods 416 xxxii Contents

14.4 Calculating Low-Loss EELS 417 Appendix 421 References 422 15 Diffraction & X-ray Excitation 425 15.1 Introduction 426 15.2 ALCHEMI 426 15.3 Gedanken ALCHEMI 426 15.4 Two Examples 428 15.4.1 Dilute Solution/Partition Coefficient Analysis 428 15.4.2 Concentrated Solution/OTL Analysis 430 15.5 Delocalization and Axial Channeling 431 15.6 Optimizing ALCHEMI: ‘Statistical’ ALCHEMI 432 15.7 Incoherent Channeling Patterns 432 15.8 Vacancies and Interstitials 432 15.9 Chemistry 434 Appendix 435 References 436 16 X-ray and EELS Imaging 439 16.1 What Are Spectral Images and Why Should We Collect Them? 440 16.2 Some History 441 16.3 Acquisition and Analysis of Spectral Images 442 16.3.1 Sampling and the Effect of Probe Versus Pixel Size (STEM- XEDS/EELS) or Magnification (EFTEM) 442 16.3.2 Signal: Count Rate, Dwell Time, Spectral Image Size, and Acquisition Time 443 16.3.3 Drift Correction and Beam Damage 446 16.3.4 Conventional Data Analysis Methods 446 16.4 Multivariate Statistical Analysis Methods ...... 451 16.4.1 Principal Components Analysis (PCA) 454 16.4.2 Factor Rotations 455 16.4.3 Multivariate Curve Resolution (MCR) 456 16.4.4 Quantification 457 16.5 Example of X-ray and Electron Energy-Loss Spectral Image Acquisition and Analysis 458 16.5.1 Fe-Ni Spectral Image Acquisition and Quantification . . . . 458

16.5.2 Mn-Doped SrTiO3 Grain Boundary Spectral Image Acquisition and Quantification 459 16.5.3 Plasmon Mapping of AG Nanorods: EELS Spectral Image Analysis 462 Contents xxxiii

Appendix 464 References 464 17 Practical Aspects and Advanced Applications of XEDS 467 17.1 Performance Parameters of XEDS Detectors 468 17.1.1 Detector, Fundamental Parameters 468 17.1.2 Monitoring Detector Contamination 470 17.1.3 Software to Determine Detector Parameters 471 17.2 X-ray Spectrum Simulation – a Tutorial and Applications of DTSA 472 17.2.1 What Is DTSA? 473 17.2.2 A Brief Tutorial of X-ray Spectrum Simulation for a Thin Specimen Using DTSA 475 17.2.3 Details of X-ray Simulation in DTSA 477 17.2.4 Application 1: Confirmation of Peak Overlap 481 17.2.5 Application 2: Evaluation of X-ray Absorption into a Thin Specimen 482 17.2.6 Application 3: Evaluation of the AEM-XEDS Interface 483 17.2.7 Application 4: Estimation of the Detectability Limits 483 17.3 The ζ-factor Method: a New Approach for Quantitative X-ray Analysis of Thin Specimens 486 17.3.1 Why Bother with Quantification? 486 17.3.2 What Is the ζ-factor? 487 17.3.3 Quantification Procedure in theζ -factor Method 488 17.3.4 Determination of ζ factors 489 17.3.5 Applications of ζ-factor Method 490 17.4 Contemporary Aplications of X-ray Analysis 492 17.4.1 Renaissance of X-ray Analysis 493 17.4.2 XEDS Tomography for 3D Elemental Distribution 494 17.4.3 Atomic Resolution X-ray Mapping 495 Appendix 500 References 501 Figure and Table Credits 505

Index 515