Electron diffraction in the transmission electron microscope

✍ Scribed by Champness, Pamela E

• Publisher: Garland Science
• Year: 2020
• Tongue: English
• Leaves: 185
• Series: Microscopy handbooks 47
• Category: Library

✦ Synopsis

This book is a practical guide to electron diffraction in the transmission electron microscope (TEM). Case studies and examples are used to provide an invaluable introduction to the subject for those new to the technique. The book explains the basic methods used to obtain diffraction patterns with the TEM. The numerous illustrations aid the understanding of the conclusions reached.;Abbreviations -- List of symbols -- Preface -- 1. Diffraction and the electron microscope -- How a lens forms a diffraction pattern -- Introduction to diffraction in the TEM -- SAD in the TEM -- Low- (or small-) angle diffraction -- Limitations to the accuracy of selected-area diffraction -- Diffraction using small probes -- Spatial resolution -- Problems with specimens -- Specimen preparation -- Beam damage -- Obtaining and recording a SAD pattern in the TEM -- Obtaining a CBED pattern -- TEM mode -- STEM mode -- Alignments that are important for diffraction -- 2. The reciprocal lattice and Bragg's Law -- Electrons as waves -- Interference of waves -- Bragg's Law -- The reciprocal lattice -- The 180° ambiguity in indexing the diffraction pattern -- Diffraction patterns from polycrystalline materials -- Diffraction patterns from amorphous materials -- Systematic absences -- Standard patterns -- Cubic patterns -- Hexagonal close-packed patterns -- Patterns from the diamond structure -- Computer indexing of electron diffraction patterns -- Input data -- Measuring the pattern and indexing it - an example -- Calibration of the camera constant -- Calibration of the rotation between the image and the diffraction pattern -- Using electron diffraction to identify unknown phases -- Exercises -- 3 The reflecting sphere -- The reflecting sphere -- Obtaining orientation relationships -- Second-phase particles or precipitates -- Twinned crystals -- Determining habit and composition planes -- The importance of crystal orientation -- Dark-field imaging -- Exercises -- 4 Finding your way around reciprocal space: Kikuchi diffraction -- How Kikuchi lines form -- The determination of the deviation parameter s -- Kikuchi maps and their uses -- Finding the exact orientation of the crystal -- Exercises -- 5 The intensities of reflections -- The atomic scattering amplitude, f -- The structure factor, Fhkl -- Systematic absences due to lattice type -- Crystal with a simple structure -- Systematic absences due to translational symmetry elements -- The kinematic and dynamical theories of electron diffraction Measuring the structure factor, Fhkl, and the extinction distance -- Exercises -- 6 Determination of the Bravais lattice, point group and space group -- Determination of the crystal system from conventional electron diffraction patterns -- Convergent-beam methods -- Zonal repeats parallel to the electron beam -- Geometry of CBED patterns from HOLZs -- The symmetry of CBED patterns -- The Tanaka method -- Exercises -- 7. The fine structure in electron diffraction patterns -- Double diffraction -- Double diffraction of 'forbidden' reflections -- Double diffraction of spots from precipitates and twins -- Detection of double diffraction in the microscope -- Diffraction from small particles -- The distribution of streaks in the diffraction pattern -- The effects of elastic strain -- Diffraction from ordered structures -- Long-range order -- Short-range order -- Periodic and modulated structures -- Spinodal decomposition and other compositional modulations -- Periodic antiphase domain boundaries -- Regular dislocation arrays -- Incommensurate structures -- Planar and linear defects -- Thermal diffuse scattering -- Exercises -- Appendices -- Appendix A: Some basic crystallography -- Appendix B: An introduction to space groups -- Appendix C: Some useful crystallographic relationships -- Appendix D: Relativistic electron wavelengths -- Appendix E: Mathematical definition of the reciprocal lattice -- Appendix F: Computer programs concerning electron diffraction -- Appendix G: Answers to exercises -- Appendix H: References -- Index.

✦ Table of Contents

Cover......Page 1
Half Title......Page 2
Title Page......Page 4
Copyright Page......Page 5
Table of Contents......Page 6
Abbreviations......Page 10
List of symbols......Page 12
Preface......Page 14
How a lens forms a diffraction pattern......Page 16
Introduction to diffraction in the TEM......Page 19
SAD in the TEM......Page 22
Limitations to the accuracy of selected-area diffraction......Page 23
Diffraction using small probes......Page 26
Spatial resolution......Page 29
Problems with specimens......Page 31
Beam damage......Page 32
Obtaining and recording a SAD pattern in the TEM......Page 34
STEM mode......Page 36
Alignments that are important for diffraction......Page 37
Electrons as waves......Page 40
Interference of waves......Page 41
Bragg's Law......Page 43
The reciprocal lattice......Page 46
The 180° ambiguity in indexing the diffraction pattern......Page 50
Diffraction patterns from amorphous materials......Page 52
Systematic absences......Page 53
Cubic patterns......Page 55
Hexagonal close-packed patterns......Page 57
Input data......Page 60
Measuring the pattern and indexing it – an example......Page 63
Calibration of the camera constant......Page 64
Calibration of the rotation between the image and the diffraction pattern......Page 65
Using electron diffraction to identify unknown phases......Page 67
Exercises......Page 68
The reflecting sphere......Page 70
Second-phase particles or precipitates......Page 75
Twinned crystals......Page 76
Determining habit and composition planes......Page 77
The importance of crystal orientation......Page 79
Dark-field imaging......Page 80
Exercises......Page 81
How Kikuchi lines form......Page 84
Kikuchi maps and their uses......Page 89
Exercises......Page 93
The structure factor, Fhkl......Page 96
Systematic absences due to lattice type......Page 98
Systematic absences due to translational symmetry elements......Page 99
The kinematic and dynamical theories of electron diffraction......Page 103
Measuring the structure factor, Fhkl, and the extinction distance, ξ......Page 104
Exercises......Page 105
Determination of the crystal system from conventional electron diffraction patterns......Page 106
Zonal repeats parallel to the electron beam......Page 107
Geometry of CBED patterns from HOLZs......Page 109
The symmetry of CBED patterns......Page 111
The Tanaka method......Page 121
Exercises......Page 124
Double diffraction......Page 128
Double diffraction of 'forbidden' reflections......Page 130
Detection of double diffraction in the microscope......Page 131
Diffraction from small particles......Page 134
The distribution of streaks in the diffraction pattern......Page 135
The effects of elastic strain......Page 136
Long-range order......Page 137
Short-range order......Page 138
Spinodal decomposition and other compositional modulations......Page 140
Periodic antiphase domain boundaries......Page 141
Regular dislocation arrays......Page 142
Planar and linear defects......Page 143
Exercises......Page 146
Appendix A: Some basic crystallography......Page 148
Appendix B: An introduction to space groups......Page 156
Appendix C: Some useful crystallographic relationships......Page 162
Appendix D: Relativistic electron wavelengths......Page 166
Appendix E: Mathematical definition of the reciprocal lattice......Page 168
Appendix F: Computer programs concerning electron diffraction......Page 170
Appendix G: Answers to exercises......Page 172
Appendix H: References......Page 178
Index......Page 182

✦ Subjects

Electrons--Diffraction;SCIENCE / Life Sciences / Biochemistry;SCIENCE / Life Sciences / Biophysics;SCIENCE / Microscopes & Microscopy;Transmission electron microscopes;Electronic books;Electrons -- Diffraction