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.
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.
Pamela Champness graduated from Cambridge University in Natural Sciences (Mineralogy) in 1964 and was awarded a PhD in Mineralogy from Cambridge in 1969. She has recently retired as Reader in Crystallography at the Department of Earth Sciences, University of Manchester and is now an Honorary Research Fellow. Her main research interests are in the applications of transmission electron microscopy to phase transformations in minerals
Inhaltsangabe
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.
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.
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