Characterization of radiation damage by transmission electron microscopy

Preface ix 1 The role of transmission electron microscopy in characterizing radiation damage 1 1.1 Introduction 1 1.2 What is radiation damage? 1 1.3 Why is electron microscopy useful for studying radiation damage? 2 1.4 The limitations of TEM 4 1.5 The scope of the book 4 1.5.1 Organization of the book 5 2 An introduction to the available contrast mechanisms and experimental techniques 6 2.1 Diffraction (or strain) contrast 6 2.1.1 Two-beam dynamical conditions 7 2.1.2 Bright-field kinematical conditions 9 2.1.3 Down-zone conditions 11 2.1.4 Weak-beam dark-field conditions 11 2.2 Structure-factor contrast 19 2.3 Phase contrast 20 2.4 A few words on image recording 22 2.5 Comments on specimen preparation and image artefacts 24 3 Analysis of small centres of strain: the determination of loop morphologies 27 3.1 Black–white contrast analysis 28 3.1.1 General properties of black–white contrast images 28 3.1.2 Burgers vector determination by ll-vector analysis 31 3.1.3 Image simulations 33 3.1.4 Examples of image matching to determine Burgers vectors and habit-planes 50 3.1.5 Black–white images of SFT 55 3.2 Weak-beam imaging 57 3.2.1 Weak-beam analyses of clusters of size >5 nm 57 v vi Contents 3.2.2 Weak-beam analyses of clusters of size <5 nm 69 3.3 The future for simulations of diffraction contrast images 70 4 Analysis of small centres of strain: determination of the vacancy or interstitial nature of small clusters 74 4.1 The inside–outside method 74 4.1.1 Edge loops 75 4.1.2 Non-edge loops 80 4.1.3 Example: loops in neutron-irradiated iron 85 4.1.4 Determining the loop habit-plane 85 4.2 The black–white stereo technique 90 4.2.1 Examples of use of black–white stereo analysis 93 4.3 The 212 D technique 100 4.4 Determining the nature of stacking-fault tetrahedra 102 4.4.1 The method of Kojima et al (1989) 102 4.4.2 The method of Coene et al (1985) 103 4.5 Indirect techniques for nature determination 106 5 Analysis of small centres of strain: counting and sizing small clusters110 5.1 Determination of loop and SFT number densities 110 5.1.1 There is a finite resolution limit—some loops are not seen because they are too small 110 5.1.2 In any one micrograph, only a proportion of the resolvable loops will be seen 111 5.1.3 Loops may be lost from the foil due to surface image forces112 5.1.4 Counting may be difficult if the loop number density is very high 112 5.1.5 Foil-thickness measurement will be necessary if volume (rather than area) number densities are needed 114 5.1.6 For defect yields in irradiation experiments, it is also necessary to consider errors in dose measurement 114 5.2 Determining loop and SFT sizes 115 5.2.1 Examples of image sizing by weak-beam microscopy 122 6 Characterization of voids and bubbles 129 6.1 ‘In-focus’ imaging of larger voids 129 6.2 ‘Out-of-focus’ imaging of smaller voids 130 6.3 Sizing of voids 132 6.4 Weak-beam imaging of small voids 138 6.5 Over-pressurized bubbles 138 6.6 Void arrays 141 7 Techniques for imaging displacement cascades 145 7.1 Imaging disordered zones in ordered alloys 145 7.2 Imaging of amorphous zones in semiconductors 154 Contents vii 8 High-resolution imaging of radiation damage 159 8.1 Conditions for structural imaging 159 8.1.1 The specimen 159 8.1.2 The microscope 160 8.2 Image simulations in HREM 161 8.3 Applications of HREM to radiation damage 161 8.3.1 Determination of the nature of stacking-fault tetrahedra in silver produced near line dislocations by electron irradiation161 8.3.2 Identification of amorphous and recrystallized zones at cascade sites in the high-temperature superconductor YBa2Cu3O7.ن 162 8.3.3 Identification of the structure of GeV ion tracks, which act as pinning defects in high-temperature superconductors 164 8.3.4 Determination of the structure of copper precipitates in electron and neutron irradiated Fe–Cu alloys 168 8.3.5 Determination of the structure of solid Xe precipitates (‘bubbles’) in electron-irradiated aluminium 169 9 In situ irradiation experiments 173 9.1 Introduction 173 9.2 In situ electron irradiation 174 9.3 In situ ion irradiation 184 9.4 Future possibilities 192 10 Applications of analytical techniques 194 10.1 Examples of the use of analytical techniques in radiation damage 195 10.2 Future trends 207 11 Radiation damage in amorphous glasses 208 11.1 Property changes caused by irradiation 208 11.2 Directions for future work 209 11.3 Variable coherence microscopy (speckle patterns) 211 A The Thompson tetrahedron 214 References 216 Index 222