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In this study, a new method is established for indexing electron backscatter diffraction (EBSD) patterns assisted by the Kikuchi bandwidth. This method utilises both interplanar angles and interplanar spacings to determine the Miller indices of the Kikuchi bands in EBSD patterns to improve the efficiency and precision of indexing in the EBSD system. Two samples of single-crystal silicon were investigated to validate the method based on (a) the detection of the edges of the EBSD Kikuchi bands and (b) the calculation of the Kikuchi bandwidths. The relationship between the Kikuchi bandwidth and the interplanar spacing at different positions was established, and the interplanar spacing of the corresponding lattice plane of each Kikuchi band was calculated with the use of the Kikuchi bandwidth information. The relative errors between the theoretical and experimental interplanar spacings are small, with an average relative error of 2.6% and a minimum relative error of 1.04%. The results indicated that the Miller index of each Kikuchi band can be determined accurately with this new method. It is demonstrated that use of this new method improves the efficiency and accuracy of the EBSD system. LAY DESCRIPTION: Electron backscatter diffraction (EBSD) is a scanning electron microscope-based technique. In our work, a new method is established for indexing EBSD patterns assisted by the Kikuchi bandwidth. This method utilizes both interplanar angles and interplanar spacings to determine the Miller indices of the Kikuchi bands in EBSD patterns to improve the efficiency and precision of indexing in the EBSD system. Two samples of single-crystal silicon were investigated to validate the method based on a) the detection of the edges of the EBSD Kikuchi bands and b) the calculation of the Kikuchi bandwidths. The relationship between the Kikuchi bandwidth and the interplanar spacing at different positions was established, and the interplanar spacing of the corresponding lattice plane of each Kikuchi band was calculated with the use of the Kikuchi bandwidth information. The relative errors between the theoretical and experimental interplanar spacings are small, with an average relative error of 2.6% and a minimum relative error of 1.04%. Compared with the results reported in the literature, the width-assisted Kikuchi pattern indexing method can well distinguish some cases with similar angles, and reduce the possibility of mis-indexing. After the introduction of the width information of the Kikuchi bands, the screening range can be narrowed by determining the crystal plane family, and the efficiency and accuracy of the indexing process can thus be improved. Specifically, for some materials with increased symmetry, such as cubic crystal materials, it is necessary to use the interplanar spacing for indexing when the interplanar angles are not diagnostic. The results indicated that the Miller index of each Kikuchi band can be determined accurately with this new method. It is demonstrated that use of this new method improves the efficiency and accuracy of the EBSD system.

International audience; EBSD analysis can provide information about grain orientation, texture and grain boundary misorientation of bulk superconducting MgB2 samples intended for supermagnet applications. However, as the grain size of the MgB2 bulks is preferably in the 100–200 nm range, the common EBSD technique operating in reflection mode works only properly on highly dense samples. In order to achieve reasonably good Kikuchi pattern quality on all types of MgB2 samples, we apply here the newly developed transmission EBSD (t-EBSD) technique to spark-plasma sintered MgB2 samples. This method requires the preparation of TEM slices by means of focused ion-beam milling, which are then analysed within the SEM, operating with a custom-built sample holder. To obtain multiphase scans, we identified the Kikuchi pattern of the MgB4 phase which appears at higher reaction temperatures and may act as additional flux pinning sites. We present here for the first time EBSD mappings of multiple phases, which include MgB2, MgB4 and MgO. Lay Description The electron backscatt er diffraction (EBSD) technique operating in the scanning electron microscope provides information on the crystallographic orientation the material by recording Kikuchi patterns. In polycrystalline samples, it becomes possible to analyse the orientations of the grains to each other. The metallic superconductor with the currently highest superconducting transition temperature, MgB2 with a Tc of 38.5 K, can be used in applications in polycrystalline form. One such application of interest are trapped field magnets or supermagnets, where the superconductor cooled in an applied magnetic field can trap the magnetic field as vortices at numerous flux pinning sites in the sample. When the external magnetic field is removed, the sample will stay magnetised as long as it is kept cool, and importantly, the trapped magnetic fields can be much higher as for any permanent magnet. However, the small size of the MgB2 grains in the 100–200 nanometre range requires a different approach when using the EBSD technique on such samples. The recently developed EBSD technique working in transmission mode (t-EBSD) helps considerably to image such materials. In this approach, a tiny TEM slice has to be milled out from the original sample by using focused ion beam milling. To understand the properties of the flux pinning in the spark-plasma sintered MgB2 sample, we had to identify the Kikuchi pattern of MgB4, which is another, non-superconducting phase appearing at higher reaction temperatures required to compact the material. Using this information, we could perform EBSD scans using three different phases, MgB2, MgB4 and MgO. The EBSD mappings enable to see where the secondary phase particles are located in the sample, and to judge if the particles could work as flux pinning sites. © 2019 The Authors Journal of Microscopy © 2019 Royal Microscopical Society

The structure of molecules using gas electron diffraction (GED) was my graduate study. However, I was making a new apparatus for precise measurements by GED and formulated a scheme for the least-squares analysis for a smooth continuous curve of scattering intensity. My research was completely shifted to the solid surface after moving to Gakushuin University, where I briefly studied the liquid structure of CCl4 molecules, and I then moved to the Institute for Solid State Physics, the University of Tokyo. My studies of surface science were focused on the electronic properties and related phenomena, and various experimental methods were developed. The plasmon dispersions elucidated the initial oxidation of aluminum and one-dimensional metal on Si(001)2 × 1-K. Irreversible phase transition was discovered on MgO(001) using the LEED Kikuchi pattern. The electronic structure of the dislocation was observed on MgO(001) by the electron time-of-flight method. The phase transition on Si(001) and the rotational epitaxy in a K monoatomic layer on Cu(001) were found. Next, I changed to studies of the dynamical phenomena on the surface, where very low energy reactive ion scattering on metal surfaces and laser-induced desorption caused by electronic transition of NO and CO molecules from metal surfaces were observed, and the hydrogen atom location at the surface and interface was measured with a high depth resolution using a resonance nuclear reaction of (1) H + (15) N(2+) at 6.385 MeV. Finally, I moved to the University of Electro-Communications and studied thin single-crystal oxide layers on transition metals, in which the band-gap narrowing was found, and then a Pt monoatomic layer was prepared on the α-Al(2)O(3) film.

We report the effects of varying specimen thickness on the generation of transmission Kikuchi patterns in the scanning electron microscope. Diffraction patterns sufficient for automated indexing were observed from films spanning nearly three orders of magnitude in thickness in several materials, from 5 nm of hafnium dioxide to 3 μm of aluminum, corresponding to a mass-thickness range of ~5 to 810 μg cm(-2) . The scattering events that are most likely to be detected in transmission are shown to be very near the exit surface of the films. The energies, spatial distribution and trajectories of the electrons that are transmitted through the film and are collected by the detector are predicted using Monte Carlo simulations.

A recently developed technique based on the transmission electron microscope, which makes use of electron beam precession together with spot diffraction pattern recognition now offers the possibility to acquire reliable orientation/phase maps with a spatial resolution down to 2 nm on a field emission gun transmission electron microscope. The technique may be described as precession-assisted crystal orientation mapping in the transmission electron microscope, precession-assisted crystal orientation mapping technique-transmission electron microscope, also known by its product name, ASTAR, and consists in scanning the precessed electron beam in nanoprobe mode over the specimen area, thus producing a collection of precession electron diffraction spot patterns, to be thereafter indexed automatically through template matching. We present a review on several application examples relative to the characterization of microstructure/microtexture of nanocrystalline metals, ceramics, nanoparticles, minerals and organics. The strengths and limitations of the technique are also discussed using several application examples.

A charge-coupled device camera of an electron backscattered diffraction system in a scanning electron microscope was positioned below a thin specimen and transmission Kikuchi patterns were collected. Contrary to electron backscattered diffraction, transmission electron forward scatter diffraction provides phase identification and orientation mapping at the nanoscale. The minimum Pd particle size for which a Kikuchi diffraction pattern was detected and indexed reliably was 5.6 nm. An orientation mapping resolution of 5 nm was measured at 30 kV. The resolution obtained with transmission electron forward scatter diffraction was of the same order of magnitude than that reported in electron nanodiffraction in the transmission electron microscope. An energy dispersive spectrometer X-ray map and a transmission electron forward scatter diffraction orientation map were acquired simultaneously. The high-resolution chemical, phase and orientation maps provided at once information on the chemical form, orientation and coherency of precipitates in an aluminium-lithium 2099 alloy.

eMap is an easy-to-use suite of computer programs devoted for crystallographic calculations in X-ray diffraction and electron crystallography. It is used in several key activities: (1) Kinematical structure factors calculation for electrons and X-rays. (2) Calculation and visualization of 3D electron density/potential maps and peak search in the generated maps. (3) Visualization of reciprocal space in different modes (X-rays, selected area electron diffraction, Kikuchi lines and bands, electron diffraction precession, etc.). (4) Simulation of HRTEM images and dynamical electron diffraction patterns by multislice method and convergent beam electron diffraction patterns by Bloch-wave method. (5) Crystal structure refinement from the electron diffraction patterns taking dynamical effects into account. The user-friendly graphical user interface facilitates the loading or manual data input, and visualization of intermediate and final results in form of 3D graphics or 2D images, plots, and diagrams. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Orientation microscopy (OM) refers to techniques for reconstruction of microstructures based on the spatially resolved measurement of individual crystallographic phases and orientations. This review gives an overview on different techniques of OM in the scanning and transmission electron mi-croscope. All rely on the automated evaluation of electron diffraction patterns. The most popular technique is based on electron backscatter diffraction (EBSD) in the SEM. In the TEM several techniques are available which are based on either Kikuchi diffraction patterns, spot diffraction patterns with and without electron precession, or reconstructed spot diffraction patterns. Each technique is introduced in detail. Subsequently the techniques are critically compared with respect to their spatial and angular resolution, their robustness in terms of orientation determination and questions of practical applicability for materials science. One point discussed in detail is the spatial resolution. It is shown that the spatial resolution, i.e. the volume from which the diffraction information is generated, is not very different for the SEM and TEM techniques. For this and other reasons we argue that the EBSD technique is in many cases the best suited method for OM. In those cases where it is not (e.g. investigations on truly nanocrystal-line materials, beam sensitive samples) it is the spot diffraction method combined with electron precession and template matching for orientation determination which offers the best resolution and robustness. The Kikuchi pattern technique in the TEM is only reasonably used when highest angular resolution is to be achieved, e.g. for lattice constant determination. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The microwave dielectric properties and microstructure of Mg 3 B 2 O 6 ceramics with the addition of 0-5 wt% Mg 2 B 2 O 5 were investigated. Scanning electron microscopy of the Mg 3 B 2 O 6 ceramics sintered at 1310°C revealed the presence of anisotropic, exaggeratedly grown grains with a crystallographic fault that extends along the direction of the anisotropy. The most pronounced, exaggerated grain growth was observed for Mg 3 B 2 O 6 with 5 wt% of Mg 2 B 2 O 5 . The anisotropic grains were examined by electron backscatter diffraction. The analysis of the Kikuchi pattern showed that the crystallographic fault is a (011) twinning plane. The duration of annealing was found to have no significant effect on the dielectric permittivity, while the Q x f values increased two times with a prolongation of the annealing from 20 to 160 h. The highest Q × f value of 240 000 GHz was measured for Mg 3 B 2 O 6 ceramics with 5 wt% of Mg 2 B 2 O 5 . These ceramics consisted of 10 times larger grains than the Mg 3 B 2 0 6 ceramics without the added Mg 2 B 2 O 5 , which also showed high Q × f values of 200 000 GHz. The decrease of the amorphous phase during the annealing could be one of the reasons for this improvement of the Q × f values.

Summary This paper presents a tutorial discussion of the principles underlyingthedepth-dependentKikuchipatternformationof backscattered electrons in the scanning electron microscope. To illustrate the connections between various electron diffractionmethods,theformationofKikuchibandsinelectron backscatter diffraction in the scanning electron microscope and in transmission electron microscopy are compared with the help of simulations employing the dynamical theory of electron diffraction. The close relationship between backscattered electron diffraction and convergent beam electrondiffractionisilluminatedbyshowinghowbotheffects can be calculated within the same theoretical framework. The influence of the depth-dependence of diffuse electron scattering on the formation of the experimentally observed electron backscatter diffraction contrast and intensity is visualized by calculations of depth-resolved Kikuchi patterns.Comparisonofanexperimentalelectronbackscatter diffractionpatternwithsimulationsassumingseveraldifferent depth distributions shows that the depth-distribution of backscattered electrons needs to be taken into account in quantitative descriptions. This should make it possible to obtain more quantitative depth-dependent information from experimental electron backscatter diffraction patterns via

Permalloy (Ni 81 Fe 19 ) films and foils were fabricated by means of electroplating. Two different types of samples were produced, (i) a patterned permalloy film on a Si wafer (type 1) and (ii) a NiFe foil (type 2), which was separated from the substrate after deposition. The samples were characterized employing magnetic force microscopy (MFM), transmission electron microscopy (TEM) and electron-backscatter diffraction (EBSD). On the foil type sample, MFM reveals a maze domain pattern, and on the structured samples (type 1), a Landau domain pattern is obtained. EBSD enables the identification of the permalloy Kikuchi pattern without the effect of a substrate. The analysis reveals randomly oriented grains with a narrow size distribution.

Summary In this study, we demonstrated the use of electron-beam-induced deposition for synthesis of artificial two-dimensional crystals with an in situ scanning transmission electron microscope. The structures were deposited from W(CO)6 in an environmental scanning transmission electron microscope on a 30-nm-thick Si3N4 substrate. We present clear electron beam diffraction patterns taken from those structures. The distance between the diffraction peaks corresponded to the dot spacing in the self-made surface crystal. We propose using these arrays of dots as anchor points for making artificial crystals for diffraction analysis of weakly scattering or beam-sensitive molecules such as proteins.

In the present study we investigate the microstructure of tempered martensite ferritic steels. It is well known that inside former austenite grains and inside packets of former martensite laths ultrafine micro grains (average size near: 1 pm) govern the strength of this material class. Micro grain boundaries are decorated by carbides (average size after creep near: 0.05 μm). However, in transmission electron micrographs it is commonly found that there are micro grain boundaries with a high carbide density while there are others where no carbides can be detected. In the present study we make an attempt to decide whether the crystallographic character of micro grain boundaries can be related to the number density of carbides at the boundaries. Kikuchi line diffraction patterns were used to determine the misorientation angle between two adjacent micro grains; we select only micro grain boundaries which represent - and - twist boundaries. A quantitative microstructural analysis was performed to determine the density of carbides on boundaries. Our results are discussed on the basis of general tendencies which were reported for grain boundaries in the literature.

A simple analytical solution for the crystallographic orientation is described. This method is based on one indexed Kikuchi pair in a known zone rather than the corresponding diffraction spots. The accuracy of this method is shown to be better than 0.1 degrees even for cases in which a zone axis deviates by a large angle (e.g. 10 degrees ) from the centre of the beam direction. This approach simplifies experiments because only one pair of Kikuchi lines and a zone axis are needed, and is especially suited when it is difficult or cumbersome to resolve a second pair of Kikuchi lines with sufficient accuracy.

The acquisition of electron backscattered diffraction (EBSD) (or Kikuchi diffraction) patterns in the scanning electron microscope is proving to be a useful technique with which to probe the structural properties of nitride thin films. In this paper we show that if a sample is cooled the patterns improve dramatically, an increase in intensity of the Kikuchi lines and a decrease in the intensity of the diffuse background is observed. Kikuchi lines from higher order planes become visible and the HOLZ rings become better defined. Such cooled patterns yield more information on the sample, particularly on non-centrosymmetric planes, from which the polarity of the nitride thin film under investigation may be deduced.

The diffraction of electrons was first observed in 1928 by Kikuchi. The phenomenon results in the formation of characteristic diagrams of the crystalline lattice and the orientation of the phase. Backscattered electrons are diffracted by the different crystallographic planes (hkl) according to the Bragg angle thetab. These describe, by symmetry, two cones of axes normal to the diffracting plane. Information is collected on a phosphor screen, leading to the acquisition of a diffraction pattern called a Kikuchi diagram. Several improvements now give a wide range of applications such as phase identification (carbides or complex compounds in a (U,Zr,O) structure), analysis of materials interfaces (ZrO2/UO2), as well as solidification studies and local texture determination (molybdenum sheets). In these applications, EBSD, as a type of quantitative metallography, is a powerful tool.

The demands for reliability and precision of crystal orientation data obtained through automatic analysis of electron backscattering patterns (EBSPs) in the SEM result in similar demands on the quality of the band position data which is provided by an image analysis procedure. This paper describes a new image processing procedure which is capable of providing accurate measurements of the location and width of typically 10–15 bands in digitized EBSPs of average quality. The new procedure is based on the Hough transform (HT) for line detection, and employs a special backmapping technique for generating two simplified HTs which separately focus on bright and dark lines in the images. A coordinated search for peaks in the two HTs leads to precise estimates of both the position and the width of bands in the patterns. A visual evaluation of the data produced by the new procedure shows that it performs significantly better than the conventional procedure with regard to both reliability and precision. Additionally, the measured band width data are fairly precise and can be used for obtaining a more robust and reliable indexing of the bands. Finally, the computational costs of the new procedure are smaller than for the conventional procedure.

Electron backscatter Kikuchi diffraction patterns (BKDPs) recorded in the scanning electron microscope (SEM) require measurements on the plane of the photographic film or on the recording screen. The parameters that require measurements are the equivalent electron source point on the pattern, or pattern centre, specimen-to-film distance, true interzonal angles, true interplanar angles, Bragg angles, and interplanar spacing. In this paper, the geometry and the methods of calculation of these parameters on BKDPs recorded directly on film are described in detail. The methods described are suitable for practical purposes, providing speed of calculation but limited accuracy. The inherent factors that limit the accuracy of any measurements on BKDPs are the limitations of the gnomonic projection, resulting in projected distortions in Kikuchi bands and diffuseness of Kikuchi band edges originating from inelastic scattering of electrons. The methods described are applied to crystallographic analysis of BKDPs recorded from silicon and polycrystalline copper.

For surface structural analysis on monolayer films composed of light elements, we investigated theoretical x-ray photoelectron diffraction (XPED) patterns from single-molecule adsorbing surfaces by using both Cr Lα (572.8 eV) and Al Kα (1486.6 eV) excitations. Forward-scattering peaks and Kikuchi-like bands were clearly observed in the pattern excited by Al Kα. In contrast, the features of the XPED patterns excited by Cr Lα were more diffuse. However, the circular patterns excited by Cr Lα are clearer than those excited by Al Kα. This result suggests that the use of a lower energy x-ray source improves XPED structural analysis on ultrathin films composed of light elements. Copyright © 2004 John Wiley & Sons, Ltd.

Grain growth is studied during the thermal treatment of thin aluminium alloy layers on oxidised silicon substrates by means of transmission electron microscopy. The grain-specific texture of annealed layers is determined on-line by the Kikuchi pattern method. Elastic coefficients such as stresses and strains in reference directions in the layer, elastic energy and resolved shear stress on the glide planes are calculated in a first approximation on the basis of a biaxial stress model and a biaxial strain model considering measured grain orientations. The mechanisms of stress relaxation, some driving forces, and the effects on grain growth are discussed. Local inhomogeneities, particularly of the resolved shear stress, have an effect on grain growth. The conclusion is drawn that changes of grain orientation enable a preferential relaxation of stress by dislocation glide during grain growth. The results are illustrated by grey-level maps of the grain structure. Das Kornwachstum bei der Warmebehandlung dunner Schichten aus Aluminiumlegierungen auf oxidierten Siliziumsubstraten wird mit dem Transmissionselektronenmikroskop untersucht. Die kornspezifische Textur der warmebehandelten Schichten wird on-line aus Kikuchi-Diagrammen ermittelt. Elastische Parameter wie die Spannung und Dehnung in ausgezeichneten Richtungen der Schicht, die elastische Energie und die resultierende Scherspannung in den Gleitebenen werden in erster Naherung auf der Grundlage des Modells biaxialer Spannung bzw. biaxialer Dehnung unter Berucksichtigung der gemessenen Kornorientierungen berechnet. Die Mechanismen der Spannungs-relaxation, einige treibende Krafte und die Auswirkungen auf das Kornwachstum werden diskutiert. Lokale Inhomogenitaten, insbesondere der resultierenden Scherspannung, wirken sich auf das Kornwachstum aus. Es wird geschlossen, das Anderungen der Kornorientierung eine bevorzugte Spannungsrelaxation durch Versetzungsgleiten wahrend des Kornwachstums ermoglichen. Die Ergebnisse werden durch Grautone in Verteilungsbildern der Kornstruktur veranschaulicht.

Reliable EBSD mapping of 90° domains in a tetragonal ferroelectric perovskite has been achieved for the first time, together with reliable automated orientation determination from TEM-Kikuchi patterns. This has been used to determine misorientation angles at 90° domain boundaries and thus local c/a ratios. The sources of orientation noise/error and their effects on the misorientation angle data have been thoroughly analyzed and it is found that this gives a cosine distribution of misorientation angles about the mean with a characteristic width related to the width of the orientation noise distribution. In most cases, a good agreement is found between local c/a ratios and global measurements by X-ray diffraction, but some clear discrepancies have also been found suggesting that real local variations are present, perhaps as a consequence of compositional inhomogeneities.

High‐precision characterization of grain boundaries with a deviation from the ideal coincidence is presented. The analysis is based on the shift of Kikuchi lines at grain boundaries. The accuracy was controlled using Frank's relationship applied to intrinsic secondary dislocations which accommodate the orientation deviation. An application is presented to coincidences with Σ = 25 and 3 observed in polycrystalline silicon. 1990 Blackwell Science Ltd

In the Laue case the absorption coefficient for the reflection plane being oblique to the surface is derived, which is of different form from the usual one, and is of the same one for the symmetric Lane case. It is shown that this absorption effect plays an important role to interpret the contrast change of Kikuchi patterns in reflection high energy electron diffraction. Although the calculation is based on the so-called two-wave approximation, two kinds of qualitative trend are revealed, which interpret the experimental situation to a certain extent. Es wird der Absorptionskoeffizient im Laue-Fall fur die mit der Oberflache verbundene Reflexionsebene abgeleitet, der sich von der ublichen Form unterscheidet und fur den symmetrischen Lauefall der gleiche ist. Es wird gezeigt, das dieser Absorptionseffekt eine wesentliche Rolle spielt bei der Erklarung der Kontrastanderungen von Reflexions-Kikuchi-Diagrammen bei Hochenergie-Elektronenbeugung. Obwohl die Rechnungen auf der sogenannten Zwei-Strahl-Naherung basieren, werden zwei Arten von qualitativen Betrachtungen aufgezeigt, die die experimentelle Situation bis zu einem bestimmten Ausmas interpretieren.

Publisher Summary The idea of observing electron diffraction in a convergent beam was born at the Technical University of Danzig, where Walther Kossel, of the Institute of Physics, together with his co-workers, discovered the interference of X-rays emitted from sources within the lattice, formed within the crystal as fluorescent radiation of the lattice atoms excited by electrons or primary X-rays. An intensive exchange of ideas with the discoverer of X-ray interference, Nobel Prize winner Max von Laue, who called this the “Kossel effect,” resulted in active attempts to interpret the details of this new kind of X-ray interference. A similar and even more striking effect was observed in S. Kikuchi's electron interference patterns. To obtain additional information on the elementary processes of electron scattering in monocrystals, W. Kossel asked Gottfried Mollenstedt to study “electron interferences in a convergent beam” as a subject for a diploma thesis. This chapter presents a view of his early work on convergent-beam electron diffraction.

Wave channeling with 350 KeV electrons in germanium crystals, the thicknesses of which were 1.8 and 3.0 μm, is studied by measuring the anisotropic X-ray-Kα- and bremsstrahlung yield. The intensity variation is controlled by the Bragg positions of the beam which are due to crystal planes of low Miller indices. A two-dimensional angle-scan picture shows patterns which are the same as the Kikuchi ones in that angle region. The reciprocity theorem gives the correlation between these two cases of wave channeling and wave blocking (Kikuchi pattern). Wellen-Channeling von 350 keV-Elektronen in Germanium-Einkristallen, deren Dicke 1,8 und 3,0 μm betragt, wird durch Messung der anisotropen Rontgen-Kα- und Bremsstrahlung-Ausbeute untersucht. Die Anderungen der Ausbeute werden durch die Bragg-Winkel des Strahles zu Ebenen mit niedrgen Miller-Indizes charakterisiert. Die zweidimensionalen Winkel-Raster-Abbildungen zeigen eine Struktur, die den Kikuchi-Bildern im gleichen Winkelbereich entspricht. Das Reziprozitats-Theorem erklart den Zusammenhang zwischen den beiden Fallen Wellen-Channeling und Wellen-Blocking (Kikuchi-Bilder).

A method for the calculation of the exact direction of the electron beam in the crystal is described. Directions represented by the intersection points of three pairs of Kikuchi lines are determined at first. Then the direction of the electron beam is calculated from the position of the center of the diffraction pattern relative to these intersection points. An example given shows that the inherent accuracy of the method approaches 1 min of arc. Comparison with other methods and with results obtained using different sets of initial data indicates that at present the deformation of the foil in the area selected for diffraction and the distortion of the microdiffraction pattern are the main factors limiting the accuracy of the orientation determination. Es wird eine Berechnungsmethode der exakten Richtung des Elektronenstrahls im Kristall beschrieben. Zuerst werden Richtungen bestimmt, die durch die Schnittpunkte dreier Paare von Kikuchilinien bestimmt sind. Dann wird die Richtung des Elektronenstrahls aus der Lage des Zentrums des Beugungsmusters relativ zu diesen Schnittpunkten berechnet. Ein Beispiel zeigt, das die innere Genauigkeit der Methode 1 Bogenminute erreicht. Ein Vergleich mit anderen Methoden und den Ergebnissen, die mit verschiedenen Satzen von Anfangswerten erhalten werden, zeigt, das gegenwartig die Deformation der Schicht in der fur die Beugung ausgewahlten Flache und die Verzerrung des Mikrobeugungsmusters die Hauptfaktoren sind, die die Genauigkeit der Orientierungsbestimmung begrenzen.

A simplified method for analysing the crystallographic orientation relationship of two adjacent grains by using electron diffraction Kikuchi line patterns is described. The error estimates of rotation axis and angle determined by the method, are formulated. The present method appears to be particularly useful in fast and accurate orientation determinations. Furthermore, as the method of analysis is in a general form, it is not dependent on the crystal system in question. Eine vereinfachte Methode zur Analyse von kristallographischen Orientierungsbeziehungen zwischen zwei angrenzenden Kornern wird mit Kikuchi-Elektronenbeugungs-Linien dargestellt. Mit dieser Methode wird die Fehlbewertung der Drehungsachse und des -winkels formuliert. Diese Methode hat sich als besonders nutzlich bei schnellen und zuverlassigen Messungen der Orientierungsbeziehungen erwiesen. Wenn die Methode zur Analyse universell formuliert wird, ist sie auserdem unabhangig vom Kristallsystem.

Es wird eine Energieanalyse der (220)-Kikuchi-Linien und Bander bei Durchstrahlung dunner Si-Einkristalle mit 75 keV-Elektronen durchgefuhrt. Dadurch konnen Intensitatsprofile, die durch Phononstreuung und verschiedene Ordnungen der Plasmastreuung entstehen, getrennt voneinander absolut gemessen werden. Es zeigt sich, das der Gesamtkontrast aus Beitragen mit sehr unterschiedlichen Intensitaten und Profilformen zusammengesetzt ist. Dies verdeutlicht die Bedeutung der Energieanalyse fur die Untersuchung von Kikuchi-Strukturen. Energy analysis is applied on (220) Kikuchi lines and bands of transmission electron-diffraction patterns of thin Si single crystals. By this means intensity distributions, which are produced by phonon scattering and different orders of plasmon scattering can be registrated separately in absolute units. It is found, that the total contrast consists of contributions with very different intensities and profiles. This demonstrates the importance of energy analysis for the investigation of Kikuchi structures.

Kikuchi patterns obtained from MgO (001) cleaved faces with primary electron energy of 1500 eV are studied both theoretically and experimentally. In particular, the temperature dependence and the primary beam angular dependence of the Kikuchi pattern intensity is recorded using a movable Faraday cage. Besides the primary beam diffraction effects are studied separately by measuring the integrated backscattered intensity using the screen as collector. The results are interpreted by the Kikuchi pattern theory used in a previous paper. Nevertheless, this theory is improved here by taking account of normal and anomalous absorption and by introducing a new term which results from the interference of the two Bloch waves. This term explains the disappearance of the Kikuchi bands when their indexes are increased and gives a better agreement with temperature dependence experiments. On etudie les diagrammes de Kikuchi obtenus a partir de la face (001) de MgO avec des electrons ayant une energie de 1500 eV. En particulier on a mesure, a l'aide d'un cylindre de Faraday mobile, l'influence de la variation de l'angle d'incidence et de la temperature sur l'intensite des diagrammes. Par ailleurs l'importance des effects lies a la diffraction du faisceau incident a ete determinee separement en mesurant l'ensemble des electrons retrodiffuses par phonon a l'aide de l'ecran fluorescent utilise comme collecteur. Les resultats experimentaux sont interpretes avec la theorie deja utilisee dans une precedente publication. Cependant cette theorie est completee ici en tenant compte de l'absorption normale et anormale et en introduisant un nouveau terme qui resulte de l'interference des deux ondes de Bloch. Ce nouveau terme explique la disparition des bandes de Kikuchi d'indices eleves et donne une variation de l'intensite en fonction de la temperature en meilleur accord avec les resultates experimentaux.

SUMMARY A description of a TEM method for accurately determining the misorientation across grain boundaries, and identification of the grain boundary plane is given. The method is equally applicable to thin or thick foils and possesses the accuracy of Kikuchi line analysis. A computer program is available to process the TEM data to yield directly the grain boundary misorientation parameters. Examples of the application of the method to grain boundary structure determination in a nickel base superalloy, Nimonic 80A, are quoted.

Investigation results of Pb1–xSnxTe crystal surfaces demonstrate the possibility to apply quantitative Auger electron spectroscopy in connection with Kikuchi pattern observation for the simultaneous analysis of the heterogeneity of surface crystalline structure and chemical composition of the sample investigated. The chemical composition of these samples after temperature treatment differs significantly from the composition given by the producer. This difference is probably due to Pb segregation to the sample surfaces. Untersuchungsergebnisse von Pb1–xSnxTe-Kristalloberflachen werden dargestellt, die bei der Analyse der Inhomogenitat der kristallinen Struktur und chemischer Zusammensetzung der Kristalloberflache auf die Moglichkeit der Ausnutzung von quantitativer Auger-Elektronen-spektroskopie in Verbindung mit Beobachtungen von Kikuchi-Linien hinweisen. Die chemische Zusammensetzung der untersuchten Proben, die der Einwirkung von Temperatur und Reinigungsfaktoren ausgesetzt werden, unterscheidet sich signifikant von derjenigen, die vom Produzenten angegeben wurde. Dieser Unterschied durfte eine Folge einer Segregation von Blei auf der Oberflache der Proben sein.

Die Zuchtung einkristalliner GaN-Schichten auf {0001}-orientierten Korundsubstraten wird im System GaCl/NH3/Ar uber den Temperaturbereich von 500 bis 1100°C untersucht. Eine hohe Kristallperfektion wird bei Zuchtungstemperaturen im Bereich 1000 bis 1050°C erreicht. Die RHEED-Diagramme solcher Proben zeigen KIKUCHI-Linien. Die hohe Elektronenkonzentration von etwa 1020 cm−3 fallt unterhalb 700°C Zuchtungstemperatur rasch mit fallender Temperatur ab. Gleichzeitig wird die Kristallperfektion infolge zunehmender Kristallitverkippung schlechter. Beugungsringe, die auf polykristalline Beschaffenheit hindeuten, treten jedoch nicht auf. Die bei 500°C gezuchteten Proben sind mit Chlorid verunreinigt. Manchmal findet ein dendritisches uberwachsen der Schicht durch GaN in der Sphaleritmodifikation statt. The vapour growth of single crystalline layers of GaN on {0001} oriented sapphire substrates in the temperature range of 500–1100°C is described for the system GaCl/NH3/Ar. The RHEED micrographes of samples grown in the high temperature range of 1000–1050°C show KIKUCHI pattern, thus indicating a good crystalline perfection of the layers. The large free electron concentration of about 1020 cm−3 decreases below 700°C rapidly with decreasing growth temperature. Simultaneously the crystalline perfection is remarcably lowered due to increasing misorientation of the subgrains, but no arcing of the RHEED spots due to polycrystalline behaviour is observed. The layers grown at 500°C are contaminated by chloride. Sometimes a dendritic overgrowth of the layers by the GaN sphalerite polytype takes place.

Electron diffraction patterns from foils containing planar defects, e.g., precipitates or stacking faults, are considered in terms of relrods normal to the plane of the defect, and/or normal to the specimen surface. The patterns can be regarded as consisting of streaked reciprocal lattices superimposed on the matrix lattice. In the materials examined, faulting did not reproduce any detectable physical shift of allowed reflections. The observations indicate that faulting is regular rather than random. Stacking faults and HCP precipitates in FCC crystals can not as a rule be distinguished in the early stages of formation of the precipitate. A complete analysis of the spot pattern from foils containing planar defects generally requires an accurate determination of the crystal orientation. For this purpose Kikuchi patterns provide sufficient accuracy and an assessment of this is made. (Author)

SUMMARY The techniques whereby an electron microscope may be used to observe the low angle electron diffraction pattern from crystallized macromolecules are described. A discussion is then presented of the advantages and disadvantages of the technique relative to X-ray diffraction, high resolution electron microscopy and optical diffraction or computer analysis of electron micrographs.

A method for determining the exact crystal or grain orientations from a diffraction pattern of a recognizable reciprocal lattice plane is presented. Due to spikes in the reciprocal lattice arising either from the thinness of the foil and/or from stacking faults, diffraction is often possible over an appreciable angular range. Consequently, the angles between selected directions in a diffraction photograph depend on the angle of tilt, and will have the expected value only when the recognizable reciprocal lattice plane is tangential to the reflecting sphere. The deviation from the expected angles permits a determination of the angle of tilt and the correct orientation. Examples illustrating the method and accuracy are given. The results determined by this method are compared with orientations determined from analysis of Kikuchi lines on the same diffraction patterns. Es wird eine Methode zur Bestimmung der genauen Kristall- oder Kornorientierung aus dem Beugungsbild einer erkennbaren reziproken Gitterebene angegeben. Infolge von Spitzen im reziproken Gitter, die entweder von der Foliendicke und/oder von Stapelfehlern herruhren, ist die Beugung oftmals uber einen betrachtlichen Winkelbereich moglich. Infolgedessen hangen die Achsen zwischen ausgewahlten Richtungen in einer Beugungsphotographie von dem Neigungswinkel ab und haben den erwarteten Wert nur dann, wenn die erkennbare reziproke Gitterebene tangential zur Reflexionskugel liegt. Abweichungen von den erwarteten Winkeln gestatten eine Bestimmung des Neigungswinkels und der richtigen Orientierung. Es werden Beispiele angegeben, die die Methode und die Genauigkeit illustrieren. Die Ergebnisse, die mit dieser Methode erhalten wurden, werden mit den Orientierungen verglichen, die aus der Analyse von Kikuchi-Linien auf demselben Beugungsbild erhalten wurden.

Making use of the non-local potential due to inelastic scattering, an expression for the transition probability of inelastic scattering in Channeling is introduced. The theory of back-scattering yield oscillation is studied as a demonstration. Expressions for the blocking pattern and the star pattern are also presented in terms of the transition probability in channeling. Mit dem durch inelastische Streuung hervorgerufenen nichtlokalen Potential wird ein Ausdruck fur die Ubergangswahrscheinlichkeit der inelastischen Streuung bei Channelling eingefuhrt. Als Beispiel wird die Theorie der Ruckstreuungsausbeuteoszillationen untersucht. Ausdrucke fur die „blocking”- und Stern-Diagramme werden mit Hilfe der Ubergangswahrscheinlichkeit des Channelling angegeben.

Electron microscopic evidence is obtained for the presence of a domain structure in anti-ferromagnetic cobalteous oxide. The domain boundaries tend to adopt [101] orientations; they are visible as fringe patterns when lying in planes inclined to the foil plane. When the domain boundary is observed edge-on, adjacent domains differ in brightness. Combining earlier neutron diffraction data with the present observations it is concluded that the spin direction, which is roughly parallel to the tetragonal c-axis, has to turn through 90° across a domain wall. The proposed models for the domain walls are verified by means of contrast theory and their geometry checked by the use of Kikuchi lines. The contrast effects observed for some particular configurations of domain walls are compared with numerical calculations based on the dynamic theory of electron diffraction, taking into account anomalous absorption. Elektronenmikroskopisch wurde eine Domanenstruktur in antiferromagnetischem Kobaltoxyd festgestellt. Die Domanengrenzen erstrecken sich etwa in [101]-Richtungen. Sie sind als Streifenbilder sichtbar, wenn sie in Ebenen liegen, die zur Folienebene geneigt sind. Wenn die Domanengrenze von oben beobachtet wird, unterscheiden sich angrenzende Domanen in der Helligkeit. Durch Kombination von fruheren Ergebnissen aus Neutronenbeugungsmessungen mit den vorliegenden Untersuchungen wird geschlossen, das sich die Spinrichtung, die annahernd parallel zur tetragonalen c-Achse ist, an einer Domanengrenze um 90° drehen mus. Die vorgeschlagenen Modelle fur die Domanengrenzen werden mit Hilfe der Kontrasttheorie verifiziert und ihre Geometrie mit Hilfe von Kikuchi-Linien uberpruft. Die beobachteten Kontrasteffekte an einigen besonderen Konfigurationen von Domanenwanden werden mit numerischen Berechnungen verglichen, die auf der dynamischen Theorie der Elektronenbeugung unter Berucksichtigung der anormalen Absorption beruhen.

It is shown that an edge dislocation parallel to the surface of a thin foil causes buckling of this foil by an angle of about θ = b/t. (b = Burgers vector; t = thickness of the foil). The angle θ depends on the position of the dislocation. It is maximum for a dislocation in the middle of the foil and it tends to zero as the dislocation approaches to the surface. It is shown that the buckling is responsible for the discontinuous change in contrast along a dislocation as observed in transmission electron microscopy. The sense of buckling which can be determined by means of Kikuchi lines depends on the sign of the dislocation. The effect therefore provides an easy means to determine the sign of edge dislocations. Es wird gezeigt, das eine parallel zur Oberflache einer dunnen Schicht liegende Stufenversetzung zu einer Verbiegung der Schicht um einen Winkel θ = b/t Veranlassung gibt (b = Burgersvektor, t = Dicke der Schicht). Der Winkel θ ist maximal fur eine Versetzung in der Mitte der Schicht und strebt gegen Null, wenn sich die Versetzung der Oberflache nahert. Es wird gezeigt, das die Verbiegung fur die unstetige Kontrastanderung verantwortlich ist, die bei elektronenmikroskopischer Untersuchung entlang einer Versetzung auftritt. Die Richtung der Verschiebung, die sich mit Hilfe von Kikuchi-Linien bestimmen last, hangt vom Vorzeichen der Versetzung ab. Dieser Effekt kann ausgenutzt werden, um in einfacher Weise das Vorzeichen von Stufenversetzungen zu bestimmen.