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Two advanced, automated crystal orientation mapping techniques suited for nanocrystalline materials—precession electron diffraction (PED) in transmission electron microscopy (TEM) and on-axis transmission Kikuchi diffraction (TKD) in scanning electron microscopy (SEM)—are evaluated by comparing the orientation maps obtained from the identical location on a 30 nm-thick nanocrystalline tungsten (W) thin film. A side-by-side comparison of the orientation maps directly showed that the large-scale orientation features are almost identical. However, there are differences in the fine details, which arise from the fundamentally different nature of the spot pattern and Kikuchi line pattern in terms of the excitation volume and the angular resolution. While TEM-PED is more reliable to characterize grains oriented along low-index zone axes, the high angular resolution of SEM-TKD allows the detection of small misorientation between grains and thus yields better quantification and statistical analysis of grain orientation. Given that both TEM-PED and SEM-TKD orientation mapping techniques are complementary tools for nanocrystalline materials, one can be favorably selected depending on the requirements of the analysis, as they have competitive performance in terms of angular resolution and texture quantification.

We discuss a refined simulation approach which treats Kikuchi diffraction patterns in electron backscatter diffraction (EBSD) and transmission Kikuchi diffraction (TKD). The model considers the result of two combined mechanisms: (a) the dynamical diffraction of electrons emitted coherently from point sources in a crystal and (b) diffraction effects on incoherent diffuse intensity distributions. Using suitable parameter settings, the refined simulation model allows to reproduce various thickness- and energy-dependent features which are observed in experimental Kikuchi diffraction patterns. Excess-deficiency features are treated by the effect of gradients in the incoherent background intensity. Based on the analytical two-beam approximation to dynamical electron diffraction, a phenomenological model of excess-deficiency features is derived, which can be used for pattern matching applications. The model allows to approximate the effect of the incident beam geometry as a correction signal for template patterns which can be reprojected from pre-calculated reference data. As an application, we find that the accuracy of fitted projection centre coordinates in EBSD and TKD can be affected by changes in the order of 10-3 - 10-2 if excess-deficiency features are not considered in the theoretical model underlying a best-fit pattern matching approach. Correspondingly, the absolute accuracy of simulation-based EBSD strain determination can suffer from biases of a similar order of magnitude if excess-deficiency effects are neglected in the simulation model.

In this study, electron diffraction patterns observed under high vacuum conditions for an SrTiO3 surface were interpreted in detail while paying special attention to the features of inelastic effects. The surface of the SrTiO2 was carefully prepared to enforce its termination with single domains of TiO2 layers at the top. The inelastic patterns were interpreted using analytical models. Two types of Kikuchi lines are recognized in this paper: those which can be described with the Bragg law and those which appear due to surface wave resonance effects. However, we also discuss that there exists a formal connection between the two types of the Kikuchi lines observed.

The necessary parameters (rotation axis, incident electron beam direction and beam tilt path) in order to describe the diffraction geometry in the Rotation Electron Diffraction (RED) method during data collection are determined and refined. These parameters are prerequisites for the subsequent calculations of excitation errors, sg, for zero (ZOLZ) or higher order Laue zones (HOLZ) reflections. Comparison with simulated results, for a CoP3 thermoelectric crystal, shows excellent agreement between the two approaches -calculated and simulated. In addition to their determination, a thorough refinement methodology for the incident electron beam direction and beam tilt path has been applied, too, based on Kikuchi lines of HOLZ reflections. Incorporation of the refined excitation error values can be considered both in theoretical calculations for diffracted beam intensities, based on the Bloch wave method, as well as in deducing integrated intensities from experimental rocking curves. The methodology described in this study is quite indispensable, as it forms an essential step for performing dynamical calculations in RED, enabling thus enhanced accuracy in structural parameter clarification. The latter is especially important in the case of thermal factors refinement for e.g. thermoelectrics, which are imperative for material properties’ evaluation.

Enantiomorph-distribution maps for chiral element and multicomponent structures by Electron Backscatter Diffraction., The assignment of enantiomorphs by diffraction methods shows fundamental differences for x-rays and electrons. This is particularly evident for the chiral allotrope of β-Mn. While it is not possible to determine the sense of chirality of β-Mn with established x-ray diffraction methods, Kikuchi pattern simulation of the enantiomorphs reveals differences, if dynamical electron diffraction is considered. Quantitative comparison between experimental and simulated Kikuchi patterns allows the spatially resolved assignment of the enantiomorph in polycrystalline materials of β-Mn, as well as the structurally strongly related phase Pt2Cu3B. On the basis of enantiomorph distribution maps, crystals were extracted from enantiopure domains by micropreparation techniques. The x-ray diffraction analyses confirm the assignment of the Kikuchi pattern evaluations for Pt2Cu3B and do not allow to distinguish between the enantiomorphs of β-Mn.

Automated orientation mapping in SEM, until now relying on EBSD solely, is currently being improved with the development of the TKD technique. As part of the development of TKD, we introduce a new, TEM-like geometric configuration, with a detector "on-axis" relative to the electron beam, while the detector was "off-axis" in its first form. This new technique produces a wide range of diffraction contrast (spots, lines, bands), varying with sample thickness, incident energy, atomic number and scattering angle. Some of the main trends are identified and discussed. In particular, a model based on the plasmon and phonon scattering is proposed to account for the disappearing of diffraction spots with thickness and incident energy. This work should help experimentalists determine which microscope and sample parameters to use in order to obtain a specific contrast. Finally, the strength and weakness of each diffraction feature for orientation mapping are also reviewed.

Convergent-beam electron diffraction (CBED) is one of the most popular techniques to measure crystal thickness. The traditional measurement involves linear fitting of several fringes across the CBED disc, but for a thin crystal with fewer than three fringes the usefulness of this method will be limited. CBED Tools, a free plugin for the DigitalMicrograph software, provides a fast (∼1–2 min) and accurate algorithm to measure the crystal thickness on the basis of the linear fitting method, but it is also capable of determining the crystal thickness when it is very thin and only one fringe or part of the first fringe is recorded. CBED Tools can also be utilized to handle the severely distorted CBED pattern obtained when the zero-order Laue zone Kikuchi lines overlap with the fringes.

A model of crystal is suggested, in which atoms are bonded by the Spinning Magnetic Force (����) created by the Nucleus Spinning Magnetic Field (NSMF); thus the passing of x-rays through the crystal lattice, having smaller width compared to x-ray wavelength, polarized the x-rays, which is part of Electromagnetic Radiation (EM-R) spectrum, by removing it's electric field component and transformed the residual magnetic part into Polarized Wave (PW), or what is known as Conical Diffraction (CD) beam; hence the emergence of PW from crystal is synonymous to the passing of Circular Magnetic Field (CMF) surrounded an electron through such crystal; hence both PW and CMF interacts with the NSMF producing the Glowing Spot-PW (GS- PW) for x-ray diffraction and Glowing Spot-CMF (GS-CMF) for an electron diffraction, appeared on the monitor screen as dots/rings or reflected as dots patterns; the Kikuchi lines are interpreted as resulted from the interaction of the CMF with the Nucleus Spinning Magnetic Lines of Force (NSMLF), producing the G-NSMLF; thus the interpretation of diffraction as an interaction between wave and matter, is extended to an interaction among intense magnetic fields, and this is the conclusion of this final paper, aimed among others at restoring the common sense in the physical world, removed by pilot wave.

We demonstrate an approach to overcome Kikuchi pattern misindexing problems caused by crystallographic pseudosymmetry in electron backscatter diffraction (EBSD) measurements. Based on the quantitative comparison of experimentally measured Kikuchi patterns with dynamical electron diffraction simulations, the algorithm identifies the best-fit orientation from a set of pseudosymmetric candidates. Using measurements on framboidal pyrite (FeS2) as an example, we also show the improvement of the orientation precision using this approach.

Electron backscatter diffraction (EBSD) is a technique to obtain microcrystallographic information from materials by collecting large-angle Kikuchi patterns in the scanning electron microscope (SEM). An important fundamental question concerns the scattering-angle dependent electron energy distribution, which is relevant for the formation of the Kikuchi diffraction patterns. Here we review the existing experimental data and explore the effective energy spectrum that is operative in the generation of backscatter Kikuchi patterns from silicon. We use a full pattern comparison of experimental data with dynamical electron diffraction simulations. Our energy-dependent cross-correlation based pattern matching approach establishes improved constraints on the effective Kikuchi pattern energy spectrum, which is relevant for high-resolution EBSD pattern simulations and their applications.

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 demonstrate the determination of crystal chirality using electron backscatter diffraction (EBSD) in the scanning electron microscope. The chirality of α-quartz as a space-group-dependent property is verified via direct comparison of experimental diffraction features to simulations using the dynamical theory of electron diffraction.

Creating oxide interfaces with precise chemical specificity at the atomic layer level is desired for the engineering of quantum phases and electronic applications, but highly challenging, owing partially to the lack of in situ tools to monitor the chemical composition and completeness of the surface layer during growth. Here we report the in situ observation of atomic layer-by-layer inner potential variations by analysing the Kikuchi lines during epitaxial growth of strontium titanate, providing a powerful real-time technique to monitor and control the chemical composition during growth. A model combining the effects of mean inner potential and step edge density (roughness) reveals the underlying mechanism of the complex and previously not well-understood reflection high-energy electron diffraction oscillations observed in the shuttered growth of oxide films. General rules are proposed to guide the synthesis of atomically and chemically sharp oxide interfaces, opening up vast opportunities for the exploration of intriguing quantum phenomena at oxide interfaces., Precisely controlled growth of oxide interfaces at the atomic layer level is critical for device applications but quite challenging. Here Sun et al. show real time monitoring and control of the surface composition of epitaxial strontium titanate perovskite films by analysing the Kikuchi lines.

Electron backscatter diffraction (EBSD) is a well-established scanning electron microscope (SEM)-based technique [1]. It allows the non-destructive mapping of the crystal structure, texture, crystal phase and strain with a spatial resolution of tens of nanometers. Conventionally this is performed by placing an electron sensitive screen, typically consisting of a phosphor screen combined with a charge coupled device (CCD) camera, in front of a specimen, usually tilted 70◦ to the normal of the exciting electron beam. Recently, a number of authors have shown that a significant increase in spatial resolution is achievable when Kikuchi diffraction patterns are acquired in transmission geometry; that is when diffraction patterns are generated by electrons transmitted through an electron-transparent, usually thinned, specimen. The resolution of this technique, called transmission Kikuchi diffraction (TKD), has been demonstrated to be better than 10 nm [2, 3]. We have recently demonstrated the advantages of a direct electron detector, Timepix [4, 5], for the acquisition of standard EBSD patterns [5]. In this article we will discuss the advantages of Timepix to perform TKD and for acquiring spot diffraction patterns and more generally for acquiring scanning transmission electron microscopy micrographs in the SEM. Particularly relevant for TKD, is its very compact size, which allows much more flexibility in the positioning of the detector in the SEM chamber. We will furthermore show recent results using Timepix as a virtual forward scatter detector, and will illustrate the information derivable on producing images through processing of data acquired from different areas of the detector. We will show results from samples ranging from gold nanoparticles to nitride semiconductor nanorods.

The histogram method has been proposed to determine strains in diamond crystals by the analysis of reflection electron diffraction bands in Kikuchi patterns. The anisotropy has been defined of the local strain distribution on the surface of two diamond samples produced by the temperature gradient method in the Fe-Al-C system and by growing on a surface of a statically synthesized diamond single crystal (Ni-Mn-C) in the Mg-C + Bor system.

A new automated crystallographic orientation mapping tool in a transmission electron microscope technique, which is based on pattern matching between every acquired electron diffraction pattern and precalculated templates, has been used for the microstructural characterization of nondeformed and deformed aluminum thin films and twinning-induced plasticity steels. The increased spatial resolution and the use of electron diffraction patterns rather than Kikuchi lines make this tool very appropriate to characterize fine grained and deformed microstructures.

In this chapter, we outline the dynamical theory of high-energy transmission electron diffraction. There have been three major, and related, approaches to the subject; each was developed for specific applications.

The application of convergent beam electron diffraction (CBED) to determine symmetry, refine structure factors, and measure specimen thickness requires rather thick specimen and is very difficult or even impossible in the case of large unit cell materials. The large-angle rocking-beam electron diffraction (LARBED) technique introduced in this paper gives access to the kind of experimental data contained in CBED patterns but over a much larger angular range. In addition to symmetry determination and thickness measurement even for thin samples this technique also allows, in principle, very accurate measurements of structure factors. Similar to precession electron diffraction (PED), LARBED uses the illumination tilt coils to sequentially change the angle of incidence of the electron beam over a very large range. I will present results obtained by a recently developed self-calibrating acquisition software which compensates for aberration-induced probe shifts during the acquisition of LARBED patterns and keeps the probe within a few nm, while covering a tilt range from 0 to 100 mrad. This paper is dedicated to Prof. John C. H. Spence on the occasion of his 65th birthday.

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)

A high-quality inclusion-free ZnWO4 crystal 90 mm in diameter and with a mass of up to 8 kg was grown by the low thermal gradient Czochralski technique. Crystallographic properties of ZnWO4(010) cleaved surfaces were evaluated with reflection high energy electron diffraction (RHEED), and the electronic structure of the surface was studied using X-ray photoelectron spectroscopy (XPS). A system of Kikuchi lines was observed for cleaved ZnWO4(010) by RHEED confirming the high crystallographic state of the surface. The XPS valence-band and core-level spectra of ZnWO4(010) have been measured. The XPS measurements reveal that tungsten and zinc atoms are in the formal valences +6 and +2, respectively, on cleaved ZnWO4(010) surface. The 3.0 keV Ar+ bombardment of the surface causes partial transformation of tungsten ions from W6+ to lower valence states; however, no partial loss of oxygen atoms belonging to ZnO6 octahedra occurs due to this bombardment of the ZnWO4(010) surface because after this treatment zinc r...

Precession electron diffraction (PED) is a new promising technique for electron diffraction pattern collection under quasi-kinematical conditions (as in X-ray Diffraction), which enables “ab-initio” solving of crystalline structures of nanocrystals. The PED technique may be used in TEM instruments of voltages 100 to 400 kV and is an effective upgrade of the TEM instrument to a true electron diffractometer. The PED technique, when combined with fast electron diffraction acquisition and pattern matching software techniques, may also be used for the high magnification ultra-fast mapping of variable crystal orientations and phases, similarly to what is achieved with the Electron Backscattered Diffraction (EBSD) technique in Scanning Electron Microscopes (SEM) at lower magnifications and longer acquisition times.

We analyze the contrast reversal of Kikuchi bands that can be seen in electron backscatter diffraction (EBSD) patterns under specific experimental conditions. The observed effect can be reproduced using dynamical electron diffraction calculations. Two crucial contributions are identified to be at work: First, the incident beam creates a depth distribution of incoherently backscattered electrons which depends on the incidence angle of the beam. Second, the localized inelastic scattering in the outgoing path leads to pronounced anomalous absorption effects for electrons at grazing emission angles, as these electrons have to go through the largest amount of material. We use simple model depth distributions to account for the incident beam effect, and we assume an exit angle dependent effective crystal thickness in the dynamical electron diffraction calculations. Very good agreement is obtained with experimental observations for silicon at 20keV primary beam energy.

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

Diffraction patterns of backscattered electrons can provide important crystallographic information with high spatial resolution. Recently, the dynamical theory of electron diffraction was applied to reproduce in great detail backscattering patterns observed in the scanning electron microscope (SEM). However, a fully quantitative comparison of theory and experiment requires angle-resolved measurements of the intensity and the energy of the backscattered electrons, which is difficult to realize in an SEM. This paper determines diffraction patterns of backscattered electrons using an electrostatic analyzer, operating at energies up to 40 keV with sub-eV energy resolution. Measurements are done for different measurement geometries and incoming energies. Generally a good agreement is found between theory and experiment. This spectrometer also allows us to test the influence of the energy loss of the detected electron on the backscattered electron diffraction pattern. It is found that the amplitude of the intensity variation decreases only slowly with increasing energy loss from 0 to 60 eV.

Commercial purity Al was severely deformed by equal channel angular pressing (ECAP) up to eight passes using route BC. The deformation microstructure was characterized quantitatively by electron-backscattered diffraction (EBSD) and transmission electron microscopy (TEM). The microstructural homogeneity was investigated by EBSD at various locations from center to surface of the samples on a longitudinal section parallel to the pressing direction. Structural parameters including mean boundary spacing, boundary misorientation angle and fraction of high angle grain boundaries were measured and characterized through the section of the ECAP samples. EBSD scans revealed a homogeneous ultrafine grained microstructure after 8 passes. The analysis showed that the fraction of high angle grain boundaries was more than 70% at most locations of the sample section. Also, an average boundary spacing of 380 nm was obtained by the linear intercept method. TEM analysis was used for more detailed characterization of the microstructure, such as low angle boundaries with misorientation angles smaller than 2°. Using the structural parameters–flow stress relationship, the flow stress was estimated based on the EBSD and TEM/Kikuchi-line analyses and compared with measured values.

In this work, the authors describe procedures to prepare the surface of close-spaced sublimation CdTe thin films necessary for producing good electron backscatter diffraction (EBSD) data. They found that polishing resulted in an amorphous layer on the surface and no Kikuchi pattern; however, ion-beam milling produced a relatively flat and good-quality surface, resulting in high-quality patterns and, consequently, excellent EBSD data. The authors used a combination of polishing and ion-beam milling or etching to study the crystalline structure of the CdTe film at different depths. They also used EBSD, in conjunction with other analytical techniques, to investigate the effects of the CdCl2 treatment, performed at different temperatures and times, on the recrystallization process of physical vapor deposition CdTe thin films. The authors found that the untreated films were ⟨111⟩ oriented, with grain sizes smaller than 1μm. The CdCl2 at 350 °C produced partially recrystallized films, whereas treatments at 400 ...

The iron-containing intermetallic compounds in type 319 aluminium casting alloys were investigated using convergent beam electron diffraction (CBED) and electron backscatter diffraction (EBSD). The Chinese script α-phase was identified as having the cubic Im space group consistent with the Al19Fe4MnSi2 phase reported in the literature. However, the atomic ordering of this phase results in complex Kikuchi lines in the CBED and EBSD patterns, which makes phase and orientation identification difficult. In fact, it is shown that the EBSD patterns in the scanning electron microscope and Kikuchi patterns in the transmission electron microscope from this phase are closely related to the structurally similar m icosahedral quasicrystals that form in numerous aluminium–transition metal alloys by both conventional and rapid solidification. The other iron-containing phase in these alloys was determined to be plate shaped and to have the orthorhombic Cmcm space group consistent with the β-Al5FeSi phase, which has some...

The authors have conducted a systematic investigation of the phase shift of the reflection high energy electron diffraction (RHEED) intensity oscillations during homoepitaxy of Ge(001) by molecular beam epitaxy for a wide range of diffraction conditions. Their results show that for small incidence angles with a beam azimuth several degrees away from the ⟨110⟩ crystallographic symmetry direction, the phase is independent of incidence angle; however, it starts to shift once the incidence angle is high enough that the (004) Kikuchi line appears in the RHEED pattern. Moreover, under some conditions they observe the oscillations from only the Kikuchi feature and not from the specular spot, and the oscillatory behavior of the Kikuchi feature is almost out of phase with that of the specular spot. They conclude that the phase shift is caused by the overlap of the specular spot and the Kikuchi features, in contrast to models involving dynamical scattering theory for the phase shift. They discuss necessary conditio...

Backscatter Kikuchi Diffraction (BKD) from crystalline solids has been known since 1928. But only during the last decade, when sufficiently sensitive cameras, fast PCs and high-performance SEMs have been available, has this technique been developed into an invaluable tool for materials' science and geology. BKD is also known as “Backscatter Electron Diffraction” (EBSD) if referred to the commercial trademarked systems OXFORD/HKL “Channel” or EDAX-TSL “OIM”. Crystal Orientation Measurement/ Mapping (COM), without user intervention, is performed in an SEM by digitally scanning the beam spot across the specimen, acquiring and transferring one Backscatter Kikuchi Pattern (BKP) after another into the computer, indexing it, and calculating the crystal orientation of the grain under the beam spot. The sample is typically tilted by 70° towards a phosphor screen for pattern collection. Spatial resolution is in the range of

The structure of (1 1 0) plane of Cr-doped CdTe single crystals has been studied by reflection high energy electron diffraction and scanning electron microscopy. Diffraction patterns consist of diffraction spots and Kikuchi lines. However, for very small incident angle, the Debye rings are observed. The constant lattice attributed to these rings is 0.8% less then for pure CdTe. These anomalous properties of the near surface layer are likely to occur due to the concentration of Cr atoms creating compressive surface strains or the effect of crystal cleavage.

This paper shows that Kikuchi pattern analysis in a transmission electron microscope (TEM) using recent techniques is superior to conventional electron diffraction analysis for determining crystal orientation in an assemblage of small crystals such as those of biogenic origin. A CCD camera with a wide view and large dynamic range was used together with a dedicated program to analyze the patterns and enable real-time and unique determination of crystal orientation. Convergent illumination of the incident beam was effective in enhancing the Kikuchi patterns and in improving spatial resolution. Two example biominerals are characterized by Kikuchi pattern analysis; one is spinel-law twins in several tens of nanometers width magnetite crystals from magnetotactic bacteria. The other is crystal orientation and the alignment of calcite fragments in coccolith.

A new reflection high-energy electron diffraction (RHEED) apparatus equipped with a hemispherical fluorescent screen upon a sample surface has been constructed. We call it astrodome screen, namely, the apparatus is named as astrodome RHEED. For the observation of Kikuchi pattern in RHEED experiment, the astrodome screen is effective because of the relatively short escape depth of Kikuchi electrons arising in bulk. Diffraction patterns have been observed in the astrodome screen for Si(111)7 × 7 clean surface, and the glancing angle and the acceleration voltage dependences were investigated. It has been found that some circular patterns exist in the Kikuchi patterns. The circular patterns are considered to be responsible for one-dimensional diffractions from certain atomic rows in bulk. The observed Kikuchi patterns and circular patterns are calculated using simple kinematical theory and a good agreement between the experimental and calculated results has been obtained. [DOI: 10.1380/ejssnt.2006.118]

Variant selection of intergranular bcc-Cr precipitates in a Ni–43 mass% Cr alloy was studied by electron backscattering diffraction (EBSD) in a scanning electron microscope equipped with a field emission gun (FESEM) and Kikuchi line analysis in transmission electron microscope (TEM). A single variant was invariably selected at the underlying grain boundaries (GB) when GB-precipitates were KS-related with respect to both the adjacent matrix grains. Meanwhile multiple variants were formed at the GB when GB-precipitates were KS-related to one of the adjacent matrix grains. Theses variant selections were examined with the tilt angle to underlying GB of low-energy interphase boundaries and the orientation relationship with respect to both the adjacent matrix grains. The underlying mechanism was discussed from the viewpoint of activation energy for nucleation of two-dimensional nuclei.

Holographic analysis is a method for directly inverting electron-diffraction data to produce a real-space image of the surface structure. A refinement called the small-cone variable axis method attempts to minimize artifacts and distortions in the image by limiting the data contributing to the inversion to ensure that the atomic scattering factors for the atoms being imaged are relatively uniform. Kikuchi electron-diffraction data from the Si(111)(3×3)R30°−Al surface structure were holographically analyzed with and without the small-cone variable axis method. Although the refinement produced a slight reduction in the background noise and improved the shapes of some atomic images, it had the adverse effect of reducing the intensities of the images of many atoms, with some of the weaker images disappearing entirely. When holographically analyzing Kikuchi electron-diffraction data, the small-cone variable axis method should be used with caution and the resulting images should be compared with images produced...

The texture and phase distribution of melt-textured YBa 2 Cu 3 O x (YBCO) was studied by means of automated electron backscatter diffraction (EBSD) analysis as a function of the position in the bulk pellet of 4 cm diameter. A total of five samples was cut from the pellet; four samples from the surface of the bulk with different distances to the seed crystal, and one cut in vertical direction in the middle of the pellet. The melt-textured YBCO samples require a two-phase analysis to be performed, so a high surface quality is necessary to enable an automated EBSD scan. Good quality Kikuchi patterns are obtained from both the 1 2 3 and 2 1 1 phases. We found an inhomogeneous distribution of the 2 1 1 particles. Whereas the samples cut from the surface contain a large amount of 2 1 1 particles, in the samples of the vertical direction only traces of 2 1 1 particles are found. Furthermore, we measured the misorientation angle distribution of all samples. The data are presented in form of phase mappings, misorientation distribution functions and pole figures.

Precursor films are deposited on SrTiO 3 single crystals at room temperature by the co-evaporation technique using Y, BaF 2 and Cu as evaporation sources. Then, the precursor films are annealed in a low-pressure oxygen atmosphere without introduction of water vapor. A sample with a reflection high-energy electron diffraction (RHEED) pattern exhibiting some streaks, Kikuchi lines and Kikuchi zone, which resembles that of a single crystal, is successfully prepared. According to the cross-sectional TEM observation results, epitaxial growth of this YBCO film is achieved for the entire film thickness. The transport properties are measured using a small bridge with a width of 0.1 mm and a length of 1 mm by a standard four-probe method. The obtained YBCO film has a high J c of over 1 MA/cm 2 at 77 K and a self-field. Furthermore, we discuss the relationship between the epitaxial YBCO layer thickness and the annealing conditions. Approximately 300- and 400-nm-thick epitaxial YBCO films are successfully prepared.

W delta doping in Si epitaxial growth by WF 6 and SiH 4 reaction has been investigated using an ultraclean cold-wall low-pressure chemical vapor deposition (CVD) system. Atomic-layer order W deposition is performed on wet-cleaned Si(1 0 0) substrate at 100°C using WF 5 and SiH 4 . Si epitaxial growth is achieved by SiH 4 reaction at 480°C on 4 × 10 13 cm -2 W deposited Si( 1 0 0), however, it is found that almost all the deposited W atoms segregate on the deposited Si film. It is also found that such segregation is suppressed by the atomic-order W diffusion into Si(1 0 0) substrate by the heat treatment at 520 C before the Si deposition. In the case of the Si film deposited on the 1.3 x 10 14 cm 2 W diffused Si, the reflection high-energy electron diffraction (RHEED) pattern indicates the crystallinity and the roughness degrade. In the case of the Si film deposited on the 5 x 10 13 cm -2 W diffused Si, the RHEED pattern shows streaks with Kikuchi lines. As a result, the W delta doping in the Si epitaxial growth is achieved, in which the W concentration is as high as 6 x 10 20 cm -3 and the incorporated W atoms is confined within 2 nm-thick region.

Orientation relationships between Mg24Y5 precipitates and matrix in a Mg-Y alloy were accurately determined using Kikuchi line diffraction. The Burgers relationship with habit planes of {10 (1) over bar0}(H) and {31 (4) over bar0}(H) were observed for all precipitates. Compared with the Mg17Al12 precipitate in AZ91, the precipitation hardening effect in this alloy was significantly increased. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

We have successfully obtained electron backscatter diffraction (EBSD) Kikuchi patterns on various bulk high-Tc superconductors (polycrystalline KClO3-doped and undoped YBa2Cu3O7−δ (YBCO), single crystalline YBCO and NdBa2Cu3O7−y) and on YBCO and NdBCO thin films. We have established a sample polishing procedure to obtain intense Kikuchi patterns without an additional carbon coating of the ceramic superconductors. We present Kikuchi patterns, pole figures and orientation maps of the samples. On the polycrystalline KClO3-doped YBCO samples we find two major orientations (001) and (100) normal to the sample surface, while the undoped sample does not exhibit any orientation maxima, which is ascribed to the effect of a liquid phase due to the KClO3-additive during the preparation process. Furthermore, we discuss the future possibilities for the application of the EBSD technique for growing larger, bulk melt-textured samples for applications.

The technique of electron backscatter Kikuchi diffraction patterns (BKDPs) in the scanning electron microscope is reviewed. The paper focuses mainly on the crystallographic applications of the technique, including discussions on point group and space group determination and strain analysis. Orientation microscopy is discussed but not reviewed. The geometrical configurations of BKDPs are reviewed in detail and the relationship between BKDPs and the technique of electron channelling patterns (ECPs) is explored briefly. Essential crystallography is discussed and methods of analysis of BKDPs to extract crystallographic information are analyzed in detail. Some important characteristics of diffraction contrast in BKDPs are analyzed with respect to the geometry of the technique, the dynamical theory of electron diffraction and crystallographic applications. Examples of the use of theoretical contrast in pattern interpretation are provided. Anomalous effects in BKDPs are analyzed in detail and ways of identifying anomalous contrast in practice are discussed. BKDPs included in the paper are zincblende (ZnS), silicon, germanium, GaAs, chalcopyrite (CuFeS2, TaTe4 and Er2Ge2O7.

Transmission electron diffraction patterns of silicon with thermal diffuse maxima around Kikuchi lines, which are analogs of the maxima of thermal diffuse electron scattering around point reflections, have been recorded. Diffuse maxima are observed only around Kikuchi lines with indices that are forbidden for the silicon structure. The diffraction conditions for forming these maxima are discussed.

International audience; A new method called ALGrId (Anti-Leak GRain IDentification) is proposed for the detection of sub-grains beyond the relative angular resolution of Electron Backscatter Diffraction maps. It does not use any additional information such as Kikuchi Pattern Quality map nor need data filtering. It uses a modified Dijkstra algorithm which seeks the continuous set of boundaries having the highest average disorientation angle.

Electron tomography is a method whereby a three-dimensional reconstruction of a nanoscale object is obtained from a series of projected images measured in a transmission electron microscope. We developed an electron-diffraction method to measure the tilt and azimuth angles, with Kikuchi lines used to align a series of diffraction patterns obtained with each image of the tilt series. Since it is based on electron diffraction, the method is not affected by sample drift and is not sensitive to sample thickness, whereas tilt angle measurement and alignment using fiducial-marker methods are affected by both sample drift and thickness. The accuracy of the diffraction method benefits reconstructions with a large number of voxels, where both high spatial resolution and a large field of view are desired. The diffraction method allows both the tilt and azimuth angle to be measured, while fiducial marker methods typically treat the tilt and azimuth angle as an unknown parameter. The diffraction method can be also used to estimate the accuracy of the fiducial marker method, and the sample-stage accuracy. A nano-dot fiducial marker measurement differs from a diffraction measurement by no more than ±1°.

One of the main advantages of the transmission electron microscope is the easy possibility to switch between the imaging of tiny structures in a thin specimen and the diffraction pattern of the same structures. Hence, we want to explain why different kinds of electron diffraction patterns are produced and which changes of the lenses are needed to see these patterns on the screen. Finally, we want to discuss which results can be obtained from the diffraction patterns regarding the materials science. For this purpose some basic knowledge about crystal structures is necessary and is explained in this chapter.

We find that electron diffraction patterns can be directly inverted to provide three-dimensional atomic structures for the system studied. Depending on the scattering process, either holography or a Patterson inversion scheme is used. For diffraction patterns which were generated from a localized emitter source or predominantly by an inelastic-scattering feature like low-energy Kikuchi electrons, holography inversion is needed. The information obtained from Kikuchi electron holography includes the building blocks on the surface and their relative position to the atoms below the surface layer. On the other hand, for diffraction patterns generated predominantly by an elastic-scattering feature like low-energy electron diffraction (LEED), a Patterson inversion is needed. The information obtained from the Patterson transform of the LEED I(E) curves is the relative positions of surface atoms to the atoms in underlying layers; no intra-layer information can be extracted with this method. High-fidelity and artifact-free three-dimensional atomic structures obtained by inversion of low-energy Kikuchi electron patterns and low-energy electron diffraction curves are presented. The results from the two inversion methods are complementary and can be used to construct or to discriminate the surface atomic structural models. The future of these direct methods by inverting diffraction patterns is discussed.

We propose all the diffraction patterns can be directly transformed to provide three-dimensional atomic structures for the system studied. Depending on the scattering process, either the holography or Patterson transform scheme is used. For diffraction patterns which are generated from a localized emitter source or dominated by an inelastic-scattering feature like core-level photoelectron or low-energy Kikuchi electron, holography transform is needed. On the other hand, for diffraction patterns which were dominated by elastic-scattering, like grazing-incidence X-ray diffraction, electron correlated thermal diffuse scattering or low-energy electron diffraction curves, Patterson transform is needed. To prove our point, high-fidelity and artifact-free three-dimensional atomic structures obtained by transform of low-energy Kikuchi electron patterns and low-energy electron diffraction curves are presented. The future of these direct methods by transforming diffraction patterns will be discussed.

Two YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) on RABiTS/sup TM/ conductors with high J/sub c/ (0 T, 77 K) values of 2.3 and 2.4 MA/cm/sup 2/ were scribed by laser cutting to constrict supercurrent flow. On one of these tracks, magneto-optical (MO) imaging of the self-field produced by a transport current directly demonstrates the percolative nature of the current flow. Using backscattered electron Kikuchi pattern (BEKP) analysis, we have found that Ni grain boundaries (GBs)>5/spl deg/ generally introduce GBs in the YBCO that have lower J/sub c/ values than the intra-grain.