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The spatial resolution of the electron backscatter diffraction signal is explored by Monte Carlo simulation for the sigma phase in steel at a typical instrumental set-up. In order to estimate the active volume corresponding to the diffracted electrons, the fraction of the backscattered electrons contributing to the diffraction signal was inferred by extrapolating the Kikuchi pattern contrast measured by other authors, as a function of the diffracted electron energy. In the resulting estimation, the contribution of the intrinsic incident beam size and the software capability to deconvolve patterns were included. A strong influence of the beam size on the lateral resolution was observed, resulting in 20 nm for the aperture considered. For longitudinal and depth directions the resolutions obtained were 75 nm and 16 nm, respectively. The reliability of this last result is discussed in terms of the survey of the last large-angle deflection undergone by the backscattered electrons involved in the diffraction process. Bearing in mind the mean transversal resolution found, it was possible to detect small area grains of sigma phase by EBSD measurements, for a stabilized austenitic AISI 347 stainless steel under heat treatments, simulating post welding (40 h at 600 °C) and aging (284 h at 484 °C) effects—as usually occurring in nuclear reactor pressure vessels. Fil: Fernandez Bordin, Santiago Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina Fil: Limandri, Silvina Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina Fil: Ranalli, J. M.. Comisión Nacional de Energía Atómica; Argentina Fil: Castellano, Gustavo Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; Argentina

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.

A quantitative approach was proposed to determine the spatial resolution of transmission electron backscatter diffraction (t-EBSD) and to understand the limits of spatial resolution of t-EBSD. In this approach, Cu bicrystals and digital image correlation were employed. The effects of accelerating voltage and specimen thickness on the spatial resolution of t-EBSD were also investigated. t-EBSD specimens with 8 μm × 10 μm dimensions and different thicknesses were prepared using focused ion beam milling. The optimized quality of Kikuchi pattern was achieved at a working distance of 12 mm and a tilting angle of 20°. The optimum depth resolution of 34.4 nm was observed in the lower surface of a 100 nm thick sample at 25 kV. Thus, the penetration depth from the upper surface is 65.6 nm. The optimum lateral and longitudinal resolutions obtained from a 100 nm thick sample at 30 kV are 25.2 and 43.4 nm, respectively. The spatial resolution of t-EBSD can be enhanced by increasing the accelerating voltage and decreasing the sample thickness.

We present Kikuchi patterns of Si single crystals measured with an electrostatic analyser, where the kinetic energy of the diffracted electron is known with sub-eV precision. Two-dimensional patterns are acquired by rotating the crystal under computer control. This makes detailed comparison of calculated and measured distributions possible with precise knowledge of the energy of the scattered electrons. The case of Si is used to validate the method, and these experiments provide a detailed comparison of measured and calculated Kikuchi patterns. In this way, we can gain more insight on Kikuchi pattern formation in non-energy resolved measurements of conventional electron backscatter diffraction (EBSD) and electron channeling patterns (ECP). It was possible to identify the influence of channeling of the incoming beam on the measured Kikuchi pattern. The effect of energy loss on the Kikuchi pattern was established, and it is demonstrated that, under certain conditions, the channeling features have a different dependence on the energy loss compared to the Kikuchi lines.

A polycrystalline Cu of 99.995% purity has been deformed by dynamic plastic deformation at liquid nitrogen temperature to a strain of 2.1 (LNT-DPD Cu). Three distinct regions that are dominated by dislocation slip, shear banding and nanotwinning, form a multi-component nanostructure. The microstructure of each region has been quantified by transmission electron microscopy assisted by Kikuchi line analysis. Based on the structural parameters the stored energy of each region was evaluated, and the total energy can be assumed to be a linear additivity of that in each region weighted by the respective volume fraction. A microstructure based evaluation of the stored energy of multi-component nanostructure has been proposed.

Orientation microscopy of polycrystalline materials has developed, within a few years, into an invaluable tool of materials science and geology. It is based on backscatter electron diffraction in the Scanning Electron Microscope. Individual grain orientations are conveniently measured by analysing backscatter Kikuchi patterns, either interactively or fully automatically. A straightforward method of noise reduction is presented which significantly improves the quality of Kikuchi patterns for analysis. The image is not filtered in real image domain, but peaks in the Radon domain are accentuated by applying an intensity enhancement operator, so automated band detection is performed more reliably. A cleansed Kikuchi pattern can be constructed, for visual inspection, by an inverse Radon transform. Experimental results are presented.

A nanostructured layer can be introduced on the surface of metallic materials by surface severe plastic deformation. A surface severe plastic deformation method-Supersonic Particles Bombarding (SSPB) was used to treat the anealled 40Cr steel. The surface and cross sectional microstructure of 40Cr steel after SSPB treatment were characterized by means of X-ray diffraction, optical microscopy and transmission electron microscopy equipped with a Kikuchi line program to determine the grain orientations. Equiaxed nanocrystallites with random crystallographic orientation were obtained on the top surface of 40Cr steel after SSPB treatment. The surface microstructure was composed of nanostructure area, deformed area and matrix. Geometrically necessary boundaries and incidental dislocation boundaries were formed in the deformed ferrite at the distance to the surface of about 50-60μm, and the original coarse ferrite grain was divided into lamaller structure.

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...

The variation in Kikuchi line widths upon the illumination of a silicon plate is studied with the help of an electronograph. This work attempts to observe the changes in the defect structure of the subsurface layer of silicon crystal due to the effect of long-range action. The mechanism of this effect is discussed.

A simple technique is presented for characterizing parameters such as the misorientation angle and the axis of rotation between two adjacent grains using transmission electron microscopy (TEM), without the need for an image of the Kikuchi pattern. The technique described makes use of the orthogonal relationship between the tilt axes used in TEM and the axes of the cubic crystal. The relationship was established using the well known triangulation method, in which the direction of the crystal parallel to the beam direction is determined from the measured tilt angles of the three zone axes. The error in measuring the tilt angles of the three zone axes can be evaluated by comparing the measured and crystallographic angles. The angle of deviation from the coincident site lattice (CSL) that results from the measurement error could be reduced by establishing the modified orthogonal relationship between the tilt and crystal axes. The use of this method could provide accurate measurement in real time for indexing a CSL boundary using TEM.

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.

Shear plastic deformation in ECAP occurs through the formation, movement and storage of dislocations. The differences which exist between shearing characteristics lead to important implications concerning the optimum processing route. It is known that the effectiveness of cell evolution into an array of high-angle boundaries (HABs) is in the order BC > C > A, or A > BC > C, depending on the two-channel-angle intersection of the ECAP die. In route A, large portions of HABs are continuously and progressively generated, while routes C and BC cause fully redundant deformation at each 2n passes, and each 4n passes, respectively. This study is focused on dislocation generation, storage and recombination during ECAP for routes A, C and BC. Kikuchi bands identified with TEM were used to quantitatively measure the cell and grain boundary misorientation. ECAP was performed on an AA1200 commercially pure aluminium alloy up to e = 8.64. A different hierarchy for HAB generation efficiency was found. Thermal stability was studied by annealing the alloy at 0.5, 0.6, 0.7 TM (where TM is the alloy melting point) for 2 h after the severe plastic deformation. It appeared that, even if route BC involves the fastest microstructure grain refining, route C is likely to be the most stable upon reheating.

In Electron Rutherford Backscattering Spectroscopy (ERBS) energetic electrons (in our case up to 40 keV) impinge on a target and one measures the energy of elastically scattered electrons. This energy depends on the mass of the scattering atom, due to the recoil effect. This technique thus provides information about the sample composition. For single crystals the interaction of the projectile electron with the crystal potential modifies the angular intensity distribution of the scattered electrons. This leads, for example, to the well-known Kikuchi patterns. Here we investigate if such modified angular distribution has any influence on the intensity ratio of the observed elastic peaks in ERBS. Dramatic effects are found. Implications of these observations for quantitative surface analysis using energetic electrons are discussed.

The analysis of the achieved texture is of great importance for the performance of ferrite materials, either bulk or thin films. The recently developed electron backscatter diffraction (EBSD) technique enables a spatially resolved study of the crystallographic orientations by means of recording of Kikuchi patterns. To our knowledge, such a thorough EBSD analysis was not yet performed in any oxidic magnetic material, and only very recently on magnetite thin films by us. A good surface polishing/cleaning is essential for this analysis, as the method requires an undisturbed surface area for a high image quality (IQ). This information is recorded to each measured Kikuchi pattern, together with a parameter describing the quality of indexation. Here, the spatially highly resolved EBSD mappings provide additional information as compared to the standard analysis techniques, which can contribute to an optimization of the growth process. Furthermore, an analysis of the grain aspect ratio is possible which provides further insight to the microstructural dependence of the magnetic properties of ferrites.

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

A new approach to resolve the slight tetragonality ofL10-ordered γ-TiAl by electron backscatter diffraction (EBSD) is presented. The phase has ac/aratio of only about 2% larger than unity. The corresponding EBSD patterns therefore exhibit cubic pseudosymmetry. As a consequence, different order variants cannot be easily distinguished on the basis of their EBSD patterns. Automated orientation mapping results in frequent misindexing. In the past, either this problem was overcome by identifying order domains by relatively laborious transmission electron microscopy, or the order domain structure was ignored altogether by using a generic face-centered cubic structure to solve for the crystal orientations, accepting a significant loss of microstructural information. The presented approach is based on the detection of the minor tetragonal distortion of the diffraction patterns by an accurate measurement of backscatter Kikuchi band positions. To this end an accurate pattern center calibration together with high-accuracy parameters for pattern acquisition and indexing are required. Together with a modified indexing algorithm, the order domains in a lamellar microstructure of Ti–45.9Al–8Nb (at%) could be reliably identified. The occurrence of superlattice reflections in the Kikuchi patterns was used to validate the technique. The developed method was successfully applied to create a crystal orientation map of Ti–45.9Al–8Nb (at%) with a fully resolved domain microstructure.

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.

Abalone shell comprises a bio-composite material, combining the properties of inorganic calcite intergrown with organic nacre. This paper reports about the microstructure of this composite. By examining the Kikuchi patterns obtained for nacre (Haliotis discus hannai) using transmission electron microscopy, we have shown that the tiles within nacre have specific orientations. The stereographic projection spheres for the tiles of nacre can be divided into two main types, namely a right oriented region and a left oriented region with respect to the c axis as a reference plane (001). The cluster character of nacre can be explained in terms of the growth mechanism of the ‘Christmas tree’ pattern. The orientation of the c-axis in the nacreous layer is elucidated for the first time. We demonstrate the use of the soluble protein obtained from the tiles of nacre in in vitro calcium carbonate crystallization.

Dislocation structures in deformed metals have been analyzed quantitatively by transmission electron microscopy, high-resolution electron microscopy and Kikuchi line analysis. A general pattern for the microstructural evolution with increasing strain has been established and structural parameters have been defined and quantified. It has been found that two dislocation patterns co-exist in all grains, however, with very different characteristics dependent on grain orientation. This correlation with the grain orientation has been applied in modeling of the tensile flow stress and the flow stress anisotropy of fcc polycrystals. In conclusion some future research areas are briefly outlined.

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.

Bonded silicon-on-insulator (SOI) materials via the Smart-cut^T^M (or ion-cut) process attract increasing interests due to their great capability and versatility in fabricating novel virtual substrates. Previously we reported the successful fabrication of silicon-on-aluminum-nitride (SOAN) structure with smart-cut process [C.L. Men, Z. Xu, Z. An, X.Y. Xie, M. Zhang, C.L. Lin, Physica B 324 (2002) 229]. In this work, we characterize the bonded SOAN structure with Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM) together with Kikuchi line diffraction patterns, and high resolution X-ray diffraction (HRXRD) techniques. It is found that, after smart-cut process, the top Si layer preserves a rather good single crystalline quality, while strain is induced in top Si and can be altered in the annealing step. The rotational misalignment during bonding step can be evaluated by Kikuchi line patterns. Our discussions here may be common for all bonded virtual substrates via smart-cut technology.

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 ...

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.

Microstructures and martensitic transformation behavior have been examined as for CoNiGa ferromagnetic shape memory alloy (FMSMA) ribbons rapidly solidified by a single-roll melt spinning. Transmission electron microscopy (TEM) bright-field images revealed dense striations in the martensite variants. These striations are identified to be thin twins, as in other FMSMAs. The analysis of a pair of Kikuchi lines in a selected-area electron diffraction pattern indicates that the b / a and c / a axial ratios of the orthorhombic martensite are 1.01 and 0.961, respectively. Crossings of fully twinned martensite variants are frequently observed in the TEM bright-field images, and the internal twins disappear in the crossing regions, that is, the regions are subjected to detwinning. In addition to the crossing of martensite variants, checkers and straight bands of martensite variants are observed in the crystal grains of the ribbon surface. These typical morphologies are supposed to be caused by some self-accommodation of martensitic transformation stress.

The thin sheets of calcite, termed folia, that make up much of the shell of an oyster are composed of foliated lath. Folia of the giant Pacific oyster (Crassostrea gigas) were examined using TEM (transmission electron microscopy) and tested using microindentation and nanoindentation techniques. Analysis of the Kikuchi patterns obtained from the folia showed that there are two types (type I and type II) of preferred orientation, with an angle of around 70° between them. Nanoindentation tests showed that the folia exhibit a hardness of about 3 GPa and elastic modulus of about 73 GPa. Microcracks were generated using a microindenter in order to study the fracture mechanisms of the folia. Following on from these investigations, fracture mechanisms are discussed in conjunction with the correlation between preferred orientation and structural characteristics during cracking of the folia. Comparing the morphology and the polymorphism with nacre (also known as mother of pearl), the advantages of the relatively fast crystal growth and less amount of organic matrix in folia may have interesting implications for the development of sophisticated synthetic materials.

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.

Oral; International audience; The grain orientation, the texture and the grain boundary misorientations are important parameters for the understanding of the magnetic properties of the bulk MgB2 samples intended for super-magnet applications. Such data can be provided by electron backscatter diffraction (EBSD) analysis. However, as the grain size of the MgB2 bulks is preferably in the 100-200 nm range, the common EBSD technique working in reflection operates only properly on highly dense samples. In order to achieve a reasonably good Kikuchi pattern quality on all samples, we apply here the newly developed transmission EBSD (t-EBSD) technique to several bulk MgB2 samples. This method requires the preparation of TEM slices by means of focused ion-beam milling, which are then analyzed within the SEM, operating with a specific sample holder. We present several EBSD mappings of samples prepared with different techniques and at various reaction temperatures.

We present the design and demonstration of a unique and novel detector for electron microscopy based on microelectromechanical systems (MEMS) technology. The detector is optimized for transmission electron backscatter diffraction, or more specifically for transmission Kikuchi diffraction, and will allow this new analytic tool to realize its full potential. In addition, this single detector is capable of simultaneous acquisition of bright field and dark field images in scanning electron microscopy and transmission electron microscopy and may replace a number of the single-purpose detectors presently used in these devices.

Optical quality Pb2MoO5 single crystals were grown by the Low Thermal Gradient Czochralski (LTG Cz) technique. The resulting Pb2MoO5 crystals had diameters of 40–50 mm and lengths of ~100 mm. The phase composition of the grown crystals was identified by X-ray single crystal structure analysis; the space group is C2/m and a = 14.2221(11), b = 5.7852(5), c = 7.3262(6) A, β = 114.168(2)° and Z = 4 (R1 = 0.0336). Pb2MoO5(20−1) substrates were prepared by cleavage, and the surface properties were evaluated by RHEED and AFM. The superposition of wide Kikuchi lines and crystal reflexes was found by RHEED. The AFM measurements indicate a surface roughness as low as ~0.2 nm. Thus, atomically smooth surfaces of Pb2MoO5 were formed by cleavage.

The convergent beam Kikuchi line diffraction technique has been used to accurately determine the orientation relationships between bainitic ferrite and retained austenite in a hard bainitic steel. A reproducible orientation relationship has been uniquely observed for both the upper and lower bainite. It is [GRAPHICS] However, the habit plane of upper bainite is different from that of lower bainite. The former has habit plane that is either within 5 degrees of (221)(A) or of (259)(A). The latter only corresponds with a habit plane that is within 5 degrees of (259)(A). The determined orientation relationship is completely consistent with reported results determined using the same technique with an accuracy of +/- 0.5 degrees in lath martensite in an Fe-20 wt.% Ni-6 wt.% Mn alloy and in a low carbon low alloy steel. It also agrees well with the orientation relationship between granular bainite and austenite in an Fe-19 wt.% Ni-3.5 wt.% Mn-0.15 wt.% C steel. Hence it is believed that, at least from a crystallographic point view, the bainite transformation has the characteristics of martensitic transformation. (c) 2006 Elsevier B.V. All rights reserved.

The orientation relationship (OR) between the beta(Zn) phase and the alpha(Al) phase and the corresponding habit planes in a Zn-Al eutectoid alloy were accurately determined using convergent beam Kikuchi line diffraction patterns. In addition to the previously reported OR. [11 (2) over bar0](beta)parallel to[110](alpha), (0002)(beta)parallel to ((1) over bar 11)alpha, two new ORs were observed. They are: [11 (2) over bar0](beta)parallel to [110], ((1) over bar 101)(beta) 0.82 degrees from (002)(alpha) and [(1) over bar 100](beta)parallel to[112](alpha), (0002)(beta) 4.5 degrees from (111)(alpha). These ORs can be explained and understood using the recently developed edge-to-edge matching model. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

We recently showed that the Multisclice method can be used to elucidate the crystal volume contribution to a CBED pattern. Here, we demonstrate in more detail how the directions of each HOLZ line, their Laue zone order, and the specimen thickness determine the volume segment of the Bragg scattering cone of the electron beam and show that secondary rescattering from this volume must take place for deficient line formation in the (000) CBED disk. Moreover, additional prospects of the multislice method are demonstrated such as calculation of line splitting in bent crystals, hollow cone dark-field CBED, large-angle CBED, and whole diffraction patterns including Kikuchi lines.

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.

A new method for unambiguous differentiation and orientation determination of six γ variants and α 2 phase in a two phase TiAl base alloy is presented. The approach involves automatic collection of transmission electron microscopy (TEM) Kikuchi patterns by a digital CCD camera at regular distance of nano steps through nanoprobe scanning. The Kikuchi patterns corresponding to various γ variants and α 2 phase were distinguished through superlattice bands. The procedure is compared with other methods for identification of six γ variants and α 2 phase in terms of their spatial and angular resolutions as well as easiness and rapidity for large data collection. As an example, the technique is utilised to characterise the lamellar structures of a Ti–48(at.%)Al–2Cr–2Nb alloy resulting from heat treatment at high temperature α domain followed by furnace cooling. Each lamella is labelled with its respective γ variant or α 2 phase. The frequencies of the γ and γ / γ interfaces were determined. Moreover, it is noticed that some of the 0° and 180° γ / γ interfaces are in fact semi-coherent, and present a slight deviation from their ideal misorientation.

Transmission electron microscopy has been used to investigate the junction between two lamellar bands in a tetragonal lead zirconate titanate (PZT) ceramic. It is found that significant bending occurs in the area due to the matching of different domains on planes. Analysis of CBED patterns shows that the orientation relationships between the long boundaries between lamellae is much as expected and allows quantification of local c/a ratios. The short boundaries at the band junction, however, are highly stressed and deviate significantly from ideal misorientation values. This reveals that the areas between the 4- domain junctions in the band junction are highly stressed with peak stresses in the GPa range, which are highly likely to function as the source of microcracks under the additional strains found in device application.

The microstructure in the electroformed copper liners of shaped charges prepared with different electrolytes was studied by Scanning Electron Microscopy (SEM) and Electron Backscattering Kikuchi Pattern (EBSP) methods. SEM observations revealed the existence of columnar grains in electroformed copper liners of shaped charges formed by electrolyte without any additive and the average grain size is about 3 μm. When an additive is introduced to the electrolyte, the grains formed in the copper liners become equiaxed and finer. EBSP results show that the columnar grain grown during electroformation has the most preferential growth direction, whereas a micro-texture does not exit in the specimen prepared by electrolyte with the additive. Further, explosive detonation deformation experiments show that penetration depth is dramatically improved when the electroformed copper liners of shaped charges exhibit equiaxed grains.