On alloy lattice images

1978 ◽  
Vol 36 (1) ◽  
pp. 308-309
Author(s):  
E.D. Boyes ◽  
P.L. Gai ◽  
A.J. Skarnulis
Keyword(s):  
Cross Sections ◽  
Phase Contrast ◽  
Atomic Scale ◽  
Lattice Imaging ◽  
Weak Beam ◽  
Transmission Electron ◽  
Purity Aluminium ◽  
Lattice Images ◽  
High Purity Aluminium ◽  
Lattice Planes

The models that are suggested to describe precipitation reactions and phase transformations are almost always on the atomic scale, but the experimental techniques that can be used to examine the phenomena often either integrate the information from many events or operate at somewhat lower resolution. However, phase-contrast lattice imaging and possibly weak beam (Yoshida et al. 1976) techniques of transmission electron microscopy and field-ion microscopy (FIM) (e.g. Boyes et al. 1975 and 1977) can be useful. In principle the images can be interpreted to yield microanalytical data about individual planes or layers of atoms.Images of (200) lattice planes, or more correctly fringes, have been produced from a rolled high purity Aluminium 4.3% Copper alloy containing GP2 or θ" zones. The polycrystalline material is used since the composition is more representative of the applications of this alloy. It was more difficult to produce images of this material than, for example of the visual gold test specimens: it is suggested that this may be due to the increased inelastic cross-sections.

Lattice Images of Non-Integer Planes in Gold

1971 ◽  
Vol 29 ◽  
pp. 182-183
Author(s):  
W. R. Bottoms ◽  
L. L. Ban
Keyword(s):  
Electron Diffraction ◽  
Phase Contrast ◽  
Objective Lens ◽  
Transmission Electron ◽  
Structure Factors ◽  
Lattice Images ◽  
Diffraction Patterns ◽  
Lattice Planes ◽  
Gold Microcrystals

A common growth habit for gold microcrystals is a thin (111) platelet of hexagonal or trigonal symmetry. It has been shown that such microcrystals contain coherent faults in the ABCABC stacking sequence giving rise to non-zero structure factors for lattice planes of index 1/3(422). Transmission electron diffraction patterns from these crystals such as shown in Figure 2 confirm the existence of this non-zero structure factor by exhibiting reflections whose spacing and orientation correspond to lattice planes of the type 1/3(422). The diffraction pattern in Figure 2 has been superimposed on the polycrystalline ring pattern of gold for reference and the spacings of the inner-most spots is equal to the 2.497Å of the 1/3(422) planes to within the experimental error. Additional confirmation of the indexing of these spots has been obtained by electron diffraction at various angles of tilt.Phase contrast lattice images of the non-integer planes shown in Figure 1 were obtained with axial illumination of the sample by defocusing the objective lens of a Philips EM-300 electron microscope.

Application of Lattice Imaging Techniques to Amorphous Films

1975 ◽  
Vol 33 ◽  
pp. 8-9
Author(s):  
S. R. Herd ◽  
P. Chaudhari
Keyword(s):  
Nearest Neighbor ◽  
Random Network ◽  
Imaging Techniques ◽  
Network Models ◽  
Accurate Method ◽  
Direct Transmission ◽  
Lattice Imaging ◽  
Transmission Electron ◽  
Lattice Planes ◽  
Nearest Neighbor Distances

Electron diffraction and direct transmission have been used extensively to study the local atomic arrangement in amorphous solids and in particular Ge. Nearest neighbor distances had been calculated from E.D. profiles and the results have been interpreted in terms of the microcrystalline or the random network models. Direct transmission electron microscopy appears the most direct and accurate method to resolve this issue since the spacial resolution of the better instruments are of the order of 3Å. In particular the tilted beam interference method is used regularly to show fringes corresponding to 1.5 to 3Å lattice planes in crystals as resolution tests.

Quantitative Investigations of Interfaces and Grain Boundaries by Phase Contrast Electron Microscopy with Ultra High Resolution

2001 ◽  
Vol 7 (S2) ◽  
pp. 288-289
Author(s):  
C. Kisielowski ◽  
J.M. Plitzko ◽  
S. Lartigue ◽  
T. Radetic ◽  
U. Dahmen
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Phase Contrast ◽  
Recent Progress ◽  
Image Interpretation ◽  
Present Contribution ◽  
Crystalline Materials ◽  
Transmission Electron ◽  
Contrast Microscopy ◽  
Lattice Images

Recent progress in High Resolution Transmission Electron Microscopy makes it possible to investigate crystalline materials by phase contrast microscopy with a resolution close to the 80 pm information limit of a 300 kV field emission microscope'"". A reconstruction of the electron exit wave from a focal series of lattice images converts the recorded information into interpretable resolution. The present contribution illustrates some recent applications of this technique to interfaces.Fig. 1 shows a reconstructed electron exit wave of a heterophase interface between GaN and sapphire. The experiment takes advantage of three factors: First, we resolved the GaN lattice in projection, which requires at least 0.15 nm resolution. The projection eliminates the stacking fault contrast that usually obscures lattice images in the commonly recorded projection. Thus, image interpretation is drastically simplified. Second, all atom columns at the interface and in the sapphire are resolvable with a smallest projected aluminum - oxygen spacing of 85 pm in the sapphire.

scholarly journals Lattice Image Contrast of Ordered Domains in Cu3Au

1974 ◽  
Vol 32 ◽  
pp. 500-501
Author(s):  
R. Sinclair ◽  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystal Lattice ◽  
Fine Scale ◽  
Lattice Imaging ◽  
Lattice Image ◽  
Transmission Electron ◽  
Radiation Induced ◽  
Considerable Controversy ◽  
Lattice Planes

Although lattice Imaging was one of the first techniques in transmission electron microscopy of crystals, only with the improved resolution (≃2Å) of modern microscope has it become possible to obtain the lattice Image of metals as a matter of routine. To date fine-scale phenomena in alloys have been studied principally by relating the distortion of the fringe image to the defect in the crystal lattice ﹛e.g. dislocation, radiation induced damage, G-P zones etc. (2)﹜ but considerable controversy exists as to the validity of interpreting the fringes in terms of a one-to-one correspondence with the lattice planes in the specimen. One of the areas of research so Ear unexplored by this technique is the study of ordering reaction is alloy. The present paper demonstrates how it is particularly useful in this field especially in avoiding the controversy associated with the interpretation of fringe distortions.

Grain boundary faceting in YBa2Cu3O7–x bicrystal thin films on SrTiO3 substrates

2002 ◽  
Vol 17 (2) ◽  
pp. 323-335 ◽  
Author(s):  
Qiang Jin ◽  
Siu-Wai Chan
Keyword(s):  
Thin Films ◽  
Boundary Plane ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Film Boundary ◽  
Lattice Images ◽  
Tilt Boundaries ◽  
The Difference ◽  
Straight Segments ◽  
Misorientation Angles

The structure of [001] tilt boundaries in YBa2Cu3O7–x (YBCO) thin films deposited on [001] tilt SrTiO3 (STO) bicrystal substrates has been characterized by transmission electron microscopy (TEM). These boundaries are (100)/(210), (310)/(510), (410)/(310), (510)/(210), (210)/(410), and (210)/(310), with corresponding misorientation angles of 26°, 29°, 32°, 37°, 40°, and 44°. It was found that the YBCO film boundaries were meandering along the relatively straight substrate boundaries. High-resolution lattice images indicated that the microscopic meandering of the film boundary essentially consisted of many straight segments of facets at the atomic scale. On the basis of the observed facets, three competing factors controlling the formation of facets are discussed. First, the boundary plane is defined by Miller indices (hk0) in both crystals with sufficiently small h, k (i.e., h, k ≤ 5) and sufficiently large effective interplanar spacing (i.e., deff > 0.06 nm). Second, the closure failure defined by the difference between the local misorientation from the design misorientation is small, i.e., less than 2°. Third, the deviation of a local facet plane is observed to be less than 30° from the design boundary plane. Higher values of deffs are observed to give tolerance to higher deviation angles.

scholarly journals Resolving hydrogen atoms at metal-metal hydride interfaces

2020 ◽  
Vol 6 (5) ◽  
pp. eaay4312 ◽  
Author(s):  
Sytze de Graaf ◽  
Jamo Momand ◽  
Christoph Mitterbauer ◽  
Sorin Lazar ◽  
Bart J. Kooi
Keyword(s):  
Metal Hydride ◽  
Phase Contrast ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Hydrogen Atoms ◽  
Volumetric Density ◽  
Transmission Electron ◽  
Metal Metal ◽  
Scanning Transmission ◽  
Differential Phase Contrast

Hydrogen as a fuel can be stored safely with high volumetric density in metals. It can, however, also be detrimental to metals, causing embrittlement. Understanding fundamental behavior of hydrogen at the atomic scale is key to improve the properties of metal-metal hydride systems. However, currently, there is no robust technique capable of visualizing hydrogen atoms. Here, we demonstrate that hydrogen atoms can be imaged unprecedentedly with integrated differential phase contrast, a recently developed technique performed in a scanning transmission electron microscope. Images of the titanium-titanium monohydride interface reveal stability of the hydride phase, originating from the interplay between compressive stress and interfacial coherence. We also uncovered, 30 years after three models were proposed, which one describes the position of hydrogen atoms with respect to the interface. Our work enables previously unidentified research on hydrides and is extendable to all materials containing light and heavy elements, including oxides, nitrides, carbides, and borides.

Analysis of Stacking Structure of Cup-Stacked Type Carbon Nanofibers

2002 ◽  
Vol 738 ◽  
Author(s):  
Kyoich Oshida ◽  
Tatsuo Nakazawa ◽  
Kozo Osawa ◽  
Takuya Hayashi ◽  
Morinobu Endo ◽  
...  
Keyword(s):  
Image Analysis ◽  
Carbon Nanofibers ◽  
Repeat Distance ◽  
Fiber Wall ◽  
Transmission Electron ◽  
Analysis Technique ◽  
Lattice Images ◽  
New Type ◽  
Lattice Planes ◽  
Stacking Structure

ABSTRACTThe lattice images of the new type (cup-stacked type) carbon nanofibers were observed by high resolution transmission electron microscopy (HRTEM) and the detailed structure was analyzed by image processing. The angle of opposed graphitic basal planes was measured from power spectrum obtained by 2 dimensional first Fourier transform. The structures of the slanted (00·1) lattice planes, which appear at the cross section of the fiber wall, were shown by means of this image analysis technique. Defects were observed in the ordered structure of this material. The (00·1) lattice planes show large fluctuation in alignment of them and the (10·0) lattice planes make several angles with the (00·1) lattice planes. The average repeat distance d002 was estimated on the basis of d100 by HRTEM image and image analysis.

Electron Microscope Study of Strain in InGaN Quantum Wells in GaN Nanowires

2009 ◽  
Vol 1184 ◽  
Author(s):  
Roy Geiss ◽  
Kris Bertness ◽  
Alexana Roshko ◽  
David Read
Keyword(s):  
Electron Microscope ◽  
Quantum Wells ◽  
Cross Sections ◽  
Lattice Spacing ◽  
Gan Nanowires ◽  
Transmission Electron ◽  
Lattice Images ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Ingan Quantum Wells

AbstractStrains in GaN nanowires with InGaN quantum wells (QW) were measured from transmission electron microscope (TEM) images. The nanowires, all from a single growth run, are single crystals of the wurtzite structure that grow along the <0001> direction, and are approximately 1000 nm long and 60 nm to 130 nm wide with hexagonal cross-sections. The In concentration in the QWs ranges from 12 to 15 at %, as determined by energy dispersive spectroscopy in both the transmission and scanning electron microscopes. Fourier transform (FT) analyses of <0002> and <1100> lattice images of the QW region show a 4 to 10 % increase of the c-axis lattice spacing, across the full specimen width, and essentially no change in the a-axis value. The magnitude of the changes in the c-axis lattice spacing far exceeds values that would be expected by using a linear Vegard's law for GaN – InN with the measured In concentration. Therefore the increases are considered to represent tensile strains in the <0001> direction. Visual representations of the location and extent of the strained regions were produced by constructing inverse FT (IFT) images from selected regions in the FT covering the range of c-axis lattice parameters in and near the QW. The present strain values for InGaN QW in nanowires are larger than any found in the literature to date for other forms of InxGa1-xN (QW)/GaN.

Lattice Imaging of Grain Boundary Precipitation Reactions

1977 ◽  
Vol 35 ◽  
pp. 116-117
Author(s):  
R. Gronsky ◽  
G. Thomas
Keyword(s):  
Grain Boundary ◽  
Materials Science ◽  
Transformation Products ◽  
Lattice Imaging ◽  
Research Division ◽  
Transmission Electron ◽  
Boundary Precipitation ◽  
Compositional Changes ◽  
Grain Boundary Precipitation ◽  
Lattice Planes

Materials and Molecular Research Division, Lawrence Berkeley Laboratory and Department of Materials Science and Mineral Engineering, University of California, Berkeley, California 94720.Grain boundaries are known to catalyze a wide variety of solid state phase transformations which drastically affect metallurgical properties. The study of these reactions has traditionally required transmission electron microscopy, particularly when the transformation products are only partially developed. In the present paper, an application of lattice fringe imaging to the study of grain boundary reactions in Al-Zn alloys is described. The technique has proven to be far superior to conventional TEM methods in providing information on not only the detailed structural configuration of lattice planes at boundaries, but also the compositional changes, to within ∽10Å of the boundary plane, accompanying the transformations.

Chitin Systems Studied by Electron Diffraction, Diffraction-Contrast Electron Microscopy and Lattice Imaging

1990 ◽  
Vol 48 (1) ◽  
pp. 582-583 ◽  
Author(s):  
Henri CHANZY ◽  
Francoise Gaill ◽  
Marie-Madeleine Giraud-Guille ◽  
Jan Persson ◽  
Junji Sugiyama ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Electron Diffraction ◽  
Cross Sections ◽  
Room Temperature ◽  
Lattice Imaging ◽  
Diffraction Contrast ◽  
Transmission Electron ◽  
Tevnia Jerichonana

Chitin the poly β (1-4)-N Acetyl D glucosamine is widespread in nature and occurs normally as a crystalline fibrillar substance. As opposed to most of the crystalline polysaccharides, chitin is quite resistant to the electron beam. In particular, at room temperature, accumulated doses as high as 200 elec/nm2 at 120 kV can be used to record successful images showing crystalline details. For this reason, chitin can be studied without too much difficulty by electron diffraction (ED), diffraction contrast transmission electron microscopy (DCTEM) and lattice imaging. This study presents some of the diversity of chitin morphology.Several chitin rich specimens were studied. They include : 1) cross sections of an ovipositor from an ichneumon fly Rhyssa persuosaria ; 2) cross sections of fragments of demineralized crab cuticle ; 3) cross sections of a tube from the vestimentiferan worm Tevnia jerichonana ; 4) bundles of chitin microfibrils isolated from Tevnia tube fragments after deproteinization.

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