An Electron Microscope Study of Defect-free YBa2Cu3O7?x (x » 0.15) with Superconductivity at 93 K

1987 ◽  
Vol 40 (5) ◽  
pp. 635 ◽  
Author(s):  
LA Bursill ◽  
P Goodman ◽  
JD Patterson ◽  
S Tonner
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope Study ◽  
Single Phase ◽  
High Temperature Superconductor ◽  
High Resolution Electron Microscopy ◽  
Surface Structures ◽  
Orthorhombic Structure ◽  
Controlled Processing ◽  
Resolution Electron ◽  
Processing Techniques

High resolution electron microscopy has been used to characterise sintered preparations of the mixed oxide YBa2Cu307_x (x::::; 0�15). By carefully controlled processing techniques a single phase defect-free orthorhombic structure having excellent characteristics for use as a high temperature superconductor was obtained. Surface structures and an image of a dislocation are included in this study.

HIGH RESOLUTION ELECTRON MICROSCOPE STUDY OF CdTe-Cd0.6Mn0.4 Te SUPERLATTICES

1985 ◽  
Vol 56 ◽  
Author(s):  
C. CHOI ◽  
N. OTSUKA ◽  
L. A. KOLODZIEJSKI ◽  
R. L. GUNSHOR-a
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Phase Contrast ◽  
Electron Microscope Study ◽  
Lattice Mismatch ◽  
Thick Layer ◽  
High Resolution Electron Microscopy ◽  
Misfit Dislocations ◽  
Resolution Electron ◽  
High Resolution Electron Microscope

AbstractStructures of CdTe-Cd0.6Mn0.4Te superlattices which are caused by the lattice mismatch between suterlattice layers have been studied by high resolution electron microscopy (HREM). In thin-layer superlattices, the crystal lattice in each layeris elastically distorted, resulting in the change of the crystal symmetry from cubic to rhombohedral. The presence of the small rhombohedral distrotion has been confirmed through a phase contrast effect in HREM images. In a thick-layer superlattice, the lattice mismatch is accommodated by dissociated misfit dislocations. Burgers vectors of partial misfit dislocations have been identified from the shift of lattice fringes in HREM images.

scholarly journals Microstructure of High Temperature Superconductors of the Perovskite Type

1987 ◽  
Vol 40 (4) ◽  
pp. 547 ◽  
Author(s):  
AF Moodie ◽  
HJ Whitfield
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
High Temperature Superconductor ◽  
High Temperature Superconductors ◽  
High Resolution Electron Microscopy ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Resolution Electron ◽  
Convergent Beam ◽  
Perovskite Type

Combined high resolution electron microscopy and convergent beam electron diffraction (CBED) of the same areas of crystals of Ba3La3Cu6014 reveals defects of various types including ordinary dislocations and polytypic intergrowths. This latter type is considered to be intimately associated with the performance of this material as a high temperature superconductor ..

Structural imaging of polytypoids in high Tc oxide superconductors

1989 ◽  
Vol 47 ◽  
pp. 156-157
Author(s):  
R. Ramesh ◽  
E. Wang ◽  
J.M. Tarascon ◽  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Liquid Nitrogen Temperature ◽  
High Resolution Electron Microscopy ◽  
Oxide Superconductors ◽  
Ion Milling ◽  
Resolution Electron ◽  
The Matrix ◽  
Diffraction Patterns ◽  
Processing Techniques

The structure of the superconducting polytypoid in the newly discovered high Tc super conducting system, Pb2Sr2Cu2Oy has been examined by high resolution electron microscopy, electron diffraction and xray microanalysis. High resolution imaging has shown the presence of the Pb2Sr2Cu2Oy at the grain boundaries. In analogy to the Bi-Ca-Sr-Cu-O(BCSCO)system, it is suggested that this polytypoid could have a lower transition temperature compared to the matrix. This may explain the steps in the resistivity plot. It is also shown that complex cationic ordering, such as replacement of Sr by Ca and/or Y, could lead to extra reflections in the diffraction patterns.Pb-Sr-(Ca-RE)-Cu-O sintered samples were prepared by standard solid state processing techniques. Samples were prepared under 1% flowing oxygen. Samples for electron microscopy were prepared by argon ion milling at liquid nitrogen temperature at 6kV. High resolution electron microscopy was carried out in the Berkeley Atomic Resolution Microscope at 800kV.

Double hexagonal superstructure of Au–Mg alloy containing 20 at.% Mg studied by high-voltage high-resolution electron microscopy

1983 ◽  
Vol 16 (2) ◽  
pp. 233-238 ◽  
Author(s):  
D. Shindo ◽  
K. Haraga ◽  
M. Hirabayashi ◽  
O. Terasaki ◽  
D. Watanabe
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Resolution ◽  
High Voltage ◽  
High Resolution Electron Microscopy ◽  
Mg Alloy ◽  
Orthorhombic Structure ◽  
Resolution Electron ◽  
The Many ◽  
Imaging Conditions

High-resolution observations of Au–20.2 at.% Mg alloy have been carried out by using a 1 MV electron microscope. The many-beam images with the [001] axial illumination are interpreted in terms of the double hexagonal superstructure of 9a 0−4H type. With the aid of computer simulations by the multislice method, it is revealed that two kinds of interpretable image are obtained for different specimen thicknesses at the optimum defocus. The imaging conditions are discussed in comparison with the orthorhombic structure of the D023 type.

High-resolution electron microscopy of the high-temperature superconductor YBa2Cu3O7

Nature ◽  
1987 ◽  
Vol 327 (6121) ◽  
pp. 400-402 ◽  
Author(s):  
E. A. Hewat ◽  
M. Dupuy ◽  
A. Bourret ◽  
J. J. Capponi ◽  
M. Marezio
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
High Resolution ◽  
High Temperature Superconductor ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

One Million Direct Magnification Microscopy

1971 ◽  
Vol 29 ◽  
pp. 166-167
Author(s):  
J. A. Hugo ◽  
V. A. Phillips
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Illumination Level ◽  
Level Of Detail ◽  
Photographic Emulsion ◽  
Low Contrast ◽  
Fluorescent Screen ◽  
Resolution Electron ◽  
Lattice Images ◽  
Electron Microscopes

A continuing problem in high resolution electron microscopy is that the level of detail visible to the microscopist while he is taking a picture is inferior to that obtainable by the microscope, readily readable on a photographic emulsion and visible in an enlargement made from the plate. Line resolutions, of 2Å or better are now achievable with top of the line 100kv microscopes. Taking the resolution of the human eye as 0.2mm, this indicates a need for a direct viewing magnification of at least one million. However, 0.2mm refers to optimum viewing conditions in daylight or the equivalent, and certainly does not apply to a (colored) image of low contrast and illumination level viewed on a fluorescent screen through a glass window by the dark-adapted eye. Experience indicates that an additional factor of 5 to 10 magnification is needed in order to view lattice images with line spacings of 2 to 4Å. Fortunately this is provided by the normal viewing telescope supplied with most electron microscopes.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

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