High-Resolution Electron Microscopy Studies of Faults and Intergrowth in Nb3O7F

1990 ◽  
Vol 183 ◽  
Author(s):  
Lotta permér ◽  
Monica Lundberg
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
High Pressure ◽  
High Resolution Electron Microscopy ◽  
Two Dimensions ◽  
Resolution Electron ◽  
Shear Type ◽  
Pressure Form ◽  
The Common ◽  
Shear Planes

AbstractHREM studies of the low-pressure form of Nb3O7F, obtained by thermal decomposition of NbO2F or by reacting stoichiometric amounts of NbO2F and Nb2O5, confirmed that the crystals are built up of a shear-type structure in which slabs of ReO3 type, infinite in two dimensions and three octahedra wide, separate the shear planes. Most of the crystals were well-ordered, although faults could occasionally be detected. However, some crystals were found to be intergrown with a structure closely related to the high-pressure form of Nb3O7F. The latter structure is composed of wavy rows of edge-sharing NbX7 pentagonal bipyramids, joined to each other by NbX6 octahedra. The connection between the two atomic arrangements can be understood in terms of the common c-axes and a slight distortion of the polyhedra along the boundary.

On the microstructure of a high-pressure phase of W3O8

1995 ◽  
Vol 10 (2) ◽  
pp. 81-85 ◽  
Author(s):  
D. Louër ◽  
M. Sundberg ◽  
P.-E. Werner ◽  
V. P. Filonenko ◽  
I. P. Zibrov
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Powder Diffraction ◽  
Average Diameter ◽  
High Resolution Electron Microscopy ◽  
Tungsten Oxides ◽  
X Ray ◽  
Pattern Decomposition ◽  
Resolution Electron ◽  
Hall Plot

The structures of two high-pressure tungsten oxides, previously studied by high-resolution electron microscopy, were confirmed by Rietveld refinement based on X-ray powder diffraction data. The phases have identical stoichiometry, W3O8, and extremely narrow 00l reflections in common. The microstructure of the dominant phase was investigated by means of X-ray powder diffraction pattern decomposition. A Williamson–Hall plot revealed that all lines, except the 00l reflections, were broadened solely due to the crystallite size effect. A cylindrical model is used to describe the average form of the coherently diffracting domains. The height of the cylinder, whose axis is colinear with the crystallographic c parameter of both phases, is considered “infinite,” and the average diameter of the cylinder model is 655(22) Å. A quantitative confirmation is obtained from electron microscopy.

High-resolution electron microscopy studies of high-pressure synthesized mercury-based superconductor

1994 ◽  
Vol 7 (6) ◽  
pp. 971-974 ◽  
Author(s):  
Liu Wei ◽  
Yao Yushu ◽  
Su Yanjing ◽  
Zhao Zhongxian ◽  
Li Fanghua ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
High Resolution ◽  
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.

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