Factors Affecting Selected Area Electron Diffraction Patterns of Micas*

1974 ◽  
Vol 22 (1) ◽  
pp. 97-106 ◽  
Author(s):  
Necip Güven
Keyword(s):  
Electron Diffraction ◽  
Factors Affecting ◽  
Selected Area Electron Diffraction ◽  
Diffraction Patterns

scholarly journals Nano-Scale Rare Earth Distribution in Fly Ash Derived from the Combustion of the Fire Clay Coal, Kentucky

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 206 ◽  
Author(s):  
James Hower ◽  
Dali Qian ◽  
Nicolas Briot ◽  
Eduardo Santillan-Jimenez ◽  
Madison Hood ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Fly Ash ◽  
Electron Diffraction ◽  
Eastern Kentucky ◽  
Nano Scale ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Fire Clay

Fly ash from the combustion of eastern Kentucky Fire Clay coal in a southeastern United States pulverized-coal power plant was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). TEM combined with elemental analysis via energy dispersive X-ray spectroscopy (EDS) showed that rare earth elements (REE; specifically, La, Ce, Nd, Pr, and Sm) were distributed within glassy particles. In certain cases, the REE were accompanied by phosphorous, suggesting a monazite or similar mineral form. However, the electron diffraction patterns of apparent phosphate minerals were not definitive, and P-lean regions of the glass consisted of amorphous phases. Therefore, the distribution of the REE in the fly ash seemed to be in the form of TEM-visible nano-scale crystalline minerals, with additional distributions corresponding to overlapping ultra-fine minerals and even true atomic dispersion within the fly ash glass.

Electron diffraction from crystal defects: Fraunhofer effects from plane faults

1966 ◽  
Vol 293 (1433) ◽  
pp. 169-180 ◽  
Keyword(s):  
Electron Diffraction ◽  
Intensity Distribution ◽  
Stacking Faults ◽  
Dynamical Theory ◽  
Crystal Defects ◽  
Similar Calculation ◽  
Selected Area Electron Diffraction ◽  
Periodic Intensity ◽  
Diffraction Patterns ◽  
Calculated Intensity

The selected area electron diffraction patterns from a crystal containing a stacking fault have been observed to exhibit a number of unusual features. In some cases a periodic intensity distribution about the Bragg spot, in other cases streaking. By applying Kirchhoff’s theory of diffraction and using the dynamical theory of electron diffraction this intensity distribution around the Bragg spots in the electron diffraction patterns from stacking faults has been calculated. The calculated intensity distributions compare favourably with experiment. A similar calculation has also been carried out to predict the intensity distribution around Bragg spots in the selected area electron diffraction patterns from a crystal containing a grain boundary.

Selected Area Electron Diffraction and its Use in Structure Determination

2010 ◽  
Vol 18 (4) ◽  
pp. 22-28
Author(s):  
William F. Tivol
Keyword(s):  
Structural Analysis ◽  
Electron Diffraction ◽  
Structure Determination ◽  
Limited Region ◽  
Selected Area Electron Diffraction ◽  
Electron Microscopes ◽  
Diffraction Patterns ◽  
Technical Considerations

One of the capabilities of electron microscopes is to obtain diffraction patterns, which can be analyzed to give information about the structure of the specimen. This brief review discusses some of the technical considerations in using electron diffraction patterns for structural analysis. The technique of selected-area electron diffraction uses diffraction obtained from a limited region of the specimen.

Fine Structure in the Selected Area Electron Diffraction Patterns of Beidellite

1975 ◽  
Vol 33 ◽  
pp. 72-73
Author(s):  
N. Güven ◽  
R.W. Pease
Keyword(s):  
Fine Structure ◽  
Electron Diffraction ◽  
Reciprocal Lattice ◽  
Linear Chain ◽  
Lattice Points ◽  
Selected Area Electron Diffraction ◽  
General Terms ◽  
Regular Network ◽  
Diffraction Patterns ◽  
Pass Through

Selected area electron diffraction (SAD) patterns of beidellite exhibit fine structure in the form of nonradial streaks and extra spots between the normal Laue spots. The streaks form a regular network as shown in Figure 1A andvery clearly after a long exposure, in Fig. IB. These streaks do not pass through the origin and they are not symmetrical with respect to the reciprocal lattice points. Therefore they cannot be caused by finite crystallite size. The distribution of the streaks suggests a strong anisotropy in the beidellite structure as they are restricted to the directions parallel to [11], [11], and [02]. However, there are no streaks along the actual [11], [11] and [02] directions. In general terms, these linear streaks are explained by the presence of ‘continuous sheets’ or ‘walls’ of intensity in reciprocal space. These intensity 'walls' are associated with a linear chain of scatterers in the crystal in the direction perpendicular to the intensity sheets. Such linear scatterers may be produced by small shifts of certain atoms due to thermal motion, isomorphic substitutions, distortions, or other lattice imperfections.

Automatic Computer Measurement of Selected Area Electron Diffraction Patterns from Asbestos Minerals

1988 ◽  
Vol 32 ◽  
pp. 593-600
Author(s):  
J. C. Russ ◽  
T. Taguchi ◽  
P. M. Peters ◽  
E. Chatfield ◽  
J. C. Russ ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Diffraction Data ◽  
Automatic Method ◽  
Automatic Computer ◽  
Selected Area Electron Diffraction ◽  
Computer Measurement ◽  
Integrated Intensity ◽  
Diffraction Patterns ◽  
True Center

Conventional selected area diffraction patterns as obtained in the TEM present difficulties for identification of materials such as asbestifonn minerals, although diffraction data is considered to be one of the preferred methods for making this identification. The preferred orientation of the fibers in each field of measurement, and the spotty patterns that are obtained, do not readily lend themselves to measurement of the integrated intensity values for each dspacing, and even the d-spacings may be hard to determine precisely because the true center location for the broken rings requires estimation. To overcome these problems, we have implemented an automatic method for diffraction pattern measurement. It automatically locates the center of patterns with high precision, measures the radius of each ring of spots in the pattern, and integrates the density of spots in that ring.

scholarly journals Electron diffraction of tilted perovskites

2005 ◽  
Vol 61 (4) ◽  
pp. 387-399 ◽  
Author(s):  
David I. Woodward ◽  
Ian M. Reaney
Keyword(s):  
Electron Diffraction ◽  
Structure Determination ◽  
Perovskite Structure ◽  
Selected Area Electron Diffraction ◽  
Diffraction Patterns

Simulations of electron diffraction patterns for each of the known perovskite tilt systems have been performed. The conditions for the appearance of superlattice reflections arising from rotations of the octahedra are modified to take into account the effects of different tilt systems for kinematical diffraction. The use of selected-area electron diffraction as a tool for perovskite structure determination is reviewed and examples are included.

Electron diffraction and the study of ferrihydrite coatings on kaolinite

Clay Minerals ◽  
1986 ◽  
Vol 21 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Angela A. Jones ◽  
A. M. Saleh
Keyword(s):  
Electron Diffraction ◽  
Crystal Size ◽  
Selected Area Electron Diffraction ◽  
Diffraction Patterns

AbstractSelected-area electron diffraction has been used to examine ferrihydrite coatings on kaolinite crystals and is shown to provide a sensitive means of detection. It also gives better diffraction patterns of ferrihydrite than does XRD and the patterns sometimes give additional indications of the crystal size. It is suggested that the technique may be useful in examining other coatings on soils and clays.

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