Pollutant Identification by Selected Area Electron Diffraction. II. The Limitations

1974 ◽  
Vol 32 ◽  
pp. 534-535
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson ◽  
C. W. Walker
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Close Agreement ◽  
Straightforward Manner ◽  
Selected Area Electron Diffraction ◽  
The Subject ◽  
Diffraction Patterns ◽  
Crystal Electron

Single crystal electron diffraction patterns can be interpreted in a fairly straightforward manner because with a little knowledge of crystallography one can predict the kind of image to be formed by certain minerals. Close agreement between observed and theoretical patterns identifies the particles. However, in practice, electron diffraction patterns can be rather ambiguous or difficult to unravel. Most of the errors are inherent characteristics of certain samples and cannot be corrected easily. The most common of these are the subject of this discussion.

Compositional variation within some sedimentary chlorites and some comments on their origin

1985 ◽  
Vol 49 (352) ◽  
pp. 375-386 ◽  
Author(s):  
C. D. Curtis ◽  
C. R. Hughes ◽  
J. A. Whiteman ◽  
C. K. Whittle
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Compositional Variation ◽  
Analytical Transmission Electron Microscopy ◽  
Decomposition Reactions ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Crystal Electron

AbstractA range of authigenic sedimentary chlorites from sandstones has been studied by analytical transmission electron microscopy. Selected area (single crystal) electron diffraction patterns are of the Ib (β = 90°) polytype confirming the earlier observations of Hayes (1970).TEM analyses show all samples to be relatively rich in both Al and Fe. In the general formula (Mg,Fe,Al)n [Si8−xAlxO20](OH)16, x varies between 1.5 and 2.6; Fe/(Fe + Mg) between 0.47 and 0.83 and n between 10.80 and 11.54. Octahedral Al is close to 3 in this formulation and Fe2+ predominates over Fe3+. Swelling chlorites have significantly different compositions which are consistent with smectite/chlorite interstratifications.The Ib (β = 90°) polytype appears to be stable under conditions of moderate to deep burial. It replaces berthierine and swelling chlorites formed at lower temperatures. As commonly seen in grain coatings, however, it precipitates from porewater; solutes probably being contributed from several mineral decomposition reactions.

Electron-optical data for crystals of scarbroite

1960 ◽  
Vol 32 (248) ◽  
pp. 363-365 ◽  
Author(s):  
G. W. Brindley ◽  
J. J. Comer
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Electron Micrographs ◽  
Optical Data ◽  
Diffraction Patterns ◽  
Crystal Electron

SummaryElectron micrographs of scarbroite show thin platy crystals of about 1 μ size, having rhombic outlines with angles 66° ± 1° and 113° ± 1°. Single-crystal electron-diffraction patterns show rectangular net patterns, with d100 = 9·90 Å., d010 = 14·67 Å., γ* = 90° ± 0·05°. Strong hk0 reflections show a pseudohexagonal arrangement, but true symmetry is probably orthorhombic or monoclinic. Faces outlining rhombic forms are of type {11l}, .

scholarly journals Indexing of icosahedral quasiperiodic crystals

1986 ◽  
Vol 1 (1) ◽  
pp. 13-26 ◽  
Author(s):  
John W. Cahn ◽  
Dan Shechtman ◽  
Denis Gratias
Keyword(s):  
Fourier Transform ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Coordinate System ◽  
Powder Diffraction ◽  
Simple Application ◽  
Coordinate Systems ◽  
Diffraction Patterns ◽  
Definition Of ◽  
Crystal Electron

Since the definition of quasiperiodicity is intimately connected to the indexing of a Fourier transform, for the case of an icosahedral solid, the step necessary to prove, using diffraction, that an object is quasiperiodic, is described. Various coordinate systems are discussed and reasons are given for choosing one aligned with a set of three orthogonal two-fold axes. Based on this coordinate system, the main crystallographic projections are presented and several analyzed single-crystal electron diffraction patterns are demonstrated. The extinction rules for three of the five icosahedral Bravais quasilattices are compared, and some simple relationships with the six-dimensional cut and projection crystallography are derived. This analysis leads to a simple application for indexing powder diffraction patterns.

Electron Diffraction Studies of Pure SiC Polytypes

1969 ◽  
Vol 27 ◽  
pp. 162-163
Author(s):  
Donald L. Gibbon
Keyword(s):  
Electron Diffraction ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray ◽  
Carbon Substrates ◽  
Diffraction Patterns ◽  
Crystal Electron

Single crystal electron diffraction patterns have been obtained for three pure SiC polytypes, 4H, 6H, and 15R. The purity of the samples was determined by optical and x-ray techniques (Hannum and Shaffer, 1969). Diffracted intensity distributions for single crystals of these polytypes have been computed using the Busing-Levy ORFLS program. The samples were prepared by crushing and dispersing the powders on carbon substrates, shadowed with Pt. In scanning these dispersions, crystals were sought which were oriented with an a axis vertical.

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.

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