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.

Orientation relationships between TiB (B27), B2, and Ti3Al phases

2009 ◽  
Vol 24 (5) ◽  
pp. 1688-1692 ◽  
Author(s):  
C.L. Chen ◽  
W. Lu ◽  
L.L. He ◽  
H.Q. Ye
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Orientation Relationship ◽  
Reciprocal Lattice ◽  
Lattice Points ◽  
Orientation Relationships ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Electron Diffraction Technique

The orientation relationships among TiB (B27), B2, and Ti3Al phases have been investigated by transmission electron microscopy. By using the composite selected-area electron diffraction technique, the orientation relationship between TiB (B27) and B2 was determined to be [100]TiB[001]B2, (001)TiB(010)B2; and that between TiB (B27) and Ti3Al was . These orientation relationships have been predicted precisely by the method of coincidence of reciprocal lattice points.

scholarly journals Unit Cell Determination of New Minerals by Using Electron Diffraction

2014 ◽  
Vol 70 (a1) ◽  
pp. C1098-C1098
Author(s):  
Galiya Bekenova
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Electron Diffraction Pattern ◽  
Reciprocal Lattice ◽  
Fine Powder ◽  
Selected Area Electron Diffraction ◽  
Ewald Sphere ◽  
Type Pattern ◽  
Diffraction Patterns

Many new minerals recently discovered in Kazakhstan had platy (niksergievite), fiber (kazakhstanite) or fine powder (mitryaevaite) structural appearance. In monoclinic minerals with perfect or good (001) cleavage, d100 i d010-spacings in the hk0 zone could be measured on selected area electron-diffraction pattern from monocrystal tilted the way that axis c is parallel to the electron beam direction. This method was used for measuring d-spacings in new minerals such as kazakhstanite, niksergievite as well as in new discovered micas – sokolovaite and orlovite. In minerals with triclinic structure (mitryaevaite) the same method was used to determine d100, d010 as well as γ=1800-γ* (γ* is an angle between reciprocal lattice axes a* and b*). hk0-indices of each ring were defined by comparison of the normal texture (ring type) pattern and selected area pattern. For example, hk0-indices for triclinic cell of mitryaevaite were (010), (100), (-110), (110), (020) etc. When specimen with preferred orientation is tilted under angle φ toward electron beam, an "oblique texture" electron-diffraction pattern is obtained. Arcs of the ellipses on such diffraction pattern are formed by intersection of Ewald sphere with ring nodes. The height of the arc's maximum above the tilt axis is calculated by using the following formula: D=hp+ks+lq, where p, s, q are measured on the diffraction pattern [1-3]. For example, on "oblique texture" electron-diffraction pattern from vanalite with perfect (010) cleavage, arcs are merged with layer lines that intersect the ellipses and D=ks. Allocation of indices on texture electron-diffraction patterns from monoclinic niksergievite, sokolovaite and orlovite with perfect (001) cleavage is more difficult. In these cases, D= hp+lq. Heights of the arcs are situated symmetrical in regards to each lq level. With the help of "oblique texture" diffraction patterns stacking polytypes were indicated for such minerals.

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.

Elektronenbeugung an Vizinalflächen und an Kugelflächen von Einkristallen / Electron Diffraction of Vicinals and of Spherically Shaped Crystal Surfaces

1972 ◽  
Vol 27 (3) ◽  
pp. 420-425 ◽  
Author(s):  
H Melle ◽  
E Menzel
Keyword(s):  
Electron Diffraction ◽  
Fourier Transformation ◽  
Reciprocal Lattice ◽  
Lattice Points ◽  
Bulk Crystal ◽  
Crystal Surfaces ◽  
Spherical Crystals

Abstract The reciprocal lattice of a periodic terrace-ledge surface is calculated by Fourier transformation. This formalism is applied to spherical crystals. In that case the reciprocal lattice consists of bundles of finite streaks; their vertices are situated on the reciprocal lattice points of the bulk crystal. That confirms a model formerly used to discuss LEED experiments with spherical crystals. The calculation is generalized to describe terraces composed of several monolayers.

An optical method of studying the diffraction from imperfect crystals II. Crystals with dislocations

1957 ◽  
Vol 239 (1217) ◽  
pp. 192-201 ◽  
Keyword(s):  
Intensity Distribution ◽  
Optical Method ◽  
Reciprocal Lattice ◽  
Lattice Points ◽  
Dimensional Problem ◽  
Single Edge ◽  
General Complex ◽  
Diffraction Patterns ◽  
Special Points ◽  
The Ideal

Lipson’s optical diffractometer has been used to determine the diffraction patterns of gratings representing crystals with dislocations. The optical method lends itself readily to the solution of the two-dimensional problem of diffraction by a single edge dislocation. The intensity distribution near the ideal reciprocal lattice points is, in general, complex, but for certain special points it is relatively simple and in agreement with that deduced by a new theory of Suzuki. An earlier theory of Wilson’s fails to explain the observed intensity distribution. Diffuse scattering, not predicted by Suzuki’s theory, occurs in the form of streaks joining the reciprocal lattice points. The diffraction has also been studied from gratings consisting of photographs of dislocated bubble rafts, and from a grating whose diffraction pattern is related to that of a screw dislocation. A brief discussion is given of the expected diffraction patterns from crystals with various arrays of dislocations.

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