scholarly journals The Texture of a Slate From Nantlle, Caernarvon, North Wales

Texture ◽  
1972 ◽  
Vol 1 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Gerhard Oertel ◽  
Prem P. Phakey
Keyword(s):  
Ultrathin Section ◽  
Orthorhombic Symmetry ◽  
X Ray ◽  
Plane Normal ◽  
North Wales ◽  
Pole Figures ◽  
Sheet Silicate ◽  
Diffraction Patterns ◽  
Local Dissolution ◽  
Mechanical Rotation

A specimen of Cambrian slate from the slate belt in North Wales has been thinned by the ion bombardment technique to produce an ultrathin section with the specimen plane normal to the cleavage plane. This specimen has been investigated with the electron microscope by electron transmission. Selected area diffraction patterns allow identification of individual sheet silicate grains. The pole figures of the basal planes of two sheet silicate minerals, muscovite and chlorite, have been measured with an X-ray pole-figure goniometer and both show an elongated maximum normal to the slaty cleavage, with orthorhombic symmetry. While the preferred orientation could be the result of mechanical rotation of rigid flakes in a deforming matrix, the texture (the overall pattern due to the shapes and sizes of grains and their angular relations to each other) can only be explained if considerable recrystallization is assumed. It is tentatively proposed that local dissolution at points of stress-concentration with simultaneous redeposition of the dissolved material in less stressed regions may have allowed closely packed grains to act as if they were mechanically rotating rigid flakes, yet to accommodate their shapes enough to prevent interlocking.

Comparison of Environmental Secondary Electron Detector (ESD) Imaging and Electron Diffraction Mapping of a Nickel Tape Using the Environmental Scanning Electron Microscope (ESEM)

1999 ◽  
Vol 5 (S2) ◽  
pp. 266-267 ◽  
Author(s):  
R. E. Goddard ◽  
Y. S. Hascicek
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Electron Backscatter Diffraction ◽  
Environmental Scanning ◽  
Entire Sample ◽  
X Ray ◽  
Pole Figures ◽  
Structure Relationship ◽  
Diffraction Patterns ◽  
Scanning Electron

A relationship between the local microstructure (crystallographic orientation) of a sample and an image from a scanning electron microscope (SEM) has been an elusive goal. Being able to show the structure from an exact area and relate it to other data is essential to the understanding of the structure relationship to the entire sample. Conventionally microtextural information of tapes is obtained by using x-ray diffraction and pole figures. But this only provides information about the global texture. The precise location is not well defined. The ability to physically transfer the sample from the x-ray diffractometer to a SEM and accurately state that this is the same area has been impossible. Electron Backscatter Diffraction Patterns (EBSPs) have been obtained in an electron microscope and the exact area in relation to the rest of the sample is determined. Thus larger areas can be defined and put together to form a composite of an entire sample. This, however, may be hard to accomplish in that defined areas for the image scan may be at a different scale than the EBSP scan. A contrast method of imaging in the ESEM using an increased vacuum and the ESD yields a good correlation to mapped areas obtained from EBSPs or also known as backscatter electron Kikuchi diffraction patterns (BEKPs or BKPs).

scholarly journals Crystallographic structural changes of Al1050 under different types of sheet metal rolling

2021 ◽  
Vol 264 ◽  
pp. 05010
Author(s):  
Ravshan Saydakhmedov ◽  
Kudratkhon Bakhadirov
Keyword(s):  
Aluminum Alloy ◽  
Structural Changes ◽  
Analysis Data ◽  
Orthorhombic Symmetry ◽  
Asymmetric Rolling ◽  
X Ray ◽  
Pole Figures ◽  
Before And After ◽  
Euler Space ◽  
Experimental Laboratory

AA1050 aluminum alloy was studied with symmetric and asymmetric rolling in various technological modes of rolling equipment. The rotational speeds of the rolls and the number of passes varied according to the initially foreseen scheme. Rolling of aluminum sheet alloy was carried out on an experimental - laboratory installation. The crystallographic texture before and after rolling was investigated using X-ray diffraction. X-ray analysis data was processed using MTEX MATLAB toolbox 75. The pole figures and the texture of the samples of aluminum alloy on the Euler space are given. It was shown that pole figures obtained based on X-ray analysis of samples, rolled by the traditional way, had orthorhombic symmetry, and the sample texture had typical components of traditional rolling, like Cu (copper), Su (with lower intensity) B (Brass).

scholarly journals Van Der Waals Epitaxial Growth of Bismuth Thin-film on Silicon (111) Substrate by MBE

2021 ◽  
Author(s):  
Chieh Chou ◽  
Po-Siun Wu ◽  
Hao-Hsiung Lin
Keyword(s):  
Thin Film ◽  
Van Der Waals ◽  
Electron Back Scatter Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Pole Figures ◽  
Angle Difference ◽  
Diffraction Patterns ◽  
Φ Angle

Abstract Crystallinity of an 80-nm-thick bismuth thin film grown on Si(111) substrate by MBE was investigated. The highly (0003) textured Bi film contains two twinning domains with different bilayer stacking sequences. The basic lattice parameters c and a as well as b, the bilayer thickness, of the two domains were determined from a series of X-ray diffraction (XRD) measurements, and found that the differences are within 0.1% as compared with those of bulk Bi reported in literature, suggesting that the Bi film has been nearly fully relaxed. From the XRD φ-scans of asymmetric Bi (01-14), (10-15), (11-26) planes and Si (220) plane as well as selected area electron diffraction patterns and electron back scatter diffraction pole figures, we confirmed the well registration between the lattices of Si and Bi lattice, i.e. the ω angle difference between Bi[0003] and Si[111] and the φ angle different between Bi[01-14] and Si[220] are 0.056° and 0.25°, respectively, and thus concluded that the growth is a quasi-van der Waals epitaxy.

Single crystals of bacterial and synthetic poly(3-hydroxyvalerate)

1995 ◽  
Vol 41 (13) ◽  
pp. 297-302 ◽  
Author(s):  
R. H. Marchessault ◽  
E. M. Debzi ◽  
J. F. Revol ◽  
A. Steinbüchel
Keyword(s):  
Electron Diffraction ◽  
Single Crystals ◽  
Unit Cell ◽  
Orthorhombic Symmetry ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Fibre Diffraction ◽  
Diffraction Patterns

Lamellar, folded-chain single crystals of bacterial homopolymer, of synthetic racemic poly(β-hydroxyvalerate) (PHV), and of bacterial poly(β-hydroxybutyrate-co-(β-hydroxyvalerate) (P(HB-co-HV)), with high HV content (superior to 77 mol%) were obtained from dilute ethanolic solutions. They all exhibited the same square shape as opposed to the characteristic lath shape of poly(β-hydroxybutyrate) single crystals and P(HB-co-HV) single crystals with low HV content. The electron diffraction patterns recorded from selected areas of these single crystals were identical and allowed the comparison of our observed basal unit cell parameters with those derived from X-ray fibre diffraction. The results provided a visual and quantitative confirmation of the isodimorphism phenomenon and confirmed the P212121 orthorhombic symmetry. The lower perfection in the morphology of the single crystals from the synthetic PHV homopolymer than in those from the bacterial samples is attributable to a stereoblock segregation during the crystallization according to block chirality.Key words: poly(3-hydroxyvalerate), single crystals, bacterial polyester, electron diffraction, isodimorphism.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Examination of Rabbit Fc Crystals

1968 ◽  
Vol 26 ◽  
pp. 140-141
Author(s):  
J. P. Robinson ◽  
P. G. Lenhert
Keyword(s):  
Molecular Weight ◽  
Flat Plate ◽  
Phosphate Buffer ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
X Ray ◽  
Neutral Ph ◽  
Small Crystals ◽  
Carbon Coated ◽  
Diffraction Patterns

Crystallographic studies of rabbit Fc using X-ray diffraction patterns were recently reported. The unit cell constants were reported to be a = 69. 2 A°, b = 73. 1 A°, c = 60. 6 A°, B = 104° 30', space group P21, monoclinic, volume of asymmetric unit V = 148, 000 A°3. The molecular weight of the fragment was determined to be 55, 000 ± 2000 which is in agreement with earlier determinations by other methods.Fc crystals were formed in water or dilute phosphate buffer at neutral pH. The resulting crystal was a flat plate as previously described. Preparations of small crystals were negatively stained by mixing the suspension with equal volumes of 2% silicotungstate at neutral pH. A drop of the mixture was placed on a carbon coated grid and allowed to stand for a few minutes. The excess liquid was removed and the grid was immediately put in the microscope.

Defect structures of Nb1+αS2 sulfidation scales

1992 ◽  
Vol 50 (1) ◽  
pp. 38-39
Author(s):  
Chuxin Zhou ◽  
L. W. Hobbs
Keyword(s):  
Stacking Faults ◽  
Rhombohedral Structure ◽  
Stacking Sequence ◽  
Defect Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plane Normal ◽  
Lower Case ◽  
Sulfur Layer ◽  
Two Phases

One of the major purposes in the present work is to study the high temperature sulfidation properties of Nb in severe sulfidizing environments. Kinetically, the sulfidation rate of Nb is satisfactorily slow, but the microstructures and non-stoichiometry of Nb1+αS2 challenge conventional oxidation/sulfidation theory and defect models of non-stoichiometric compounds. This challenge reflects our limited knowledge of the dependence of kinetics and atomic migration processes in solid state materials on their defect structures.Figure 1 shows a high resolution image of a platelet from the middle portion of the Nb1+αS2 scale. A thin lamellar heterogeneity (about 5nm) is observed. From X-ray diffraction results, we have shown that Nb1+αS2 scale is principally rhombohedral structure, but 2H-NbS2 can result locally due to stacking faults, because the only difference between these 2H and 3R phases is variation in the stacking sequence along the c axis. Following an ABC notation, we use capital letters A, B and C to represent the sulfur layer, and lower case letters a, b and c to refer to Nb layers. For example, the stacking sequence of 2H phase is AbACbCA, which is a ∼12Å period along the c axis; the stacking sequence of 3R phase is AbABcBCaCA to form an ∼18Å period along the c axis. Intergrowth of these two phases can take place at stacking faults or by a shear in the basal plane normal to the c axis.

Electron diffraction studies of amorphous and polycrystalline thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 118-119
Author(s):  
D J H Cockayne ◽  
D R McKenzie
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Polycrystalline Materials ◽  
Good Resolution ◽  
Scattered Intensity ◽  
Radial Density ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Nitrogen Ion ◽  
Diffraction Patterns

The study of amorphous and polycrystalline materials by obtaining radial density functions G(r) from X-ray or neutron diffraction patterns is a well-developed technique. We have developed a method for carrying out the same technique using electron diffraction in a standard TEM. It has the advantage that studies can be made of thin films, and on regions of specimen too small for X-ray and neutron studies. As well, it can be used to obtain nearest neighbour distances and coordination numbers from the same region of specimen from which HREM, EDS and EELS data is obtained.The reduction of the scattered intensity I(s) (s = 2sinθ/λ ) to the radial density function, G(r), assumes single and elastic scattering. For good resolution in r, data must be collected to high s. Previous work in this field includes pioneering experiments by Grigson and by Graczyk and Moss. In our work, the electron diffraction pattern from an amorphous or polycrystalline thin film is scanned across the entrance aperture to a PEELS fitted to a conventional TEM, using a ramp applied to the post specimen scan coils. The elastically scattered intensity I(s) is obtained by selecting the elastically scattered electrons with the PEELS, and collecting directly into the MCA. Figure 1 shows examples of I(s) collected from two thin ZrN films, one polycrystalline and one amorphous, prepared by evaporation while under nitrogen ion bombardment.

Electron diffraction detection of ordliking in annealed PbTe thin film

1990 ◽  
Vol 48 (4) ◽  
pp. 1018-1019
Author(s):  
Karimat El-Sayed
Keyword(s):  
Thin Film ◽  
Electron Diffraction ◽  
Lead Telluride ◽  
Structural Basis ◽  
Face Centered Cubic ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Stage Process ◽  
Diffraction Patterns ◽  
Face Centered

Lead telluride is an important semiconductor of many applications. Many Investigators showed that there are anamolous descripancies in most of the electrophysical properties of PbTe polycrystalline thin films on annealing. X-Ray and electron diffraction studies are being undertaken in the present work in order to explain the cause of this anamolous behaviour.Figures 1-3 show the electron diffraction of the unheated, heated in air at 100°C and heated in air at 250°C respectively of a 300°A polycrystalline PbTe thin film. It can be seen that Fig. 1 is a typical [100] projection of a face centered cubic with unmixed (hkl) indices. Fig. 2 shows the appearance of faint superlattice reflections having mixed (hkl) indices. Fig. 3 shows the disappearance of thf superlattice reflections and the appearance of polycrystalline PbO phase superimposed on the [l00] PbTe diffraction patterns. The mechanism of this three stage process can be explained on structural basis as follows :

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