A Computer Method for Facilitating Rapid Quantitative Use of the Philips 300 Goniometer Stage

1973 ◽  
Vol 31 ◽  
pp. 100-101
Author(s):  
Wen-Shian Tzeng ◽  
P. R. Strutt
Keyword(s):  
Stacking Faults ◽  
Thin Foil ◽  
Atomic Displacement ◽  
Computer Method ◽  
Crystallographic Structure ◽  
Polycrystalline Specimen ◽  
Planar Defects ◽  
Precise Characterization ◽  
Actual Computer

A computer method has been developed which facilitates the rapid use of the Philips 300 goniometer stage for quantitative diffraction contrast analyses of lattice imperfections in thin-foil specimens. Using this method it is a straightforward matter to obtain 20 (or even more) different two beam conditions on a single randomly oriented grain in a polycrystalline specimen. Furthermore, the method avoids ambiguity in determining the sense of the atomic displacement of planar defects. Thus it is particularly useful for the precise characterization of stacking faults and anti-phase boundaries. The generality of the method enables it to be used for thin-foil specimens with any crystallographic structure. Basic steps involved in the actual computer program are briefly summarized.

Planar Defects in Small Particles

1985 ◽  
Vol 43 ◽  
pp. 392-393
Author(s):  
R. Pérez ◽  
M. Avalos-Borja
Keyword(s):  
Stacking Faults ◽  
Particle Growth ◽  
Small Particles ◽  
Planar Defects ◽  
Metallic Particles ◽  
Weak Beam ◽  
Transmission Electron ◽  
Imaging Conditions

Transmission electron microscope techniques have been extensively used in the determination of the morphology of fine metallic particles. These techniques have been of particular importance in obtaining topographical information during particle growth and sintering. Thus, for example, it has been found that some of the most elementary forms consist of half cubo-octahedral units with (111) faces and (100) basis. Furthermore, full cubo-octahedral units have also been found, some of them showing stacking faults (SF) through the particles.It is important to point out that the characterization of this type of planar defects in small metallic particles has commonly been based on geometrical con. siderations. Additionally, the imaging conditions which have been used are the so-called weak beam (WB) diffraction conditions. Recent investigations have shown, on the other hand, that SF images under WB conditions present serious inconveniences, for example, contrast asymmetries in SF images which are not totally explained. Another difficulty with these WB fault images arises from twin boundaries which display image contrast similar to SF when a common reflection is strongly excited.

Microstructural characterization of CoPtCr/Cr thin film disks by cross-section TEM and elongated probe micro-diffraction

1991 ◽  
Vol 49 ◽  
pp. 762-763
Author(s):  
M.A. Parker ◽  
K.E. Johnson ◽  
C. Hwang ◽  
A. Bermea
Keyword(s):  
Magnetic Recording ◽  
Electron Probe ◽  
Microstructural Characterization ◽  
Crystallographic Structure ◽  
Recording Media ◽  
Layer By Layer ◽  
Cross Sectional ◽  
New Techniques ◽  
Polished Side

We have reported the dependence of the magnetic and recording properties of CoPtCr recording media on the thickness of the Cr underlayer. It was inferred from XRD data that grain-to-grain epitaxy of the Cr with the CoPtCr was responsible for the interaction observed between these layers. However, no cross-sectional TEM (XTEM) work was performed to confirm this inference. In this paper, we report the application of new techniques for preparing XTEM specimens from actual magnetic recording disks, and for layer-by-layer micro-diffraction with an electron probe elongated parallel to the surface of the deposited structure which elucidate the effect of the crystallographic structure of the Cr on that of the CoPtCr.XTEM specimens were prepared from magnetic recording disks by modifying a technique used to prepare semiconductor specimens. After 3mm disks were prepared per the standard XTEM procedure, these disks were then lapped using a tripod polishing device. A grid with a single 1mmx2mm hole was then glued with M-bond 610 to the polished side of the disk.

Crystallographic Characterization of Dislocation Loops in Irradiated Tungsten

1968 ◽  
Vol 26 ◽  
pp. 290-291
Author(s):  
Robert C. Rau
Keyword(s):  
Electron Microscope ◽  
Ambient Temperature ◽  
Dislocation Loops ◽  
Polycrystalline Specimen ◽  
Post Irradiation ◽  
Neutron Fluences

Previous work has shown that post-irradiation annealing, at temperatures near 1100°C, produces resolvable dislocation loops in tungsten irradiated to fast (E > 1 MeV) neutron fluences of about 4 x 1019 n/cm2 or greater. To crystallographically characterize these loops, tilting experiments were carried out in the electron microscope on a polycrystalline specimen which had been irradiated to 1.5 × 1021 n/cm2 at reactor ambient temperature (∼ 70°C), and subseouently annealed for 315 hours at 1100°C. This treatment produced large loops averaging 1000 Å in diameter, as shown in the micrographs of Fig. 1. The orientation of this grain was near (001), and tilting was carried out about axes near [100], [10] and [110].

scholarly journals Optically Switchable MeV Ion/Electron Accelerator

2021 ◽  
Vol 11 (12) ◽  
pp. 5424
Author(s):  
Itamar Cohen ◽  
Yonatan Gershuni ◽  
Michal Elkind ◽  
Guy Azouz ◽  
Assaf Levanon ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Electron Accelerator ◽  
Energy Charge ◽  
Thin Foil ◽  
Main Pulse ◽  
Experimental Characterization ◽  
Particle Beams ◽  
Laser Accelerators

The versatility of laser accelerators in generating particle beams of various types is often promoted as a key applicative advantage. These multiple types of particles, however, are generated on vastly different irradiation setups, so that switching from one type to another involves substantial mechanical changes. In this letter, we report on a laser-based accelerator that generates beams of either multi-MeV electrons or ions from the same thin-foil irradiation setup. Switching from generation of ions to electrons is achieved by introducing an auxiliary laser pulse, which pre-explodes the foil tens of ns before irradiation by the main pulse. We present an experimental characterization of the emitted beams in terms of energy, charge, divergence, and repeatability, and conclude with several examples of prospective applications for industry and research.

Highly precise characterization of the hydration state upon thermal denaturation of human serum albumin using a 65 GHz dielectric sensor

2020 ◽  
Vol 22 (35) ◽  
pp. 19468-19479 ◽  
Author(s):  
Keiichiro Shiraga ◽  
Mako Urabe ◽  
Takeshi Matsui ◽  
Shojiro Kikuchi ◽  
Yuichi Ogawa
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Thermal Denaturation ◽  
Hydration Water ◽  
Biological Functions ◽  
Dielectric Sensor ◽  
Hydration State ◽  
Precise Characterization

The biological functions of proteins depend on harmonization with hydration water surrounding them.

Distorted chiolite crystal structures of α-Na5M3F14 (M=Cr,Fe,Ga) studied by X-ray powder diffraction

2003 ◽  
Vol 18 (2) ◽  
pp. 128-134 ◽  
Author(s):  
A. Le Bail ◽  
A.-M. Mercier
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Rietveld Refinements ◽  
Space Group ◽  
X Ray ◽  
Precise Characterization

The crystal structures of the chiolite-related room temperature phases α-Na5M3F14 (MIII=Cr,Fe,Ga) are determined. For all of them, the space group is P21/n, Z=2; a=10.5096(3) Å, b=7.2253(2) Å, c=7.2713(2) Å, β=90.6753(7)° (M=Cr); a=10.4342(7) Å, b=7.3418(6) Å, c=7.4023(6) Å, β=90.799(5)° (M=Fe), and a=10.4052(1) Å, b=7.2251(1) Å, c=7.2689(1), β=90.6640(4)° (M=Ga). Rietveld refinements produce final RF factors 0.036, 0.033, and 0.035, and RWP factors, 0.125, 0.116, and 0.096, for MIII=Cr, Fe, and Ga, respectively. The MF6 polyhedra in the defective isolated perovskite-like layers deviate very few from perfect octahedra. Subtle octahedra tiltings lead to the symmetry decrease from the P4/mnc space group adopted by the Na5Al3F14 chiolite aristotype to the P21/n space group adopted by the title series. Facile twinning precluded till now the precise characterization of these compounds.

Simple and Precise Characterization of Differential Modal Group Delay arising in Few-Mode Fiber

2021 ◽  
Author(s):  
Zhe Fu ◽  
Junjie Zhang ◽  
Ziheng Zhang ◽  
Songnian Fu ◽  
Yuwen Qin ◽  
...  
Keyword(s):  
Group Delay ◽  
Precise Characterization ◽  
Modal Group

Crystalline perfection of chemical vapor deposited diamond films

1990 ◽  
Vol 5 (8) ◽  
pp. 1591-1594 ◽  
Author(s):  
A. V. Hetherington ◽  
C. J. H. Wort ◽  
P. Southworth
Keyword(s):  
Grain Boundaries ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Stacking Faults ◽  
Chemical Vapor ◽  
Cvd Diamond ◽  
Growth Conditions ◽  
Crystalline Perfection ◽  
Planar Defects ◽  
Chemical Vapor Deposited

The crystalline perfection of microwave plasma assisted chemical vapor deposited (MPACVD) diamond films grown under various conditions has been examined by TEM. Most CVD diamond films thus far reported contain a high density of defects, predominantly twins and stacking faults on {111} planes. We show that under appropriate growth conditions, these planar defects are eliminated from the center of the crystallites, and occur only at grain boundaries where the growing crystallites meet.

scholarly journals Stacking faults in β-Ga2O3 crystals observed by X-ray topography

2018 ◽  
Vol 51 (5) ◽  
pp. 1372-1377 ◽  
Author(s):  
Hirotaka Yamaguchi ◽  
Akito Kuramata
Keyword(s):  
Crystal Growth ◽  
Partial Dislocation ◽  
Structural Model ◽  
Stacking Faults ◽  
Elastic Instability ◽  
Planar Defects ◽  
X Ray ◽  
Self Energy ◽  
Unique Structural Feature ◽  
Edge Component

Planar defects in (\overline{2}01)-oriented β-Ga2O3 wafers were studied using X-ray topography. These planar defects were rectangular with dimensions of 50–150 µm, and the X-ray topography analysis revealed that they were stacking faults (SFs) enclosed by a single partial dislocation loop on the (\overline{2}01) plane. The SF formation was found to be supported by a unique structural feature of the (\overline{2}01) plane as a slip plane; the (\overline{2}01) plane consists of close-packed octahedral Ga and O layers, allowing slips to form SFs. Vacancy arrays along the b axis in the octahedral Ga layer reduce the self-energy of the edge component in the partial dislocation extending along the b axis. It is speculated that the SFs occur during the crystal growth process for unknown reasons and then recover owing to elastic instability after initially increasing in size as crystal growth proceeds. Based on this analysis, a structural model for the SFs is proposed.

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