scholarly journals On the Stability of 3C-SiC Single Crystals at High Temperatures

2012 ◽  
Vol 717-720 ◽  
pp. 493-496
Author(s):  
Deborah Dompoint ◽  
Irina G. Galben-Sandulache ◽  
Alexandre Boulle ◽  
Didier Chaussende ◽  
Dominique Eyidi ◽  
...  
Keyword(s):  
Single Crystals ◽  
Volume Fraction ◽  
Diffuse Intensity ◽  
X Ray ◽  
Partial Dislocations ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
The Stability ◽  
Kinetics Of ◽  
Evolution With Time

The 3C-6H polytypic transition in 3C-SiC single crystals is studied by means of diffuse X-ray scattering (DXS) coupled with transmission electron microscopy (TEM). TEM reveals that the partially transformed SiC crystals contain regions of significantly transformed SiC (characterized by a high density of stacking faults) co-existing with regions of pure 3C-SiC. The simulation of the diffuse intensity allows to determine both the volume fraction of transformed material and the transformation level within these regions. It is further shown that the evolution with time and temperature of the transition implies the multiplication and glide of partial dislocations, the kinetics of which are quantified by means of DXS.

scholarly journals Kinetics of the 3C-6H polytypic transition in 3C-SiC single crystals: A diffuse X-ray scattering study

2011 ◽  
Vol 110 (5) ◽  
pp. 053508 ◽  
Author(s):  
D. Dompoint ◽  
A. Boulle ◽  
I. Galben-Sandulache ◽  
D. Chaussende ◽  
L. T. M. Hoa ◽  
...  
Keyword(s):  
Single Crystals ◽  
X Ray ◽  
X Ray Scattering ◽  
Scattering Study ◽  
Kinetics Of ◽  
Ray Scattering

Observations of G-P Zone Reversion in Al-Zn-Mg Alloys by Small-Angle X-Ray Scattering and Transmission Electron Microscopy

1965 ◽  
Vol 9 ◽  
pp. 59-73
Author(s):  
R. W. Gould ◽  
E. A. Starke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Small Angle ◽  
Volume Fraction ◽  
Magnesium Content ◽  
Mg Alloys ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Ray Scattering

AbstractA study of the reversion process in Al-Zn-Mg alloys has been made using small-angle X-ray scattering and transmission electron microscopy techniques. The rate and mode of Guinier-Preston zone dissolutions was investigated as a function of magnesium content, prior zone radius, and reversion temperature. Results indicate that in this system the reversion process is characterized by the preferential dissolution of the smallest G-P zones present after cold aging with a corresponding decrease in the volume fraction of zones. The amount of reversion at a specific temperature is dependent on magnesium content, however, the rate of reversion is independent of magnesium content.

scholarly journals Evolution of Helium with Temperature in Neutron-Irradiated10B-Doped Aluminum by Small-Angle X-Ray Scattering

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Chaoqiang Huang ◽  
Guanyun Yan ◽  
Qiang Tian ◽  
Guangai Sun ◽  
Bo Chen ◽  
...  
Keyword(s):  
Small Angle ◽  
Volume Fraction ◽  
X Ray ◽  
Helium Bubbles ◽  
Saxs Measurement ◽  
X Ray Scattering ◽  
Arc Melting ◽  
Transmission Electron ◽  
Melting Technique ◽  
Ray Scattering

Helium status is the primary effect of material properties under radiation.10B-doped aluminum samples were prepared via arc melting technique and rapidly cooled with liquid nitrogen to increase the boron concentration during the formation of compounds. An accumulated helium concentration of ~6.2 × 1025 m−3was obtained via reactor neutron irradiation with the reaction of10B(n,α)7Li. Temperature-stimulated helium evolution was observed via small-angle X-ray scattering (SAXS) and was confirmed via transmission electron microscopy (TEM). The SAXS results show that the volume fraction of helium bubbles significantly increased with temperature. The amount of helium bubbles reached its maximum at 600°C, and the most probable diameter of the helium bubbles increased with temperature until 14.6 nm at 700°C. A similar size distribution of helium bubbles was obtained via TEM after in situ SAXS measurement at 700°C, except that the most probable diameter was 3.9 nm smaller.

Study of the Stability of 3C-SiC Single Crystals Using High-Resolution Diffuse X-Ray Scattering

2010 ◽  
Author(s):  
D. Dompoint ◽  
A. Boulle ◽  
I. G. Galben-Sandulache ◽  
D. Chaussende ◽  
Gabriel Ferro ◽  
...  
Keyword(s):  
High Resolution ◽  
Single Crystals ◽  
X Ray ◽  
X Ray Scattering ◽  
The Stability ◽  
Ray Scattering

scholarly journals Using crystallography tools to improve vaccine formulations

IUCrJ ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Márcia Carvalho de Abreu Fantini ◽  
Cristiano Luis Pinto Oliveira ◽  
José Luiz de Souza Lopes ◽  
Tereza da Silva Martins ◽  
Milena Apetito Akamatsu ◽  
...  
Keyword(s):  
Oral Vaccine ◽  
Porous Silica ◽  
Protein Antigens ◽  
X Ray ◽  
X Ray Crystallography ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
X Ray Imaging ◽  
The Stability ◽  
Phase Contrast Tomography

This article summarizes developments attained in oral vaccine formulations based on the encapsulation of antigen proteins inside porous silica matrices. These vaccine vehicles show great efficacy in protecting the proteins from the harsh acidic stomach medium, allowing the Peyer's patches in the small intestine to be reached and consequently enhancing immunity. Focusing on the pioneering research conducted at the Butantan Institute in Brazil, the optimization of the antigen encapsulation yield is reported, as well as their distribution inside the meso- and macroporous network of the porous silica. As the development of vaccines requires proper inclusion of antigens in the antibody cells, X-ray crystallography is one of the most commonly used techniques to unveil the structure of antibody-combining sites with protein antigens. Thus structural characterization and modelling of pure antigen structures, showing different dimensions, as well as their complexes, such as silica with encapsulated hepatitis B virus-like particles and diphtheria anatoxin, were performed using small-angle X-ray scattering, X-ray absorption spectroscopy, X-ray phase contrast tomography, and neutron and X-ray imaging. By combining crystallography with dynamic light scattering and transmission electron microscopy, a clearer picture of the proposed vaccine complexes is shown. Additionally, the stability of the immunogenic complex at different pH values and temperatures was checked and the efficacy of the proposed oral immunogenic complex was demonstrated. The latter was obtained by comparing the antibodies in mice with variable high and low antibody responses.

Crystal structure and morphology of syndiotactic polypropylene single crystals

1996 ◽  
Vol 54 ◽  
pp. 172-173
Author(s):  
Jenny Z. Bu ◽  
Stephen Z. D. Cheng
Keyword(s):  
Crystal Structure ◽  
Single Crystals ◽  
Syndiotactic Polypropylene ◽  
X Ray ◽  
Molecular Weights ◽  
Structure And Morphology ◽  
Molecular Weight Distributions ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
New Development

In the past several years there have been an increased interest in the crystal structure and morphology of s-PP due to the new development of homogeneous metallocene catalysts which can produce s-PP having a high stercoregularity. In this research, the crystal structure and morphology of s-PP single crystals grown from the melt were investigated. A series of ten fractions of s-PP was studied with dillcrent molecular weights ranging from 10,300 to 234,000 (g/mol). These fractions all possess narrow molecular weight distributions (around 1.1-1.2) and high syndiotacticitics ([r]˜95%). The main techniques employed including transmission electron microscopy (T1:M), atomic: lorcc microscopy (AFM), wide-angle X-ray diflraction (WAXD), and small-angle X-ray scattering (SAXS).

Cavity Evolution During Tensile Creep of Si3N4

1992 ◽  
Vol 287 ◽  
Author(s):  
William Luecke ◽  
S. M. Wiederhorn ◽  
B. J. Hockey ◽  
G. G. Long
Keyword(s):  
Electron Microscopy ◽  
Volume Fraction ◽  
Tensile Creep ◽  
Cavity Volume ◽  
Density Measurements ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Total Volume Fraction ◽  
Cavity Evolution

ABSTRACTWe have characterized the evolution of cavities during tensile creep of a Y2O3-hot isostatically pressed Si3N4, using precision density measurements, small-angle x-ray scattering (SAXS) and transmission electron microscopy (TEM). The cavities are bimodally distributed in size. Lenticular, 200 nm-size cavities are common, and lie primarily on two-grain boundaries. Irregularly shaped 500-1000 nm-size cavities are rare and lie at multi-grain junctions, but comprise approximately half of the total volume fraction of cavities. Although the material shows a continuous decrease in strain rate with strain, the cavity volume fraction evolves linearly with strain. Cavities account for approximately 85% of the total strain at any point during creep.

Sign in / Sign up

Export Citation Format

Share Document