Structural Studies by X-Ray and Neutron Diffraction Techniques on Mechanically Alloyed Powders

1992 ◽  
Vol 88-90 ◽  
pp. 703-710 ◽  
Author(s):  
Giorgio Cocco
Keyword(s):  
Neutron Diffraction ◽  
Structural Studies ◽  
Mechanically Alloyed ◽  
X Ray

Structural Studies of Hydrogen Storage Alloys using X-ray/Neutron Diffraction and Total Scattering

2011 ◽  
Vol 1334 ◽  
Author(s):  
Yumiko Nakamura ◽  
Hyunjeong Kim ◽  
Saishun Yamazaki ◽  
Kouji Sakaki ◽  
Thomas Proffen ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Pair Distribution Function ◽  
Ex Situ ◽  
Structural Studies ◽  
Hydrogen Storage Alloys ◽  
Total Scattering ◽  
X Ray ◽  
Local Structures ◽  
Rich Domain

ABSTRACTCrystal and local structures and hydrogen occupation of Mg containing materials, (Mg,Ca)Nix (x = 2, 3) intermetallic compounds and a MgCo metastable alloy, have been investigated using in-situ and ex-situ X-ray/neutron diffraction and total scattering.A C15 Laves phase (Mg0.67Ca0.33)Ni2 showed isotropic lattice expansion upon hydrogenation. Mg and Ca occupied the same site randomly. It has two hydrogen sites, Mg(Ca)2Ni2 site and M(Ca)Ni3 site.Mg2CaNi9, MgCa2Ni9, and CaNi3 compounds consisted of MgZn2-type (Mg,Ca)2Ni4 cell and CaCu5-type CaNi5 cell stacking along the c-axis. The MgZn2-type cell was occupied by only Mg in Mg2CaNi9, and randomly occupied by both Mg and Ca in MgCa2Ni9. Expansion of this cell strongly depended on the composition: larger expansion was observed in a Ca-rich composition.Local structure of a Mg-Co alloy synthesized by mechanical alloying has been studied using the PDF (Pair Distribution Function) method. The analysis suggested that material contained two 1-2 nm domains with different compositions and local structures, i.e. Mg-rich and Co-rich domains, and hydrogen was located only in the Mg-rich domain.

The interplay between X-ray crystallography, neutron diffraction, image reconstruction, organo-metallic chemistry and biochemistry in structural studies of ribosomes

Biochimie ◽  
1991 ◽  
Vol 73 (7-8) ◽  
pp. 879-886 ◽  
Author(s):  
M. Eisenstein ◽  
R. Sharon ◽  
Z. Berkovitch-Yellin ◽  
H.S. Gewitz ◽  
S. Weinstein ◽  
...  
Keyword(s):  
Image Reconstruction ◽  
Neutron Diffraction ◽  
Structural Studies ◽  
Diffraction Image ◽  
X Ray ◽  
X Ray Crystallography

Structural studies of water in hydrophilic and hydrophobic mesoporous silicas: An x-ray and neutron diffraction study at 297 K

2011 ◽  
Vol 134 (6) ◽  
pp. 064509 ◽  
Author(s):  
J. Jelassi ◽  
T. Grosz ◽  
I. Bako ◽  
M.-C. Bellissent-Funel ◽  
J. C. Dore ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Diffraction Study ◽  
Neutron Diffraction Study ◽  
Mesoporous Silicas ◽  
Structural Studies ◽  
X Ray

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Texture measurements in Al2O3 using BEKP

1994 ◽  
Vol 52 ◽  
pp. 608-609
Author(s):  
M. D. Vaudin ◽  
J. P. Cline
Keyword(s):  
Neutron Diffraction ◽  
Rapid Method ◽  
Crystallographic Orientation ◽  
Specimen Surface ◽  
X Ray Diffraction ◽  
Anisotropic Crystal ◽  
X Ray ◽  
Verification Method ◽  
Crystal Properties ◽  
Backscattered Electron

The study of preferred crystallographic orientation (texture) in ceramics is assuming greater importance as their anisotropic crystal properties are being used to advantage in an increasing number of applications. The quantification of texture by a reliable and rapid method is required. Analysis of backscattered electron Kikuchi patterns (BEKPs) can be used to provide the crystallographic orientation of as many grains as time and resources allow. The technique is relatively slow, particularly for noncubic materials, but the data are more accurate than any comparable technique when a sufficient number of grains are analyzed. Thus, BEKP is well-suited as a verification method for data obtained in faster ways, such as x-ray or neutron diffraction. We have compared texture data obtained using BEKP, x-ray diffraction and neutron diffraction. Alumina specimens displaying differing levels of axisymmetric (0001) texture normal to the specimen surface were investigated.BEKP patterns were obtained from about a hundred grains selected at random in each specimen.

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