Search results for " diffraction"
showing 10 items of 896 documents
Study of plastic deformation modes in zirconium by color image analysis
2004
Abstract Twinning, as a deformation mode, is a complement to slip. This paper deals with the study from a qualitative point of view, as well as from a quantitative one. Besides techniques widely used in materials science studies such as electron backscattered diffraction (EBSD) or X-ray diffraction (XRD), colour image analysis technique are presented here. Its results manage to confirm or complete the ones obtained, thanks to others methods.
Application of delta recycling to electron automated diffraction tomography data from inorganic crystalline nanovolumes
2013
δ Recycling is a simple procedure for directly extracting phase information from Patterson-type functions [Rius (2012). Acta Cryst. A68, 399-400]. This new phasing method has a clear theoretical basis and was developed with ideal single-crystal X-ray diffraction data. On the other hand, introduction of the automated diffraction tomography (ADT) technique has represented a significant advance in electron diffraction data collection [Kolb et al. (2007). Ultramicroscopy, 107, 507-513]. When combined with precession electron diffraction, it delivers quasi-kinematical intensity data even for complex inorganic compounds, so that single-crystal diffraction data of nanometric volumes are now availa…
An Analysis of the Broadening Induced by Beam Damage in Transmission Electron Diffraction Spots from an Oriented Aliphatic Monolayer
1991
We have analysed the progressive changes in diffraction spot shape during prolonged transmission electron diffraction observation of a soap monolayer supported on a thin polymer film. The material used to form the monolayer was cadmium eicosanoate (arachidate). The observed changes cannot be explained at all in terms of the chemical crosslinking which is known to occur as a result of beam damage, nor completely in terms of the strain fields caused by unbound dislocation defects of the crystalline lattice. The most plausible explanation involves the formation of linear dislocation aggregates which resemble grain boundaries but yet which are not linked into a continuous network. The evolution…
Structural characterization of carane derivative stereoisomers - Potent local anesthetics
2002
The paper reports on structural investigation and phase analysis of a newly synthesized potent local anesthetic with chiral molecular structure. Absolute structure and absolute configuration on four chiral centres was determined using microcrystalline single-crystal difracti on with anomalous scattering of X-ray radiation azimuthal scan technique. Phase analysis for new compound (K P23SS) and its epimer (K P23 RS) was carried out using classical and synchrotron radiation powder difraction. Enantiopurity of the bulk material was verifed for both isomers by comparison of experimental and simulated high- resolution powder difraction diagrams. The presence of two new polymorphic phases of K P23…
X-ray powder diffraction pattern for lactitol and lactitol monohydrate
1994
Diffraction patterns were recorded, and unit cell dimensions refined by the least-squares method, for lactitol and lactitol monohydrate. Refined unit cell parameters for lactitol are: a =7.622(1) Å, b = 10.764(2) Å, c = 9.375(1) Å, β= 108.25(1)° in space group P21, and those for lactitol monohydrate a =7.844(1) Å, b = 12.673(2) Å, c = 15.942(2) Å in space group P212121.
In situ analysis of garnet inclusion in diamond using single-crystal X-ray diffraction and X-ray micro-tomography
2012
A single crystal of garnet enclosed in a diamond from the Jericho kimberlite (Slave Craton, Canada) has been investigated using X-ray diffraction and X-ray micro-tomography. The novel experimental approach allowed us to determine the crystal structure of the garnet. The unit-cell edge a and fractional atomic coordinates of oxygen were used to determine the composition via an updated Margules model for garnets. The composition is Pyr(0.41(5))Alm(0.36(7))Gro(0.22(1))Uva(0.01(1)), which is indistinguishable from the eclogitic garnets found in other Jericho diamonds. We also demonstrated that residual pressures on the inclusion of up to 1 GPa do not affect significantly the determination of the…
STACKING-FAULTS IN VERY FINE PALLADIUM PARTICLES SUPPORTED ON PUMICE
1990
By means of an X-ray diffraction study, carried out with best-fitting procedures, of the asymmetry and peak maximum shifts of some reflections, stacking-faults in the FCC lattice of very fine palladium particles supported on pumice were detected using the Warren-Wagner-Cohen theoretical approach.
II–VI and II1−xMnxVI semiconductor nanocrystals formed by the pressure cycle method
2005
II–VI and II1−x Mn x VI nanocrystals were prepared by the pressure cycle method using the Paris–Edinburgh cell. The recovered samples are nanocrystals in the cubic phase zinc-blend (ZB) structure and were characterized using transmission electron microscopy, electron diffraction, X-ray diffraction and Raman scattering. Transmission electron micrographs show that these nanocrystals are nearly spherical with diameters ranging from 20 to 50 nm depending on the sample under investigation. The Raman scattering measurements confirm the existence of II–VI nanocrystals in the cubic phase (ZB). The magnetic properties of Cd0.5Mn0.5Te nanoparticles were found to vary with the particle size and were d…
Structure analysis of titanate nanorods by automated electron diffraction tomography
2011
A hitherto unknown phase of sodium titanate, NaTi3O6(OH)·2H2O, was identified as the intermediate species in the synthesis of TiO2 nanorods. This new phase, prepared as nanorods, was investigated by electron diffraction, X-ray powder diffraction, thermogravimetric analysis and high-resolution transmission electron microscopy. The structure was determined ab initio using electron diffraction data collected by the recently developed automated diffraction tomography technique. NaTi3O6(OH)·2H2O crystallizes in the monoclinic space group C2/m. Corrugated layers of corner- and edge-sharing distorted TiO6 octahedra are intercalated with Na+ and water of crystallization. The nanorods are typically …
Using FOCUS to solve zeolite structures from three-dimensional electron diffraction data
2013
The programFOCUS[Grosse-Kunstleve, McCusker & Baerlocher (1997).J. Appl. Cryst.30, 985–995] was originally developed to solve zeolite structures from X-ray powder diffraction data. It uses zeolite-specific chemical information (three-dimensional 4-connected framework structure with known bond distances and angles) to supplement the diffraction data. In this way, it is possible to compensate, at least in part, for the ambiguity of the reflection intensities resulting from reflection overlap, and the program has proven to be quite successful. Recently, advances in electron microscopy have led to the development of automated diffraction tomography (ADT) and rotation electron diffraction (R…