Search results for "diffraction"
showing 10 items of 1584 documents
Combining EXAFS and XRay Powder Diffraction to Solve Structures Containing Heavy Atoms
2005
Determination of structures using x-ray powder diffraction is complicated if the reflection intensities are mainly influenced by the scattering from heavy atoms and the atomic coordinates of light atoms remain uncertain. A method like EXAFS, which is sensitive to short range order, gives reliable atomic distances in the surroundings of heavy atoms with a precision of ±0.02 A. The probability for obtaining the complete structure from x-ray powder diffraction increases if one includes parameters derived from EXAFS measurements as restraints during the procedure of structure solving. We demonstrate the potential of combining EXAFS and x-ray powder diffraction by solving the structure UO2[H2AsO…
The crystallisation of copper(ii) phenylphosphonates
2016
The crystal structures and syntheses of four different copper(II) phenylphosphonates, the monophenylphosphonates α-, β-, and γ-Cu(O3PC6H5)·H2O (α-CuPhPmH (1) β-CuPhPmH (2) and γ-CuPhPmH (3)), and the diphosphonate Cu(HO3PC6H5)2·H2O (CuPhP2mH (4)), are presented. The compounds were synthesized from solution at room temperature, at elevated temperature, under hydrothermal conditions, and mechanochemical conditions. The structures of α-CuPhPmH (1) and CuPhP2mH (4) were solved from powder X-ray diffraction data. The structure of β-CuPhPmH (2) was solved by single crystal X-ray analysis. The structures were validated by extended X-ray absorption fine structure (EXAFS) and DTA analyses. Disorder …
Seed layer technique for high quality epitaxial manganite films
2016
We introduce an innovative approach to the simultaneous control of growth mode and magnetotransport properties of manganite thin films, based on an easy-to-implement film/substrate interface engineering. The deposition of a manganite seed layer and the optimization of the substrate temperature allows a persistent bi-dimensional epitaxy and robust ferromagnetic properties at the same time. Structural measurements confirm that in such interface-engineered films, the optimal properties are related to improved epitaxy. A new growth scenario is envisaged, compatible with a shift from heteroepitaxy towards pseudo-homoepitaxy. Relevant growth parameters such as formation energy, roughening tempera…
Fractal approach in petrology: Combining ultra small angle (USANS), and small angle neutron scattering (SANS)
2000
Ultra small angle neutron scattering instruments have recently covered the gap between the size resolution available with conventional intermediate angle neutron scattering and small angle neutron scattering instruments on one side and optical microscopy on the other side. Rocks showing fractal behavior in over two decades of momentum transfer and seven orders of magnitude of intensity are examined and fractal parameters are extracted from the combined USANS and SANS curves.
A high pressure gas target system for the determination of absolute electron scattering cross sections
1979
A high pressure gas target system is described, which is suitable for measurements of absolute electron scattering cross sections and for high resolution electron scattering experiments at medium energies. Details of design and construction are given and special investigations are discussed with respect to straggling effects that take place in the walls and in the gases, and to changes in the gas density, due to heating by the electron beam.
The Elusive Structure of Magadiite, Solved by 3D Electron Diffraction and Model Building
2021
In addition to a great swelling ability, layered silicates also allow the functionalization of their interlayer region to form various robust green materials that are used as CO2 adsorbents, drug c...
Structural Relationships between Floating and Deposited Monolayers of Docosanoic Acid
1991
Floating docosanoic acid (behenic acid) monolayers in the SmI and SmH phase were deposited with the Langmuir-Blodgett technique onto thin polymethylmethacrylate (PMMA) and Formvar substrates and investigated by electron diffraction. The molecular packing of the monolayers on the substrates vary from those on the water surface and are different for different substrates. On PMMA four phases (H, SmB, SmI, SmL) have been identified, depending on the deposition conditions. While SmB and SmI are known for docosanoic acid on the water surface, H and SmL have only been unequivocally observed in other substances or on other subphases. The monolayer structure on Formvar was identical under all deposi…
Synthesis of a New Copper-Azobenzene Dicarboxylate Framework in the Form of Hierarchical Bulk Solids and Thin Films without and with Patterning
2011
Reaction of copper(II) acetate with azobenzene-4,4′-dicarboxylic acid results in the formation of a metal–organic framework with the unexpected stoichiometry of Cu(II):ligand of 2:1. The bulk synthesis results in microspheres assembled from either nanobricks or nanoflakes, depending on the ratio of the reactants in solution. While the former behaves like a bulk solid with clear reflections in the X-ray and electron diffraction experiments, the latter obviously is dominated by surface effects, with a significant fraction of slightly expanded elemental cells and a significantly increased outer surface area. The material could also be deposited on a variety of surfaces using a stepwise layer-b…
Influence of plastic deformation on the microstructure and corrosion behaviour of Ti–10Mo–4Zr and Ti–6Al–4V alloys in the Ringer’s solution at 37°C
2015
Abstract The influence of plastic deformation on the microstructure and passivity of Ti–6Al–4V and Ti–10Mo–4Zr is studied. The content of titanium-based compounds in the passive film formed on the alloys increases under straining. In the region where necking occurs, the β-phase content drops in Ti–6Al–4V. The grain orientation spread increases with increasing strain. The quality index of EBSD maps is affected on Ti–10Mo–4Zr (dislocation structures along preferential orientations). The corrosion behaviour is investigated in the Ringer’s solution (37 °C). Results obtained in the anodic and cathodic domains are discussed considering changes described previously.
Efficient Gas Separation and Transport Mechanism in Rare Hemilabile Metal–Organic Framework
2019
Understanding/visualizing the established interactions between gases and adsorbents is mandatory to implement better performance materials in adsorption/separation processes. Here we report the unique behavior of a rare example of a hemilabile chiral three-dimensional metal–organic framework (MOF) with an unprecedented qtz-e-type topology, with formula CuII2(S,S)-hismox·5H2O (1) (hismox = bis[(S)-histidine]oxalyl diamide). 1 exhibits a continuous and reversible breathing behavior, based on the hemilability of carboxylate groups from l-histidine. In situ powder (PXRD) and single crystal X-ray diffraction (SCXRD) using synchrotron radiation allowed us to unveil the crystal structures of four …