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Powder Diffraction Measurements (powder + diffraction_measurement)
Selected AbstractsPerformance of a new furnace for high-resolution synchrotron powder diffraction up to 1900,K: application to determine electron density distribution of the cubic CaTiO3 perovskite at 1674,KJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2004Masatomo Yashima Accurate crystal structure analysis at high temperatures is an important challenge in science and technology. A new electric furnace for the measurement of high-resolution (,d/d = 0.03%) synchrotron radiation powder diffraction profiles from materials at high temperatures (up to 1900,K in air) has been designed and fabricated. This furnace consists of a ceramic refractory with MoSi2 heaters, an aluminium body cooled by flowing water, and a sample stage with a spinner and a controller for sample-height adjustment. In situ synchrotron powder diffraction measurement for a calcium titanate perovskite specimen at 1674,K has been performed using the furnace at beamline 3A of the Photon Factory. The electron density distribution of the cubic perovskite at 1674,K was successfully obtained using a combination of Rietveld refinement, the maximum-entropy method (MEM) and MEM-based pattern-fitting techniques. The Ti atoms exhibit covalent bonding with the O atoms in the cubic CaTiO3 perovskite at this temperature, while the Ca atoms are ionic. These results indicate that the new furnace yields high-quality data for accurate crystal structure analysis. [source] Supramolecular Assembly of Perylene Bisimide with , -Cyclodextrin Grafts as a Solid-State Fluorescence Sensor for Vapor DetectionADVANCED FUNCTIONAL MATERIALS, Issue 14 2009Yu Liu Abstract A nanoscopic supramolecular aggregate is constructed from perylene bisimide-bridged bis-(permethyl- , -cyclodextrins) 1 via ,,, stacking interactions. Its self-assembly behavior in organic and aqueous solutions is investigated by UV,Vis, fluorescence, and 1H NMR spectroscopy. Transmission electron microscopy and scanning electron microscopy images show the 1D nanorod aggregation of 1, which is birefringent under crossed polarizer conditions and strongly fluorescent as depicted in the fluorescence microscopy image. X-ray powder diffraction measurements indicate that 1 forms a well-ordered crystalline arrangement with a ,,, stacking distance of 4.02,Å. Furthermore, the solid-state fluorescence sensing is explored by utilizing the poly(vinylidene fluoride) membrane-embedded 1, giving that 1, as a novel vapor detecting material, can probe several kinds of volatile organic compounds and, especially, exhibits high sensitivity to organic amines. [source] The small-angle and wide-angle X-ray scattering set-up at beamline BL9 of DELTAJOURNAL OF SYNCHROTRON RADIATION, Issue 3 2007Christina Krywka The multi-purpose experimental endstation of beamline BL9 at the Dortmund Electron Accelerator (DELTA) is dedicated to diffraction experiments in grazing-incidence geometry, reflectivity and powder diffraction measurements. Moreover, fluorescence analysis and inelastic X-ray scattering experiments can be performed. Recently, a new set-up for small-angle and wide-angle X-ray scattering utilizing detection by means of an image-plate scanner was installed and is described in detail here. First small-angle X-ray scattering experiments on aqueous solutions of lysozyme with different cosolvents and of staphylococcal nuclease are discussed. The application of the set-up for texture analysis is emphasized and a study of the crystallographic texture of natural bio-nanocomposites, using lobster and crab cuticles as model materials, is presented. [source] ChemInform Abstract: Pressure-Induced Spin-State Transition in BiCoO3.CHEMINFORM, Issue 41 2010Kengo Oka Abstract Synchrotron X-ray and neutron powder diffraction measurements show that the structure of the title compound changes from a polar tetragonal PbTiO3 -type (space group P4mm) to a centrosymmetric orthorhombic GdFeO3 -type (space group Pbnm) above 3 GPa with a large volume decrease of 13% at room temperature revealing a spin-state change. [source] | ||||||||||