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  • 1
    Electronic Resource
    Electronic Resource
    Structural studies of an organic liquid through the glass transition (1996)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 7783-7794 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have performed neutron diffraction experiments on deuterated propylene glycol, an organic glass former, at temperatures ranging from where its dynamical response approaches that of normal liquids to below the point where relaxation times appear to diverge. Our studies extend over a very broad range of scattering wave vector (0.01〈Q〈30 A(ring)−1). In contrast to models which predict clustering, we find no evidence in the liquid at any temperature for heterogeneities large on molecular scales. However, we do note subtle changes at shorter lengths. Using molecular dynamics simulations to model our results, we identify these changes with increasing density and increasing orientational order induced by hydrogen bonding in the liquid as it cools. Analysis of the orientational correlations between molecules reveals a strong dependence on their relative positions. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.472561
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  • 2
    Electronic Resource
    Electronic Resource
    Atomic-Scale Structure of Polymer-Route Si-C-O Fibers Observed by Synchrotron Radiation X-Ray Diffraction (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 352 (Aug. 2007), p. 65-68 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The atomic scale structure of amorphous Si-C-O ceramics fibers produced from thepyrolysis of a polycarbosilane precursor has been investigated by X-ray diffraction using high-energysynchrotron radiation at SPring-8. First peak in the total correlation function T(r) of the amorphousand the heat-treated fibers is analyzed to consist of two contributions: Si-C (1.89 Å) and Si-O (1.61 Å)bonds. The coordination number of C and/or O around Si is about four. This suggests that the Si-C-Ofibers basically have a network structure that consists of two tetrahedral units: SiC4 and SiO4. Thelocal chemical and structural orders vary continuously in the materials from the disordered networkstructure of SiC4 and SiO4 tetrahedra (mixture of amorphous SiC and SiO2) to nanocrystals of SiCand SiO2, through the ternary Si-C-O solid solution which is believed to have an intermediatestructure between the amorphous and crystalline states
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.352.65.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Design of Engineering Diffractometer at J-PARC (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 524-525 (Sept. 2006), p. 199-204 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An engineering diffractometer designed to solve many problems in materials science andengineering including investigations of stresses and crystallographic structures within engineeringcomponents is now being developed at J-PARC project. This instrument views a decoupled-poisonedliquid H2 moderator providing neutrons with good symmetrical diffraction profiles in the acceptablewavelength range. The primary flight path and the secondary flight path are 40 m and 2.0 m,respectively, for 90 degree scattering detector banks. A curved supermirror neutron guide will beinstalled to avoid intensity loss due to the long flight path and to reduce backgrounds from fastneutrons and gamma rays. Therefore, stress measurements with sufficient accuracies in manyengineering studies are quite promising. The optimization of this instrument has been performed witha Monte Carlo simulation, and an appropriate resolution of less than 0.2 % in [removed info]d/d has beenconfirmed. A prototyped radial collimator to define a gauge width of 1 mm has been designed andmanufactured. From performance tests conducted at the neutron diffractometer for residual stressanalysis RESA in JRR-3 of Japan Atomic Energy Agency, the normal distribution with a full width athalf maximum of 1 mm was obtained in a good agreement with the simulation
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/13/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.524-525.199.pdf
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