The neutron diffraction anomalous dispersion technique and its application to vitreous SM2O3.4P(2)O(5)

Wright, A.C. and Cole, J.M. and Newport, R.J. and Fisher, C.E. and Clarke, S.J. and Sinclair, R.N. and Fischer, H.E. and Cuello, G.J. (2007) The neutron diffraction anomalous dispersion technique and its application to vitreous SM2O3.4P(2)O(5). Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 571 (3). pp. 622-635. ISSN 0168-9002 . (Access to this publication is restricted)

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Abstract

The first successful complete neutron diffraction anomalous dispersion experiment has been performed to investigate the role of the Sm3+ ions in the structure of vitreous Sm(2)O(3)(.)4P(2)O(5). The ideal form of this technique, which employs the wavelength dependence of the real and imaginary parts of the neutron scattering length close to an absorption resonance, is used and involves measurements at two pairs of wavelengths: the real part of the scattering length is varied, keeping the imaginary part constant, and then the imaginary part is varied, keeping the real part constant. If A denotes the element with the isotope (Sm-149) having the absorption resonance and X any other element present in the sample, the first measurement can be used to extract the A-A + A-X or A-A + X-X contribution to the real space correlation function, T(r), and the second yields the A-A component correlation function. For the present glass, the Sm-Sm + Sm-X contribution (X = P or 0) reveals that the Sm3+ ions have an average co-ordination number, n(Sm(O)) of 7, with a mean Sm-O bond length of 2.375 +/- 0.005 angstrom, while the anomalous difference correlation function indicates that the SM3+ ions are similar to 4.6 angstrom apart. The paper concludes with a discussion of the relative merits of the various neutron diffraction techniques for isolating individual or subsets of real-space component correlation functions. (c) 2006 Elsevier B.V. All rights reserved.

Item Type: Article
Uncontrolled keywords: neutron diffraction; anomalous dispersion; glass structure
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Physical Sciences > Functional Materials Group
Depositing User: Bob Newport
Date Deposited: 26 Jun 2008 18:36
Last Modified: 22 May 2012 11:36
Resource URI: http://kar.kent.ac.uk/id/eprint/8235 (The current URI for this page, for reference purposes)
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