The local environment of trivalent lanthanide ions in sodium silicate glasses: A neutron diffraction study using isotopic substitution

WILDING, Martin, BADYAL, Yaspal and NAVROTSKY, Alexandra (2007). The local environment of trivalent lanthanide ions in sodium silicate glasses: A neutron diffraction study using isotopic substitution. Journal of Non-Crystalline Solids, 353 (52-54), 4792-4800.

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Official URL: https://www.sciencedirect.com/science/article/pii/...
Link to published version:: https://doi.org/10.1016/j.jnoncrysol.2007.06.071

Abstract

Neutron diffraction data on lanthanide-bearing sodium silicate glasses were collected using the glass, liquid and amorphous materials diffractometer (GLAD) at the intense pulsed neutron source (IPNS), Argonne. Measurements were made on four glass samples; a sodium silicate base glass with no added lanthanide, a sample with 6 mol% La2O3 added to the base composition, and two isotopically-distinct samples containing 6 mol% Dy2O3. Of the Dy-bearing samples, one contained natural enrichment Dy, and the other a ‘null scattering’ mixture of natural and 162Dy isotopes. The first-order isotope difference of the scattering from the Dy-bearing samples revealed a Dy–O nearest-neighbor distance of 2.3 Å and a mean coordination number of 5.9 oxygen atoms around each dysprosium ion; the latter is in good agreement with the coordination number derived from bond–valence theory. The results for the La-bearing glass were also consistent with a sixfold coordination of oxygen atoms around the rare earth. The diffraction data are used in combination with Reverse Monte Carlo modeling techniques to interpreter the structural role of the rare earth ions. From these models, it is apparent that there is competition between monovalent sodium ions and the rare earth ions for the same non-bridging oxygen atoms. As a result the addition of rare earth ions appears to cause disruption of the Na-rich percolation domains characteristic of the sodium silicate base glass. These neutron results are consistent with the formation of a specific lanthanide Q3 as suggested by NMR and Raman spectroscopy, but offer no direct evidence for the formation of ‘oxide-like’ lanthanide clusters.

Item Type: Article
Research Institute, Centre or Group - Does NOT include content added after October 2018: Materials and Engineering Research Institute > Engineering Research
Departments - Does NOT include content added after October 2018: Faculty of Science, Technology and Arts > Department of Engineering and Mathematics
Identification Number: https://doi.org/10.1016/j.jnoncrysol.2007.06.071
Depositing User: Martin Wilding
Date Deposited: 04 Jul 2018 10:13
Last Modified: 04 Jul 2018 10:13
URI: http://shura.shu.ac.uk/id/eprint/21500

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