title: Influence of rare-earth ions on SiO₂-Na₂O-RE₂O₃ glass structure.
abstract: Praseodymium and europium sodium silicate glasses of nominal composition (SiO(2))(0.70 - x)(Na(2)O)(0.30)(RE(2)O(3))(x), where RE is the rare earth and 0 ≤ x ≤ 0.10, were studied by neutron and high-energy x-ray scattering and classical molecular dynamics simulations. The observation of a significant x-ray intensity in doped as compared to un-doped glasses is indicative of RE-RE correlations at a distance of ∼ 3.7-3.9 Å, much shorter than would be expected for a homogeneous distribution, suggesting that clustering of the rare-earth cations occurs in both these glass systems at low concentrations. Above x = 0.075 (nominal), minimal changes in this region indicate that the RE atoms are incorporated much more randomly into the glass structure. The molecular dynamics simulations suggest that the rare-earth ions enter the sodium-rich regions in the sodium silicate glasses and act as modifiers. A cluster analysis performed on the model systems indicates that the tendency for clustering is higher in praseodymium-containing glasses than in the europium glasses.
authors.affiliation: Department of Materials Science and Engineering, University of Tennessee Space Institute, Tullahoma, TN 37388, USA. jjohnson@utsi.edu
authors.forename: J A
authors.initials: JA
authors.lastname: Johnson
authors.forename: C J
authors.initials: CJ
authors.lastname: Benmore
authors.forename: D
authors.initials: D
authors.lastname: Holland
authors.forename: J
authors.initials: J
authors.lastname: Du
authors.forename: B
authors.initials: B
authors.lastname: Beuneu
authors.forename: A
authors.initials: A
authors.lastname: Mekki