Comparison of the low-Q features in diffraction data for silicate glasses and crystals containing Sr or Ba

Neutron scattering data have been obtained for a strontium- and a barium-containing silicate glass and a strontium aluminosilicate glass. These data are compared with previously published anomalous wide-angle X-ray scattering data for the Sr-containing glasses. Features in the diffraction data at the smaller scattering vectors, Q, are compared with simulated X-ray and neutron diffraction patterns for compositionally similar crystals. Peaks are found at es close to the 'first sharp diffraction peaks' of the glasses and have a cation-cation dependence. We suggest that this correspondence shows that the smaller Q features in the glasses have similar structural origins to those in the scattering data for the crystals with the same composition and therefore that the medium-range structures and cation-cation arrangements in the glasses are similar too. (C) 1999 Published by Elsevier Science B.V. All rights reserved.