NETWORK STRUCTURE OF BORATE AND GERMANATE GLASSES STUDIED BY MEANS OFPULSED-NEUTRON SCATTERING

Modification of the network structure of B2O3 glass caused by network modifiers has been studied by pulsed neutron scattering. To observe th e network structure, mixed alkali oxide M2O with M = Li0.62Na0.38, whi ch is a null scatterer for neutron scattering, was added to the berate samples. The first sharp diffraction peak of the structure factor S(Q ), for B2O3-M2O glasses does not change by addition of M2O, which is i n contrast to the silicate glasses. We suggest that this observation c ombined with a molecular dynamics simulation indicates that the alkali ions fill the voids in the dass without modifying the B-O framework o r the distribution of voids. The change of network structure of german ate glasses due to the addition of V2O5 was also examined. The average oxygen coordination-number around a Ge atom was increased by the addi tion of V2O5. This increase is interpreted as the creation of GeO6 oct ahedra. (C) 1998 Elsevier Science B.V. All rights reserved.