Pulsed neutron diffraction study on the short range structure of B2O3-Ag2O glasses

The short range structure of (1-x)B2O3-xAg(2)O (x=0.05-0.30) glasses was investigated by time-of-flight neutron scattering experiments. Radial distribution analyses were applied to extract the structural information. but the structural parameters for each atomic pair were finally optimized in the Q-space. The bond distances of near neighbor B-O pairs were estimated at 0.138 and 0.145 nm, and the corresponding coordination numbers were 3 and 4, respectively. These were ascribed to the B-O correlations in distorted six-membered rings consisting of planer trigonal units and tetrahedral ones. The silver atoms serve to hold the networks together through coordination with oxygen atoms, thereby the nearly octahedral arrangements of oxygen atoms around a silver atom were found to exist in these glasses. The octahedral units were distorted to such an extent that the Ag-O distances were ranging from 0.25 to 0.32 nm. The existence of medium range order was also confirmed in the structure factor S(Q) over the composition range of this work. (C) 2001 Elsevier Science B.V. All rights reserved.