Atomic ordering in xGa(2)O(3)center dot(100-x)TeO2 glasses (x=10, 17.5, 25) by X-ray diffraction

Atomic distribution functions for sGa(2)O(3).(100 - x)TeO2 glasses (x = 10, 17.5, 25) have been obtained from diffraction experiments employing a sync hrotron radiation source. First neighbour atomic distances and coordination numbers in the glasses investigated have been determined by decomposing th e experimental atomic distribution functions into a set of Gaussians each p ertaining to a particular type of atomic pairs. It has been found that xGa( 2)O(3).(100 - x)TeO2 glasses (x=10, 17.5, 25) may well be described as an a ssembly of tetrahedral GaO4 units uniformly embedded into a matrix of more (TeO3+1) or less distorted (TeO4) trigonal bipyramids where each Te in a pe rfect TeO4 bipyramid is surrounded by four oxygens distributed over equator ial and axial positions and each Te in a distorted TeO3+1 bipyramid has one of its axial Te-O bonds considerably elongated. (C) 1999 Published by Else vier Science B.V. All rights reserved.