COORDINATION CHANGES IN TELLURO-VANADATE GLASSES CONTAINING ZNO OR CDO

The structure around the metal ions in xTeO2 .(1 - x)V2O5, xZnO .(1 - x)V2O5, xZnO .(1 - x)[2TeO(2). V2O5] and xCdO .(1 - x)[2TeO(2). V2O5] glasses has been investigated by Raman and X-ray absorption fine struc ture (XAFS) spectroscopies. In xTeO(2).(1 - x)V2O5, the coordination o f Te changes from TeO4 to TeO3 with increasing x. The main effect of t he addition of modifier oxides in vanadate and telluro-vanadate glasse s is a transformation of the VO5 bi-pyramids to VO4 tetrahedra. No app arent change in the local structure around the modifier atoms is revea led by XAFS measurements. (C) 1998 Elsevier Science B.V. All rights re served.