125Te NMR Study of MO-TeO2(M=Mg, Zn, Sr, Ba and Pb) Glasses.

Abstract

The structure of MO-TeO2 (M=Mg, Zn, Sr, Ba and Pb) glasses has been studied by means of 125Te static NMR technique. The fraction of TeO4 trigonal bipyramid (tbp), N4 decreased and that of TeO3 trigonal pyramid (tp), N3 increased almost linearly up to 33.3mol% MO and rapidly in the range of 33.3 to 40mol% MO, with increasing MO content. It was found that the glasses containing MO in the range of 40 to 45mol% MO consisted only of TeO3 tp. On the basis of the structural model proposed in a previous paper, the fractions of TeO4 tbp without a non-bridging oxygen (NBO) atom, TeO4/2 (N40), TeO4 tbp with an NBO atom, O3/2 Te-O- (N4-) and TeO3 tp with two NBO atoms, O1/2Te(=O)-O- (N3-) were calculated. The structural change for MO-TeO2 glasses in the range of 0 to 33.3mol% MO could be well represented by the model previously proposed for alkali tellurite binary glasses. A new model which represents the structural change for MO-TeO2 glasses containing more than 33.3mol% MO has been proposed.