Te-125 NMR study of MO-TeO2 (M=Mg, Zn, Sr, Ba and Pb) glasses

The structure of MO-TeO2 (RI Mg Zn, Sr, Ba and Pb) glasses has been studied by means of Te-125 static NMR technique. The fraction of TeO4, trigonal bi pyramid (tbp), N-4 decreased and that of TeO3 trigonal pyramid (tp), N-3 in creased almost linearly up to 33.3 mol% MO and rapidly in the range of 33.3 to 40 mol% MO, with increasing MO content, It was found that the glasses c ontaining MO in the range of 40 to 45 mol% MO consisted only of TeO3 tp. On the basis of the structural model proposed in a previous paper, the fracti ons of TeO4 tbp without a non-bridging oxygen (NBO) atom, TeO4/2 (N-4(0)), TeO4 tbp with an NBO atom, O-3/2 Te-O- (N-4(-)) and TeO3 tp with two NBO at oms, O1/2Te(= O)-O- (N-3(-)) were calculated. The structural change for MO- TeO2 glasses in the range of 0 to 33.3 mol% MO could be well represented by the model previously proposed for alkali tellurite binary glasses. A new m odel which represents the structural change for MO-TeO2 glasses containing more than 33.3 mol% MO has been proposed.