Thermal and structural studies on TeO2 substituted (PbO)0.5(P2O5)0.5 glasses

Abstract (PbO)0.50(P2O5)0.50−x(TeO2)x and (PbO)0.50−y(P2O5)0.50(TeO2)y glasses with 0.0 ⩽ x ⩽ 0.2 and 0.0 ⩽ y ⩽ 0.2, were prepared by conventional melt-quench method and characterized by 31P magic angle spinning nuclear magnetic resonance (MAS NMR), Infrared (IR) and Differential Thermal Analysis (DTA) techniques. For (PbO)0.50(P2O5)0.50−x(TeO2)x glasses, there is a systematic conversion of Q2 structural units of P to Q1 structural units and the glass transition temperature is found to increase systematically with increase in TeO2 content as revealed by DTA. Unlike this behavior for (PbO)0.5−y(P2O5)0.5(TeO2)y glasses, the 31P MAS NMR patterns are found to be unchanged and the glass transition temperature is found to decrease slightly due to TeO2 substitution. There is no P–O–Te type of linkage present in both series of glass as revealed by 31P MAS NMR and IR studies. The observed increase in the Tg and crystallization temperature for (PbO)0.5(P2O5)0.5−x(TeO2)x glasses, compared to binary (PbO)0.50(P2O5)0.50 glass, is attributed to the interaction of TeO2 with PbO structural units and the nucleation of Pb2P2O7 crystalline phase in the glassy matrix.