Structural aspects of PbO–P2O5 glasses containing ThO2

PbO–P2O5 glasses in which part of PbO/P2O5 was replaced by ThO2 have been prepared by the conventional melt quench method and their structural aspects have been studied by 31P MAS NMR, Raman and FTIR techniques. Binary PbO–P2O5 glass is characterized by mainly Q2 and Q1 structural units of P (Qn represents the phosphorus structural units having ‘n’ number of bridging oxygen atoms). When part of the PbO has been replaced by ThO2, the phosphorus structural units are not significantly affected, indicating that Th4+ replaces Pb2+ at the interstitial positions in the glass network. Unlike this when part of P2O5 has been replaced by ThO2 extensive depolymerisation of the phosphate network resulted in the conversion of Q2 to Q1 structural units of P. Above 10 mol% of ThO2 replacement in either case resulted in the partial devitrification of the glass.