Structural aspects of PbO–P2O5 glasses containing ThO2

Abstract PbO–P 2 O 5 glasses in which part of PbO/P 2 O 5 was replaced by ThO 2 have been prepared by the conventional melt quench method and their structural aspects have been studied by 31 P MAS NMR, Raman and FTIR techniques. Binary PbO–P 2 O 5 glass is characterized by mainly Q 2 and Q 1 structural units of P (Q n represents the phosphorus structural units having ‘ n ’ number of bridging oxygen atoms). When part of the PbO has been replaced by ThO 2 , the phosphorus structural units are not significantly affected, indicating that Th 4+ replaces Pb 2+ at the interstitial positions in the glass network. Unlike this when part of P 2 O 5 has been replaced by ThO 2 extensive depolymerisation of the phosphate network resulted in the conversion of Q 2 to Q 1 structural units of P. Above 10 mol% of ThO 2 replacement in either case resulted in the partial devitrification of the glass.