A multinuclear NMR study of sodium–borovanadophosphate glasses

xNaVO3 · yNaPO3 · (1 − y)NaBO2 glasses were prepared where x = 0.0, 0.05, 0.5 and 0 ⩽ y ⩽ 1. These glasses have been investigated with multinuclear MAS NMR. 51V NMR spectra show that two vanadate configurations are possible, assigned as four and five coordinated vanadium. The concentration of the latter group decreases upon addition of sodium-borate. The presence of four and three coordinated boron sites can be deduced from the 11B NMR spectra. The latter boron sites appear only when borate groups are connected to each other. 31P NMR spectra of borophosphates and borovanadophosphates show that the ratio of pyro- and metaphosphates is greater in the glasses containing vanadate than in simple borophosphates. These results indicate phosphate to be the most acidic agent and therefore the best chain-terminating group in these glasses.