New insights into the structure of oxynitride NaPON phosphate glasses by 17-oxygen NMR

► Nitrided and 17O enriched sodium phosphate glasses have been successfully prepared. ► 17O 3Q MASNMR experiments have revealed two types of non-bridging NBO oxygen atoms. ► An original NMR data treatment allowed for the quantification of the two NBO sites. ► BO/NBO ratio decreases going from pure oxide PO4 to the oxynitride PO2N2 tetrahedra.