Structural study of phosphorus oxynitride glasses LiNaPbPON by nuclear magnetic resonance and X-ray photoelectron spectroscopy

The structure of Li0.25Na0.25Pb0.25PO3−3x/2Nx (0<x⩽0.69) nitrided glasses has been studied by nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). 31P magic angle spinning (MAS) NMR shows that the glass network is built up of PO4, PO3N and PO2N2 tetrahedral units. PO4–PO4, PO4–PO3N and PO3N–PO2N2 connections, characterized with double quantum (DQ) 31P MAS NMR, are homogeneously distributed within the glass network. XPS at the N1s core level indicates that nitrogen atoms substitute for bridging (–O–) and terminal (O) oxygen atoms, as two-coordinated –N = (Nd) or three-coordinated –N < (Nt) species. A higher amount of Nd than Nt species is found for the highest nitrogen contents. 23Na and 207Pb NMR results show that the oxygen atoms coordinating modifier cations are not concerned by the nitrogen–oxygen substitution. The role played by lead in these ‘LiNaPbPON’ glasses can be deduced from a comparison with similar ‘LiNaPON’ glasses. The presence of Pb2+ ions clearly affects the nitridation mechanism and their network former character increases with nitridation.