31P NMR study of magnesium phosphate glasses

1-D magic angle spinning (MAS) and 2-D double quantum solid-state 31P nuclear magnetic resonance (NMR) investigations have been carried out on (MgO)x(P2O5)1−x glasses over compositional range from x=0.44 to 0.59. The distribution of the Qn phosphate units, obtained from the simulation of 31P MAS spectra, is close to a binary distribution of bridging and non-bridging oxygen atoms, indicating that the Mg2+ cations act as network modifiers. High-resolution 31P double quantum NMR is used to probe the intermediate range order in phosphate glasses and suggests that the anomalous behavior near the metaphosphate composition is due to a change from ring structures to phosphate chains.