Solid-state (31)p/Al-27 and P-31/Na-23 TRAPDOR NMR investigations of the phosphorus environments in sodium aluminophosphate glasses

Solid-state (31)p/Al-27 and (31)p/Na-23 TRAPDOR NMR experiments have been u sed to investigate the spatial distribution of aluminum and sodium cations with respect to the phosphate backbone for a Series of sodium aluminophosph ate glasses, xAl(2)O(4). 50Na(2)O (50-x)P2O5 (0 less than or equal to x les s than or equal to 17.5). From the (31)p/Al-27 and (31)p/Na-23 TRAPDOR data gathered, information about the medium-range order in these glasses was ob tained. The expanded data allow for better identification and interpretatio n of the new resonances observed in the P-31 MAS NMR spectra with the addit ion of aluminum. The results of these experiments show that the sodium phos phate distribution remains relatively unchanged for the glass series and th at the addition of aluminum occurs primarily through the modification of th e phosphate tetrahedral backbone in the melt.