Cation Effects on ³¹ P MAS NMR Chemical Shifts of Metaphosphate Glasses

We have examined a series of metaphosphate glasses with 31 P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. Increasing the ionic potential ( Z/a ) of the modifying cation from sodium to magnesium causes a systematic change to more shielded isotropic chemical shifts with a concomitant increase in the peak FWHM. These spectral trends are consistent with counterion‐induced modifications to the ionic character of the P–O bond. Such modifications do not produce significant changes in either the chemical shift anisotropy or the asymmetry parameter.