Multinuclear MAS NMR Study of the Short-Range Structure of Fluorophosphate Glass
We have examined the bonding arrangements in Na-P-O-F and Na-Al-P-O-F glasses using 19F, 27Al, and 31P solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. For the Al-free series of glasses, the 19F NMR spectra are dominated by peaks near +90 ppm, representative of F terminating P-chains. The formation of these bonds has little effect on the 31P chemical shifts, indicating that F preferentially replaces bridging oxygen on the phosphate tetrahedra, consistent with previous NMR studies of crystalline fluorophosphates and other spectroscopic studies of fluorophosphate glass. For the Na-Al-P-O-F glasses, 27Al NMR detects only octahedral Al-sites, the 19F NMR spectra include a second peak near -12 ppm due to F bonded to Al, and the 31P NMR spectra contain signals due to Q1-sites with one or more Al next-nearest neighbors. The relative intensity of the two 19F peaks correlates well with previous spectroscopic studies and shows that a greater fraction of F-P bonds forms when the base glass is remelted in NH4HF2.
R. K. Brow et al., "Multinuclear MAS NMR Study of the Short-Range Structure of Fluorophosphate Glass," Journal of Materials Research, Materials Research Society, Jan 1992.
The definitive version is available at https://doi.org/10.1557/JMR.1992.1892
Materials Science and Engineering
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