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005ChemInform Abstract has been investigated using a combination of solid-state 31P, 15N, and 23Na NMR and Raman spectroscopy. The Raman spectra of model phosphazene compounds with different types of P-N bonding have been used for the spectral assignment. The structural results are shown to be consistent with known chemical and physical properties of nitrided NaPO3 glasses. The N atoms replace O in the phosphate glass network both as N bonded to two P atoms via one double and on single bond and as N bonded to three P atoms via single bonds. Nitrogen influences the chemical durability, thermal expansion, and other properties by cross-linking polymeric phosphate chains together in the glass network.

The structures of phosphorus oxynitride glasses have been determined using a combination of solid-state 3'P, "N, and *'Na nuclear magnetic resonance and Raman spectroscopies. Raman spectra of model phosphazene compounds with different types of P-N bonding have been used to confirm spectral assignments. Results indicate that nitrogen replaces oxygen in the phosphate glass network both as nitrogen bonded to two phosphorus atoms (via one double bond and one single bond) and as nitrogen bonded to three phosphorus atoms via three single bonds. The observed structural features are consistent with data which show that nitrogen influences the chemical durability, thermal expansion, and other properties of phosphate glasses by cross-linking polymeric phosphate chains together in the glass network.

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Raman spectroscopic studies on gel-derived silicates have confirmed that narrow bands near 607 cm-1 and 492 cm-1, first observed in the Raman spectrum of fused silica, are associated with three- and four-fold siloxane rings. Using these results, we have identified three- and four-fold siloxane rings in other high-surface-area silica materials, including leached glasses and Cab-OSil. This Raman spectroscopic evidence not only shows that small siloxane rings are a common characteristic of a number of silica materials but also suggests that they form preferentially at silica surfaces. This paper reviews the Raman spectroscopic evidence that led to the identification of the vibrational frequencies of the small siloxane rings and presents the results of Raman experiments on high-surface-area silica materials in which the concentration of small siloxane rings is enhanced compared to fused silica.