Potassium hydrogen disilicate: A possible model compound for O-17 NMR spectra of hydrous silicate glasses

Oxygen-17 magic angle spinning, non-spinning, H-1-decoupled, H-1-O-17 cross -polarization, and triple-quantum magic-angle spinning nuclear magnetic res onance (NMR) spectroscopy experiments were performed at two different magne tic fields on crystalline potassium hydrogen disilicate (KHSi2O5) and hydro us and anhydrous potassium tetrasilicate (K2Si4O9), sanidine (KAlSi3O8), an d haplogranite (KAlSi3O8-NaAlSi3O8-SiO2) glasses. Crystalline KHSi2O5 has t wo bridging oxygen sites and one non-bridging oxygen site, and the NMR para meters for these two types of sites have been determined. The non-bridging oxygen (silanol) site is well-resolved and observed in a crystalline compou nd with an isotropic chemical shift (delta (iso)) of 60 ppm, a quadrupolar coupling constant (C-Q) of 3.5 MHz, and an asymmetry parameter (eta) of 0.3 5. Knowledge of the non-bridging-oxygen site parameters allows for comparis ons to glassy or other materials that might have silanol-type structures. A similar peak can be found in the hydrous potassium silicate spectrum but n ot in the hydrous potassium aluminosilicate glass spectrum.