Solid-state 27Al and 29Si NMR investigations on Si-substituted hydrogarnets

Abstract

Partially deuterated Ca 3Al 2(SiO 4) 3− x (OH) 4 x hydrates prepared by a reaction in the presence of D 2O of synthetic tricalcium aluminate with different amounts of amorphous silica were characterized by 29Si and 27Al magic-angle spinning nuclear magnetic resonance (NMR) spectroscopy. The 29Si NMR spectroscopy was used for quantifying the non-reacted silica and the resulting hydrated products. The incorporation of Si into Ca 3Al 2(SiO 4) 3− x (OH) 4 x was followed by 27Al NMR spectroscopy: Si:OH ratios were determined quantitatively from octahedral Al signals ascribed to Al(OH) 6 and Al(OSi)(OH) 5 environments. The NMR data obtained were consistent with the concentrations of the Al and Si species deduced from transmission electron microscopy energy-dispersive spectrometry and Rietveld analysis of both X-ray and neutron diffraction data.