Abstrakt
This work is aimed at monitoring of Al ions coordination in clays and clay minerals by the nuclear magnetic resonance (NMR) spectroscopy. Knowledge of the clays structure is important for their use as raw materials in engineering practice.
For further processing (e.g. preparation of geopolymers), the 5- and 4-fold coordination of oxygen around aluminium atoms is crucial, and therefore it is necessary to transform the original 6-fold coordinations of the Al ions by proper thermal treatment. The 27Al isotope is suitable for NMR investigations as the spectral parameters (chemical shift and quadrupole interactions) are very sensitive to the surrounding (coordination, chemical bonding) of the resonating nuclei.
NMR of 29Si yields complementing information on structure. Magic angle spinning (MAS) technique was applied to measure spectra of selected clay samples.