Order-disorder in 1:1 type clay minerals by solid-state27Al and29Si magic-angle-spinning NMR spectroscopy

Abstract
The applicability of27Al and29Si magic-angle-spinning nuclear magnetic resonance (MASNMR) spectroscopy to the investigation of order-disorder in 1 : 1 dioctahedral layer-silicates was tested.27Al and29Si MASNMR showed the existence of short-range order in all these systems while XRD showed different degrees of long-range order-disorder. Spectra obtained on kaolinite and metakaolin clearly showed the transformation of some octahedral Al in kaolinite to tetrahedral coordination in metakaolin and also showed short-range Al and Si disorder in the latter. This suggests that structural re-arrangement on thermal treatment can be monitored by this technique. These results further suggest that MASNMR can detect short-range order, which is complimentary to the information that XRD provides regarding long-range order.