Multiple-quantum and cross-polarized Al-27 MAS NMR of mechanically treatedmixtures of kaolinite and gibbsite

Mixtures of the clay mineral kaolinite with gibbsite, when heated, form mul lite, a high-temperature ceramic. The Al-27 multiple-quantum magic angle sp inning (MQMAS) NMR technique is used to study the local Al environment in m ixtures of kaolinite and gibbsite that have been ground together for varyin g amounts of time. This mechanical treatment forms new chemical species tha t are amorphous in nature and, therefore, unsuited to analysis by X-ray dif fraction. Both novel and established cross-polarization techniques are empl oyed to characterize the starting materials and mixtures, confirm the spati al proximity of H-1 and Al-27 nuclei, and "edit" the two-dimensional Al-27 MQMAS NMR spectra, thereby allowing overlapping peaks corresponding to octa hedral Al sites to be studied.