The solid state NMR techniques of magic-angle spinning (MAS), dynamic-angle spinning (DAS) and double rotation (DOR) are used to study the local atomic environments in tugtupite, Na 8 [Al 2 Be 2 Si 8 O 24 ](Cl,S) 2 . The structure is found to be exceptionally well ordered, with only one Si, A1, Na and Be environment. The quadrupolar parameters C Q (quadrupolar coupling constant) and eta (asymmetry parameter) of 23 Na and 27 Al were obtained by a comparison of a computer simulation of the MAS central transition lineshape at two different fields with experimental results. These results were verified in two ways: firstly, from the comparison of the observed difference in chemical shift of the same peak at two different fields with that calculated from the simulated results of C Q and eta , and secondly, from the comparison of the measured and calculated difference in position of the two peaks within the first set of spinning sidebands, which are due to the central transition and + or -1/2<-->+ or -3/2 satellite transition.

First Page Preview

First page PDF preview
You do not currently have access to this article.