Steven Dec - Observation of Five-Coordinated Aluminum in Pyrophyllite Dehydroxylate by Solid-State 27Al Nuclear Magnetic Resonance Spectroscopy at 14 Tesla.

Version 1

      Publication Details (including relevant citation   information):

    1. J.J. Fitzgerald;  S.F. Dec and A.I. Hamza, American   Mineralogist, 74, 1405 (1989).


      The observation and quantification of four-, five-, and   six-coordinated Al sites in Alcontaining

      materials such as silica-aluminas, transition aluminas, and   clay-derived solids

      are major problems in solid-state2 ?Alr .run spectroscopy.W e   report herein solid-s|ate2TAl

      NMR spectra of the mineral derivative pyrophyllite dehydroxylate;   these spectra were obtained

      at 14 T (the highest available magnetic field), I1.7 T, and 8.4 T   under high-speed

      (> 12 kHz) magic-angles ample-spinning( rranssc)o nditions.   The results representt he first

      observation of the I5lAl site in this mineral derivative. The   27Al MASs NMR spectrum at 14

      T demonstrates the advantage of high-field NMR measurements for   observing the signal

      due to this highly distorted rslAl site. The Nun spectra and   computer simulations were

      used to determine the isotropic chemical shift (29 ppm),   quadrupolar coupling constant

      (10.5 MHz), and asymmetry parameter (a : 0.6) for the Al atom in   the trigonal-bipyramidal

      Al-O local environment of this mineral derivative. These   high-resolution zzAl uess

      Nun results provide impetus for future solid-state xun studies of   important Al-containing

      catalysts, ceramic preclusors, and other solid oxide materials   containing quadrupolar nuclides

      amenable to solid-state NMR .

      Address (URL):