Structural studies of imogolite and allophanes by aluminum-27 and silicon-29 nuclear magnetic resonance spectroscopy

B. A. Goodman, J. D. Russell, B. Montez, Eric Oldfield, R. J. Kirkpatrick

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High-resolution aluminum-27 and silicon-29 nuclear magnetic resonance spectra of natural and synthetic imogolites and allophanes obtained using high-field "magic-angle" sample-spinning (MASS) techniques indicate that the imogolite and protoimogolite components of allophanes are characterized by sharp (≈3 ppm) silicon-29 resonances at -78±1 ppm from tetramethylsilane (in accord with Barron et al. 1982), and quite narrow (≈10 ppm at 11.7 Tesla) aluminum-27 resonances, at 5.2±1 ppm from Al(H2O)63+(in accord with Wilson et al. 1984). However, the spectra of natural allophanes usually contain significant intensity arising from a less well defined material, characterized by a broad (≈20 ppm) silicon-29 resonance centered at -90±2 ppm from tetramethylsilane, and a second relatively narrow (≈15 ppm at 11.7 Tesla) aluminum-27 resonance at 58.5±2 ppm from Al(H2O)63+. Similar characteristic spectral features are exhibited by a synthetic amorphous Si:Al (1:1) gel, and presumably indicate the presence of framework aluminosilicate materials in the gel, and in most allophanes.

Original languageEnglish (US)
Pages (from-to)342-346
Number of pages5
JournalPhysics and Chemistry of Minerals
Issue number6
StatePublished - Nov 1 1985


ASJC Scopus subject areas

  • Materials Science(all)
  • Geochemistry and Petrology

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