Hostname: page-component-586b7cd67f-vdxz6 Total loading time: 0 Render date: 2024-11-26T05:18:15.907Z Has data issue: false hasContentIssue false

Structure and Thermal Transformations of Imogolite Studied by 29Si and 27Al High-Resolution Solid-State Nuclear Magnetic Resonance

Published online by Cambridge University Press:  02 April 2024

K. J. D. MacKenzie
Affiliation:
Chemistry Division, Department of Scientific and Industrial Research, Private Bag, Petone, New Zealand
M. E. Bowden
Affiliation:
Chemistry Division, Department of Scientific and Industrial Research, Private Bag, Petone, New Zealand
I. W. M. Brown
Affiliation:
Chemistry Division, Department of Scientific and Industrial Research, Private Bag, Petone, New Zealand
R. H. Meinhold
Affiliation:
Chemistry Division, Department of Scientific and Industrial Research, Private Bag, Petone, New Zealand
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Solid-state nuclear magnetic resonance (NMR) spectroscopy, thermal analysis, and X-ray powder diffraction data on the tubular, hydrous aluminosilicate imogolite were found to be fully consistent with a previously proposed crystal structure consisting of a rolled-up, 6-coordinate Al-O(OH) sheet, bonded to isolated orthosilicate groups. The calculated 29Si chemical shift of this structure agreed with the observed shift within 3 ppm. Thermal dehydroxylation of the Al-O(OH) sheet produced predominantly NMR-transparent 5-coordinate Al, but a few 4- and 6-coordinate sites and some residual hydroxyl groups may also have formed, as shown by NMR spectroscopy. Changes in the 29Si NMR spectrum on dehydroxylation suggest a condensation of the orthosilicate groups, but steric considerations rule out bonding between adjacent silicons. To account for these observations, an alternative mechanism to orthosilicate condensation has been proposed, involving the fracture and unrolling of the tubes, followed by the condensation of fragments to form a layer structure. The layer structure has a calculated 29Si chemical shift of -95.6 ppm, in good agreement with the observed value of -93 ppm.

Type
Research Article
Copyright
Copyright © 1989, The Clay Minerals Society

References

Alemany, L. B. and Kirker, G. W., 1986 First observation of 5-coordinate aluminium by MAS 27Al NMR in wellcharacterized solids J. Amer. Chem. Soc. 108 61586162.CrossRefGoogle Scholar
Barron, P. F., Wilson, M. A., Campbell, A. S. and Frost, R. L., 1982 Detection of imogolite in soils using solid state 29-Si NMR Nature (Lond.) 299 616618.CrossRefGoogle Scholar
Baur, W. H., 1978 Variation of mean Si-O bond lengths in silicon-oxygen tetrahedra Acta Crystallogr. B34 17511756.CrossRefGoogle Scholar
Brindley, G. W., Fancher, D. and Heller, L., 1970 Kaolinite defect structures; Possible relation to allophanes Proc. Int. Clay Conf, Tokyo, 1969, Vol. 2 Jerusalem Israel Univ. Press 2934.Google Scholar
Brown, G., Brindley, G. W. and Brown, G., 1980 Associated minerals Crystal Structures of Clay Minerals and Their X-ray Identification London Mineralogical Society 406.Google Scholar
Brown, I. W. M. MacKenzie, K. J. D. and Meinhold, R. H., 1987 The thermal reactions of montmorillonite studied by high resolution solid-state 29-Si and 27-Al NMR J. Mater. Sci. 22 32653275.CrossRefGoogle Scholar
Cameron, W. E., 1977 Composition and cell dimensions of mullite Amer. Ceram. Soc. Bull. 56 10031011.Google Scholar
Cradwick, P. D. G. Farmer, V. C., Russell, J. D., Masson, C. R., Wada, K. and Yoshinaga, N., 1972 Imogolite, a hydrated aluminium silicate of tubular structure Nature Phys. Sci. 240 187189.CrossRefGoogle Scholar
Goodman, B. A., Russell, J. D., Montez, B., Oldfield, E. and Kirkpatrick, R. J., 1985 Structural studies of imogolite and allophanes by aluminium-27 and silicon-29 nuclear magnetic resonance spectroscopy Phys. Chem. Mineral. 12 342346.CrossRefGoogle Scholar
Komameni, S., Roy, R., Fyfe, C. A., Kennedy, G. J. and Strobl, H., 1986 Solid-state 27-Al and 29-Si magic-angle spinning NMR of aluminosilicate gels J. Amer. Ceram. Soc. 69 C42C44.Google Scholar
MacKenzie, K. J. D. Brown, I. W. M. Cardile, C. M. and Meinhold, R. H., 1987 The thermal reactions of muscovite studied by high-resolution solid-state 29-Si and 27-Al NMR J. Material. Sci. 22 26452654.CrossRefGoogle Scholar
MacKenzie, K. J. D. Brown, I. W. M. Meinhold, R. H. and Bowden, M. E., 1985 Thermal reactions of pyrophyllite studied by high-resolution solid-state 27-Al and 29-Si nuclear magnetic resonance spectroscopy J. Amer. Ceram. Soc. 68 266272.CrossRefGoogle Scholar
MacKenzie, K. J. D. Brown, I. W. M. Meinhold, R. H. and Bowden, M. E., 1985 Outstanding problems in the kaolinite-mullite reaction sequence investigated by 29-Si and 27-Al solid-state nuclear magnetic resonance: I. Metakaolinite J. Amer. Ceram. Soc. 68 293297.CrossRefGoogle Scholar
O’Keefe, M. and Hyde, B. G., 1978 On Si-O-Si configurations in silicates Acta Crystallogr. B34 2732.CrossRefGoogle Scholar
Parfitt, R. L. and Henmi, T., 1980 Structure of some allophanes from New Zealand Clays & Clay Minerals 28 285294.CrossRefGoogle Scholar
Russell, J. D., McHardy, W. J. and Fraser, A. R., 1969 Imogolite: A unique aluminosilicate Clay Miner. 8 8799.CrossRefGoogle Scholar
Smith, J. V. and Blackwell, C. S., 1983 Nuclear magnetic resonance of silica polymorphs Nature (Lond.) 303 223225.CrossRefGoogle Scholar
Van der Gaast, S. J., Wada, K., Wada, S.-I. and Kakuto, Y., 1985 Small-angle X-ray powder diffraction, morphology and structure of allophane and imogolite Clays & Clay Minerals 33 237243.CrossRefGoogle Scholar
Wada, K., 1967 A structural scheme ofsoil allophane Amer. Mineral. 52 690708.Google Scholar
Wada, K. and Yoshinaga, N., 1968 The structure of “imogolite” Amer. Mineral. 54 5071.Google Scholar
Wada, S.-I. and Wada, K., 1977 Density and structure of allophane Clay Miner. 12 289298.CrossRefGoogle Scholar
Wilson, M. A., Wada, K., Wada, S.-I. and Kakuto, Y., 1988 Thermal transformations of synthetic allophane and imogolite as revealed by nuclear magnetic resonance Clay Miner. 23 175190.CrossRefGoogle Scholar