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Effects of Secondary Iron Phases on Kaolinite 27Al MAS NMR Spectra

Published online by Cambridge University Press:  28 February 2024

Paul A. Schroeder ,
Robert J. Pruett  and
Vernon J. Hurst
Paul A. Schroeder
Affiliation:
University of Georgia, Department of Geology, Athens, Georgia 30602-2501
Robert J. Pruett
Affiliation:
ECC International, Inc., P.O. Box 471, Sandersville, Georgia 31082
Vernon J. Hurst
Affiliation:
University of Georgia, Department of Geology, Athens, Georgia 30602-2501
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Abstract

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Eight kaolinite and 2 halloysite samples were analyzed using 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, chemical analysis and magnetic susceptibility to understand the effect of isomorphously substituted Fe3+ and secondary Fe phases on the NMR signal. Known additions of goethite and hematite were made to determine the response of kaolinite 27Al MAS NMR spectra and sample magnetic susceptibilities.

Results from high field (11.7 T) NMR studies show positive correlations between 1) Fe content, 2) magnetic susceptibility and 3) relative intensity of the spinning side band (SSB) to central band (CB) ratio. No correlation is observed between the mass-corrected NMR spectral intensity and Fe content. Comparative high/low field (11.7 T/8.46 T) NMR studies show a decrease in the relative ratio of line broadening with increasing Fe content. Projected trends of known additions of hematite and goethite versus magnetic susceptibility extrapolate back to zero y intercepts that have Fe concentrations higher than actually measured.

Absolute intensity observations have negative implications for the use of 27Al MAS NMR spectroscopy in assessing Fe-ordering in kaolinites. First, high-energy, short (1/6 of π/2 solutions) pulse sequences do not produce reliable quantitative data needed to assess paramagnetic line-broadening affects caused by different Fe-ordering clustering scenarios. The lack of perfect correlation between SSB/CB, Fe content and magnetic susceptibility indicates that differences exist with respect to 1) the amount of isomorphously substituted Fe, 2) the ordering of the Fe within kaolinite, 3) the concentration of secondary Fe phases and 4) magnetic susceptibility of the secondary Fe assemblage. Variability of line-width ratios at different field strengths indicates an increasing second-order quadrupole effect (SOQE) with increasing Fe. Finally, the difference between the observed Fe content and that predicted from magnetic susceptibility measurements suggest that magnetic domain properties of secondary Fe phases behave differently from Fe domains bound in kaolinite.

Keywords

27Al NMR SpectroscopyGoethiteHalloysiteHematiteIronKaoliniteMagnetic Susceptibility
Type
Research Article
Information
Clays and Clay Minerals , Volume 46 , Issue 4 , August 1998 , pp. 429 - 435
Copyright
Copyright © 1998, The Clay Minerals Society

References

Fukushima, E. and Roeder, S.B.W., 1981 Experimental pulse NMR: A nuts and bolts approach Reading, MA Addison-Wesley Publ..Google Scholar
Haase, J. and Oldfield, E., 1996 Quantitative determination of noninteger spin quadrulpole nuclei in solids using nuclear magnetic spin-echo techniques J Mag Res 104 104 9.Google Scholar
Hunt, C.P. Moskowitz, B.M. Banerjee, S.K. and Ahrens, T.J., 1995 Magnetic properties of rocks and minerals Rock physics and phase relations: A handbook of physical constants Washington, DC Am Geophysical Union 189–204.Google Scholar
Hurst, V.J. and Bósio, N.J., 1975 Rio Capim kaolin deposits, Brazil Econ Geol 70 990–992 10.2113/gsecongeo.70.5.990.CrossRefGoogle Scholar
Kinsey, R.A. Kirkpatrick, R.J. Hower, J. Smith, K.A. and Oldfield, E., 1985 High resolution aluminum-27 and silicon-29 nuclear magnetic resonance spectroscopic study of layer silicates, including clay minerals Am Mineral 70 537–548.Google Scholar
Kirkpatrick, R.J. and Hawthorne, F.C., 1988 MAS NMR spectroscopy of minerals and glasses Spectroscopic methods in mineralogy and geology. Rev Mineral Washington, DC Mineral Soc Am. 341–404 10.1515/9781501508974-011.CrossRefGoogle Scholar
Kirkpatrick, R.J. Weiss, C.A., Stucki, J.W. and Banwart, W.L., 1987 Magic-angle sample-spinning NMR spectroscopy of clay minerals NATO conference volume on analytical chemical methods in clay minerals research Boston, MA D. Reidel Publ..Google Scholar
Massiot, D. Bessada, C. Courures, J.P. and Taulelle, F., 1990 A quantitative study of 27Al MAS NMR in YAG J Mag Res 90 231–242.Google Scholar
Newman, R.H. Childs, C.W. and Churchman, G.J., 1994 Aluminum coordination and structural disorder in halloysite and kaolinite by 27Al NMR spectroscopy Clay Miner 29 29–312 10.1180/claymin.1994.029.3.01.CrossRefGoogle Scholar
Oldfield, E. Kinsey, R.A. Smith, K.A. Nichols, J.A. and Kirkpatrick, R.J., 1983 High-resolution NMR of inorganic solids. Influence of magnetic centers on magic-angle sample-spinning lineshapes in some natural aluminosilicates J Mag Res 51 51–329.Google Scholar
O’Reilly, W., 1984 Rock and mineral magnetism New York Blackie 10.1007/978-1-4684-8468-7.CrossRefGoogle Scholar
Pruett, R.J. Murray, H.H., Murray, H. Bundy, W. and Harvey, C., 1993 The mineralogical and geochemical controls that source rocks impose on sedimentary kaolins Kaolin genesis and utilization Boulder, CO Clay Miner Soc. 149–170.Google Scholar
Schroeder, P.A., 1993 A chemical, XRD and 27Al NMR investigation of Miocene Gulf Coast shales with application to understanding illite/smectite crystal-chemistry Clays Clay Miner 41 668–679 10.1346/CCMN.1993.0410605.CrossRefGoogle Scholar
Schroeder, P.A. and Pruett, R.J., 1996 Iron ordering in kaolinites: Insights from 29Si and 27Al NMR spectroscopy Am Mineral 81 81 38 10.2138/am-1996-1-204.CrossRefGoogle Scholar
Schulze, D.G., 1984 The influence of aluminum on iron oxides. VIII. Unit-cell dimension of Al-substituted goethites and estimation of Al from them Clays Clay Miner 32 32–44 10.1346/CCMN.1984.0320105.CrossRefGoogle Scholar