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ESCA and solid-state NMR studies of allophane

Published online by Cambridge University Press:  09 July 2018

N. He
Affiliation:
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
T. L. Barr*
Affiliation:
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
J. Klinowski
Affiliation:
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
*
*Permanent Address: Department of Materials and Laboratory for Surface Studies, University of Wisconsin-Milwaukee, MilwaukeeWisconsin 53201, USA

Abstract

The surface/near-surface chemistry of allophane has been studied by X-ray photoelectron spectroscopy (ESCA) and the bulk material by 27A1 and 29Si solid-state NMR and other techniques. The surface/near-surface Si/Al ratio of allophane is c.1.0, similar to that for kaolinite, zeolite Na-A and sodalite. The core level binding energies for kaolinite and allophane are almost identical, but quite different from those for zeolite Na-A and sodalite, both framework aluminosilicates. The nature and size of these differences is consistent with the differences between the chemistry of sheet and framework silicates. The small variations in the Si(2p) spectra for kaolinite and allophane are discussed in terms of bonding of the tetrahedral units in the two materials.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1995

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