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Surface oxidation studies of chalcopyrite and pyrite by glancing-angle X-ray absorption spectroscopy (REFLEXAFS)

Published online by Cambridge University Press:  05 July 2018

K. E. R. England
Affiliation:
Department of Earth Sciences, University of Manchester, Manchester M13 9PL, UK
J. M. Charnock
Affiliation:
Department of Earth Sciences, University of Manchester, Manchester M13 9PL, UK CCLRC Daresbury Laboratory, Warrington WA4 4AD, UK
R. A. D. Pattrick
Affiliation:
Department of Earth Sciences, University of Manchester, Manchester M13 9PL, UK
D. J. Vaughan
Affiliation:
Department of Earth Sciences, University of Manchester, Manchester M13 9PL, UK

Abstract

The oxidation of chalcopyrite and pyrite was examined using Fe-K- and Cu-K-edge REFLEXAFS spectroscopy. The Fe XANES of the pyrite proved to be a very sensitive indicator of oxidation, revealing the development of a goethite-like surface species; the EXAFS data showed an increasing O:S ratio with the degree of oxidation and gave Fe–O distances of c. 1.9 Å. On the oxidized chalcopyrite surfaces, the development of Fe-O and Cu-O species was observed, with both the XANES and EXAFS revealing the progressive development of these species with oxidation. Differences in the sensitivity of the XANES and EXAFS to the degree of oxidation can be related to the degree of long range order and changes in the intensity of the pre-edge feature of the Fe are a function of its oxidation state and coordination geometry in the surface species.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1999

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