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Rietveld refinement of the ranciéite structure using synchrotron powder diffraction data

Published online by Cambridge University Press:  29 February 2012

Jeffrey E. Post
Affiliation:
Department of Mineral Sciences, Smithsonian Institution, Washington, D.C.20560-0119
Peter J. Heaney
Affiliation:
Department of Geosciences, 309 Deike Building, Pennsylvania State University, University Park, Pennsylvania 16802
Andreas Ertl
Affiliation:
Institut für Mineralogie und Kristallographie, Geozentrum, Universität Wien, Althanstraße 14, 1090 Wien, Austria

Abstract

Rietveld refinement using synchrotron powder X-ray diffraction data of the ranciéite, Ca0.19K0.01(Mn4+0.910.09)O2⋅0.63H2O, crystal structure reveals significant differences from that reported previously. The interlayer H2O molecules occupy sites halfway between the Mn,O octahedral sheets. The Mn sites in the octahedral sheets have 10% vacancies, and the mean Mn–O distance indicates that all Mn is tetravalent (Mn4+). The interlayer Ca cations are located above and below the Mn vacancies and are octahedrally coordinated to three O2 atoms in the octahedral sheet and three H2O molecules in the interlayer.

Type
Technical Articles
Copyright
Copyright © Cambridge University Press 2008

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