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Local structure around Fe in Mg (sub 0.9) Fe (sub 0.1) SiO (sub 3) perovskite; an X-ray absorption spectroscopy study at Fe-K edge

Francois Farges, Francois Guyot, Denis Andrault and Yanbin Wang
Local structure around Fe in Mg (sub 0.9) Fe (sub 0.1) SiO (sub 3) perovskite; an X-ray absorption spectroscopy study at Fe-K edge
European Journal of Mineralogy (June 1994) 6 (3): 303-312

Abstract

A polycrystalline Mg (sub 0.90) Fe (sub 0.10) SiO (sub 3) perovskite, synthesized at 260 kbar and 1973 K in a multi-anvil apparatus, and the enstatite starting material have been examined by X-ray absorption fine structure (XAFS) spectroscopy at the Fe-K edge under ambient conditions. Evidence was found for: 1) the presence of major amounts of Fe (super 2+) , 2) a higher average Fe-O distance in perovskite than in enstatite and 3) a wide distribution of the individual Fe-O distances, suggesting that a simple harmonic model to fit XAFS data may not be appropriate. Although a classic Gaussian model of the O environment is consistent with the presence of 6 X Fe (super 2+) -O correlations at 2.16 Angstrom, a double harmonic (e.g. 2 X Gaussian) fit reveals the presence of 2.8 +- 0.5 additional Fe-O first-neighbours correlation at a mean Fe-O distance of approx 2.30 Angstrom, yielding 8.4 +- 1 Fe-O first-neighbours correlation around Fe with a mean Fe-O distance of 2.23 Angstrom . These data compare favourably with those for the Mg site in the same perovskite (8 X Mg-O at 2.20 Angstrom), suggesting that Fe substitutes preferentially for Mg in this perovskite.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 6
Serial Issue: 3
Title: Local structure around Fe in Mg (sub 0.9) Fe (sub 0.1) SiO (sub 3) perovskite; an X-ray absorption spectroscopy study at Fe-K edge
Affiliation: Universite Marne-la-Vallee, Departement des Geomateriaux, Paris, France
Pages: 303-312
Published: 199406
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 34
Accession Number: 1995-009767
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Secondary Affiliation: State University of New York at Stony Brook, USA, United States
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199504
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