X-ray magnetic circular dichroism provides strong evidence for tetrahedral iron in ferrihydrite | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  X-ray magnetic circular dichroism provides strong evidence for tetrahedral iron in ferrihydrite

Type de publication:

Journal Article

Source:

Geochemistry Geophysics Geosystems, Volume 13 (2012)

ISBN:

1525-2027

Numéro d'accès:

WOS:000305144200001

URL:

http://www.agu.org/pubs/crossref/2012/2012GC004182.shtml

Mots-clés:

UMR 7154 ; Paléomagnétisme ; XMCD ; ferrihydrite ; magnetic properties

Résumé:

Ferrihydrite is an important iron oxyhydroxide for earth and environmental sciences, biology, and technology. Nevertheless, its mineral structure remains a matter of debate. The stumbling block is whether a significant amount of tetrahedrally coordinated iron is present. Here we present the first X-ray magnetic circular dichroism (XMCD) measurements performed on a well characterized synthetic sample of 6-line ferrihydrite, at both K and L2,3 energy edges of iron. XMCD results demonstrate unambiguously the presence of tetrahedrally coordinated Fe(III) in the mineral structure, in quantities compatible with the latest extended X-ray absorption fine structure (EXAFS) analyses suggesting a concentration of 20-30%. Moreover, we find an antiferromagnetic coupling between tetrahedral and octahedral sublattices, with the octahedral sublattice parallel to the external magnetic field.

Notes:

Times Cited: 0