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

作者：Guyodo Yohan^*; Sainctavit Philippe; Arrio Marie Anne; Carvallo Claire; Penn R Lee; Erbs Jasmine J; For**erg Brady S; Morin Guillaume; Maillot Fabien; Lagroix France; Bonville Pierre; Wilhelm Fabrice; Rogalev Andrei

来源：Geochemistry Geophysics Geosystems, 2012, 13(6): Q06Z44.

DOI：10.1029/2012GC004182

• XMCD
• ferrihydrite
• magnetic properties

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.

• 出版日期2012-6-7
• 单位中国地震局