A Mossbauer study of pentacoordinated ferric iron in orthoericssonite
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Mössbauer spectra of orthoericssonite in the temperature range 78–547 K reveal very low quadrupole splittings (QS=0.26–0.31 mm/s) for pentacoordinated Fe<SUP>3+</SUP>, which is shown to be a consequence of the size of the angle between equatorial bonds and the apical bond of this site. At temperatures above 298 K the Mössbauer centroid shift (CS) decreases linearly at −8.0 (±1.1) ·10<SUP>−4</SUP>mm·s<SUP>−1</SUP> ·deg<SUP>−1</SUP>, which is in good agreement with the theoretical value of −7.3 ·10<SUP>−4</SUP>mm ·s<SUP>−1</SUP> ·deg<SUP>−1</SUP>. In agreement with previous chemical analyses of the studied samples minor absorption doublets caused by the presence of ferrous iron were recorded in the spectra of a sample from the Hijikuzu mine, Japan. Mössbauer spectra indicate that ferrous iron substitutes for manganese randomly at all three types of octahedral sites found in the orthoericssonite structure.
- Mineralogical Journal
Mineralogical Journal 17(8), 363-371, 1995-10-01
Japan Association of Mineralogical Sciences