Fe2+ -Fe3+ ordering in chromite and Cr-bearing spinels

Margery D. Osborne; Michael E. Fleet; G. Michael Bancroft

doi:10.1007/BF00373539

Fe²⁺ -Fe³⁺ ordering in chromite and Cr-bearing spinels

Margery D. Osborne, Michael E. Fleet, G. Michael Bancroft

Research output: Contribution to journal › Article › peer-review

Abstract

Mössbauer spectra for a variety of analysed spinel phases, representing a very wide range in both total iron content and Fe³⁺/(Fe²⁺+Fe³⁺) ratio, indicate an essentially ordered arrangement of iron atoms in the crystal structures of natural chromite and Cr-bearing spinels. All of the Mössbauer spectra have been rationalised by fitting just two doublets, assigned to Fe²⁺ in the tetrahedral (T) cation site and Fe³⁺ in the octahedral (M) site, using initial Mössbauer parameters for synthetic end-member compositions. Calculated Fe³⁺ to Fe²⁺ ratios agree well with wet chemical data. This ideal Fe²⁺ (T site) -Fe³⁺ (M site) ordering scheme has been disregarded in recent Mössbauer studies on chromite, and complex fits and explanations have been proposed. However, we find no evidence in the Mössbauer spectra of the spinels investigated in this study of T site Fe³⁺ and M site Fe²⁺ or of electron delocalization (or chargehopping) effects.

Original language	English (US)
Pages (from-to)	251-255
Number of pages	5
Journal	Contributions to Mineralogy and Petrology
Volume	77
Issue number	3
DOIs	https://doi.org/10.1007/BF00373539
State	Published - Oct 1981
Externally published	Yes

ASJC Scopus subject areas

Geophysics
Geochemistry and Petrology

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10.1007/BF00373539

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@article{b4dba2a5547e4a4cbf730edd1fe5721c,

title = "Fe2+ -Fe3+ ordering in chromite and Cr-bearing spinels",

abstract = "M{\"o}ssbauer spectra for a variety of analysed spinel phases, representing a very wide range in both total iron content and Fe3+/(Fe2++Fe3+) ratio, indicate an essentially ordered arrangement of iron atoms in the crystal structures of natural chromite and Cr-bearing spinels. All of the M{\"o}ssbauer spectra have been rationalised by fitting just two doublets, assigned to Fe2+ in the tetrahedral (T) cation site and Fe3+ in the octahedral (M) site, using initial M{\"o}ssbauer parameters for synthetic end-member compositions. Calculated Fe3+ to Fe2+ ratios agree well with wet chemical data. This ideal Fe2+ (T site) -Fe3+ (M site) ordering scheme has been disregarded in recent M{\"o}ssbauer studies on chromite, and complex fits and explanations have been proposed. However, we find no evidence in the M{\"o}ssbauer spectra of the spinels investigated in this study of T site Fe3+ and M site Fe2+ or of electron delocalization (or chargehopping) effects.",

author = "Osborne, {Margery D.} and Fleet, {Michael E.} and {Michael Bancroft}, G.",

year = "1981",

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AU - Osborne, Margery D.

AU - Fleet, Michael E.

AU - Michael Bancroft, G.

PY - 1981/10

Y1 - 1981/10

N2 - Mössbauer spectra for a variety of analysed spinel phases, representing a very wide range in both total iron content and Fe3+/(Fe2++Fe3+) ratio, indicate an essentially ordered arrangement of iron atoms in the crystal structures of natural chromite and Cr-bearing spinels. All of the Mössbauer spectra have been rationalised by fitting just two doublets, assigned to Fe2+ in the tetrahedral (T) cation site and Fe3+ in the octahedral (M) site, using initial Mössbauer parameters for synthetic end-member compositions. Calculated Fe3+ to Fe2+ ratios agree well with wet chemical data. This ideal Fe2+ (T site) -Fe3+ (M site) ordering scheme has been disregarded in recent Mössbauer studies on chromite, and complex fits and explanations have been proposed. However, we find no evidence in the Mössbauer spectra of the spinels investigated in this study of T site Fe3+ and M site Fe2+ or of electron delocalization (or chargehopping) effects.

AB - Mössbauer spectra for a variety of analysed spinel phases, representing a very wide range in both total iron content and Fe3+/(Fe2++Fe3+) ratio, indicate an essentially ordered arrangement of iron atoms in the crystal structures of natural chromite and Cr-bearing spinels. All of the Mössbauer spectra have been rationalised by fitting just two doublets, assigned to Fe2+ in the tetrahedral (T) cation site and Fe3+ in the octahedral (M) site, using initial Mössbauer parameters for synthetic end-member compositions. Calculated Fe3+ to Fe2+ ratios agree well with wet chemical data. This ideal Fe2+ (T site) -Fe3+ (M site) ordering scheme has been disregarded in recent Mössbauer studies on chromite, and complex fits and explanations have been proposed. However, we find no evidence in the Mössbauer spectra of the spinels investigated in this study of T site Fe3+ and M site Fe2+ or of electron delocalization (or chargehopping) effects.

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