Kinetics of the (Fe2++OH−)mica→(Fe3++O2−)mica+H oxidation reaction in bulk single-crystal biotite studied by Mössbauer spectroscopy
| ISSN: |
1432-2021
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| Source: |
Springer Online Journal Archives 1860-2000
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| Topics: |
Chemistry and Pharmacology
Geosciences
Physics
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| Notes: |
Abstract We report the first kinetic study of iron oxidation in a mica. Large singly-crystal biotite wafers were heated in air to various temperatures and for various times. Room temperature 57Fe Mössbauer spectroscopy was used to quantify the resulting Fe2+ and Fe3+ amounts. A simple activation model is consistent with the measurements and gives an activation energy of e b = 2.36 eV and an attempt frequency of f 0 = 2.9×107 Hz. We are lead to propose that, iron oxidation and ordinary dehydroxylation have the same rate limiting step: local dissociation of an OH group as OH−→O2-+H+. In oxidation this is followed by Fe2+ +H+→Fe3+H whereas in dehydroxylation it is followed by OH− +H+→H2O.
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| Type of Medium: |
Electronic Resource
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| URL: |