Identification of Mackinawite and Constraints on Its Electronic Configuration Using Mössbauer Spectroscopy
The Fe(II) monosulfide mineral mackinawite (FeS) is an important phase in low-temperature iron and sulfur cycles, yet it is challenging to characterize since it often occurs in X-ray amorphous or nanoparticulate forms and is extremely sensitive to oxidation. Moreover, the electronic configuration of...
| Main Authors: | , , , , , |
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| Format: | Article |
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MDPI AG
2020-12-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/10/12/1090 |
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| author | Christian Schröder Moli Wan Ian B. Butler Alastair Tait Stefan Peiffer Catherine A. McCammon |
| author_facet | Christian Schröder Moli Wan Ian B. Butler Alastair Tait Stefan Peiffer Catherine A. McCammon |
| author_sort | Christian Schröder |
| collection | DOAJ |
| description | The Fe(II) monosulfide mineral mackinawite (FeS) is an important phase in low-temperature iron and sulfur cycles, yet it is challenging to characterize since it often occurs in X-ray amorphous or nanoparticulate forms and is extremely sensitive to oxidation. Moreover, the electronic configuration of iron in mackinawite is still under debate. Mössbauer spectroscopy has the potential to distinguish mackinawite from other FeS phases and provide clarity on the electronic configuration, but conflicting results have been reported. We therefore conducted a Mössbauer study at 5 K of five samples of mackinawite synthesized through different pathways. Samples show two different Mössbauer patterns: a singlet that remains unsplit at all temperatures studied, and a sextet with a hyperfine magnetic field of 27(1) T at 5 K, or both. Our results suggest that the singlet corresponds to stoichiometric mackinawite (FeS), while the sextet corresponds to mackinawite with excess S (FeS<sub>1+<i>x</i></sub>). Both phases show center shifts near 0.5 mm/s at 5 K. Coupled with observations from the literature, our data support non-zero magnetic moments on iron atoms in both phases, with strong itinerant spin fluctuations in stoichiometric FeS. Our results provide a clear approach for the identification of mackinawite in both laboratory and natural environments. |
| first_indexed | 2024-03-10T14:18:47Z |
| format | Article |
| id | doaj.art-c22462ec87e34e559323b31e5ad5362f |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-10T14:18:47Z |
| publishDate | 2020-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-c22462ec87e34e559323b31e5ad5362f2023-11-20T23:36:59ZengMDPI AGMinerals2075-163X2020-12-011012109010.3390/min10121090Identification of Mackinawite and Constraints on Its Electronic Configuration Using Mössbauer SpectroscopyChristian Schröder0Moli Wan1Ian B. Butler2Alastair Tait3Stefan Peiffer4Catherine A. McCammon5Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, UKDepartment of Hydrology, University of Bayreuth, 95440 Bayreuth, GermanyEarth and Planetary Science, School of GeoSciences, University of Edinburgh, Edinburgh EH9 3FE, UKBiological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling FK9 4LA, UKDepartment of Hydrology, University of Bayreuth, 95440 Bayreuth, GermanyBayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, GermanyThe Fe(II) monosulfide mineral mackinawite (FeS) is an important phase in low-temperature iron and sulfur cycles, yet it is challenging to characterize since it often occurs in X-ray amorphous or nanoparticulate forms and is extremely sensitive to oxidation. Moreover, the electronic configuration of iron in mackinawite is still under debate. Mössbauer spectroscopy has the potential to distinguish mackinawite from other FeS phases and provide clarity on the electronic configuration, but conflicting results have been reported. We therefore conducted a Mössbauer study at 5 K of five samples of mackinawite synthesized through different pathways. Samples show two different Mössbauer patterns: a singlet that remains unsplit at all temperatures studied, and a sextet with a hyperfine magnetic field of 27(1) T at 5 K, or both. Our results suggest that the singlet corresponds to stoichiometric mackinawite (FeS), while the sextet corresponds to mackinawite with excess S (FeS<sub>1+<i>x</i></sub>). Both phases show center shifts near 0.5 mm/s at 5 K. Coupled with observations from the literature, our data support non-zero magnetic moments on iron atoms in both phases, with strong itinerant spin fluctuations in stoichiometric FeS. Our results provide a clear approach for the identification of mackinawite in both laboratory and natural environments.https://www.mdpi.com/2075-163X/10/12/1090mackinawiteiron sulfidelepidocrocitepolysulfideMössbauer spectroscopyelectronic configuration |
| spellingShingle | Christian Schröder Moli Wan Ian B. Butler Alastair Tait Stefan Peiffer Catherine A. McCammon Identification of Mackinawite and Constraints on Its Electronic Configuration Using Mössbauer Spectroscopy Minerals mackinawite iron sulfide lepidocrocite polysulfide Mössbauer spectroscopy electronic configuration |
| title | Identification of Mackinawite and Constraints on Its Electronic Configuration Using Mössbauer Spectroscopy |
| title_full | Identification of Mackinawite and Constraints on Its Electronic Configuration Using Mössbauer Spectroscopy |
| title_fullStr | Identification of Mackinawite and Constraints on Its Electronic Configuration Using Mössbauer Spectroscopy |
| title_full_unstemmed | Identification of Mackinawite and Constraints on Its Electronic Configuration Using Mössbauer Spectroscopy |
| title_short | Identification of Mackinawite and Constraints on Its Electronic Configuration Using Mössbauer Spectroscopy |
| title_sort | identification of mackinawite and constraints on its electronic configuration using mossbauer spectroscopy |
| topic | mackinawite iron sulfide lepidocrocite polysulfide Mössbauer spectroscopy electronic configuration |
| url | https://www.mdpi.com/2075-163X/10/12/1090 |
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