Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite
The spin and valence states of iron in (Mg0.8Fe0.2)SiO3 perovskite were measured between 0 and 65 GPa using synchrotron Mössbauer spectroscopy. Samples were synthesized in situ in the laser-heated diamond cell under reducing conditions. The dominant spin state of iron in perovskite is high spin at p...
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American Geophysical Union
2011
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| Online Access: | http://hdl.handle.net/1721.1/60550 |
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| author | Grocholski, Brent Shim, Sang-Heon Dan Sturhahn, W. Zhao, J. Xiao, Y. Chow, P. C. |
| author2 | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences |
| author_facet | Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Grocholski, Brent Shim, Sang-Heon Dan Sturhahn, W. Zhao, J. Xiao, Y. Chow, P. C. |
| author_sort | Grocholski, Brent |
| collection | MIT |
| description | The spin and valence states of iron in (Mg0.8Fe0.2)SiO3 perovskite were measured between 0 and 65 GPa using synchrotron Mössbauer spectroscopy. Samples were synthesized in situ in the laser-heated diamond cell under reducing conditions. The dominant spin state of iron in perovskite is high spin at pressures below 50 GPa. Above 50 GPa, the spectra shows severe changes which can be explained by appearance of two distinct iron sites with similar site weightings. One site has Mössbauer parameters consistent with high spin Fe2+, while the other has the parameters previously interpreted as intermediate spin. The latter intermediate-spin assignment is not unique, as similar Mössbauer parameters have been reported for high spin Fe2+ in almandine at ambient pressure. However, our data do not rule out the existence of low-spin iron, which may exist with a smaller fraction and explain the observation of lower spin moments in the X-ray emission spectroscopy of perovskite at high pressure. From these considerations, our preferred interpretation is that iron in perovskite is mixed or high spin to at least 2000 km depths in the mantle, consistent with computational results. Our study also reveals that reducing conditions do not inhibit the formation of Fe3+ in perovskite at deep-mantle pressures. |
| first_indexed | 2024-09-23T16:41:33Z |
| format | Article |
| id | mit-1721.1/60550 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:41:33Z |
| publishDate | 2011 |
| publisher | American Geophysical Union |
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| spelling | mit-1721.1/605502022-10-03T07:36:58Z Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite Spin and valence states of iron in (Mg0.8Fe0.2)SiO3 perovskite Grocholski, Brent Shim, Sang-Heon Dan Sturhahn, W. Zhao, J. Xiao, Y. Chow, P. C. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Shim, Sang-Heon Grocholski, Brent Shim, Sang-Heon Dan The spin and valence states of iron in (Mg0.8Fe0.2)SiO3 perovskite were measured between 0 and 65 GPa using synchrotron Mössbauer spectroscopy. Samples were synthesized in situ in the laser-heated diamond cell under reducing conditions. The dominant spin state of iron in perovskite is high spin at pressures below 50 GPa. Above 50 GPa, the spectra shows severe changes which can be explained by appearance of two distinct iron sites with similar site weightings. One site has Mössbauer parameters consistent with high spin Fe2+, while the other has the parameters previously interpreted as intermediate spin. The latter intermediate-spin assignment is not unique, as similar Mössbauer parameters have been reported for high spin Fe2+ in almandine at ambient pressure. However, our data do not rule out the existence of low-spin iron, which may exist with a smaller fraction and explain the observation of lower spin moments in the X-ray emission spectroscopy of perovskite at high pressure. From these considerations, our preferred interpretation is that iron in perovskite is mixed or high spin to at least 2000 km depths in the mantle, consistent with computational results. Our study also reveals that reducing conditions do not inhibit the formation of Fe3+ in perovskite at deep-mantle pressures. United States. Dept. of Energy. Office of Basic Energy Sciences United States. National Nuclear Security Administration National Science Foundation (U.S.) (EAR0738655) United States. Dept of Energy (DE-AC02-06CH11357) W. M. Keck Foundation 2011-01-13T21:00:22Z 2011-01-13T21:00:22Z 2009-12 2009-10 Article http://purl.org/eprint/type/JournalArticle 0094-8276 http://hdl.handle.net/1721.1/60550 Grocholski, B. et al. “Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite.” Geophys. Res. Lett. 36.24 (2009): L24303. ©2009 by the American Geophysical Union. en_US http://dx.doi.org/10.1029/2009gl041262 Geophysical Research Letters Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Geophysical Union MIT web domain |
| spellingShingle | Grocholski, Brent Shim, Sang-Heon Dan Sturhahn, W. Zhao, J. Xiao, Y. Chow, P. C. Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite |
| title | Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite |
| title_full | Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite |
| title_fullStr | Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite |
| title_full_unstemmed | Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite |
| title_short | Spin and valence states of iron in (Mg[subscript 0.8]Fe[subscript 0.2])SiO[subscript 3] perovskite |
| title_sort | spin and valence states of iron in mg subscript 0 8 fe subscript 0 2 sio subscript 3 perovskite |
| url | http://hdl.handle.net/1721.1/60550 |
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