Projects per year
Abstract
MgGeO3-perovskite is known to be a low-pressure analog of MgSiO3-perovskite in many respects, but especially in regard to the post-perovskite transition. As such, investigation of spin state changes in Fe-bearing MgGeO3 might help to clarify some aspects of this type of state change in Fe-bearing MgSiO3. Using DFT+U calculations, we have investigated pressure induced spin state changes in Fe2+ and Fe3+ in MgGeO3 perovskite and post-perovskite. Owing to the larger ionic radius of germanium compared to silicon, germanate phases have larger unit cell volume and inter-atomic distances than equivalent silicate phases at same pressures. As a result, all pressure induced state changes in iron occur at higher pressures in germanate phases than in the silicate ones, be it a spin state change or position change of (ferrous) iron in the perovskite A site. We showed that iron state transitions occur at particular average Fe-O bond-length (i.e., ~2.22 (1)Å and ~1.86 (1)Å for Fe2+ and Fe3+ substitutions, respectively) irrespective of mineral composition (silicate or germanate) or exchange-correlation functionals used in the calculation (LDA+Usc or GGA+Usc). Ferrous iron substitution decreases the perovskite to post-perovskite (PPv) transition pressure while coupled ferric iron substitution increases it noticeably.
Original language | English (US) |
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Pages (from-to) | 11-17 |
Number of pages | 7 |
Journal | Physics of the Earth and Planetary Interiors |
Volume | 249 |
DOIs | |
State | Published - Dec 1 2015 |
Keywords
- Ferrous and ferric iron
- Iron-spin crossover
- Pv to PPv transition
How much support was provided by MRSEC?
- Partial
Reporting period for MRSEC
- Period 2
Fingerprint Dive into the research topics of 'Spin crossovers in iron-bearing MgSiO<sub>3</sub> and MgGeO<sub>3</sub>: Their influence on the post-perovskite transition'. Together they form a unique fingerprint.
Projects
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MRSEC IRG-1: Electrostatic Control of Materials
Leighton, C., Birol, T., Fernandes, R. M., Frisbie, D., Goldman, A. M., Greven, M., Jalan, B., Koester, S. J., He, T., Jeong, J. S., Koirala, S., Paul, A., Thoutam, L. R. & Yu, G.
9/1/98 → …
Project: Research project
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