| Autor: |
Iuliia Koemets, Biao Wang, Egor Koemets, Takayuki Ishii, Zhaodong Liu, Catherine McCammon, Artem Chanyshev, Tomo Katsura, Michael Hanfland, Alexander Chumakov, Leonid Dubrovinsky |
| Jazyk: |
angličtina |
| Rok vydání: |
2023 |
| Předmět: |
|
| Zdroj: |
Frontiers in Chemistry, Vol 11 (2023) |
| Druh dokumentu: |
article |
| ISSN: |
2296-2646 |
| DOI: |
10.3389/fchem.2023.1258389 |
| Popis: |
Silicate perovskite, with the mineral name bridgmanite, is the most abundant mineral in the Earth’s lower mantle. We investigated crystal structures and equations of state of two perovskite-type Fe3+-rich phases, FeMg0.5Si0.5O3 and Fe0.5Mg0.5Al0.5Si0.5O3, at high pressures, employing single-crystal X-ray diffraction and synchrotron Mössbauer spectroscopy. We solved their crystal structures at high pressures and found that the FeMg0.5Si0.5O3 phase adopts a novel monoclinic double-perovskite structure with the space group of P21/n at pressures above 12 GPa, whereas the Fe0.5Mg0.5Al0.5Si0.5O3 phase adopts an orthorhombic perovskite structure with the space group of Pnma at pressures above 8 GPa. The pressure induces an iron spin transition for Fe3+ in a (Fe0.7,Mg0.3)O6 octahedral site of the FeMg0.5Si0.5O3 phase at pressures higher than 40 GPa. No iron spin transition was observed for the Fe0.5Mg0.5Al0.5Si0.5O3 phase as all Fe3+ ions are located in bicapped prism sites, which have larger volumes than an octahedral site of (Al0.5,Si0.5)O6. |
| Databáze: |
Directory of Open Access Journals |
| Externí odkaz: |
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