Composition Dependence of Pressure-Induced Spin Transitions in the (Mg,Fe)O System
Abstract
One of the most abundant phases in the lower mantle is believed to be rocksalt magnesiowustite (Mg,Fe)O with approximately 20% Fe. At ambient conditions, the Fe2+ ion in (Mg,Fe)O is in high-spin configuration. Recently, experiments have shown that the Fe2+ ion in (Mg,Fe)O undergoes a pressure-induced high-spin to low-spin transition which could possibly influence lower mantle dynamics. We present ab initio calculations of the rocksalt (Mg,Fe)O spin state as a function of pressure and composition. We find that the spin-transition pressure increases with increasing Fe content, consistent with present experimental evidence. We demonstrate that this can be explained through a simple size argument, but only after differences in elastic properties are taken into account.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFMMR23A0039P
- Keywords:
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- 3924 High-pressure behavior;
- 5109 Magnetic and electrical properties (0925)