High-spin Fe2+ and Fe3+ in single-crystal aluminous bridgmanite in the lower mantle

Jung Fu Lin, Zhu Mao, Jing Yang, Jin Liu, Yuming Xiao, Paul Chow, Takuo Okuchi

    Research output: Contribution to journalArticlepeer-review

    18 Citations (Scopus)

    Abstract

    Spin and valence states of iron in single-crystal bridgmanite (Mg0.89Fe0.12Al0.11Si0.89O3) are investigated using X-ray emission and Mössbauer spectroscopies with laser annealing up to 115 GPa. The results show that Fe predominantly substitutes for Mg2+ in the pseudo-dodecahedral A site, in which 80% of the iron is Fe3+ that enters the lattice via the charge-coupled substitution with Al3+ in the octahedral B site. The total spin momentum and hyperfine parameters indicate that these ions remain in the high-spin state with Fe2+ having extremely high quadrupole splitting due to lattice distortion. (Al,Fe)-bearing bridgmanite is expected to contain mostly high-spin, A-site Fe3+, together with a smaller amount of A-site Fe2+, that remains stable throughout the region. Even though the spin transition of B-site Fe3+ in bridgmanite was reported to cause changes in its elasticity at high pressures, (Fe,Al)-bearing bridgmanite with predominantly A-site Fe will not exhibit elastic anomalies associated with the spin transition.

    Original languageEnglish
    Pages (from-to)6952-6959
    Number of pages8
    JournalGeophysical Research Letters
    Volume43
    Issue number13
    DOIs
    Publication statusPublished - Jul 16 2016

    Keywords

    • bridgmanite
    • high pressure
    • lower mantle
    • mineral physics
    • spin and valence states
    • spin transition

    ASJC Scopus subject areas

    • Geophysics
    • Earth and Planetary Sciences(all)

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