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 journalArticle

16 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

  • Earth and Planetary Sciences(all)
  • Geophysics

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    Lin, J. F., Mao, Z., Yang, J., Liu, J., Xiao, Y., Chow, P., & Okuchi, T. (2016). High-spin Fe2+ and Fe3+ in single-crystal aluminous bridgmanite in the lower mantle. Geophysical Research Letters, 43(13), 6952-6959. https://doi.org/10.1002/2016GL069836