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Title: The spin state of iron in minerals of Earth's lower mantle

Here, the spin state of Fe(II) and Fe(III) at temperatures and pressures typical for the Earth's lower mantle is discussed. We predict an extended high-spin to low-spin crossover region along the geotherm for Fe-dilute systems depending on crystal-field splitting, pairing energy, and cooperative interactions. In particular, spin transitions in ferromagnesium silicate perovskite and ferropericlase, the dominant lower mantle components, should occur in a wide temperature-pressure range. We also derive a gradual volume change associated with such transitions in the lower mantle. The gradual density changes and the wide spin crossover regions seem incompatible with lower mantle stratification resulting from a spin transition.
Authors:
 [1] ;  [2] ;  [3]
  1. Argonne National Lab. (ANL), Lemont, IL (United States)
  2. Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
  3. Carnegie Institution of Washington, Washington, DC (United States)
Publication Date:
OSTI Identifier:
898678
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Geophysical Research Letters
Additional Journal Information:
Journal Volume: 32; Journal Issue: 12; Journal ID: ISSN 0094-8276
Publisher:
American Geophysical Union
Research Org:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Lemont, IL (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; IRON; SPIN; EARTH MANTLE; MINERALS advanced photon source