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Title: Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle

Abstract

Pressure-induced electronic spin-pairing transitions of iron and associated effects on the physical properties have been reported to occur in the lower-mantle ferropericlase, silicate perosvkite, and perhaps in post silicate perovskite at high pressures and room temperature. These recent results are motivating geophysicists and geodynamicists to reevaluate the implications of spin transitions on the seismic heterogeneity, composition, as well as the stability of the thermal upwellings of the Earth's lower mantle. Here we have measured the spin states of iron in ferropericlase and its crystal structure up to 95 GPa and 2000 K using a newly constructed X-ray emission spectroscopy and diffraction with the laser-heated diamond cell. Our results show that an isosymmetric spin crossover occurs over a pressure-temperature range extending from the upper part to the lower part of the lower mantle, and low-spin ferropericlase likely exists in the lowermost mantle. Although continuous changes in physical and chemical properties are expected to occur across the spin crossover, the spin crossover results in peculiar behavior in the thermal compression and sound velocities. Therefore, knowledge of the fraction of the spin states in the lower-mantle phases is thus essential to correctly evaluate the composition, geophysics, and dynamics of the Earth's lower mantle.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
919593
Report Number(s):
UCRL-JRNL-227767
Journal ID: ISSN 0193-4511; SCEHDK; TRN: US200822%%433
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Science, vol. 317, n/a, September 21, 2007, pp. 1740-1743; Journal Volume: 317
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; CHEMICAL PROPERTIES; CRYSTAL STRUCTURE; EMISSION SPECTROSCOPY; IRON; PHYSICAL PROPERTIES; SPIN

Citation Formats

Lin, J F, Vanko, G, Jacobsen, S D, Iota, V, Struzhkin, V V, Prakapenka, V B, Kuznetsov, A, and Yoo, C S. Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle. United States: N. p., 2007. Web.
Lin, J F, Vanko, G, Jacobsen, S D, Iota, V, Struzhkin, V V, Prakapenka, V B, Kuznetsov, A, & Yoo, C S. Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle. United States.
Lin, J F, Vanko, G, Jacobsen, S D, Iota, V, Struzhkin, V V, Prakapenka, V B, Kuznetsov, A, and Yoo, C S. Thu . "Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle". United States. doi:. https://www.osti.gov/servlets/purl/919593.
@article{osti_919593,
title = {Electronic Spin Crossover of Iron in Ferroperclase in Earth?s Lower Mantle},
author = {Lin, J F and Vanko, G and Jacobsen, S D and Iota, V and Struzhkin, V V and Prakapenka, V B and Kuznetsov, A and Yoo, C S},
abstractNote = {Pressure-induced electronic spin-pairing transitions of iron and associated effects on the physical properties have been reported to occur in the lower-mantle ferropericlase, silicate perosvkite, and perhaps in post silicate perovskite at high pressures and room temperature. These recent results are motivating geophysicists and geodynamicists to reevaluate the implications of spin transitions on the seismic heterogeneity, composition, as well as the stability of the thermal upwellings of the Earth's lower mantle. Here we have measured the spin states of iron in ferropericlase and its crystal structure up to 95 GPa and 2000 K using a newly constructed X-ray emission spectroscopy and diffraction with the laser-heated diamond cell. Our results show that an isosymmetric spin crossover occurs over a pressure-temperature range extending from the upper part to the lower part of the lower mantle, and low-spin ferropericlase likely exists in the lowermost mantle. Although continuous changes in physical and chemical properties are expected to occur across the spin crossover, the spin crossover results in peculiar behavior in the thermal compression and sound velocities. Therefore, knowledge of the fraction of the spin states in the lower-mantle phases is thus essential to correctly evaluate the composition, geophysics, and dynamics of the Earth's lower mantle.},
doi = {},
journal = {Science, vol. 317, n/a, September 21, 2007, pp. 1740-1743},
number = ,
volume = 317,
place = {United States},
year = {Thu Jan 25 00:00:00 EST 2007},
month = {Thu Jan 25 00:00:00 EST 2007}
}