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Title: Electrical Conductivity of the Lower-Mantle Ferropericlase

Abstract

Electrical conductivity of the lower-mantle ferropericlase-(Mg{sub 0.75},Fe{sub 0.25})O has been studied using designer diamond anvils to pressures over one megabar and temperatures up to 500 K. The electrical conductivity of (Mg{sub 0.75},Fe{sub 0.25})O gradually rises by an order of magnitude up to 50 GPa but decreases by a factor of approximately three between 50 to 70 GPa. This decrease in the electrical conductivity is attributed to the electronic high-spin to low-spin transition of iron in ferropericlase. That is, the electronic spin transition of iron results in a decrease in the mobility and/or density of the charge transfer carriers in the low-spin ferropericlase. The activation energy of the low-spin ferropericlase is 0.27 eV at 101 GPa, similar to that of the high-spin ferropericlase at relatively low temperatures. Our results indicate that low-spin ferropericlase exhibits lower electrical conductivity than high-spin ferropericlase, which needs to be considered in future geomagnetic models for the lower mantle. The extrapolated electrical conductivity of the low-spin ferropericlase, together with that of silicate perovskite, at the lower mantle pressure-temperature conditions is consistent with the model electrical conductivity profile of the lower mantle.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
920481
Report Number(s):
UCRL-JRNL-230312
Journal ID: ISSN 0094-8276; GPRLAJ; TRN: US200818%%666
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geophysical Research Letters, vol. 34, n/a, August 21, 2007, L16305; Journal Volume: 34
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; ACTIVATION ENERGY; DIAMONDS; ELECTRIC CONDUCTIVITY; IRON; PEROVSKITE; SILICATES; SPIN

Citation Formats

Lin, J F, Weir, S T, Jackson, D D, Evans, W J, Vohra, Y K, Qiu, W, and Yoo, C S. Electrical Conductivity of the Lower-Mantle Ferropericlase. United States: N. p., 2007. Web.
Lin, J F, Weir, S T, Jackson, D D, Evans, W J, Vohra, Y K, Qiu, W, & Yoo, C S. Electrical Conductivity of the Lower-Mantle Ferropericlase. United States.
Lin, J F, Weir, S T, Jackson, D D, Evans, W J, Vohra, Y K, Qiu, W, and Yoo, C S. Thu . "Electrical Conductivity of the Lower-Mantle Ferropericlase". United States. doi:. https://www.osti.gov/servlets/purl/920481.
@article{osti_920481,
title = {Electrical Conductivity of the Lower-Mantle Ferropericlase},
author = {Lin, J F and Weir, S T and Jackson, D D and Evans, W J and Vohra, Y K and Qiu, W and Yoo, C S},
abstractNote = {Electrical conductivity of the lower-mantle ferropericlase-(Mg{sub 0.75},Fe{sub 0.25})O has been studied using designer diamond anvils to pressures over one megabar and temperatures up to 500 K. The electrical conductivity of (Mg{sub 0.75},Fe{sub 0.25})O gradually rises by an order of magnitude up to 50 GPa but decreases by a factor of approximately three between 50 to 70 GPa. This decrease in the electrical conductivity is attributed to the electronic high-spin to low-spin transition of iron in ferropericlase. That is, the electronic spin transition of iron results in a decrease in the mobility and/or density of the charge transfer carriers in the low-spin ferropericlase. The activation energy of the low-spin ferropericlase is 0.27 eV at 101 GPa, similar to that of the high-spin ferropericlase at relatively low temperatures. Our results indicate that low-spin ferropericlase exhibits lower electrical conductivity than high-spin ferropericlase, which needs to be considered in future geomagnetic models for the lower mantle. The extrapolated electrical conductivity of the low-spin ferropericlase, together with that of silicate perovskite, at the lower mantle pressure-temperature conditions is consistent with the model electrical conductivity profile of the lower mantle.},
doi = {},
journal = {Geophysical Research Letters, vol. 34, n/a, August 21, 2007, L16305},
number = ,
volume = 34,
place = {United States},
year = {Thu Apr 19 00:00:00 EDT 2007},
month = {Thu Apr 19 00:00:00 EDT 2007}
}