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AGU: Geophysical Research Letters

 

Keywords

  • FeO
  • metallization
  • phase diagram
  • phase transition
  • wüstite
  • x-ray diffraction

Index Terms

  • 3612 - Reactions and phase equilibria
  • 3914 - Electrical properties
  • 3924 - High-pressure behavior
  • 3939 - Physical thermodynamics
  • 3954 - X-ray, neutron, and electron spectroscopy and diffraction

Paper in Press

GEOPHYSICAL RESEARCH LETTERS, doi:10.1029/2011GL049800

Phase transition and metallization of FeO at high pressures and temperatures

Key Points
  • FeO becomes metallic at P-T conditions of the Earth's lower mantle and core.
  • This new phase boundary resolves major discrepancies in the FeO phase diagram.

Authors:

Rebecca A. Fischer

Andrew J. Campbell

Oliver T Lord

Gregory A. Shofner

Przemyslaw K. Dera

Vitali B Prakapenka

Wüstite, Fe(1-x)O, is an important component in the mineralogy of Earth's lower mantle and may also be a component of the core. Therefore its high pressure-temperature behavior, including its electronic structure, is essential to understanding the nature and evolution of Earth's deep interior. We performed X-ray diffraction and radiometric measurements on wüstite in a laser-heated diamond anvil cell, finding an insulator-metal transition at high pressures and temperatures. Our data show a negative slope for this apparently isostructural phase boundary, which is characterized by a volume decrease and emissivity increase. The metallic phase of FeO is stable at conditions of the lower mantle and core, which has implications for the high P-T character of Fe-O bonds, magnetic field propagation, and lower mantle conductivity.

Received 29 September 2011; accepted 1 November 2011.

Citation: Fischer, R. A., A. J. Campbell, O. T. Lord, G. A. Shofner, P. K. Dera, and V. B. Prakapenka (2011), Phase transition and metallization of FeO at high pressures and temperatures, Geophys. Res. Lett., doi:10.1029/2011GL049800, in press.