The Phase Diagram of FeO Rebecca A. Fischer1, Andrew J. Campbell1, Oliver T. Lord2, Gregory A. Shofner3, Przemyslaw Dera4, and Vitali B. Prakapenka4 1Department of the Geophysical Sciences, University of Chicago 2Department of Earth Sciences, University College London 3Department of Geology, University of Maryland 4Center for Advanced Radiation Sources, University of Chicago 15 June 2011 COMPRES Annual Meeting Photo credit: Calvin Hamilton

Current Phase Diagram of FeO melt B1/B8 boundary has a positive slope B1-B8-rhombohedral triple point would violate Schreinemaker’s rules B1 B8-LS B8-HS rhombohedral

Electrical Resistivity of FeO metal melt insulator B1 Knittle et al. (1986) Shock wave data show that B1-FeO becomes metallic at high pressures and temperatures Ohta et al. (2010) B8-LS B8-HS rhombohedral

Radiometric Methods Four-color temperature imaging system (Campbell, 2008) Phase transition identified from discontinuities in temperature-emissivity relationship 59 GPa 50 GPa

X-Ray Diffraction Methods NaCl 100 NaCl 110 NaCl 200 NaCl 211 NaCl 220 Fe 100 Fe 101 Fe 102 B1 FeO 220 Fe 110 B1 FeO 311 B1 FeO 111 B1 FeO 200 B1 FeO 222 B1 FeO 400 X-Ray Diffraction Methods Laser-heated diamond anvil cell experiments at sector 13-ID-D of APS Isostructural transition 0.3% average volume drop in FeO across the transition 65-70 GPa

Results: Phase Boundary in FeO B1 insulator B1 metal melt Knittle et al. (1986) Agreement between optical, XRD, and shock wave methods

Results: Phase Diagram of FeO melt B1 insulator B1 metal B8 LS B8 HS rhombohedral Numerous datasets from several different research groups Thermodynamically self-consistent

Acknowledgements: NSF, NSF-GRFP, GSECARS, APS, COMPRES Conclusions FeO undergoes an insulator- metal transition at high pressures and temperatures Agreement between different experimental methods defining the B1 insulator/metal boundary B1 metal is stable at P-T conditions of the lower mantle and outer core Implications for ferropericlase stability, lower mantle conductivity, Fe-O bond at high pressures melt B1 insulator B1 metal B8 LS B8 HS rhombohedral Come see my poster this afternoon! Acknowledgements: NSF, NSF-GRFP, GSECARS, APS, COMPRES