1. 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

2. 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

3. 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

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

5. 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

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

7. 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

8. 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