Effects of the Spin Transition of Iron in Magnesiowuestite

HR: 16:45h
AN: MR14A-04 [Abstracts]
TI: Effects of the Spin Transition of Iron in Magnesiowuestite
AU: * Lin, J
EM: j.lin@gl.ciw.edu
AF: Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 United States
AU: * Lin, J
EM: j.lin@gl.ciw.edu
AF: Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC, DC 20015 United States
AU: Struzhkin, V V
EM: v.struzhkin@gl.ciw.edu
AF: Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC, DC 20015 United States
AU: Jacobsen, S D
EM: s.jacobsen@gl.ciw.edu
AF: Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC, DC 20015 United States
AU: Sturhahn, W
EM: sturhahn@aps.anl.gov
AF: Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Gavriliuk, A G
EM: gavriliuk@mail.ru
AF: Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC, DC 20015 United States
AU: Gavriliuk, A G
EM: gavriliuk@mail.ru
AF: Institute of Crystallography, Russian Academy of Sciences, Leninskii pr. 59, Moscow, 117333 Russian Federation
AU: Jackson, J M
EM: jmjackso@uiuc.edu
AF: Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC, DC 20015 United States
AU: Jackson, J M
EM: jmjackso@uiuc.edu
AF: Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Hu, M
EM: myhu@anl.gov
AF: HPCAT, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Chow, P
EM: pchow@hpcat.aps.anl.gov
AF: HPCAT, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Kung, J
EM: jkung@mail.ncku.edu.tw
AF: National Cheng-Kung University, 1 University Rd., Tainan, 70101 Taiwan
AU: Liu, H
EM: hliu@hpcat.aps.anl.gov
AF: HPCAT, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Shen, G
EM: shen@cars.uchicago.edu
AF: HPCAT, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Shen, G
EM: shen@cars.uchicago.edu
AF: CARS, The University of Chicago, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Prakapenka, V
EM: prakapenka@cars.uchicago.edu
AF: CARS, The University of Chicago, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Zhao, J
EM: jzhao@aps.anl.gov
AF: Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 United States
AU: Mao, H
EM: mao@gl.ciw.edu
AF: Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC, DC 20015 United States
AU: Yoo, C
EM: yoo1@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 United States
AU: Hemley, R J
EM: hemley@gl.ciw.edu
AF: Carnegie Institution of Washington, 5251 Broad Branch Rd. NW, Washington, DC, DC 20015 United States
AB: Recent experimental and theoretical studies indicate that pressure-induced electronic spin transitions of iron from high-spin to low-spin states occur in magnesiowüstite and silicate perovskite. The electronic spin transitions have been postulated to have important geophysical and geochemical consequences; causing a large density change, shifting the partitioning of iron between magnesiowü stite and perovskite, changing radiative thermal conductivity, and layering in the composition of the lower mantle. Here we have studied the spin states of iron in magnesiowüstite and the isolated effects of the electronic transitions on the elastic, thermodynamic, magnetic, and vibrational properties of magnesiowüstite under high pressures and/or high temperatures. In situ X-ray emission spectroscopy and X-ray diffraction studies showed that an observed high-spin to low-spin transition of iron in magnesiowüstite results in an abnormal compressional behaviour between the high-spin and the low- spin states; the high-pressure low-spin state exhibits a much higher bulk modulus (K_T) and bulk sound velocity (V_φ) than the low-pressure high-spin state in (Mg_0.83,Fe_0.17) O. Magnetic, elastic, thermodynamic, and vibrational properties of (Mg_0.75,Fe_0.25)O across the transition have also been studied with nuclear forward scattering and nuclear resonant inelastic X- ray scattering at high pressures. To experimentally address the temperature effect on the transition, X- ray emission spectroscopy and X-ray diffraction have been used in conjunction with the double-sided laser- heated diamond cell technique for studying local electronic spin states of iron in magnesiowü stite and its crystal structure under lower mantle pressure-temperature conditions. Here we combine all these results to understand the effects of the electronic transition on the physical properties of magnesiowüstite and to explore possible geophysical and geochemical consequences of the transition in the Earth's lower mantle. This work was performed under the auspices of the U.S. DOE by UC/LLNL under Contract W-7405-Eng-48.
DE: 3630 Experimental mineralogy and petrology
DE: 3919 Equations of state
DE: 3924 High-pressure behavior
DE: 3929 NMR, Mossbauer spectroscopy, and other magnetic techniques
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005