TY - JOUR
T1 - Magnetic and spin transitions in wüstite
T2 - A synchrotron Mössbauer spectroscopic study
AU - Hamada, Maki
AU - Kamada, Seiji
AU - Ohtani, Eiji
AU - Mitsui, Takaya
AU - Masuda, Ryo
AU - Sakamaki, Tatsuya
AU - Suzuki, Nanami
AU - Maeda, Fumiya
AU - Akasaka, Masahide
N1 - Funding Information:
This work was supported by Grant-in-Aid awards for Scientific Research (No. 22000002, No. 15H05748) to E.O. from the Ministry of Education, Culture, Sports, Science, and Technology of the Japanese Government. This work was also supported partly by the Ministry of Education and Science of the Russian Federation, project 14.B25.31.0032 to E.O. The synchrotron radiation experiments were performed at the SPring-8 facility with the approval of the Japan Synchrotron Radiation Research Institute (Proposals No. 2013A3513, No. 2013B1014, No. 2013B3517, No. 2014A3516, and No. 2015A1014) and the Japan Atomic Energy Agency (Proposals No. 2013B-E07 and No. 2015A-3501). We thank to Dr. Naohisa Hirao and Dr. Yasuo Ohishi of JASRI for their guide and support on the measurement of a Mssbauer spectrum of wstite at 200 GPa using BL10XU.
Publisher Copyright:
© 2016 American Physical Society.
PY - 2016/4/28
Y1 - 2016/4/28
N2 - This is a Mössbauer study of wüstite at pressures above 200 GPa using synchrotron Mössbauer spectroscopy. Synthetic Fe0.96O-wüstite was investigated at 91(2), 95(4), 109(2), 114.5(3), 131.1(7), 133.2(2), 155(2), 167(2), 193(2) and 203(1) GPa at 300 K at the SPring-8 BL11XU beamline. The Mössbauer spectrum at 91 GPa consists of both magnetic and nonmagnetic components. The magnetic high-spin component decreases gradually with increasing pressure from 91 to 203 GPa, while the nonmagnetic low-spin component increases with pressure in the same pressure range. The result suggests that the spin state of Fe in the outer core at pressures above 203 GPa is the low-spin state. If oxygen exists in the core, the low-spin Fe-O bonding is shorter than high-spin Fe-O bonding, suggesting dense Fe-O liquid in the Earth's outer core. The gradual increase of the density of the metallic liquid with depth by the spin transition of Fe-O bonding in the shallow outer core region will stabilize the outer core against thermal convection.
AB - This is a Mössbauer study of wüstite at pressures above 200 GPa using synchrotron Mössbauer spectroscopy. Synthetic Fe0.96O-wüstite was investigated at 91(2), 95(4), 109(2), 114.5(3), 131.1(7), 133.2(2), 155(2), 167(2), 193(2) and 203(1) GPa at 300 K at the SPring-8 BL11XU beamline. The Mössbauer spectrum at 91 GPa consists of both magnetic and nonmagnetic components. The magnetic high-spin component decreases gradually with increasing pressure from 91 to 203 GPa, while the nonmagnetic low-spin component increases with pressure in the same pressure range. The result suggests that the spin state of Fe in the outer core at pressures above 203 GPa is the low-spin state. If oxygen exists in the core, the low-spin Fe-O bonding is shorter than high-spin Fe-O bonding, suggesting dense Fe-O liquid in the Earth's outer core. The gradual increase of the density of the metallic liquid with depth by the spin transition of Fe-O bonding in the shallow outer core region will stabilize the outer core against thermal convection.
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U2 - 10.1103/PhysRevB.93.155165
DO - 10.1103/PhysRevB.93.155165
M3 - Article
AN - SCOPUS:84964659777
VL - 93
JO - Physical Review B
JF - Physical Review B
SN - 2469-9950
IS - 15
M1 - 155165
ER -