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Equation of State for Fe‐9.0 wt% O up to 246 GPa: Implications for Oxygen in the Earth's Outer Core
Author(s) -
Young G.,
Fan Lili,
Zhao Bin,
Chen Xing,
Liu Xun,
Huang Haijun
Publication year - 2021
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2020jb021056
Subject(s) - outer core , equation of state , earth (classical element) , inner core , bulk modulus , isothermal process , core (optical fiber) , speed of sound , thermodynamics , oxygen , compression (physics) , mixing (physics) , materials science , physics , chemistry , composite material , mathematical physics , quantum mechanics
To constrain the amount of oxygen in Earth's outer core, the equation of sate (EoS) for Fe‐9 wt% O (Fe‐9O) was measured up to ∼246 GPa using the dynamic compression technique. The shock velocity ( U s ) and particle velocity ( u p ) relationship can be described byU s = 4.07 ( 21 ) + 1.62 ( 7 ) u p . Using the ideal mixing model, the isothermal equation of state for Fe‐9O at 300 K was fitted to the third‐order Birch‐Murnaghan EoS with bulk modulusK 0 = 163.6 ( 17 ) GPa and its pressure derivative K0 ′ = 4.11 ( 6 ) . Based on the EoS of Mie‐Grüneisen, the calculated adiabat coincides with our experimental data when its Grüneisen parameters are given byγ 0 = 2.3 , q = 0.3 . Using the determined parameters, bulk sound velocities were obtained from the Hugoniot data. By comparing the pressure‐density profiles and sound velocities of Fe‐O system with the preliminary reference Earth model, it was determined that the oxygen‐rich composition does not provide a good match to the observations in the Earth's outer core.