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Equation of State for Shocked Fe‐8.6 wt% Si up to 240 GPa and 4,670 K
Author(s) -
Huang Haijun,
Leng Chunwei,
Wang Qingsong,
Young Gang,
Liu Xun,
Wu Ye,
Xu Feng,
Fei Yingwei
Publication year - 2019
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 - 10.1029/2019jb017983
Subject(s) - outer core , isothermal process , equation of state , inner core , core (optical fiber) , compression (physics) , materials science , thermodynamics , lattice (music) , analytical chemistry (journal) , chemistry , physics , composite material , chromatography , acoustics
Using dynamic compression technique, the equation of state for Fe‐8.6 wt% Si was measured up to 240 GPa and 4,670 K. A least squares fit to the experimental data yields the Hugoniot parameters C 0 = 4.603±0.101 km/s and λ = 1.505±0.037 with initial density ρ 0 =7.386±0.021 g/cm 3 . Based on the Hugoniot data, the calculated isothermal equation of state is consistent with static compression data when the lattice Grüneisen parameter γ l =1.65(7.578/ ρ ) and electronic Grüneisen parameter γ e =1.83. The calculated pressure‐density data at 300 K were fitted to a third‐order Birch‐Murnaghan equation of state with zero pressure the parameters K 0 =192.1±6.3 GPa, K 0 ' =4.71±0.27 with fixed ρ 0 ε =7.578±0.050 g/cm 3 . Under the conditions of Earth's core, the densities of Fe‐8.6±2.0 wt% Si and Fe‐3.8±2.9 wt% Si agree with preliminary reference Earth mode (PREM) data of the outer and the inner core, respectively. These are the upper limits for Si in the core assuming Si is the only light element. Simultaneously considering the geophysical and geochemical constraints for a Si‐S‐bearing core, the outer core may contain 3.8±2.9 wt% Si and 5.6±3.0 wt% S.