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Measurements of Sound Velocity of Liquid Fe‐11.8 wt % S up to 211.4 GPa and 6,150 K
Author(s) -
Huang H.,
Leng C.,
Wang Q.,
Yang G.,
Hu X.,
Wu Y.,
Liu X.,
Fei Y.
Publication year - 2018
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 - 10.1029/2017jb015269
Subject(s) - liquidus , outer core , classification of discontinuities , inner core , core (optical fiber) , thermodynamics , mineralogy , analytical chemistry (journal) , chemistry , earth (classical element) , quartz , geology , materials science , physics , geophysics , phase (matter) , metallurgy , composite material , mathematical physics , mathematical analysis , mathematics , organic chemistry , chromatography
Abstract Using the dynamic compression technique, the sound velocities of Fe‐11.8 wt % S were measured up to 211.4 (4.5) GPa and 6,150 K. Discontinuities both in shock velocity and sound velocity indicate that Fe‐11.8 wt % S completely melts at a pressure of 111.3 (2.3) GPa. By the energy conservation law, the calculated liquidus temperature is about 2,500 (300) K. Extrapolated to the inner‐core boundary based on the Lindeman law, the liquidus temperature of Fe‐11.8 wt % S is 4,300 (300) K. We developed a thermodynamic model fit to the experimental data, which allows calculation of the densities and sound velocities of liquid Fe‐S under core conditions. For liquid Fe‐11.8 wt % S and Fe‐10 wt % S, good agreement was achieved between the extrapolations using our model and experimental measurements at very low pressure. Under the conditions of the outer core, the densities and bulk sound velocities of Fe‐10 wt % S provide a good fit to observed seismic profiles of Earth's core. Our results imply that an upper limit of 10 wt % S content in Earth's core satisfies the geophysical constraints. Simultaneously considering other geochemical constraints, the outer core may contain about 6 wt % sulfur and 4 wt % silicon.