[SIT20-P06] Inelastic X-ray scattering measurements of liquid Fe-N alloy under high pressure
Keywords:Earth's liquid outer core, Light element, P-wave velocity, High pressure
We carried out high-pressure and -temperature IXS measurements using a laser-heated diamond-anvil cell (LH-DAC) at the beamline BL43LXU of SPring-8 . We used an Fe4N foil (hereafter called Fe80N20) as a starting sample and single crystal Al2O3 discs as a thermal insulator. We judged the sample melting based on X-ray diffraction measurements during heating and then measured IXS of the liquid sample. The longitudinal sound wave (P-wave) velocity of liquid Fe80N20 was determined from the dispersion relation of the longitudinal acoustic phonon mode of the sample. We obtained the velocity of liquid Fe80N20 up to 76 GPa and 2200 K. We found that the P-wave velocity of liquid Fe80N20 is slightly faster by c.a. 4% than that of liquid Fe . The P-wave velocity of liquid outer core is faster by 4% than liquid Fe . Therefore, the present results give the upper limit of 5.9 wt.% (20 at.%) for the nitrogen content in the outer core.
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