Sound velocity of liquid Fe‐Ni‐S at high pressure. Issue 5 (27th May 2017) - Kawaguchi, Saori I.
Abstract: The sound velocity of liquid Fe47 Ni28 S25 and Fe63 Ni12 S25 was measured up to 52 GPa/2480 K in externally resistance‐heated and laser‐heated diamond‐anvil cells using high‐resolution inelastic X‐ray scattering. From these experimental data, we obtained the elastic parameters of liquid Fe47 Ni28 S25, K S0 = 96.1 ± 2.7 GPa and K S0 ′ = 4.00 ± 0.13, where K S0 and K S0 ′ are the adiabatic bulk modulus and its pressure derivative at 1 bar, when the density is fixed at ρ 0 = 5.62 ± 0.09 g/cm 3 for 1 bar and 2000 K. With these parameters, the sound velocity and density of liquid Fe47 Ni28 S25 were calculated to be 8.41 ± 0.17 km/s and 8.93 ± 0.19 to 9.10 ± 0.18 g/cm 3, respectively, at the core mantle boundary conditions of 135 GPa and 3600–4300 K. These values are 9.4% higher and 17–18% lower than those of pure Fe, respectively. Extrapolation of measurements and comparison with seismological models suggest the presence of 5.8–7.5 wt % sulfur in the Earth's outer core if it is the only light element. Key Points: The sound velocity of liquid Fe47 Ni28 S25 was measured up to 52 GPa Extrapolation of measurements and comparison with seismic models suggest the presence of 5.8–7.5 wt % sulfur in the Earth's outer core