The sound velocity of hcp Fe0.89Si0.11 (Fe-6wt% Si) alloy was measured at pressures from 45 to 84 GPa and temperatures of 300 and 1800 K using inelastic X-ray scattering (IXS) from laser-heated samples in diamond-anvil cells (DACs). The compressional velocity (νP) and density (ρ) of the Fe-Si alloy are observed to follow a linear relationship at a given temperature. For hcp Fe0.89Si0.11 alloy we found νP = 1.030 (±0.008) × ρ - 1.45 (±0.08) + [3.8 × 10-5(T - 300)×(ρ - 15.37)], including non-negligible temperature dependence. The present results of sound velocity and density of hcp Fe0.89Si0.11 alloy indicates that 3~6 wt% of silicon in the inner core with additional amount of Ni can explain the compressional velocity (νP) and density (ρ) of the "preliminary Earth reference model" (PREM), assuming a temperature of 5500 K and that silicon is the only light element in the inner core.
ASJC Scopus subject areas
- Geochemistry and Petrology