Here we determine the compressional and shear wave velocities (v_p and v_s) of hexagonal close-packed iron, a candidate for the main constituent of the Earth’s inner core, to pressures above 300 gigapascals using a newly designed diamond anvil cell and inelastic X-ray scattering combined with X-ray diffraction. The present results reveal that the v_p and v_s of the Preliminary reference Earth model (PREM) inner core are 4(±2)% and 36(±17)% slower than those of the pure iron, respectively at the centre of the core. The density and sound velocity of the PREM inner core can be explained by addition of 3(±1) wt% silicon and 3(±2) wt% sulphur to iron‒5 wt% nickel alloy. Our suggested inner core composition is consistent with the existing outer core model with oxygen, as the growth of the inner core may have created a secular enrichment of the element in the outer core.

在这里，我们使用新设计的金刚石砧单元和非弹性 X 确定了六方密排铁（地球内核主要成分的候选材料）在 300 吉帕斯卡以上压力下的压缩波速度和剪切波速度（ v _p和v _s ） -射线散射与X射线衍射相结合。目前的结果表明，初步参考地球模型（PREM）内核的v _p和v _s分别比纯铁慢 4（±2）% 和 36（±17）%。核。 PREM内核的密度和声速可以通过在铁-5 wt%镍合金中添加3(±1) wt%硅和3(±2) wt%硫来解释。我们建议的内核成分与现有的含氧外核模型一致，因为内核的生长可能导致外核中元素的长期富集。