Sound velocity measurements in dhcp-FeH up to 70GPa with inelastic X-ray scattering: Implications for the composition of the Earth's core

Yuki Shibazaki, Eiji Ohtani, Hiroshi Fukui, Takeshi Sakai, Seiji Kamada, Daisuke Ishikawa, Satoshi Tsutsui, Alfred Q.R. Baron, Naoya Nishitani, Naohisa Hirao, Kenichi Takemura

Research output: Contribution to journalArticlepeer-review

48 Citations (Scopus)

Abstract

We have determined the density evolution of the sound velocity of dhcp-FeH x (x≈1) up to 70GPa at room temperature, by inelastic X-ray scattering and by X-ray diffraction. We find that the variation of V P with density is different for the ferromagnetic and nonmagnetic dhcp-FeH x, and that only nonmagnetic dhcp-FeH x follows Birch's law. Combining our results with Birch's law for iron and assuming an ideal two-component mixing model, we obtain an upper bound of the hydrogen content in the Earth's inner core, 0.23(6) wt.% H, corresponding to FeH 0.13(3). The iron alloy with 0.23(6) wt.% H can satisfy the density, and compressional and shear sound velocities of the PREM inner core, assuming that there are no other light elements in the inner core.

Original languageEnglish
Pages (from-to)79-85
Number of pages7
JournalEarth and Planetary Science Letters
Volume313-314
Issue number1
DOIs
Publication statusPublished - 2012 Jan 1

Keywords

  • Earth's inner core
  • High pressure
  • Inelastic X-ray scattering
  • Iron hydride
  • Sound velocity

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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