Abstract
The relative abundance of light elements in the Earth's core has long been controversial. Recently, the presence of carbon in the core has been emphasized, because the density and sound velocities of the inner core may be consistent with solid Fe7C3. Here we report the longitudinal wave velocity of liquid Fe84C16 up to 70GPa based on inelastic X-ray scattering measurements. We find the velocity to be substantially slower than that of solid iron and Fe3C and to be faster than that of liquid iron. The thermodynamic equation of state for liquid Fe84C16 is also obtained from the velocity data combined with previous density measurements at 1 bar. The longitudinal velocity of the outer core, about 4% faster than that of liquid iron, is consistent with the presence of 4-5 at.% carbon. However, that amount of carbon is too small to account for the outer core density deficit, suggesting that carbon cannot be a predominant light element in the core.
| Original language | English |
|---|---|
| Article number | 8942 |
| Journal | Nature Communications |
| Volume | 6 |
| DOIs | |
| Publication status | Published - Nov 24 2015 |
Fingerprint
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Chemistry(all)
- Physics and Astronomy(all)
Cite this
Carbon-depleted outer core revealed by sound velocity measurements of liquid iron-carbon alloy. / Nakajima, Yoichi; Imada, Saori; Hirose, Kei; Komabayashi, Tetsuya; Ozawa, Haruka; Tateno, Shigehiko; Tsutsui, Satoshi; Kuwayama, Yasuhiro; Baron, Alfred Q R.
In: Nature Communications, Vol. 6, 8942, 24.11.2015.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Carbon-depleted outer core revealed by sound velocity measurements of liquid iron-carbon alloy
AU - Nakajima, Yoichi
AU - Imada, Saori
AU - Hirose, Kei
AU - Komabayashi, Tetsuya
AU - Ozawa, Haruka
AU - Tateno, Shigehiko
AU - Tsutsui, Satoshi
AU - Kuwayama, Yasuhiro
AU - Baron, Alfred Q R
PY - 2015/11/24
Y1 - 2015/11/24
N2 - The relative abundance of light elements in the Earth's core has long been controversial. Recently, the presence of carbon in the core has been emphasized, because the density and sound velocities of the inner core may be consistent with solid Fe7C3. Here we report the longitudinal wave velocity of liquid Fe84C16 up to 70GPa based on inelastic X-ray scattering measurements. We find the velocity to be substantially slower than that of solid iron and Fe3C and to be faster than that of liquid iron. The thermodynamic equation of state for liquid Fe84C16 is also obtained from the velocity data combined with previous density measurements at 1 bar. The longitudinal velocity of the outer core, about 4% faster than that of liquid iron, is consistent with the presence of 4-5 at.% carbon. However, that amount of carbon is too small to account for the outer core density deficit, suggesting that carbon cannot be a predominant light element in the core.
AB - The relative abundance of light elements in the Earth's core has long been controversial. Recently, the presence of carbon in the core has been emphasized, because the density and sound velocities of the inner core may be consistent with solid Fe7C3. Here we report the longitudinal wave velocity of liquid Fe84C16 up to 70GPa based on inelastic X-ray scattering measurements. We find the velocity to be substantially slower than that of solid iron and Fe3C and to be faster than that of liquid iron. The thermodynamic equation of state for liquid Fe84C16 is also obtained from the velocity data combined with previous density measurements at 1 bar. The longitudinal velocity of the outer core, about 4% faster than that of liquid iron, is consistent with the presence of 4-5 at.% carbon. However, that amount of carbon is too small to account for the outer core density deficit, suggesting that carbon cannot be a predominant light element in the core.
UR - http://www.scopus.com/inward/record.url?scp=84948443676&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84948443676&partnerID=8YFLogxK
U2 - 10.1038/ncomms9942
DO - 10.1038/ncomms9942
M3 - Article
AN - SCOPUS:84948443676
VL - 6
JO - Nature Communications
JF - Nature Communications
SN - 2041-1723
M1 - 8942
ER -