Structure of Iron in Earth's Inner Core

Earth's solid inner core is mainly composed of iron (Fe). Because the relevant ultrahigh pressure and temperature conditions are difficult to produce experimentally, the preferred crystal structure of Fe at the inner core remains uncertain. Static compression experiments showed that the hexagon...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2010-10, Vol.330 (6002), p.359-361
Main Authors: Tateno, Shigehiko, Hirose, Kei, Ohishi, Yasuo, Tatsumi, Yoshiyuki
Format: Article
Language:English
Subjects:
Anisotropy
Close packed lattices
Compressing
Crystal structure
Earth
Earth sciences
Earth, ocean, space
Elastic anisotropy
Exact sciences and technology
Fees
Geomorphology
Hexagonal cells
Inner cores
Internal geophysics
Iron
Melting
Seismic engineering
Seismic phenomena
Solid-earth geophysics, tectonophysics, gravimetry
Temperature dependence
Temperature gradients
Temperature ratio
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Summary:Earth's solid inner core is mainly composed of iron (Fe). Because the relevant ultrahigh pressure and temperature conditions are difficult to produce experimentally, the preferred crystal structure of Fe at the inner core remains uncertain. Static compression experiments showed that the hexagonal close-packed (hcp) structure of Fe is stable up to 377 gigapascals and 5700 kelvin, corresponding to inner core conditions. The observed weak temperature dependence of the c/a axial ratio suggests that hcp Fe is elastically anisotropic at core temperatures. Preferred orientation of the hcp phase may explain previously observed inner core seismic anisotropy.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1194662