Sound Velocities in Iron to 110 Gigapascals

The dispersion of longitudinal acoustic phonons was measured by inelastic x-ray scattering in the hexagonal closed-packed (hcp) structure of iron from 19 to 110 gigapascals. Phonon dispersion curves were recorded on polycrystalline iron compressed in a diamond anvil cell, revealing an increase of th...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2001-01, Vol.291 (5503), p.468-471
Main Authors: Fiquet, Guillaume, Badro, James, Guyot, François, Requardt, Herwig, Krisch, Michael
Format: Article
Language:English
Subjects:
Acoustics
Anvils
Atoms
Cratons
Earth
Earth sciences
Earth, ocean, space
Earthquakes, seismology
Energy
Exact sciences and technology
Geology
Geometry
Grade Point Average
Inner cores
Internal geophysics
Iron
Iron (Metal)
Mantle
Momentum transfer
Motion
Particle velocity
Phonons
Solid-earth geophysics, tectonophysics, gravimetry
Sound
Speed
Speed of sound
Velocity
Wave velocity
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Summary:The dispersion of longitudinal acoustic phonons was measured by inelastic x-ray scattering in the hexagonal closed-packed (hcp) structure of iron from 19 to 110 gigapascals. Phonon dispersion curves were recorded on polycrystalline iron compressed in a diamond anvil cell, revealing an increase of the longitudinal wave velocity (Vp) from 7000 to 8800 meters per second. We show that hcp iron follows a Birch law for Vp, which is used to extrapolate velocities to inner core conditions. Extrapolated longitudinal acoustic wave velocities compared with seismic data suggest an inner core that is 4 to 5% lighter than hcp iron.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.291.5503.468