title: Phonon density of states of iron up to 153 gigapascals.
abstract: We report phonon densities of states (DOS) of iron measured by nuclear resonant inelastic x-ray scattering to 153 gigapascals and calculated from ab initio theory. Qualitatively, they are in agreement, but the theory predicts density at higher energies. From the DOS, we derive elastic and thermodynamic parameters of iron, including shear modulus, compressional and shear velocities, heat capacity, entropy, kinetic energy, zero-point energy, and Debye temperature. In comparison to the compressional and shear velocities from the preliminary reference Earth model (PREM) seismic model, our results suggest that Earth's inner core has a mean atomic number equal to or higher than pure iron, which is consistent with an iron-nickel alloy.
authors.affiliation: Geophysical Laboratory and Center for High Pressure Research, Carnegie Institution of Washington, Washington, DC 20015, USA.
authors.forename: H K
authors.initials: HK
authors.lastname: Mao
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: V V
authors.initials: VV
authors.lastname: Struzhkin
authors.forename: J
authors.initials: J
authors.lastname: Shu
authors.forename: R J
authors.initials: RJ
authors.lastname: Hemley
authors.forename: W
authors.initials: W
authors.lastname: Sturhahn
authors.forename: M Y
authors.initials: MY
authors.lastname: Hu
authors.forename: E E
authors.initials: EE
authors.lastname: Alp
authors.forename: L
authors.initials: L
authors.lastname: Vocadlo
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authors.lastname: Alfè
authors.forename: G D
authors.initials: GD
authors.lastname: Price
authors.forename: M J
authors.initials: MJ
authors.lastname: Gillan
authors.forename: M
authors.initials: M
authors.lastname: Schwoerer-Böhning
authors.forename: D
authors.initials: D
authors.lastname: Häusermann
authors.forename: P
authors.initials: P
authors.lastname: Eng
authors.forename: G
authors.initials: G
authors.lastname: Shen
authors.forename: H
authors.initials: H
authors.lastname: Giefers
authors.forename: R
authors.initials: R
authors.lastname: Lübbers
authors.forename: G
authors.initials: G
authors.lastname: Wortmann