Premium
Sound velocity of hexagonal close‐packed iron up to core pressures
Author(s) -
Ohtani Eiji,
Shibazaki Yuki,
Sakai Takeshi,
Mibe Kenji,
Fukui Hiroshi,
Kamada Seiji,
Sakamaki Tatsuya,
Seto Yusuke,
Tsutsui Satoshi,
Baron Alfred Q. R.
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50992
Subject(s) - core (optical fiber) , diffraction , outer core , scattering , atmospheric temperature range , inner core , materials science , shock wave , impurity , condensed matter physics , speed of sound , thermodynamics , physics , optics , composite material , quantum mechanics
We determined the compressional velocity of hcp‐Fe using high‐resolution inelastic X‐ray scattering combined with in situ X‐ray powder diffraction: Our measurements extend up to 174 GPa at room temperature, to 88 GPa at 700 K, and to 61.5 GPa at 1000 K. Our data, including those obtained at high temperature, are well described by a linear relation to density, extending the range of verification of Birch's law and suggesting only small temperature dependence up to 1000 K. This result, once compared to the preliminary reference Earth model seismologically based model, indicates that there is either a strong temperature effect on Birch's law above 1000 K or the composition of the core is rather different than expected, containing, e.g., heavy impurities. Noting that both recent theoretical calculations and shock wave velocity measurements are consistent with modification of Birch's law at high temperature, we favor the former explanation.