Crystal Structure and Melting of Fe Shock Compressed to 273 GPa: In Situ X-Ray Diffraction

Despite extensive shock wave and static compression experiments and corresponding theoretical work, consensus on the crystal structure and the melt boundary of Fe at Earth's core conditions is lacking. We present in situ x-ray diffraction measurements in laser-shock compressed Fe that establish...

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Bibliographic Details
Published in:Physical review letters 2020-11, Vol.125 (21), p.215702-215702, Article 215702
Main Authors: Turneaure, Stefan J., Sharma, Surinder M., Gupta, Y. M.
Format: Article
Language:English
Subjects:
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Crystal melting
Crystal structure
Earth core
Earth's interior
Longitudinal waves
Melt temperature
Phase diagrams
Shock waves
Solid-solid transformations
Wave diffraction
X-ray diffraction
X-ray powder diffraction
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Summary:Despite extensive shock wave and static compression experiments and corresponding theoretical work, consensus on the crystal structure and the melt boundary of Fe at Earth's core conditions is lacking. We present in situ x-ray diffraction measurements in laser-shock compressed Fe that establish the stability of the hexagonal-close-packed (hcp) structure along the Hugoniot through shock melting, which occurs between ∼ 242 to ∼ 247 GPa . Using previously reported hcp Fe Hugoniot temperatures, the melt temperature is estimated to be 5560(360) K at 242 GPa, consistent with several reported Fe melt curves. Extrapolation of this value suggests ∼ 6400 K melt temperature at Earth's inner core boundary pressure.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.125.215702