Measuring the Melting Curve of Iron at Super-Earth Core Conditions by Dynamic Solidification

ORAL  · Invited

Abstract

The prominence of iron in planetary interiors requires accurate and precise physical properties at extreme pressure and temperature. A first-order property of iron is the melting point, which is still debated for the conditions of Earth’s interior. Using precisely tuned laser pulses at the National Ignition Facility we were able to shock melt samples of iron and then further shocklessly compress the iron to pressures of 5 and 10 Mbar. We used in-situ x-ray diffraction to directly observe dynamic solidification of iron into the hexagonal close packed structure on the nanosecond timescale. From these experiments we determine the criteria for solidification and ultimately the melting point of iron up to 1000 GPa, three times the pressure of Earth’s inner core [1].

[1] Kraus et al., Measuring the melting curve of iron at super-Earth core conditions, Science, 375, 6577, 2022.

*This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, a wholly owned subsidiary of Honeywell International, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-NA0003525. RH acknowledges support from DOE/NNSA (DE-NA0003975, CDAC). STS was supported by the Center for Matter under Extreme Conditions, funded by the Department of Energy, National Nuclear Security Administration under Award Number DE-NA0003842. GWC and JRR recognize support from NSF Physics Frontier Center award PHY-2020249. REC gratefully acknowledges the Gauss Centre for Supercomputing e.V. (www.gausscentre.eu) for funding this project by providing computing time on the GCS Supercomputer SuperMUC-NG at Leibniz Supercomputing Centre (LRZ, www.lrz.d

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Publication: [1] Kraus et al., Measuring the melting curve of iron at super-Earth core conditions, Science, 375, 6577, 2022.

Presenters

  • Richard G Kraus

    • Lawrence Livermore Natl Lab
    • Lawrence Livermore National Laboratory

Authors

  • Richard G Kraus

    • Lawrence Livermore Natl Lab
    • Lawrence Livermore National Laboratory