First observation of bcc gold and melting on the shock Hugoniot measured using x-ray diffraction

ORAL

Abstract

Au is one of the most recognizable and noblest of the elements in the periodic table. Its face-centered cubic crystal structure was observed in static experiments at room temperature up to almost two-fold compression, inviting a myriad of theoretical work on its structural stability. Here we report the first observation of bcc gold near 220 GPa on the shock Hugoniot, using dynamic compression and \textit{in situ} x-ray diffraction. Experiments were carried out at the Dynamic Compression Sector of the Advanced Photon Source. A high-energy laser ($\textless$ 80 J at 351 nm, 5 or 10 ns flat top) sent an ablatively-driven shockwave through a polyimide ablator and the Au sample glued to a LiF window. Velocimetry measurements were made at the Au/LiF interface to determine pressure using impedance matching techniques. At pressures above 250 GPa, shock-induced melting is observed and is completed by 323 GPa, providing experimental constrains on the melting curve of gold on the Hugoniot.

*This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344

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Authors

  • Richard Briggs

    • Lawrence Livermore National Laboratory
    • Lawrence Livermore Natl Lab

  • Federica Coppari

    • LLNL
    • Lawrence Livermore National Laboratory
    • Lawrence Livermore Natl Lab

  • Martin Gorman

    • Lawrence Livermore National Laboratory
    • LLNL

  • Raymond Smith

    • Lawrence Livermore National Laboratory
    • LLNL

  • S. Tracy

    • Carnegie Institution
    • Carnegie Institution for Science
    • Geophysical Laboratory, Carnegie Institution of Washington

  • Amy L Coleman

    • Lawrence Livermore National Laboratory
    • Lawrence Livermore Natl Lab

  • Amalia Fernandez-Panella

    • Lawrence Livermore Natl Lab
    • Lawrence Livermore National Laboratory

  • Marius Millot

    • Lawrence Livermore National Laboratory
    • Lawrence Livermore National Laboratory (LLNL)
    • Lawrence Livermore Natl Lab

  • Jon Eggert

    • Lawrence Livermore National Laboratory
    • LLNL
    • Lawrence Livermore National Laboratories
    • Lawrence Livermore Natl Lab

  • Dayne Fratanduono

    • Lawrence Livermore National Laboratories
    • Lawrence Livermore National Laboratory