Detonation-induced transformation of graphite to hexagonal diamond.

ORAL

Abstract

The structural evolution of graphite under elevated thermodynamic conditions has been the subject of intense research interest. Early studies, back in 90s, clearly indicate the shock-induced transformation of graphite to a phase with much higher density, presumably a sp3 allotrope, above 20 GPa. However, only recently the capability of in-situ X-ray diffraction under shock conditions allowed the structural characterization of the relevant phases. Here we explore the structural evolution of highly oriented pyrolytic graphite (HOPG) under detonation-induced shock conditions using in situ synchrotron X-ray diffraction in the ns time scale. We observe the formation of hexagonal diamond (lonsdaleite) at pressures above 50 GPa, in qualitative agreement with recent gas gun experiments. Moreover, we observe an extended pressure stability of the initial HOPG crystal structure up to ~50 GPa, in contrast with previous shock and static compression results.


*This work was performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Security, LLC under Contract DE-AC52-07NA27344. We gratefully acknowledge the LLNL LDRD program for funding support of this project under 18-SI-004.

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Presenters

  • Elissaios Stavrou

    • Lawrence Livermore Natl Lab

Authors

  • Elissaios Stavrou

    • Lawrence Livermore Natl Lab

  • Michael Bagge-Hansen

    • Lawrence Livermore Natl Lab

  • Joshua A Hammons

    • Lawrence Livermore Natl Lab

  • William L Shaw

    • Lawrence Livermore Natl Lab

  • Will Bassett

    • Lawrence Livermore Natl Lab

  • Sorin Bastea

    • Lawrence Livermore Natl Lab

  • Lisa Lauderbach

    • Lawrence Livermore Natl Lab

  • Ralph Hodgin

    • Lawrence Livermore Natl Lab

  • Nicholas Perez-Marty

    • Lawrence Livermore Natl Lab

  • Matt Nelms

    • Lawrence Livermore Natl Lab

  • Matthew P Kroonblawd

    • Lawrence Livermore Natl Lab
    • Lawrence Livermore National Laboratory

  • Brad Steele

    • Lawrence Livermore Natl Lab

  • Saransh Singh

    • Lawrence Livermore Natl Lab

  • Nicholas Sinclair

    • Dynamic Compression Sector (DCS), Washington State University
    • Washington State University

  • Yuelin Li

    • Dynamic Compression Sector (DCS), Washington State University

  • Pinaki Das

    • Ames Laboratory, Iowa State University
    • Dynamic Compression Sector (DCS), Washington State University

  • Adam Schuman

    • Dynamic Compression Sector (DCS), Washington State University

  • Kamel Fezzaa

    • Advanced Photon Source, Argonne National Laboratory
    • APS, Argonne National Laboratory

  • Alex Deriy

    • Advanced Photon Source, Argonne National Laboratory

  • Thomas Bunt

    • Lawrence Livermore Natl Lab

  • Lara Leininger

    • Lawrence Livermore Natl Lab

  • Trevor M Willey

    • Lawrence Livermore Natl Lab