Measurement of Body-Centered Cubic Gold and Melting under Shock Compression
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Carnegie Inst. of Washington, Washington, D.C. (United States)
We combined laser shock compression with in situ x-ray diffraction to probe the crystallographic state of gold (Au) on its principal shock Hugoniot. Au has long been recognized as an important calibration standard in diamond anvil cell experiments due to the stability of its face-centered cubic (fcc) structure to extremely high pressures (P > 600 GPa at 300 K). This is in contrast to density functional theory and first principles calculations of the high-pressure phases of Au that predict a variety of fcc-like structures with different stacking arrangements at intermediate pressures. In this Letter, we probe high-pressure and high-temperature conditions on the shock Hugoniot and observe fcc Au at 169 GPa and the first evidence of body-centered cubic (bcc) Au at 223 GPa. Upon further compression, the bcc phase is observed in coexistence with liquid scattering as the Hugoniot crosses the Au melt curve before 322 GPa. Here, the results suggest a triple point on the Au phase diagram that lies very close to the principal shock Hugoniot near ~220 GPa.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC52-07NA27344
- OSTI ID:
- 1559920
- Alternate ID(s):
- OSTI ID: 1545434
OSTI ID: 1545878
OSTI ID: 1571907
- Report Number(s):
- LLNL-JRNL--782110; 961726
- Journal Information:
- Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 4 Vol. 123; ISSN 0031-9007; ISSN PRLTAO
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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