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Title: Formation of diamonds in laser-compressed hydrocarbons at planetary interior conditions

Journal Article · · Nature Astronomy
ORCiD logo [1];  [2];  [3]; ORCiD logo [4];  [5];  [6];  [5];  [5];  [7];  [5];  [5];  [8];  [5];  [9];  [5];  [10];  [11];  [12];  [2];  [13] more »;  [5];  [3];  [14] « less
  1. Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Univ. of California, Berkeley, CA (United States). Department of Physics; Technische Universitat Dresden (Germany). Institute of Solid State and Materials Physics
  2. Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Osaka University (Japan). Open and Transdisciplinary Research Institute
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  6. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Technische Universitat Darmstadt (Germany). Institut fur Kernphysik
  7. University of Warwick, Coventry (United Kingdom). Centre for Fusion, Space and Astrophysics, Department of Physics
  8. SLAC National Accelerator Lab., Menlo Park, CA (United States); Univ. of Michigan, Ann Arbor, MI (United States)
  9. SLAC National Accelerator Lab., Menlo Park, CA (United States); European XFEL GmbH, Schenefeld (Germany)
  10. GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany)
  11. Technische Universitat Darmstadt (Germany). Institut fur Kernphysik
  12. Univ. of California, Berkeley, CA (United States). Department of Physics
  13. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., CA (United States). Department of Physics
  14. Univ. of California, Berkeley, CA (United States). Department of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

The effects of hydrocarbon reactions and diamond precipitation on the internal structure and evolution of icy giant planets such as Neptune and Uranus have been discussed for more than three decades1. Inside these celestial bodies, simple hydrocarbons such as methane, which are highly abundant in the atmospheres2, are believed to undergo structural transitions3,4 that release hydrogen from deeper layers and may lead to compact stratified cores5-7. Indeed, from the surface towards the core, the isentropes of Uranus and Neptune intersect a temperature-pressure regime in which methane first transforms into a mixture of hydrocarbon polymers8, whereas, in deeper layers, a phase separation into diamond and hydrogen may be possible. Here we show experimental evidence for this phase separation process obtained by in situ X-ray diffraction from polystyrene (C8H8)n samples dynamically compressed to conditions around 150 GPa and 5,000 K; these conditions resemble the environment around 10,000 km below the surfaces of Neptune and Uranus9. Our findings demonstrate the necessity of high pressures for initiating carbon-hydrogen separation3 and imply that diamond precipitation may require pressures about ten times as high as previously indicated by static compression experiments4,8,10. Our results will inform mass-radius relationships of carbon-bearing exoplanets11, provide constraints for their internal layer structure and improve evolutionary models of Uranus and Neptune, in which carbon-hydrogen separation could influence the convective heat transport7.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC52-07NA27344; AC02-76SF00515; FG52-10NA29649; NA0001859; AC02-05CH11231
OSTI ID:
1393331
Alternate ID(s):
OSTI ID: 1476528
Report Number(s):
LLNL-JRNL-707514; PII: 219
Journal Information:
Nature Astronomy, Vol. 1, Issue 9; ISSN 2397-3366
Publisher:
SpringerCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 126 works
Citation information provided by
Web of Science

References (24)

HELIOS-CR – A 1-D radiation-magnetohydrodynamics code with inline atomic kinetics modeling journal May 2006
Line-imaging velocimeter for shock diagnostics at the OMEGA laser facility journal November 2004
High-precision measurements of the equation of state of hydrocarbons at 1–10 Mbar using laser-driven shock waves journal May 2010
Interiors of Giant Planets Inside and Outside the Solar System journal October 1999
Laser interferometer for measuring high velocities of any reflecting surface journal November 1972
H/He demixing and the cooling behavior of Saturn journal March 2016
CSPAD-140k: A versatile detector for LCLS experiments
  • Herrmann, Sven; Boutet, Sébastien; Duda, Brian
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 718 https://doi.org/10.1016/j.nima.2013.01.057
journal August 2013
Chemical processes in the deep interior of Uranus journal February 2011
Uranus evolution models with simple thermal boundary layers journal September 2016
Electrical conductivities of methane, benzene, and polybutene shock compressed to 60 GPa (600 kbar) journal July 2001
Dissociation of Methane into Hydrocarbons at Extreme (Planetary) Pressure and Temperature journal February 1997
Decomposition of hydrocarbons to hydrogen and carbon journal May 2009
Interior Structure of Neptune: Comparison with Uranus journal August 1991
Matter under extreme conditions experiments at the Linac Coherent Light Source journal April 2016
The ice layer in Uranus and Neptune—diamonds in the sky? journal July 1981
Shock Wave Compression of Condensed Matter book January 2012
Dissociation of CH4 at High Pressures and Temperatures: Diamond Formation in Giant Planet Interiors? journal October 1999
Polymerization and diamond formation from melting methane and their implications in ice layer of giant planets journal May 2009
Diffusion of hydrogen from a microwave plasma into diamond and its interaction with dopants and defects journal March 2002
The properties and applications of nanodiamonds journal December 2011
Shock compression of liquid carbon monoxide and methane to 90 GPa (900 kbar) journal September 1981
Multiphase equation of state for carbon addressing high pressures and temperatures journal June 2014
Giant Planets text January 2014
Uranus evolution models with simple thermal boundary layers text January 2016

Cited By (27)

Density response to short-pulse excitation in gold journal March 2019
Refractive index and polarizability of polystyrene under shock compression journal May 2018
Fifth User Workshop on high-power lasers at the Linac Coherent Light Source journal September 2018
Sixth user workshop on high-power lasers at the linac coherent light source journal March 2019
Femtosecond laser produced periodic plasma in a colloidal crystal probed by XFEL radiation journal July 2020
Thermal evolution of Uranus and Neptune: I. Adiabatic models journal December 2019
High-pressure chemistry of hydrocarbons relevant to planetary interiors and inertial confinement fusion journal May 2018
Development and characterization of liquid argon and methane microjets for high-rep-rate laser-plasma experiments journal October 2018
Equations of state for polyethylene and its shock-driven decomposition products journal July 2019
Electronic bandgap of water in the superionic and plasma phases journal September 2019
Thermomechanical response of thickly tamped targets and diamond anvil cells under pulsed hard x-ray irradiation journal May 2020
Characterizing the ionization potential depression in dense carbon plasmas with high-precision spectrally resolved x-ray scattering journal November 2018
Effect of non-adiabatic thermal profiles on the inferred compositions of Uranus and Neptune journal May 2019
Evidence for Crystalline Structure in Dynamically-Compressed Polyethylene up to 200 GPa text January 2019
Simultaneous 8.2 keV phase-contrast imaging and 24.6 keV X-ray diffraction from shock-compressed matter at the LCLS text January 2018
High Pressure Hydrocarbons Revisited: From van der Waals Compounds to Diamond journal May 2019
Simultaneous 8.2 keV phase-contrast imaging and 24.6 keV X-ray diffraction from shock-compressed matter at the LCLS journal May 2018
Femtosecond laser produced periodic plasma in a colloidal crystal probed by XFEL radiation text January 2020
Effect of non-adiabatic thermal profiles on the inferred compositions of Uranus and Neptune text January 2019
Evidence for Crystalline Structure in Dynamically-Compressed Polyethylene up to 200 GPa journal March 2019
Thermal evolution of Uranus and Neptune: II. Deep thermal boundary layer journal June 2021
Recovery of nanodiamonds from dynamically shock-compressed graphite and hydrocarbon samples text January 2021
Recovery of nanodiamonds from dynamically shock-compressed graphite and hydrocarbon samples text January 2021
Measurement of diamond nucleation rates from hydrocarbons at conditions comparable to the interiors of icy giant planets text January 2020
Thermomechanical response of thickly tamped targets and diamond anvil cells under pulsed hard x-ray irradiation text January 2018
Thermal evolution of Uranus and Neptune I: adiabatic models text January 2019
Femtosecond laser produced periodic plasma in a colloidal crystal probed by XFEL radiation text January 2019