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

@article{Kraus2017FormationOD,
  title={Formation of diamonds in laser-compressed hydrocarbons at planetary interior conditions},
  author={Dominik Kraus and Jan Vorberger and A. Pak and N. J. Hartley and L. B. Fletcher and Simon Frydrych and Eric Galtier and Eliseo J. Gamboa and D. O. Gericke and Siegfried H. Glenzer and E. Granados and Michael MacDonald and A J Mackinnon and Emma E McBride and Inhyuk Nam and Paul Neumayer and M. Roth and A. M. Saunders and Anja K. Schuster and Phobos Sun and Tim B. Van Driel and Tilo D{\"o}ppner and Roger W. Falcone},
  journal={Nature Astronomy},
  year={2017},
  volume={1},
  pages={606-611}
}
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… 
Diamond formation from methane hydrate under the internal conditions of giant icy planets
TLDR
This work demonstrates the formation of diamond from methane hydrate up to 3800 K and 45 GPa using a CO2 laser-heated diamond anvil cell combined with synchrotron X-ray diffraction, Raman spectroscopy, and scanning electron microscope observations and suggests that diamond formation can also occur in the upper parts of the icy mantles of giant icy planets.
High-pressure chemistry of hydrocarbons relevant to planetary interiors and inertial confinement fusion
Diamond formation in polystyrene (C8H8)n, which is laser-compressed and heated to conditions around 150 GPa and 5000 K, has recently been demonstrated in the laboratory [Kraus et al., Nat. Astron. 1,
Demonstration of X-ray Thomson scattering as diagnostics for miscibility in warm dense matter
TLDR
The feasibility of X-ray Thomson scattering is demonstrated to quantify the degree of species separation in a 1:1 carbon–hydrogen mixture at a pressure of ~150 GPa and a temperature of ~5000 K and will enable unprecedented measurements of mixing/demixing kinetics in dense plasma environments, e.g., induced by chemistry or hydrodynamic instabilities.
Evidence for Crystalline Structure in Dynamically-Compressed Polyethylene up to 200 GPa
TLDR
This work investigates the high-pressure behavior of polyethylene (CH2) by probing dynamically-compressed samples with X-ray diffraction, and infer the presence of significant covalent bonding at pressures up to 200 GPa.
Liquid Structure of Shock-Compressed Hydrocarbons at Megabar Pressures.
TLDR
Results for the ionic structure in hydrocarbons that were shock compressed to pressures of up to 190 GPa, inducing rapid melting of the samples indicate that diffraction is not always a sufficient diagnostic for this phenomenon.
Stability of H3O at extreme conditions and implications for the magnetic fields of Uranus and Neptune
TLDR
Detailed quantum-mechanical calculations of polymorphism in the hydrogen–oxygen system at the pressures and temperatures of the deep interiors of these ice giant planets reveal the surprising stability of solid and fluid trihydrogen oxide (H3O) at these extreme conditions.
High Pressure Hydrocarbons Revisited: From van der Waals Compounds to Diamond
Methane and other hydrocarbons are major components of the mantle regions of icy planets. Several recent computational studies have investigated the high-pressure behaviour of specific hydrocarbons.
Rules of formation of H–C–N–O compounds at high pressure and the fates of planetary ices
TLDR
It is demonstrated that simple chemical rules drive stability in this composition space, which explains why the simplest possible quaternary mixture HCNO—isoelectronic to diamond—emerges as a stable compound and discusses dominant decomposition products of planetary ice mixtures.
Coexistence of plastic and partially diffusive phases in a helium-methane compound
TLDR
An unusual phase which exhibits coexistence of diffusive helium and plastic methane is discovered and the range of the diffusive behavior within the helium-methane phase diagram is found to be much narrower compared to that of previously predicted helium-water compounds.
Experimental methods for warm dense matter research
  • K. Falk
  • Physics
    High Power Laser Science and Engineering
  • 2018
The study of structure, thermodynamic state, equation of state (EOS) and transport properties of warm dense matter (WDM) has become one of the key aspects of laboratory astrophysics. This field has
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 43 REFERENCES
Carbon precipitation from heavy hydrocarbon fluid in deep planetary interiors.
TLDR
It is argued that reduced mantle fluids precipitate diamond upon re-equilibration to lighter species in the upwelling mantle, and geophysical models of Uranus and Neptune require reassessment because chemical reactivity of planetary ices is underestimated.
Dissociation of methane under high pressure.
TLDR
The pressure-temperature phase diagram is computed, which sheds light into the seemingly conflicting observations of the unusually low formation pressure of diamond at high temperature and the failure of experimental observation of dissociation at room temperature.
Ramp compression of diamond to five terapascals
TLDR
Ramp-compression measurements for diamond are described, which can be compared to first-principles density functional calculations and theories long used to describe matter present in the interiors of giant planets, in stars, and in inertial-confinement fusion experiments, and provide new constraints on mass–radius relationships for carbon-rich planets.
Dissociation of CH4 at high pressures and temperatures: diamond formation in giant planet interiors?
TLDR
Experiments using laser-heated diamond anvil cells show that methane (CH4) breaks down to form diamond at pressures between 10 and 50 gigapascals and temperatures of about 2000 to 3000 kelvin, in agreement with theoretical predictions.
Nanosecond formation of diamond and lonsdaleite by shock compression of graphite
TLDR
This experiment provides new insights into the processes of the shock-induced transition from graphite to diamond and uniquely resolves the dynamics that explain the main natural occurrence of the lonsdaleite crystal structure being close to meteor impact sites.
The ice layer in Uranus and Neptune—diamonds in the sky?
Many of the current models of Uranus and Neptune postulate a three-layer structure, consisting of an inner rocky core, a middle ‘ice’ layer of fluid, H2O, CH4, NH3 and an outer hydrogen–helium layer
Chemical processes in the deep interior of Uranus.
TLDR
An experimental and computational study of the physical properties of a fluid representative of the interior of Uranus and Neptune, and electrical conductivity results confirm that the core cannot be well mixed if it is to generate non-axisymmetric magnetic fields.
Interiors of giant planets inside and outside the solar system.
An understanding of the structure and composition of the giant planets is rapidly evolving because of (i) high-pressure experiments with the ability to study metallic hydrogen and define the
Dissociation of Methane into Hydrocarbons at Extreme (Planetary) Pressure and Temperature
TLDR
Constant-pressure, first-principles molecular dynamic simulations were used to investigate the behavior of methane at high pressure and temperature, and suggest that, below 100 gigapascals, methane dissociates into a mixture of hydrocarbons, and it separates into hydrogen and carbon only above 300 gigapascalals.
...
1
2
3
4
5
...