000001662 001__ 1662
000001662 005__ 20190130104945.0
000001662 02470 $$2doi$$a10.1038/s41550-017-0219-9
000001662 037__ $$aARTICLE-2018-048
000001662 041__ $$aeng
000001662 245__ $$aFormation of diamonds in laser-compressed hydrocarbons at planetary interior conditions
000001662 260__ $$c2018
000001662 269__ $$a2018
000001662 336__ $$aArticles
000001662 520__ $$aThe effects of hydrocarbon reactions and diamond precipitation on the internal structure and evolution of icy giant planets such as Neptune and Uranus have been discussed for more than three decades. Inside these celestial bodies, simple hydrocarbons such as methane, which are highly abundant in the atmospheres, are believed to undergo structural transitions that release hydrogen from deeper layers and may lead to compact stratified cores. Indeed, from the surface towards the core, the isentropes of Uranus and Neptune intersect a temperature–pressure regime in which methane first transforms into a mixture of hydrocarbon polymers, whereas, in deeper layers, a phase separation into diamond and hydrogen may be possible. Here we show experimental evidence for this phase separation process obtained by in situ X-ray diffraction from polystyrene $(C_{8}H_{8})_{n}$ samples dynamically compressed to conditions around 150 GPa and 5,000 K; these conditions resemble the environment around 10,000 km below the surfaces of Neptune and Uranus. Our findings demonstrate the necessity of high pressures for initiating carbon–hydrogen separation and imply that diamond precipitation may require pressures about ten times as high as previously indicated by static compression experiments. Our results will inform mass–radius relationships of carbon-bearing exoplanets, provide constraints for their internal layer structure and improve evolutionary models of Uranus and Neptune, in which carbon–hydrogen separation could influence the convective heat transport.
000001662 546__ $$aEnglish
000001662 655__ $$aMatter under extreme conditions, warm dense matter, and plasmas
000001662 655__ $$aHard condensed matter, structure, and dynamics
000001662 690__ $$aExternal experiment
000001662 7001_ $$aKraus, D.
000001662 7001_ $$aVorberger, J.
000001662 7001_ $$aPak, A.
000001662 7001_ $$aHartley, N. J.
000001662 7001_ $$aFletcher, L. B.
000001662 7001_ $$aFrydrych, S.
000001662 7001_ $$aGaltier, E.
000001662 7001_ $$aGamboa, E. J.
000001662 7001_ $$aGericke, D. O.
000001662 7001_ $$aGlenzer, S. H.
000001662 7001_ $$aGranados, E.
000001662 7001_ $$aMacDonald, M. J.
000001662 7001_ $$aMacKinnon, A. J.
000001662 7001_ $$01290$$aMcBride, E. E.
000001662 7001_ $$aNam, I.
000001662 7001_ $$aNeumayer, P.
000001662 7001_ $$aRoth, M.
000001662 7001_ $$aSaunders, A. M.
000001662 7001_ $$aSchuster, A. K.
000001662 7001_ $$aSun, P.
000001662 7001_ $$avan Driel, T.
000001662 7001_ $$aDöppner, T.
000001662 7001_ $$aFalcone, R. W.
000001662 773__ $$j1$$k9$$pNat. Astron.$$q606-611$$tNature Astronomy
000001662 790__ $$aEuXFEL staff
000001662 790__ $$aOther
000001662 85641 $$uhttps://www.nature.com/articles/s41550-017-0219-9
000001662 8560_ $$fkurt.ament@xfel.eu
000001662 8564_ $$s3943181$$uhttps://xfel.tind.io/record/1662/files/Kraus_PoP_2018.pdf
000001662 900__ $$aInstrument HED
000001662 980__ $$aARTICLE