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Crystalline polymeric carbon dioxide stable at megabar pressures.

ABSTRACT: Carbon dioxide is a widespread simple molecule in the Universe. In spite of its simplicity it has a very complex phase diagram, forming both amorphous and crystalline extended phases above 40?GPa. The stability range and nature of these phases are still debated, especially in view of their possible role within the deep carbon cycle. Here, we report static synchrotron X-ray diffraction and Raman high-pressure experiments in the megabar range providing evidence for the stability of the polymeric phase V at pressure-temperature conditions relevant to the Earth's lowermost mantle. The equation of state has been extended to 120?GPa and, contrary to earlier experimental findings, neither dissociation into diamond and ?-oxygen nor ionization was observed. Severe deviatoric stress and lattice deformation along with preferred orientation are removed on progressive annealing, thus suggesting CO2-V as the stable structure also above one megabar.

SUBMITTER: Dziubek KF 

PROVIDER: S-EPMC6082874 | biostudies-other | 2018 Aug

REPOSITORIES: biostudies-other

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Crystalline polymeric carbon dioxide stable at megabar pressures.

Dziubek Kamil F KF   Ende Martin M   Scelta Demetrio D   Bini Roberto R   Mezouar Mohamed M   Garbarino Gaston G   Miletich Ronald R  

Nature communications 20180808 1

Carbon dioxide is a widespread simple molecule in the Universe. In spite of its simplicity it has a very complex phase diagram, forming both amorphous and crystalline extended phases above 40 GPa. The stability range and nature of these phases are still debated, especially in view of their possible role within the deep carbon cycle. Here, we report static synchrotron X-ray diffraction and Raman high-pressure experiments in the megabar range providing evidence for the stability of the polymeric p  ...[more]