Crystal structure of carbon dioxide at high pressure: "Superhard" polymeric carbon dioxide

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The crystal structures of two molecular phases (I and III) and a polymeric phase (V) of CO2 have been investigated to 60 GPa. CO2-1 (Pa3) transforms to CO2-III (Cmca) at 12 GPa with almost no change of density. Although CO2-III persists in Cmca to at least 60 GPa at ambient temperature, it transforms when heated to 1800 K above 40 GPa to tridymite (P212121) CO2-V with 15.3% volume change. Each carbon atom of CO2-V is tetrahedrally bonded to four oxygen atoms. CO2-V is likely superhard with low compressibility B0 = 365 GPa, similar to cubic BN.


  • C. S. Yoo
  • H. Cynn
  • F. Gygi
  • G. Galli
  • V. Iota
  • M. Nicol
  • S. Carlson
  • D. Häusermann
  • C. Mailhiot
Externa organisationer
  • Lawrence Livermore National Laboratory
  • University of Nevada, Las Vegas
  • European Synchrotron Radiation Facility
Sidor (från-till)5527-5530
Antal sidor4
TidskriftPhysical Review Letters
Utgåva nummer26 I
StatusPublished - 1999 dec 27
Peer review utfördJa
Externt publiceradJa