High-pressure polymeric phases of carbon dioxide

  1. Get@NRC: High-pressure polymeric phases of carbon dioxide (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1073/pnas.0812624106
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Journal titleProceedings of the National Academy of Sciences of the United States of America
Pages60776081; # of pages: 5
AbstractUnderstanding the structural transformations of solid CO2 from a molecular solid characterized by weak intermolecular bonding to a 3-dimensional network solid at high pressure has challenged researchers for the past decade. We employ the recently developed metadynamics method combined with ab initio calculations to provide fundamental insight into recent experimental reports on carbon dioxide in the 60–80 GPa pressure region. Pressure-induced polymeric phases and their transformation mechanisms are found. Metadynamics simulations starting from the CO2-II (P42/mnm) at 60 GPa and 600 K proceed via an intermediate, partially polymerized phase, and finally yield a fully tetrahedral, layered structure (P-4m2). Based on the agreement between calculated and experimental Raman and X-ray patterns, the recently identified phase VI [Iota V, et al. (2007) Sixfold coordinated carbon dioxide VI. Nature Mat 6:34–38], assumed to be disordered stishovite-like, is instead interpreted as the result of an incomplete transformation of the molecular phase into a final layered structure. In addition, an α-cristobalite-like structure (P41212), is predicted to be formed from CO2-III (Cmca) via an intermediate Pbca structure at 80 GPa and low temperatures (<300 K). Defects in the crystals are frequently observed in the calculations at 300 K whereas at 500 to 700 K, CO2-III transforms to an amorphous form, consistent with experiment [Santoro M, et al. (2006) Amorphous silica-like carbon dioxide. Nature 441:857–860], but the simulation yields additional structural details for this disordered solid.
Publication date
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedYes
NPARC number16710822
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Record identifier4fd1b1d3-733c-40e7-811c-650c99ff46d9
Record created2011-02-15
Record modified2016-05-09
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