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Science 21 January 1994:
Vol. 263. no. 5145, pp. 356 - 358
DOI: 10.1126/science.263.5145.356
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Articles

Crystal Structure of the High-Pressure Phase of Solid CO2

K. Aoki 1, H. Yamawaki 1, M. Sakashita 1, Y. Gotoh 1, and K. Takemura 2

1 National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305, Japan
2 National Institute for Research in Inorganic Materials, Tsukuba, Ibaraki 305, Japan

X-ray diffraction study of solid CO2 at room temperature has shown that the powder pattern of the high-pressure phase, which supersedes the low-pressure cubic Pa3 phase at about 10 gigapascals, is consistently interpreted in terms of an orthorhombic Cmca structure. The orthorhombic cell at 11.8 gigapascals has dimensions of 4.330 ± 0.015, 4.657 ± 0.005, 5.963 ± 0.009 angstroms for its a, b, and c faces, respectively, and a volume of 120.3 ± 0.5 cubic angstroms. Four molecules contained in the unit cell are located at the base-centered positions with their molecular axes inclined at about 52° with respect to the crystallographic c axis. The volume change associated with the Pa3-Cmca transition is close to zero. The structural dimensions obtained for the high-pressure crystalline phase of CO2 are of great importance for a theoretical understanding of the role of intermolecular interactions, including quadrupole-quadrupole interactions, in molecular condensation.

Submitted on August 30, 1993
Accepted on December 1, 1993


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Pressure-Induced Solid Carbonates from Molecular CO2 by Computer Simulation.
S. Serra, C. Cavazzoni, G. L. Chiarotti, S. Scandolo, and E. Tosatti (1999)
Science 284, 788-790
   Abstract »    Full Text »
Quartzlike Carbon Dioxide: An Optically Nonlinear Extended Solid at High Pressures and Temperatures.
V. Iota, C. S. Yoo, and H. Cynn (1999)
Science 283, 1510-1513
   Abstract »    Full Text »


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