title: New transformations of CO(2) at high pressures and temperatures.
abstract: CO(2) laser heating of solid CO(2) at pressures between 30 and 80 GPa shows that this compound breaks down to oxygen and diamond along a boundary having a negative P-T slope. This decomposition occurs at temperatures much lower than predicted in theory or inferred from previous experiment. Raman spectroscopy and x-ray diffraction were used as structural probes. At pressures higher than 40 GPa the decomposition is preceded by the formation of a new CO(2) phase (CO(2)-VI). These findings limit the stability of nonmolecular CO(2) phases to moderate temperatures and provide a new topology of the CO(2) phase diagram.
authors.affiliation: Geophysical Laboratory and Center for High-Pressure Research, Carnegie Institution of Washington, 5251 Broad Branch Road, NW, Washington, D.C. 20015, USA.
authors.forename: O
authors.initials: O
authors.lastname: Tschauner
authors.forename: H K
authors.initials: HK
authors.lastname: Mao
authors.forename: R J
authors.initials: RJ
authors.lastname: Hemley