Journal article
Six-fold coordinated carbon dioxide VI
Nature materials, Vol.6(1), pp.34-38
01/2007
Handle:
https://hdl.handle.net/2376/108465
PMID: 17160005
Abstract
Under standard conditions, carbon dioxide (CO2) is a simple molecular gas and an important atmospheric constituent, whereas silicon dioxide (SiO2) is a covalent solid, and one of the fundamental minerals of the planet. The remarkable dissimilarity between these two group IV oxides is diminished at higher pressures and temperatures as CO2 transforms to a series of solid phases, from simple molecular to a fully covalent extended-solid V, structurally analogous to SiO2 tridymite. Here, we present the discovery of an extended-solid phase of CO2: a six-fold coordinated stishovite-like phase VI, obtained by isothermal compression of associated CO2-II (refs 1,2) above 50 GPa at 530-650 K. Together with the previously reported CO2-V (refs 3-5) and a-carbonia, this extended phase indicates a fundamental similarity between CO2 (a prototypical molecular solid) and SiO2 (one of Earth's fundamental building blocks). We present a phase diagram with a limited stability domain for molecular CO2-I, and suggest that the conversion to extended-network solids above 40-50 GPa occurs via intermediate phases II (refs 1,2), III (refs 7,8) and IV (refs 9,10). The crystal structure of phase VI suggests strong disorder along the c axis in stishovite-like P42/mnm, with carbon atoms manifesting an average six-fold coordination within the framework of sp3 hybridization.
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Details
- Title
- Six-fold coordinated carbon dioxide VI
- Creators
- Choong-Shik YooZsolt JeneiWilliam EvansJae-Hyun KlepeisValentin IotaHyunchae Cynn
- Publication Details
- Nature materials, Vol.6(1), pp.34-38
- Academic Unit
- Institute for Shock Physics
- Identifiers
- 99900547241201842
- Language
- English
- Resource Type
- Journal article