Amorphous silica-like carbon dioxide
Year: 2006
Authors: Santoro M., Gorelli F.A., Bini R., Ruocco G., Scandolo S., Crichton W.A.
Autors Affiliation: European Lab Nonlinear Spect, LENS, I-50019 Florence, Italy; INFM, I-50019 Florence, Italy; Univ Roma La Sapienza, CNR, INFM, CRS,SOFT, I-00185 Rome, Italy; Univ Florence, Dipartimento Chim, I-50019 Florence, Italy; Univ Roma La Sapienza, Dipartimento Fis, I-00185 Rome, Italy; INFM, Democritos Natl Smithsonian Ctr, I-34014 Trieste, Italy; European Synchrotron Res Facil, F-38043 Grenoble, France.
Abstract: Among the group IV elements, only carbon forms stable double bonds with oxygen at ambient conditions. At variance with silica and germania, the non-molecular single-bonded crystalline form of carbon dioxide, phase V, only exists at high pressure(1-9). The amorphous forms of silica (a-SiO2) and germania (a-GeO2) are well known at ambient conditions; however, the amorphous, non-molecular form of CO2 has so far been described only as a result of first-principles simulations(9). Here we report the synthesis of an amorphous, silica-like form of carbon dioxide, a-CO2, which we call ’a-carbonia’. The compression of the molecular phase III of CO2 between 40 and 48 GPa at room temperature initiated the transformation to the non-molecular amorphous phase. Infrared spectra measured at temperatures up to 680 K show the progressive formation of C-O single bonds and the simultaneous disappearance of all molecular signatures. Furthermore, state-of-the-art Raman and synchrotron X-ray diffraction measurements on temperature-quenched samples confirm the amorphous character of the material. Comparison with vibrational and diffraction data for a-SiO2 and a-GeO2, as well as with the structure factor calculated for the a-CO2 sample obtained by first-principles molecular dynamics(9), shows that a-CO2 is structurally homologous to the other group IV dioxide glasses. We therefore conclude that the class of archetypal network-forming disordered systems, including a-SiO2, a-GeO2 and water, must be extended to include a-CO2.
Journal/Review: NATURE
Volume: 441 (7095) Pages from: 857 to: 860
More Information: Acknowledgements We thank F. Sette and M. Mezouar for discussions and the ESRF for provision of beamtime at ID27. S.S. thanks Y. Liang for preparing the molecular dynamics configurations. This work was supported by the European Community and the Ente Cassa di Risparmio di Firenze.KeyWords: High-pressure; Raman-spectroscopy; Crystal-structure; Co2; Phase; Nitrogen; QuartzDOI: 10.1038/nature04879Citations: 135data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-11-17References taken from IsiWeb of Knowledge: (subscribers only)