• DOI:10.1038/nature04879
• Corpus ID: 4363092

Amorphous silica-like carbon dioxide

@article{Santoro2006AmorphousSC,
  title={Amorphous silica-like carbon dioxide},
  author={Mario Santoro and Federico Aiace Gorelli and Roberto Bini and Giancarlo Ruocco and Sandro Scandolo and Wilson A. Crichton},
  journal={Nature},
  year={2006},
  volume={441},
  pages={857-860}
}

• M. Santoro, F. Gorelli, +3 authors W. Crichton
• Published 15 June 2006
• Chemistry, Materials Science
• Nature

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. 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. 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, 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.