CO2 Has Glassy Form Similar to Silica

Confirming theoretical predictions and potentially opening the door to novel, ultrahard optical materials, a collaboration of scientists in Italy and France has produced “amorphous carbonia,” a glassy form of CO₂ that is structurally homologous to the group IV dioxide glasses SiO₂ and GeO₂. A report of the team’s work appears in the June 15 issue of Nature.

Using an externally heated diamond anvil cell, the investigators subjected molecular solid CO₂ to pressures of 40 to 76 GPa and to temperatures of 300 to 680 K. Infrared and Raman spectroscopy and x-ray diffraction measurements suggest that the carbon-oxygen double bonds break under such conditions and that an extended network of carbon-oxygen single bonds dominates.

The team included researchers from the European Laboratory for Non-linear Spectroscopy and from Università di Firenze, both in Sesto Fiorentino, Italy; from CRS-SOFT of the Istituto Nazionale per la Fisica della Materia (INFM-CNR) and from Università di Roma “La Sapienza,” both in Rome; from the Abdus Salam International Centre for Theoretical Physics and the INFM/Democritos National Simulation Center, both in Trieste, Italy; and from the European Synchrotron Research Facility in Grenoble, France.