Tech Shout!

A group of researchers in Italy have discovered that carbon dioxide can form a glass, reports the British journal Nature.

They revealed that under extremely high pressure of around half a million atmospheres, molecules of carbon dioxide (CO2) form a glassy crystalline solid.

Carbon is a member of the same chemical group as silicon and germanium.

Silicon and germanium combine with oxygen to form glass — one is silicon dioxide, which is used for windows, bottles and other everyday glasses, and the other is germanium dioxide, which is added to silica to provide the fibers used in optical communication.

Carbon, though, is the odd one out, since it combines with oxygen to give out the poisonous gas carbon monoxide or the suffocating gas carbon dioxide. CO2, when frozen and squeezed, also forms the “dry ice” which provides atmospheric smoke for stage shows.

The new material has been baptised amorphous carbonia, or a-CO2.

At present, a-CO2 is a curiosity because it cannot be tested or used outside the pressure chamber. The CO2 that in these extraordinary conditions takes up a chaotic “amorphous” structure, becoming glass, reverts to orderly molecules of CO2 under decompression.

The first challenge will be to develop a form of a-CO2 that can survive in room temperatures.

“Carbonia-based minerals and glasses could give rise to useful technological materials, if we can recover them to ambient conditions,” says Paul McMillan, a University College London chemist.

The discovery of a-CO2 raises intriguing questions about the huge gas planets in the outer Solar System.

In theory, the tremendous pressures of Jupiter, Saturn and the other gas giants could turn the planetary interior into hard, stiff a-carbonia.

The paper is lead-authored by Federico Gorelli and Mario Santoro of the European Laboratory for Non-Linear Spectroscopy (LENS), based in Florence, Italy.