Silicon Cage Clusters: Better Than Buckyballs?

The discovery of carbon fullerenes (Update 2) caught the imagination of scientists and the public alike as researchers raced to find applications for the tiny spheres commonly called buckyballs. Now researchers at the Joint Research Center for Atom Technology have managed to create similar arrangements of silicon atoms, a feat previously thought impossible owing to silicon's chemical nature. Potential applications of the silicon assemblies range from components in quantum computers to chemical catalysts to new superconducting compounds.

Silicon is, of course, a vital material for the vast semiconductor industry and one of the most studied elements in all of science. Therefore this new discovery might lead to applications that could match or even exceed those expected for carbon fullerenes. Unlike carbon atoms, pure silicon cannot form stable, closed cages. The new research, however, reveals that silicon can gather around a central metal atom and settle into basket-like arrangements called silicon cage clusters. One particularly low energy, and therefore stable, configuration consists of twelve silicon atoms forming a regular, hexagonal cage that surrounds a tungsten atom (see figure at Physics News Graphics).

Because the choice of a central metal atom affects the chemical behavior of cage clusters, scientists should be able to tailor the clusters to create novel nanodevices and catalysts. The researchers (Hidefumi Hiura,
h-hiura@bq.jp.nec.com, 011-81-298-50-2615) note in particular that clusters efficiently isolate their guest metal atoms from the surrounding environment, a characteristic that could permit a cluster to act as a robust qubit in a quantum computer by storing a single bit of information in the spin state of the enclosed metal atom. (H. Hiura et al, Physical Review Letters, 26 February 2001; text at Physics News Select.)