Getting down to basics with buckytubes.

Ever since chemists discovered buckytubes (SN: 11/16/91, p. 310), they've speculated that these hollow, nanometer-size carbon cylinders - related to the spherical buckyball- could prove the strongest fibers known and may also make good wires for molecular-scale electrical devices,

Scientists should soon have the materials to test those predictions. Two research groups report in the June 17 NATURE that they can make uniform batches of single-layer buckytubes. The ability to make this most basic of buckytubes will help chemists better understand the material's mechanical and electronic properties.

Previously, large-scale synthesis methods produced different sizes of bucky-tubes, often with several nested inside one another like Russian dolls (SN: 7/18/92, p.36). Such variability made it difficult for chemists to study these molecules. Re- searchers have explored the chemistry of single-shell buckytubes using computer simulations (SN: 11/14/92, p.327).

Now, a team of scientists at IBM's Almaden Research Center in San Jose, Calif., has made the real thing -- although they were attempting to make metal-stuffed buckyballs. The group used the standard carbon arc technique for synthesizing buckminsterfullerenes, but added various powdered metals to one of the graphite electrodes. When they added cobalt, an unusual spider-web-like material grew all over the chamber, says IBM's Donald S. Bethune. A transmission electron microscope revealed that the rubbery material consisted largely of interwoven buckytubes, all about 1.2 nanometers in diameter and with walls a single atomic layer thick.

"There may be a magic-sized cobalt cluster that specifically triggers the growth of these tubes." Bethune posits.

Sumio Iijima and Toshinari Ichihashi of NEC Corp. in Tsukuba, Japan, also grew single-layer buckytubes in a carbon arc reactor, but iron served as the catalyst. They added methane and argon gases to the chamber, which proved essential to their synthesis, they report in NATURE.