Tool of the Future Lies in the Answer to the Nanotubes
W&M professor seeks breakthrough in study
The scrapings inside two vials on Brian Holloway's desk looked more like shavings from a blown-out tire than a substance stronger than steel, material that could one day help create computers 1 billion times faster than typical silicon-based machines.
Before that digital dash, however, scientists will need to know how they even got to the starting line.
Holloway, an assistant professor in the Department of Applied Science at the College of William and Mary, is preparing to continue studying nanotubes, the equivalent of rolling up sheets of carbon into microscopic rods. Many scientists think those structures are the strongest man-made materials on the planet.
Researchers hope the tubes can be used in such items as bulletproof glass and Kevlar vests. That's because of the structure, said Michael W. Smith, aerospace engineer at NASA Langley, which is helping fund Holloway's research.
Smith compared it to flat newspapers.
"If you take one of those newspapers and roll it up to smack your buddy, you can have a stronger structure," he said.
Another promising aspect of nanotubes is that they conduct electricity with no resistance, a plus for building components, such as transistors, for quantum computers. Quantum computers eliminate the use of 0s and 1s — essentially, whether a switch is on or off, which is how they convey information — by using different energy levels of atoms.
Before that's possible, however, researchers will need to understand how they're making the tubes and how to make them better.
"That's a very good question, and it's a question we don't really understand yet," Holloway said.
Holloway's work focuses on gaining more information on how the tubes form and how to control how many do form.
Using the free-electron laser at the Thomas Jefferson National Accelerator Facility in Newport News, Holloway shoots the laser into half-inch long rods made of graphite combined with other materials, such as iron or cobalt.
"The laser's going in and smacking this thing and it's just blowing up," Holloway said.
By the time the gaseous debris has cooled and settled, however, tubes with diameters 20,000 times smaller than a red blood cell have formed.
The lab's machine allows Holloway to control the power level and amount of time the laser hits the rod, which appears to affect how many nanotubes are made and how well they're structured.
What the test doesn't provide is insight into exactly what's going on, Holloway said.
"As far as when the nanotubes form, that's a good question," he said. "No one has actually watched them grow."
Sumio Iijima, a Japanese scientist, discovered nanotubes accidentally in 1991. Since then, one of the biggest questions is why tubes form at all, Holloway said.
"You have individual atoms. You don't have sheets of graphite" in the vapor, he said. "The most logical thing for them to form are sheets of graphite."
What researchers are sure of, however, is that the tubes will be the tools for the future.
In fact, NASA has its money on the micro-material.
Officials with NASA Langley Research Center hope the tubes can be used as light-weight components of planes as well as controlling mechanisms, such as allowing wings to warp themselves to control air flow instead of using flaps.
The agency is one of the first organizations to pay Jefferson Lab to continue using the laser at a time when it would normally be shut down. At a cost of about $20,000, the agency will buy Holloway an additional week and a half worth of beam time divided into four hour intervals during the coming weeks. That's on top of an additional $100,000 NASA Langley is spending for equipment to produce nanotubes.
Currently, creating the amount of nanotubes necessary for commercial ventures takes too long, Holloway said, and that translates into high prices: nanotube soot can be 10 times more expensive than gold.
Holloway's research, however, is churning out as many nanotubes in six minutes as it typically takes labs several hours to create.
Still, the amount is minuscule. Since starting last July, his research has made about a gram of the tubes. While Jefferson Lab shuts down the laser for maintenance toward year's end, Holloway hopes to improve that technique by building on the information learned so far from using the laser.
"It's difficult to find anyone who can give you more than milligrams per week," he said. "Our research can identify the high-power requirements to make nanotubes in a commercially viable way."