It may sound like something from a sci-fi tale, but a material invisible to the naked eye yet harder than diamonds and many times stronger than steel is likely to become a key building block for the 21st century. And the man who discovered it, Sumio Iijima of Japan, is a prime candidate for a future Nobel prize. The material is known as the carbon nanotube. Not only will the nanotube yield stronger, lighter industrial materials, but because of its electrically charged properties it's also expected to give rise to a new class of tiny-yet-powerful logic chips, new types of power lines, low-energy computer display terminals, and supercompact fuel-cell batteries for cars and other machines.

Iijima discovered the hollow carbon cylinders in 1991. Since then, he has analyzed the way they work, learned how to manipulate them, and made progress toward molding them into useful products. His work has sparked a parallel global research effort in carbon nanotechnology. But Iijima is still the research leader. In April, Philadelphia's Franklin Institute awarded him the Benjamin Franklin Medal in Physics, one of the world's most prestigious science prizes, whose recipients include many Nobel laureates.

The congenial scientist, who splits his time between his home in Nagoya, where he teaches at Meijo University, and a lab operated by the electronics giant NEC Corp. (NIPNY ) near Tokyo, is too busy to enjoy such accolades. Although he is 63, Iijima believes he still has plenty to contribute. Over the past year, he and his team at NEC have used nanotubes as a component in hydrogen-powered fuel cells that could prove to be the key energy source for automobiles in the future. He has also used a layer of nanotubes as an electrode to power a compact fuel cell for use in mobile devices. That way, laptops and cell phones may go days or weeks without the need for recharging. "I may be doing my best work in my 60s," says Iijima. "I've always been a late bloomer."

Indeed, in his youth there was nothing to indicate that Iijima would develop an interest in the molecular world. He grew up in then-rural Saitama, which borders Tokyo to the north. Although he enjoyed chemistry and physics in high school, he recalls being too busy with his favorite pastime, climbing mountains, to pay much attention to his studies. As a result, he failed the national university entrance exams. So he buckled down for a year and in 1959 was accepted at the University of Electro-Communications, which trains engineers. He wound up in the lab of an interesting chemistry professor and chose to pursue graduate studies at Tohoku University, one of Japan's finest tech schools.

From then on, says Iijima, his life was one fortunate coincidence after another. At his admissions interview, the Tohoku professors decided to place Iijima in the microscopy lab, where research into the atomic structure of materials is conducted using high-resolution electron microscopes. "This one interview determined the rest of my life," he says. "It was an accident that suited me well." Iijima became an expert in manipulating the difficult machines. He started studying the atomic structure of carbon in the 1970s while a visiting professor at Arizona State University and deserves some credit for the discovery of a molecular carbon called C60 that in 1996 won a U.S.-British team a Nobel prize in chemistry. Iijima adopted the same method used to create C60 in his nanotube experiments: He passed electrical sparks between two graphite rods. When he placed the resulting soot under the microscope, he discovered it consisted of many layers of tiny carbon tubes stacked within tubes. These are now called multi-wall carbon nanotubes. Later, he discovered an even stronger single-wall variety.

When he's not working, Iijima pursues a higher mission--encouraging his students to seek scientific careers. He also advises them to be prepared to seize opportunities. "Everything that has happened to me has been serendipitous," he says. Sound advice from a master of the unexpected.

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