One of the most promising materials in this new field is the carbon nanotube, discovered in 1991 by Sumio Iijima, a senior research fellow at NEC Corp. and a professor of materials science at Meijo University in Nagoya. A new type of carbon, these microscopic tubes are up to 100 times stronger than steel. Since his landmark discovery, Iijima has learned how to manipulate nanotubes and is now developing applications for their use in fuel-cell batteries.
The scientist, who could become the next Japanese to receive a Nobel prize, recently took time to talk about his life work with BusinessWeek Correspondent Irene M. Kunii at his laboratory in Tsukuba, north of Tokyo. Following are edited excerpts of the interview:Q: What inspired you as a child? Were you interested in science early on?
A: I grew up in Koshigaya, Saitama prefecture, which was rural then -- though now it's regarded as a suburb of Tokyo. I spent my time chasing butterflies, catching snakes, and raising rabbits and pigeons. I attended a rural school that had only three classes with 40 students each. I did have a good science teacher who influenced me very much. That's the only teacher I remember from that school.
In high school, I was fortunate again to have good chemistry and physics teachers. But instead of studying, I had a great time mountain climbing. I didn't have very good grades -- somewhere in the lower middle -- because I never studied. You see, I had so many things to do. I loved sports, collecting minerals, and looking at the stars at night.
I ended up failing my university entrance exams. I was free for a year and spent the time learning how to play the mandolin. I also studied on my own, going everyday to a library to prepare for the exams. I didn't like it because it just required memorizing facts.Q: Did you become interested in science in university?
A: I ended up getting accepted at the University of Electro-Communications, which specializes in communications engineering. I found out it was not my forte. In my last year, I switched my major to chemistry, and that's where I gradually became interested in my studies. In my senior year, my classmates had all decided on where they would work upon graduation. That was when I started to think about graduate school. For the first time in my life, I studied very hard and won entrance to Tohoku University [in Sendai, Japan].
During my interview with a group of physics professors at the university, one of them recommended that I join the lab of Professor Hibi, the smallest in the department and one that specialized in microscopy [using high-resolution microscopes to study the atomic structure of materials]. This one interview determined the rest of my life. But it was an accident that suited me well.Q: When did you do your first groundbreaking work?
A: I was hired [in 1970] as a research associate by Arizona State University, where they had just opened a new lab and needed someone to operate their electron microscope. It was great because I had complete freedom and a very good microscope. One year later, I produced the first atomic resolution microscopy, which means I was able to see the atomic structure on a screen.
Later [in the 1970s], I observed a round spherical structure, but I didn't know what it was. I wrote a paper about it in 1979, when I was spending some time at Cambridge University. Then, in 1985, three professors [in Britain and the U.S.] published a paper reporting that they had discovered a new form of carbon known as C60. The molecular structure had a shape similar to what I had observed.
I wrote to one of the professors, Richard Smalley of Rice University in Texas, who was then looking for some evidence to support their research. Smalley encouraged me to write another paper about my observation, which I did in 1987. Everyone was excited by this new form of carbon, because it had interesting applications. But it didn't live up to expectations.Q: It did lead you to the carbon nanotube, however. Please explain how.
A: When C60 was discovered, I was very careful about what I should do. I wanted to use my experience, but I knew it wasn't enough. I was interested in how these molecules were formed in an atomic cloud. Then, in the winter of 1990, I attended an academic conference. Although I made a presentation on the structure of a diamond, I joined a group afterward that was talking about C60 until late in the night. Harry Kroto [of the University of Sussex], who was one of the three discoverers of the C60, told me that I should be in their community.
When I returned to Japan, I immediately started to look for a specimen that would provide an onion-layered graphite structure. Several months later, I used two carbon rods, the ends of which I welded. I took the soot that was created, smashed it, and then examined it under a microscope. And that's when I saw something very interesting. The date was June 23, 1991.
It had a very unusual form resembling whiskers. As a graduate student at Tohoku University, I had studied silver bromide, the structure of which was also whisker-like. So this is why I noticed it. Upon closer examination, I realized that it had a tubular structure. I was able to write up my paper quite quickly, publishing it in Nature in November, 1991.Q: What can we expect as a result of this discovery?
A: The carbon nanotube has properties similar to silicon, so it's possible that it can be used as a logic circuit. Because it's so durable, it could be used to create very strong materials. The U.S. military is reportedly interested in bulletproof vests made of nanotubes, but we'd have to produce kilograms of this material to make something like that. That's the biggest hurdle now. The production rate is not very good, so it's difficult to make quantities of carbon nanotubes.Q: What type of research have you been doing recently?
A: Since last year, I and my team have been using the surface of nanotubes in fuel cells. Like charcoal, carbon nanotubes have a lot of gaps and pores, making them superabsorbent. So it can absorb hydrogen gas used in car fuel-cell batteries. We're also using them for an electrode in fuel cells for portable gadgets. This could lead to an energy revolution. Japan has no natural resources, so it makes sense for us to pursue this area. It could take 100 years, but it's still very important.
In computers, we can reduce energy loss and improve the speed if we use nanotubes. We can also make smaller computers.Q: You've had an unusual career for a Japanese scientist, moving from one university or research facility to another. How has this affected your research?
A: The good part is that by moving around, I met very interesting people who inspired me. However, the negative part is that I have no pension plan, and my family has had to suffer. When I first returned to Japan in 1982, I joined a government research program in Nagoya. I bought a house there, and my children entered school in that city. When NEC offered me this research post in 1987, I found it difficult to leave Nagoya because it's not easy selling a house or switching schools. This society doesn't make it easy to move around.