a Product of Nanotechnology
These days, following the surge of interest in information technology and biotechnology,
the talk of the town is nanotechnology. Scientists around the world are excitedly
discussing the possibilities inherent within this frontier field. The "carbon
nanotube," a mesh of carbon atoms arranged in atubular shape, is said
to be likely to produce the first practical applications of nanotechnology.
The person who discovered and named this object, found in a tiny realm with
dimensions measured in millionths ofmillimeters, is one of today's leading
scientists, and he is in Aichi Prefecture.
image of a carbon nanotube. This double-walled nanotube hasone cylinder
of carbon atoms within another. Carbon nanotubes with variousforms
have been found, but it was this sort of multiwalled structure that Iijima
came across in 1991.
A nano is a one-billionth part of a specified unit. A nanometer
is one-billionth of a meter, or one millionth of a millimeter. Just
how short such a length is can be readily grasped when one considers
that a typical hairfrom the head stretches some 10,000 nanometers
across. Nanotechnology is the overall term used to designate an assortment
of technologies that operate on this extraordinarily tiny scale.
The nanometer is the level on which atoms and molecules are built.Technologies
making use of the properties and behavior of substances inthis microcosm
have a very wide range of potential applications. It is hoped that
they can be utilized in all sorts of existing technologies infields
starting from computers and telecommunications and extending farbeyond,
including biotechnology, chemistry, medicine, engineering, energy,and
Institutions around the world have started up basic research in this
field. Many countries, regarding it as a twenty-first-centurytechnology
of the likes of the IT and biotech fields, are competing in its development.
No single technology has yet reached the applications stage, but
the first off the bloc, many people think, will be the carbon nanotube.
fifth form of carbon
A carbon nanotube is an atomic array of carbon atoms
in acylindrical shape. Diamonds and graphite and charcoal are three
common substances made entirely of carbon atoms. Carbon can also
take the form ofthe "fullerene," a molecule of carbon
atoms with the shape of a soccerball. The first of these was discovered
in 19851 by three American andBritish scientists, and it has 60
carbon atoms. Fullerenes with 70 or 82 atoms and more turned up later.
The only other known form pure carbon may take is the carbon nanotube.
Although others may be discovered in the future, it can be calledthe
fifth form of carbon. It was discovered in 1991 by Sumio Iijima,
asenior research fellow in the NEC Laboratories of NEC Corp. and
professorat Nagoya's Meijo University. And it has a number of unique
characteristics that may make it a very useful substance, Iijima
In terms of properties, the carbon nanotube is chemically and thermally
stable. It is highly absorptive, which may make it a good storage
device for substances. It can be either a conductor or an insulator depending
on the direction of the electric field applied to it. "We have also
found," Iijima reports, "that it interacts with certain
substances selectively and aids electricity generation in a hydrogen-oxygen
reaction,which opens the door to its use in the fuel cell.
The fuel cell is one of the places where Iijima is most hopeful
of applications. This is a battery that reverses the normal process
of electrolysis, in which hydrogen and oxygen are separated from
water by passing a current through it. A fuel cell combines hydrogen
and oxygen,thereby producing electricity. As is commonly known,
automakers are currently engaged in intensive R&D programs to
commercialize fuel cellelectric vehicles, which hold the promise
of being next-generation,environment-friendly vehicles. If carbon
nanotubes can be successfully incorporated into them, fuel cells
will be significantly reduced in efficiency and cost, giving them
a much broader range of applications.
equipment in the Department of Materials Science and Engineering
for making carbon nanotubes using laser plasma.Carbon melts
and evaporates in the plasma from a pulse laser, leaving behind
deposits containing carbon nanotubes.
Various other uses for carbon
nanotubes may also turn up. Iijima observes that within a couple
of years, we will see a large size flat panel display for television,
that they may supply a superior substitute for thesilicon in the
computer chip, that they may serve biotechnology in a variety of
ways, and that they may even find use as reservoirs for storing hydrogen.
"But the biggest challenge before us today is to overcome energy problems,"
he adds, "and people are looking to technology for help. Just possibly
carbon nanotubes may give us the materials we need for solving these
problems and thereby conserving the global environment."
the eyes of the electron microscope
After his discovery of the fifth form of carbon in 1991, Iijima
soon gained recognition around the world as one of the foremost authorities
in this field of research. But this has not caused him to swagger
about. After all,he says, he happened to come across carbon nanotubes
"just by pure luck."
"Discoveries can be into two broad groups," he suggests.
"In some cases the discovery comes about as a result of having
set a goal and applied knowledge and theory to attain it. In other
cases the discovery unexpectedly turns up one day in the course of
a trial-and-error process,or perhaps thanks to knowledge and experience
gained in an entirely separate field. The latter are gifts of fortune,
but they actually account for the bulk of the discoveries that have
triggered major scientific advances."
Iijima graduated from the University of Electro-Communications in1963
and went on to pursue graduate studies at Tohoku University. There
he became acquainted with the electron microscope, which at the time
was stilla rare instrument. After earning his doctorate he picked
up experience in anumber of places, serving as a research associate
at Arizona StateUniversity and working for the Research Development
Corporation of Japan(now the Japan Science and Technology Corporation).
Since 1987 he has been a research fellow in the NEC Laboratories. Since
1999 he has also served as a professor at Meijo University, where he
works in the Department of Materials Science and Engineering, but throughout
his career he has specialized in electron microscopy.
"I found carbon nanotubes while using an electron microscope
to investigate fullerenes, the fourth carbon form," he tells us.
"I was looking at carbon deposits on electrodes, and my eye was
caught by some whiskers I could see. Right away I sensed I was on to
something. I happened to know about such tubular crystal structures
because when I was in graduate school, I'd studied under one of the
leading authorities on asbestos. That experience enabled me to grasp
the essence of the nanotubes quickly. In fact, I probably wouldn't
even have noticed them if I hadn't spent so many years working with
discoverer of the carbon nanotube. A senior research fellowin
the NEC Laboratories and professor at Nagoya's Meijo University,
he is known around the world as a leading authority in his field.
"Carbonnanotubes," he says, "may become a key
material for fundamentally resolving energy problems."
This is a classic example of the serendipity people in the world
of science often talk about. Many epochal advances, we are told,
come from researchers with a gift for making serendipitous discoveries.
Indeed, itwas a botched experiment that set Hideki Shirakawa on
the road to his receipt of the 2000 Nobel Prize in Chemistry.
There is also another episode of happenstance leading to happy results
in Iijima's story. The American and British scientists who discovered
fullerenes, for which they received a Nobel Prize in 1996, made their
discovery in 1985. Before that, in the 1970s, Iijima had in fact already
seen fullerenes and taken photos of them. What he had come up with,though,
was not real proof of their existence but only an indication that they
existed. His interest thereafter moved off in other directions,
but then he returned to the subject and embarked on research into
fullerenes,with encouragement from their discoverers." And
it was this research thatturned up carbon nanotubes.
"Actually there were already attempts to make carbon nanotubes
backin the 1950s," Iijima elaborates. But in those days it
was impossible to see these things, since electron microscopy hadn't
yet reached the level for seeing atoms. There's a world of difference
between 'apparently exists' and 'exists.' Something that 'apparently
exists' is still in the realm ofscience fiction. It enters the realm
of science only when its existence is objectively demonstrated."
Iijima introduced carbon nanotubes to the world using just such
an objective demonstration. It may have been serendipity that put
him in this position, but this was serendipity backed by a certain
inevitability, one that could have produced happy results only for
place in carbon nanotubes
The mechanisms involved in the creation of carbon nanotubes are now
being elucidated, and the research at Meijo University has shifted
to how the production process can be controlled. Mass production is
still difficult,but Iijima is confident it will be achieved in time.
Already a number of companies have come up with plate panel displays
making use of carbon nanotubes, so the first practical applications
can be said to be within shooting range.
The samples Iijima used in his discovery of carbon nanotubes came from
Aichi, supplied by the laboratory of Professor Yoshinori Ando at Meijo University.
And now steady progress is being made within the prefecture toward
the application of this fifth form of carbon, which has potential within
it for reshaping the society of the twenty-first century. (Masahiro Ota)