Sumio Iijima’s production of multiwall tubes of interconnected carbon atoms many nanometers in diameter, which he later named carbon nanotubes, heralded the birth of electronic nanoscience.
Sumio Iijima’s interest in carbon nanostructures began during the 1970’s while he was a research crystallographer at Arizona State University. After developing an improved electron microscope, Iijima used the instrument to examine closely the crystals of many substances. During the course of this work, he observed sooty, nanoscale, onionlike spheroids of graphite, and he published his observations in 1980. (Nanoscale objects are extremely small, measurable in nanometers; a nanometer is equal to one-billionth of a meter.) He did not explore the significance of these spheroids further until the subsequent laboratory production and structural documentation of graphitic fullerenes.
In 1985, Richard E. Smalley and Robert F. Curl of Rice University in Houston, Texas, along with Harold W. Kroto of the University of Sussex in the United Kingdom, found small quantities of nanoscale carbon 60 (C
60
) after they vaporized graphite in their laboratory with a laser. Along with amorphous soot, C
60
was latently deposited on the wall of their experimental containment vessel. The molecules were shaped like soccer balls, with each closed, hollow orb comprising sixty hexagonally interconnected carbon atoms. Because the molecule structurally resembled the geodesic architecture of R. Buckminster Fuller, it was named Buckminsterfullerene,
Although carbon nanostructures occur in nature, they became apparent to scientists only after the development of X-ray diffraction and invention of the transmission electron microscope in the 1930’s. In October, 1991, during a scientific conference at Richmond, Virginia, Iijima, who by that time was working as an industrial scientist with Japan’s NEC Corporation,
The imaged carbon nanotubes strikingly appeared as elongated, tubular fullerenes, closed at each end, with variable diameters comprising multiple layers of rolled graphite. Each multiwall carbon nanotube resembled a large roll of chicken wire with an inside hollow diameter. Each hexagonal ring within the crystal lattice of the rolled carbon nanotube displayed even smaller individual, interconnected atoms, each measuring approximately one angstrom (an angstrom is equal to one ten-billionth of a meter).
After the Richmond conference, Iijima published his findings in Nature, and his announcement initiated a second enthusiastic wave of applied research regarding graphitic carbon. Like most scientists, Iijima was unaware that his report represented at least the third independent documentation of carbon nanotubes. These structures, and possibly fullerenes, were first definitively discovered and photomicrographed in 1952 by two Russian scientists, L. V. Radushkevich and V. M. Lukyanovich, after they thermally decomposed carbon monoxide in the presence of catalytic iron particles. Unfortunately, little information was recorded in the former Soviet Union about these two resourceful investigators, although their published report has remained readily available.
Carbon has the extraordinary property of being capable of bonding not only with itself but also with the atoms of many other elements in chains, rings, and combinations of these two structures, producing an incredible diversity of natural and human-made substances. Like fullerenes and nanotubes, graphite and diamond are composed solely of interconnected carbon atoms—that is, they contain no atoms of other elements. The significant qualitative differences between diamond and graphite are a consequence of their different physical arrangements and crystal lattices. The atoms of lamellar graphite are cyclically bound to three adjacent carbon atoms of the same planar sheet. Not directly connected, the individual, slippery sheets of graphite are easily separated, making the erasable substance found to be useful in pencils. Cubic diamonds, in contrast, contain carbon atoms densely connected to four other carbon atoms. Much softer than diamond but more tensile, graphite looks and behaves like a metal. A graphitic derivative, carbon nanotubes share graphite’s conductive properties and lamellar, polycyclical crystalline structure with electrons freely circumnavigating individual sheets.
As a scientist with NEC, Iijima comprehended the commercial significance of nanoscale graphitic carbon structures. Founded in 1899 as Nippon Electric Company, NEC had become a multinational conglomerate of affiliated companies specializing in electronic components, including semiconductors and video displays. Unlike diamonds, graphitic carbon nanotubes were found to conduct electricity even better than copper; thus they lent themselves well to electronic applications.
Iijima’s published research reached a broad scientific audience that also understood the potential applications for carbon nanotubes. Before the rapid advances that were made in the electronics industry in the late twentieth century, other discoveries concerning multiwall carbon nanotubes had been reported to very limited audiences. Nevertheless, the substantial international examinations of solid-state carbon prior to the discovery of fullerenes and single-wall carbon nanotubes prepared a strong foundation for the groundbreaking research of the 1980’s and 1990’s.
Not surprisingly, carbon nanotubes drew the interest of industrial researchers at another international electronic giant, International Business Machines (IBM)
Historically, carbon nanotubes were productively deposited after different methods of high temperature graphite, hydrocarbon, or carbon oxide decomposition in the absence of free oxygen. These processes prevented the reactive production of carbon dioxide, a gaseous compound physically more stable than either graphite or diamond. Although these processes were cost-effective, by 1999 manufacturing focused on catalytically controlling the structural quality, electrical conductivity, and tensility of carbon nanotubes. One of the strongest known materials, carbon nanotubes reportedly exhibited a tensile strength approximately fifty times greater than steel. Soon after their discovery, carbon nanotubes were combined with other industrially manufactured composite materials, such as concrete, to enhance the structural integrity of those materials.
By the beginning of the twenty-first century, IBM and NEC researchers had announced significant progress toward the mass production and use of carbon nanotubes as fuel cell electrodes to power electronic devices efficiently and as potential nanowiring and switches in efficient, low-voltage electrical circuits. Hoping to exploit carbon nanotubes as storage vessels, in 2004, scientists at the Argonne National Laboratory in Illinois successfully drew water into a single-wall carbon nanotube.
-
Bethune, Donald S., et al. “Cobalt-Catalysed Growth of Carbon Nanotubes with Single-Atomic-Layer Walls.” Nature 363 (1993): 605-607. Documents the production of single-wall carbon nanotubes at IBM’s research laboratories in Almaden, California. Includes micrographic illustrations. -
Harris, Peter J. F. Carbon Nanotubes and Related Structures. New Materials for the Twenty-First Century. New York: Cambridge University Press, 1999. Presents a thorough examination of the history, science, manufacturing, and potential applications of carbon nanotubes. Introductory chapter describes the beginnings of nanotube research. Includes illustrations and indexes. -
Iijima, Sumio. “Helical Microtubules of Graphitic Carbon.” Nature 354 (1991): 56-58. Outlines the serendipitous 1991 production of multiwalled, graphitic carbon nanotubes at NEC’s research laboratory in Japan. Includes micrographic illustrations. -
_______. “High Resolution Microscopy of Some Carbonaceous Materials.” Journal of Microscopy 119 (1980): 99-111. Iijima’s earliest documentation of sooty, nano-sized, graphitic carbon particles as elaborated through his electron microscopy at Arizona State University. -
Iijima, Sumio, and Takehashi Ichihashi. “Single-Shell Carbon Nanotubes of 1-nm Diameter.” Nature 363 (1993): 603-605. Documents the 1993 discovery at NEC of single-wall carbon tubes having diameters of 1 to 4 nanometers. Includes micrographic illustrations. -
Kroto, Harold W., Richard E. Smalley, and Robert F. Curl. “C
60
: Buckminsterfullerene.” Nature 318 (1985): 162-163. Highlights the laboratory production of carbon-60, or fullerenes, at Rice University by these collaborative researchers. -
Monthioux, Marc, and Vladimir L. Kuznetzov. “Who Should Be Given the Credit for the Discovery of Carbon Nanotubes?” Carbon 44 (2006): 1621. Clarifies the confusion regarding the time line of discovery for both multiwall and single-wall carbon nanotubes. -
Oberlin, A., M. Endo, and T. Koyama. “Filamentous Growth of Carbon Through Benzene Decomposition.” Journal of Crystal Growth 32 (1976): 335-349. Details the independent 1970’s production of multiwall carbon nanotubes through controlled laboratory decomposition of liquid benzene. Includes micrographic illustrations. -
Radushkevich, L. V., and V. M. Lukyanovich. “O strukture ugleroda, obrazujucegosja pri termiceskom razlozenii okisi ugleroda na zeleznom kontakte.” Russian Journal of Physical Chemistry 26 (1952): 88-95. Earliest known report photodocumenting the discovery of metalocatalyzed multiwall carbon nanotubes (the title translates as “Carbon structures formed during thermal decomposition of carbon oxide on an iron contact”). General global knowledge of this report was hampered by the Cold War and limited readership for this Russian journal.
IBM Introduces Its Personal Computer