Tag Archives: Sumio Ijima

Beginner’s guide to carbon nanotubes and nanowires

There’s a very nice Apr. 11, 2013  introductory article by David L. Chandler for the Massachusetts Institute of Technology (MIT) news office) about carbon and other nanotubes and nanowires,

The initial discovery of carbon nanotubes — tiny tubes of pure carbon, essentially sheets of graphene rolled up unto a cylinder — is generally credited to a paper published in 1991 by the Japanese physicist Sumio Ijima (although some forms of carbon nanotubes had been observed earlier). Almost immediately, there was an explosion of interest in this exotic form of a commonplace material. Nanowires — solid crystalline fibers, rather than hollow tubes — gained similar prominence a few years later.

Due to their extreme slenderness, both nanotubes and nanowires are essentially one-dimensional. “They are quasi-one-dimensional materials,” says MIT associate professor of materials science and engineering Silvija Gradečak: “Two of their dimensions are on the nanometer scale.” This one-dimensionality confers distinctive electrical and optical properties.

For one thing, it means that the electrons and photons within these nanowires experience “quantum confinement effects,” Gradečak says. And yet, unlike other materials that produce such quantum effects, such as quantum dots, nanowires’ length makes it possible for them to connect with other macroscopic devices and the outside world.

The structure of a nanowire is so simple that there’s no room for defects, and electrons pass through unimpeded, Gradečak explains. This sidesteps a major problem with typical crystalline semiconductors, such as those made from a wafer of silicon: There are always defects in those structures, and those defects interfere with the passage of electrons.

H/T Nanowerk Apr. 11, 2013 news item. There’s more to read at the MIT website and I recommend this as a good beginner’s piece since the focus is entirely on what carbon nanotubes and nanowires are , how they are formed, and which distinctive properties are theirs. You can find some of this information in the odd paragraph of a news release touting the latest research but I’m very excited to find this much explanatory material in one place.

Another very good explanatory piece, this one focused on carbon nanotubes and risk, is a video produced by Dr. Andrew Maynard for his Risk Bites series. I featured and embedded it in my Mar. 15, 2013 posting. titled, The long, the short, the straight, and the curved of them: all about carbon nanotubes.  You can also find the video in Andrew’s Mar. 14, 2013 posting on his 2020 Science blog where he also writes about the then recently released information from the US National Institute of Occupational Health and Safety on carbon nanotubes and toxicity.