Evanston, IL — Northwestern University researchers have become the first to image and analyze a class of nanostructures that are stronger and lighter than steel and that could be used in the transportation industry, possibly as hard coatings on gears to improve the efficiency of vehicles or as an oxidation-resistant outer coating for airplane windows.
Once developed fully, the nanostructures also could be embedded in other materials, such as polymers, to increase their strength.
The analysis of the single-walled boron nitride (BN) nanostructures will be published in the March 12 issue of the journal Physical Review Letters.
"Knowledge of these exotic new structures will open the doors to making novel hard coatings for a variety of materials," said Laurence Marks, director of the new Center for Transportation Nanotechnology at Northwestern. "Understanding the strengths and weaknesses of the BN nanostructures will enable us to make better materials at a reasonable cost."
The structures include tiny nanotubes made up of atoms of boron and nitrogen that are more oxidation resistant and are expected to have better mechanical and electronic properties than their well-known cousins, carbon nanotubes.
Marks, who also is professor of materials science and engineering, led a team in imaging the BN nanostructures — tubes, buckyballs and cones that are more than 1,000 times smaller than a human hair. The high-resolution, high-vacuum electron microscope used for the study was designed and built at Northwestern and is the only one of its kind.
The researchers have shown that the BN nanostructures, which have walls only one atom thick, are essentially made up of hexagons of boron and nitrogen with the occasional fourfold and eightfold rings connecting them and allowing them to bend, giving them their distinct shapes. Carbon nanotubes, on the other hand, are primarily hexagons with occasional fivefold and sevenfold rings.
Marks and his team made the nanostructures by directly depositing boron and nitrogen onto a substrate, unlike with the creation of carbon nanotubes, which are normally made in the gas phase.
The other author on the paper is Erman Bengu, currently a research engineer at Intel Corporation in San Francisco. The research was supported by the Air Force Office of Scientific Research.
An article describing Marks’ paper, published by the American Physical Society, is on the Web site of Physical Review Focus at http://focus.aps.org.
Northwestern University, a leader in nanotechnology research and home of the first federally funded nanotechnology facility in the country, established the Center for Transportation Nanotechnology in November 2000 to advance the education and research frontiers of nanotechnology as applied to the transportation sector. The center, which is part of the University’s Institute for Nanotechnology, brings together scientists, engineers and transportation experts to develop new technologies that will lead to faster, cheaper and safer transportation systems.
Materials provided by Northwestern University. Note: Content may be edited for style and length.
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