Nanotechnology Now - Press Release: No Small Measure: Origins of Nanorod Diameter Discovered

Home > Press > No Small Measure: Origins of Nanorod Diameter Discovered

Abstract:
A new study answers a key question at the very heart of nanotechnology: Why are nanorods so small?

No Small Measure: Origins of Nanorod Diameter Discovered

Troy, NY | Posted on March 24th, 2009

Researchers at Rensselaer Polytechnic Institute have discovered the origins of nanorod diameter, demonstrating that the competition and collaboration among various mechanisms of atomic transport hold the key to nanorod size. The researchers say it is the first study to identify the fundamental reasons why nearly all nanorods have a diameter on the order of 100 nanometers.

"Scientists have been fabricating nanorods for decades, but no one has ever answered the question, ‘Why is that possible?'" said Hanchen Huang, professor in Rensselaer's Department of Mechanical, Aerospace, and Nuclear Engineering, who led the study. "We have used computer modeling to identify, for the first time, the fundamental reasons behind nanorod diameter. With this new understanding, we should be able to better control nanorods, and therefore design better devices."

Results of the study, titled "A characteristic length scale of nanorods diameter during growth," were recently published in the journal Physical Review Letters.

When fabricating nanorods, atoms are released at an oblique angle onto a surface, and the atoms accumulate and grow into nanorods about 100 nanometers in diameter. A nanometer is one billionth of a meter in length.

The accumulating atoms form small layers. After being deposited onto a layer, it takes varying amounts of energy for atoms to travel or "step" downward to a lower layer, depending on the step height. In a previous study, Huang and colleagues calculated and identified these precise energy requirements. As a result, the researchers discovered the fundamental reason nanorods grow tall: as atoms are unable to step down to the next lowest layer, they begin to stack up and grow higher.

It is the cooperation and competition of atoms in this process of multi-layer diffusion that accounts for the fundamental diameter of nanorods, Huang shows in the new study. The rate at which atoms are being deposited onto the surface, as well as the temperature of the surface, also factor into the equation.

"Surface steps are effective in slowing down the mass transport of surface atoms, and aggregated surface steps are even more effective," Huang said. "This extra effectiveness makes the diameter of nanorods around 100 nanometers; without it the diameter would go up to 10 microns."

Beyond advancing scientific theory, Huang said the discovery could have implications for developing photonic materials and fuel cell catalysts.

Huang co-authored the paper with Rensselaer Research Scientist Longguang Zhou.

Funding for this research was provided by the U.S. Department of Energy Office of Basic Energy Science.

Visit Huang's Web site (http://www.rpi.edu/~huangh/) for more information on his nanotechnology and materials research.

####

About Rensselaer Polytechnic Institute
Throughout its history, Rensselaer research has produced ground-breaking work in a broad range of important areas.

Early RPI engineering graduates built bridges that linked people, commerce, and communities. Today, Rensselaer people are building the bridges that will link the world to the promises of new technologies.

The collaborative efforts of our students, faculty, corporate partners, and government agencies are generating a new momentum in research and the development of innovative technologies, including biotechnology, information technology, and nanotechnology.

Creating and applying knowledge, and interdisciplinary inquiry, with a rigorous approach to solving problems, Rensselaer men and Rensselaer women are fulfilling the university’s role as a place where people find innovative solutions to complex technical challenges.

Contacts:
Michael Mullaney
Phone: (518) 276-6161

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark: