Nanotech researchers create darkest man-made material
- — 24 January, 2008 08:03
Nanotechnology researchers have built the darkest material ever made by man.
The material, a thin carpet of tiny hollow tubes of pure carbon vertically aligned like packaged spaghetti, absorbs more than 99.9% of light, according to researchers from Rice University and Rensselaer Polytechnic Institute.
The nanotech-based material, which looks like a thin piece of black paper, could be used for solar energy converters, infrared detection and astronomical observation. The secret to the material's darkness lies in the way the tubes are loosely packed together. Researchers from Rice University noted that light is trapped in the spaces between the tubes.
Scientists from the two schools worked together on the project, which was funded by the U.S. Department of Energy's Office of Basic Energy Sciences and the Focus Center New York for Interconnects.
"It is a fascinating technology, and this discovery will allow us to increase the absorption efficiency of light, as well as the overall radiation-to-electricity efficiency of solar energy conservation," said Shawn-Yu Lin, professor of physics at Rensselaer, in a statement. "The key to this discovery was finding how to create a long, extremely porous vertically-aligned carbon nanotube array with certain surface randomness, therefore minimizing reflection and maximizing absorption simultaneously."
Every material - water, plastic or even rocks - reflects some a certain amount of light. Basic black paint reflects 5% to 10%, for instance - or 100 times more light than the nanotube carpet. Researchers at Rensselaer noted that scientists have long tried to create a material that would absorb all the colors that make up light, while reflecting none. They have not been able to create a material that didn't reflect any light at all. Before this latest advancement, the darkest manmade material reflected 0.16% to 0.18%.
This new nanotech-based material has a total reflective index of 0.045%, which is more than three times darker than the previous record, which used a film deposition of nickel-phosphorous alloy, according to scientists at Rensselaer.
"The loosely-packed forest of carbon nanotubes, which is full of nanoscale gaps and holes to collect and trap light, is what gives this material its unique properties," said Lin. "Such a nanotube array not only reflects light weakly, but also absorbs light strongly. These combined features make it an ideal candidate for one day realizing a super black object."
The researchers have applied for a Guinness World Record recognition.