The Blackest Black: MIT Engineers Develop a Material so Dark, That It Makes Things Disappear
Engineers at MIT have created a material so dark, that it seems to make objects, such as brilliant diamonds invisible to the naked eye.
They also say the material or coating is 10 times darker than other very black materials. And, they found it accidentally.
The material is made of carbon nanotubes or (CNTs) — tiny filaments of carbon with a mesh-like structure. The researchers grew the material on a chlorine-etched aluminum foil. They say that "the foil captures more than 99.96% of any incoming light, making it the blackest material on record." But, during the research, they also saw that the material absorbed almost 99.99% of the light from different angles.
The material is actually part of an art exhibit called "The Redemption of Vanity" at the New York Stock Exchange, a collaboration between MIT Prof. Brian Wardle, the co-author of the study, and MIT artist-in-residence, Diemut Strebe.
The most interesting part of this art exhibit is that this new CNT material coats, "a 16.78-carat natural yellow diamond, estimated to be worth $2 million."
The effect is amazing: the diamond has been made invisible, and becomes "a flat, black void."
The researchers, Wardle and co-author Kehang Cui, a former MIT postdoc, had no intention of creating this new, ultra-black material. "Instead, they were experimenting with ways to grow carbon nanotubes on electrically conducting materials such as aluminum, to boost their electrical and thermal properties," notes the MIT press release.
They initially didn't expect to focus on the optical properties of the material. They were really surprised by the material's color and they measured the color optical reflectance, which led to the accidental discovery.
'Blackest's Black' vs. Vantablack
A few years ago, Surrey NanoSystems created a similar material called 'Vantablack,' which it claims absorbs 99.965% of light. Later, they broke their own record by creating something that couldn't be detected under a spectrometer, i.e., it absorbed 99.99% of light.
However, given this new development, this accidental discovery can be claimed as the world's blackest black to date, with "99.995 percent [absorption] of incoming light," if the incoming light is reflected from every angle.
Prof. Wardle does comment on this constant effort to make the world's blackest black material: "Our material is 10 times blacker than anything that's ever been reported."
"Someone will find a blacker material, and eventually we'll understand all the underlying mechanisms, and will be able to properly engineer the ultimate black," — just like what the engineers at Surrey NanoSystems did — whose Vantablack is now being used as car paint by none other than BMW.
Other than car paint, these kinds of CNT materials are incredibly useful in a variety of industry, especially the aerospace industry. They "reduce unwanted glare, help space telescopes spot orbiting exoplanets," says Wardle.
Now, Astrophysicist and Nobel laureate John Mather is also interested in the new material to make a 'star shade' that will shield a space telescope from light.
He asks, "Would you like to see an Earth orbiting another star?"
"We need something very black. … And this black has to be tough to withstand a rocket launch. Old versions were fragile forests of fur, but these are more like pot scrubbers — built to take abuse."
The researchers have filed for a patent, but have made the new CNT process freely available for artists in a noncommercial setting.
The findings are published in the journal ACS-Applied Materials and Interfaces.