Researchers are working to create a material that is usually light and extremely strong.
The potential material could float without gas while maintaining its shape; the innovation could help ease the effects of the world's current helium shortage, the California Institute of Technology reported.
The researchers created a method for constructing materials by employing the unusual properties solids take on at the nanometer scale. The method allowed them to produce a ceramic that contains 99.9 percent air but is exceptionally strong and can recover its original shape after being smashed by more than 50 percent.
"Ceramics have always been thought to be heavy and brittle," said Caltech materials scientist Julia Greer. "We're showing that in fact, they don't have to be either. This very clearly demonstrates that if you use the concept of the nanoscale to create structures and then use those nanostructures like LEGO to construct larger materials, you can obtain nearly any set of properties you want. You can create materials by design."
The tem used a direct laser writing method called d two-photon lithography in order to "write" a three-dimensional pattern in a polymer by allowing a laser to harden it wherever it was focused. The parts of the polymer exposed to the laser remained intact while the others melted away, leaving behind a three-dimensional scaffold. The structure can then be coated with any material, including an alloy, glass, or semiconductor and etched out to form a hollow architecture.
The team found alumina structures with a wall thickness of 50 nanometers and a tube diameter of about one micron shattered when compressed, but when the ratio of wall thickness to tube diameter was reduced the results were much different.
"You deform it, and all of a sudden, it springs back," Greer said. "In some cases, we were able to deform these samples by as much as 85 percent, and they could still recover."
The technique could be used in "optics, energy efficiency, and biomedicine," such as to reproduce bone structures.
"One of the benefits of using nanolattices is that you significantly improve the quality of the material because you're using such small dimensions," Greer said. "It's basically as close to an ideal material as you can get, and you get the added benefit of needing only a very small amount of material in making them."
The findings were published in the Sept. 12 issue of the journal Science.
