A piece of aerogel in a petri dish. Inset shows cubes of the aerogel.
Researchers captured 3D images of the internal structure of an aerogel, which allowed them to determine the material’s strength. Anton Barty at Lawrence Livermore National Laboratory and others used inverted coherent X-ray diffraction patterns to capture the 3D bulk lattice arrangement of a micron-sized piece of aerogel (Phys. Rev. Lett. 101, 055501).
Aerogels, also called nanofoams, are very low-density foams of polymer, metal or ceramic. They appear in nature in both geology and biology. With high strength-to-weight ratios, they also offer unmatched abilities as solid electrical, acoustic and thermal insulators. In addition, aerogels have the highest internal surface area per gram of any material, with a complicated internal structure full of tiny pores, with pore sizes ranging from about 2 to 50 nm.
Although researchers have broadly known the internal structure, actual imaging has been difficult because conventional microscopes cannot observe the smallest pores. The researchers used X-ray diffraction to image the internal structure of a tantalum oxide nanofoam and determine its mechanical properties.
The structure consisted of nodes connected by thin beams. “This blob-and-beam structure explains why these low-density materials are weaker than predicted and explains the high mass-scaling exponent seen in the materials,” Barty said.
Yvonne Carts-Powell is a freelance science writer who specializes in optics and photonics.