Discovered: An easier way to create “Flexible Diamonds”

As hard as diamond and as flexible as plastic, highly sought-after diamond nanothreads would be poised to revolutionize our world—if they weren’t so difficult to make. A team of scientists led by Samuel Dunning and Timothy Strobel of the Carnegie Institution for Science using high-brightness x-rays from the U.S. Department of Energy’s (DOE’s) Advanced Photon Source developed an original technique that predicts and guides the ordered creation of strong, yet flexible, diamond nanothreads, surmounting several existing challenges.  The innovation will make it easier for scientists to synthesize the nanothreads—an important step toward applying the material to practical problems in the future. The work was published in the Journal of the American Chemical Society.

Diamond nanothreads are ultra-thin, one-dimensional carbon chains, tens of thousands of times thinner than a human hair. They are often created by compressing smaller carbon-based rings together to form the same type of bond that makes diamonds the hardest mineral on our planet. However, instead of the three-dimensional carbon lattice found in a normal diamond, the edges of these threads are “capped” with carbon-hydrogen bonds, which make the whole structure flexible.

Dunning explains: “Because the nanothreads only have these bonds in one direction, they can bend and flex in ways that normal diamonds can’t.”

Scientists predict that the unique properties of carbon nanothreads will have a range of useful applications from providing sci-fi-like scaffolding on space elevators to creating ultra-strong fabrics. However, scientists have had a hard time creating enough nanothread material to actually test their proposed superpowers.

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Image: The starting sample of pyridazine—a six atom ring made up of four carbons and two nitrogens—changes under pressure as diamond nanothread formation progresses. The first and last images show that there has been a permanent color change between the samples after thread formation. The images don’t show individual threads, but “bulk” samples of pyridazine during compression, each around 40 microns thick with a 180-micron diameter.

Credit: Samuel Dunning