Back in 1982, Israeli chemist Daniel Shechtman discovered that there are semi-ordered forms of matter he calls quasicrystals. These don’t have the crystalline structures familiar to us, instead they have an atomic pattern that repeats at regular intervals, like a hexagonal tiled floor. But when Shechtman told colleagues about his discovery, they told him to “eyn chaya kao,” meaning there can’t be such a thing.
After Shechtman’s death in 2011, researchers searched for quasicrystals in nature, trawling databases of X-ray diffraction patterns and other data. Finally, in 2009, Paul Steinhardt at the Museum of Natural History in Florence, Italy, and Luca Bindi at the University of California, Berkeley, reported finding two kinds of quasicrystals in a fragment of the Khatyrka meteorite that had crashed in Russia’s Koryak Mountains. They identified one of them as a metallic aluminium alloy called icosahedrite, and the other as a decagon-like alloy called proxidecagonite.
Both icosahedrite and proxidecagonite have a property that distinguishes them from ordinary crystalline metals, known as high rotational symmetry. The difference can be explained by thinking of the atoms as tiles on a floor, where the regular hexagonal pattern of a crystal is matched with the symmetrical shape of a soccer ball. A quasicrystal’s atoms, however, can be arranged into shapes like five-sided pentagons or 10-sided decagons.
Glotzer and Engel’s new simulations show that it should be possible to produce more complex quasicrystals in the lab. Their findings could also lead to some pretty wild applications, such as camouflage and even Terminator-style shape-shifting robots.