The first atomic bomb test created a quasicrystal

Somewhere outside the definition of “crystal” lies a special class of materials known as quasicrystals. Their structures are ordered but not periodic. Although researchers have found quasicrystals that were created through natural processes, such as meteor impacts, most are manufactured in labs.

But new research by Luca Bindi of the University of Florence in Italy, Paul Steinhardt of Princeton University, and their colleagues has revealed another source for human-made quasicrystals. The researchers discovered that such a material formed during the first atomic bomb test in Alamogordo, New Mexico, making it the oldest known extant anthropogenic quasicrystal.

Bindi and Steinhardt examined six pieces of red trinitite, a glass that formed from desert sand and copper cable at the Trinity test blast site and was later collected by meteor scientist Lincoln LaPaz in 1945. The researchers found that the samples contained multiple candidates for unknown quasicrystals. They painstakingly removed the candidate grains—each only 20 µm across—and tested their diffraction patterns. Of the 12 tested samples, only one displayed an icosahedral quasicrystal diffraction pattern, which is characterized by five-, two-, and threefold axes of symmetry.

Using x-ray mapping, the researchers identified silicon, copper, calcium, and iron in the material. No other known quasicrystal is made of that combination of elements. The most prevalent element was Si, another characteristic unique to the discovery.

A major challenge in creating new quasicrystals has to do with stability. Researchers haven’t confirmed that the Trinity quasicrystal is stable, but it is notable that the material has existed in that state for 75 years.

In their paper, the researchers note a key difference between synthetic quasicrystals and those found in the rubble of impact events: Discovered materials form under extreme conditions that are seldom explored in the lab. The discovery of more impact-produced quasicrystals could lead to greater clarity on the diversity of elemental combinations that can morph into ordered structures when exposed to extreme temperature and pressure. (L. Bindi et al., Proc. Natl. Acad. Sci. USA 118, e2101350118, 2021 .)