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A new quasicrystal formed in the first atomic bomb test


In an instant, the bomb destroyed everything.

The tower on which he sat and the copper wires were fixed around him: they vaporized. The desert sand below: melted.

After the first test of an atomic bomb, in July 1945, all these remains melted, leaving the terrain of the New Mexico test site covered with a glassy substance now called trinitite. High temperatures and pressures helped forge an unusual structure inside a piece of trinitite, in a grain of material only 10 micrometers in diameter, slightly longer than a red blood cell.

That grain contains a rare form of matter called quasicrystal, born at the time the nuclear age began, scientists reported on May 17 in Proceedings of the National Academy of Sciences.

Normal crystals are made of atoms enclosed in a lattice that is repeated in a regular pattern. Quasicrystals have an ordered structure like a normal crystal but that is not repeated. This means that quasicrystals may have properties forbidden to normal crystals. First discovered in the laboratory in the 1980s, quasicrystals also appear in nature in meteorites (SN: 12/8/16).

Penrose mosaics (one of them shown) are an example of an orderly but unrepeatable structure. Quasicrystals are a three-dimensional version of this idea.Inductiveload / Wikimedia Commons

The quasicrystal recently discovered at the New Mexico site is the oldest known and made by humans.

Trinitite takes its nickname from the nuclear test, called Trinity, in which the material was created in abundance (SN: 8/4/21). “You can still buy a lot on eBay,” says geophysicist Terry Wallace, co-author of the study and emeritus director of the Los Alamos National Laboratory in New Mexico.

But, he points out, the trinitite the team studied was a rarer variety, called red trinitite. Most trinitite has a greenish hue, but red trinitite contains copper, remnants of wires that stretched from the ground to the pump. Quasicrystals are often found in materials that have experienced a violent impact and typically involve metals. Red trinitite fits both criteria.

But first the team had to find some.

“I’ve been wondering for months looking for red trinitite,” says theoretical physicist Paul Steinhardt of Princeton University. But Steinhardt, who is known for walking to Siberia to look for quasi-crystals, was not deterred (SN: 19/02/19). Eventually, he and his colleagues got some from a trinitite expert who began collaborating with the team. Then began the meticulous work, “looking through every little microscopic spot” of the trinitite sample, Steinhardt says. Finally, the researchers extracted the small grain. By scattering X-rays through it, the researchers revealed that the material had a type of symmetry that was only found in the quasicrystals.

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The new quasicrystal, made up of silicon, copper, calcium and iron, is "completely new to science," says Caltech mineralogist Chi Ma, who did not participate in the study. “It’s a pretty cool and exciting discovery,” he says.

Future quasicrystal searches could examine other materials that have suffered a punishing blow, such as impact craters or lightning, molten structures formed when lightning strikes the ground (SN: 3/16/21).

The study shows that artifacts from the birth of the atomic age are still of scientific interest, says materials scientist Miriam Hiebert of the University of Maryland at College Park, who analyzed materials from other key moments in nuclear history (SN: 5/1/19 ). “Historical objects and materials are not just curiosities in collectors’ closets but can have real scientific value, ”he says.



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