‘Impossible’ quasicrystal created in world’s first nuclear bomb test – ScienceAlert

At 5:29 a.m. on July 16, 1945, in New Mexico, a shocking slice of history was made.

The calm of dawn was shattered when the United States Army detonated a plutonium-explosive device known as the Instrument – the world’s first test of a nuclear bomb, known as the Trinity Test. This moment will change the war forever.

The energy release, equivalent to 21 kilotons of TNT, vaporized the 30-meter (98-foot) test tower and the miles of copper wire connecting it to the recording devices. The resulting fireball fused the tower, copper with asphalt, and desert sand below into green glass – a new mineral called trinitite.

Decades later, scientists discovered a secret hidden in a piece of that trinitite – a rare form of the substance known as a quasicrystal, once thought to be impossible.

“Semi-crystalline crystals form in extreme environments rarely found on Earth,” Geophysicist Terry Wallace of Los Alamos National Laboratory explained last year.

“It requires a traumatic event with severe shock, temperature and pressure. We don’t usually see that, except in something as dramatic as a nuclear explosion.”

Most crystals, from the humble table salt to the toughest diamond, obey the same rule: their atoms are arranged in a lattice structure that repeats in three-dimensional space. Semi-crystalline crystals break this rule – the pattern in which their atoms are arranged does not repeat.

When the concept first appeared in the scientific world in 1984, this was thought to be the case impossible: The crystals were either ordered or disordered, with no intermediate between them. Then they were found in reality, created in laboratory conditions and in the wild – inside deep meteorites, formed by thermodynamic shock from events such as the hypervelocity impact.

Knowing that extreme conditions are required to produce quasicrystals, a team of scientists led by geologist Luca Bindi of the University of Florence in Italy decided to take a closer look at trinitite.

But not the green stuff. Although it’s uncommon, we’ve seen enough quasicrystals to know that they tend to fuse with minerals, so the team went looking for a very rare form of the mineral — red trinitite, given its color through the vaporized copper wires embedded in it.

Using techniques such as scanning electron microscopy and X-ray diffraction, they analyzed six small samples of red tripotassium. Finally, they had a hit in one of the samples—a tiny 20-sided grain of silicon, copper, calcium, and iron, with a pentagonal spin symmetry impossible in conventional crystals—an “unintended consequence” of stirring wars.

“This quasicrystal is remarkable in its complexity—but no one can yet tell us why it was formed in this way,” Wallace explained In 2021 when the team’s research was published.

“But one day a scientist or engineer will find out and the scales will be lifted from our eyes and we will have a thermodynamic explanation to create it. Then, I hope, we can use this knowledge to better understand nuclear explosions and eventually lead to a more complete picture of what a nuclear experiment represents.”

This finding represents the oldest anthropogenic semi-crystalline crystals, and it indicates that there may be other natural pathways for semi-crystalline formation. For example, molten sand fulgures made of lightning and material from meteorite impact sites could be a source of quasicrystals in the wild.

The research could also help us better understand illicit nuclear testing, the researchers said, with the ultimate goal of curbing the spread of nuclear weapons. Studying metals forged at other nuclear test sites could reveal more quasicrystals, whose thermodynamic properties could be a tool for nuclear forensics.

“Understanding other nations’ nuclear weapons requires that we have a clear understanding of their nuclear test programs,” Wallace said.

“We typically analyze debris and radioactive gases to understand how weapons are made or the materials they contain, but these fingerprints decay. A quasicrystal that formed at the site of a nuclear explosion can tell us new kinds of information — an illusion ‘I will stay forever.’

The search was published in PNAS.

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