Scientists have been searching for quasicrystals that have what they term “impossible” materials inside their unusual, non-repeating structures. They have discovered the quasicrystal they were searching for in a remnant of the world’s first test detonation of a nuclear bomb. The previously unknown structure is made of iron, silicon, copper, and calcium and is thought to have formed from the fusion of vaporized desert sand and copper cables.
The resulting quasicrystals are the first known with this combination of elements. Quasicrystals are formed using building blocks of atoms that are unlike those found in ordinary crystals in that they don’t repeat a regular, brickwork-like pattern. Scientists say that ordinary crystal structures look identical when shifted along certain directions compared to quasicrystals with symmetries that were previously considered impossible.
One example is that some quasicrystals have a pentagonal symmetry; it appears the same if rotated by one-fifth of a full twist. In 1982, scientist Daniel Shechtman first discovered a so-called impossible symmetry in a synthetic alloy. That material had pentagonal symmetry when rotated in each of various possible directions. Such symmetry would occur if the building blocks for the material were icosahedral, meaning had a regular shape with 20 faces.
Many researchers questioned those findings because it’s mathematically impossible to fill a space using only icosahedrons. Shechtman’s work won the 2011 Nobel Prize in chemistry. The new material scientists are looking into formed in the aftermath of the Trinity test in July 1945 at the New Mexico Alamogordo Bombing Range. In the aftermath of that explosion, scientists found a vast field of greenish glassy material formed from the liquidation of desert sand dubbed trinitite.
The plutonium bomb exploded on top of a 30-meter high tower fitted with lots of sensors and cables. Some of the trinitite formed after the explosion had reddish inclusions that were a fusion of natural material with copper from the transmission lines. Quasicrystals often form from elements that wouldn’t usually combine, leading researchers to investigate red trinitite for quasicrystals. Over ten months, the researchers found a tiny grain of what they were looking for that featured the same sort of icosahedral symmetry that Shechtman discovered in 1982. Researchers believe that quasicrystals could be used for a type of nuclear forensic science with the possibility of revealing sites where covert nuclear tests have occurred.