ultra-rare “impossible” quasicrystal found in Russian meteorite

Posted on 9 Dec 2016

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A quasicrystal’s atomic structure combines the symmetrical properties of a crystal and the chaos of an amorphous solid.

Originating in outer space, these crystals aren’t just incredible because of how rare they are – their atomic structure is so peculiar, for decades their existence was dismissed as “impossible”, and they cost the scientist who first discovered them his job.

This new quasicrystal specimen was found by a team led by geologist Luca Bindi from the University of Florence in Italy. … 

Regular crystals, such as snowflakes, diamonds, and table salt, are made up of atoms that are arranged in near-perfect symmetry.

Polycrystals, including most metals, rocks, and ice, have more randomised and disordered structures, just like amorphous solids, such as glass, wax, and many plastics.

Back in 1982, Israeli chemist Daniel Shechtman proposed that another type of atomic structure could exist in nature – a strange, semi-ordered form of matter, with an atomic structure that displays no repeating patterns anywhere you look. …

Shechtman was awarded the 2011 Nobel Prize in Chemistry for his discovery, but not before being literally laughed out of his lab and ridiculed by his peers for decades for daring to suggest something so preposterous as a semi-ordered structure. …

Before the existence of quasicrystals was confirmed, scientists assumed that for a structure to grow with a repeating, symmetrical structure, it could exhibit one of four types of rotational symmetry: two-fold, three-fold, four-fold, or six-fold.

Quasicrystals broke this rule, because they have crystal-like structure with a five-fold rotational symmetry.

As Pat Theil, a senior scientist at the US Department of Energy’s Ames Laboratory, explained to PBS, if you want to cover your bathroom floor in perfectly tessellating tiles, they can only be rectangles, triangles, squares or hexagons. Any other simple shape won’t work, because it will leave a gap. Quasicrystals are like pentagonal tiles – they can’t tessellate like squares or triangles can, but other atomic shapes move in to fill in the gaps.

When the researchers examined the composition of the new quasicrystal, they confirmed that it was made from a combination of aluminium, copper, and iron atoms, all arranged like the pentagon-based pattern on a soccer ball.

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Posted in: Physics, Space, Strange