What are Quasicrystals?

In news– Scientists have discovered a third natural source of quasicrystals, extending the latter’s reputation for violent origins.

What are quasicrystals?

Crystal matter formed atomically in a manner somewhere between the amorphous solids of glasses (special forms of metals and other minerals, as well as common glass) and the precise pattern of crystals.
Quasicrystals imbue a symbolic power. They’re not like other crystals (their name means ‘almost crystals’) yet they share important properties.
In solids, the constituent atoms are confined to a fixed arrangement. In crystals, the atoms are arranged in a pattern that periodically repeats itself.
In quasicrystals, the atoms are arranged in a pattern that repeats itself at irregular, yet predictable, intervals.
Quasicrystals simply represent an incremental deviation from the natural order – but when you think about creating one in a lab or in nature, their quiet power comes to the fore.
Creating quasicrystals is not easy because of why crystals form in the first place.
Take the crystals of common salt (NaCl) for example, whose atoms are arranged in a repeating cubic pattern.
Why don’t they assume tetrahedral or rhomboidal patterns? Because the sodium and the chloride ions have different sizes and exert different electric forces, and a cubic pattern allows them to pack themselves in without upsetting each other, while also optimising for their density, thermal stability, etc.
Anything that is naturally abundant implies a natural preference for that form over other possibilities. So whenever sodium chloride crystals take shape, they adopt the cubic pattern, unless extenuating circumstances force them to pick something else.
Quasicrystals, now, embody these extenuating circumstances.
Quasicrystals are crystals that have defied a peaceful logic of crystal formation in favour of less-than-optimum, more contested patterns.
In order to create them that way, the forces that shape them need to constantly nudge them away from the form they would rather take, if left alone, and towards a form that they can take.
It’s not unlike keeping a spring compressed between your fingers: the spring can be compressed but it would rather be relaxed, so it pushes against you, exerts a force demanding freedom from your oppression.
By adopting a suboptimal crystal structure (an anthropocentric view, to be sure), quasicrystals offer a similar narrative: they may not be oppressed, kept in a state of stress, but the structure of their atomic lattice still contains the imprints of some stressful event.