quasicrystaller

A quasicrystal is a solid material whose atoms are arranged in a pattern that is ordered but not periodic. Unlike conventional crystals, which have repeating unit cells, quasicrystals exhibit a long-range order that does not translate through space in a simple repeating pattern. This means that if you try to tile a space with the atomic structure of a quasicrystal, you will never be able to perfectly repeat the pattern by simply shifting it.

The discovery of quasicrystals in 1982 by Dan Shechtman was groundbreaking, as it challenged the prevailing definition of a crystal, which required periodic atomic arrangements. Shechtman observed a structure with five-fold symmetry, which was previously thought to be impossible in crystalline materials. This symmetry is a hallmark of many quasicrystals.

Quasicrystals can possess symmetries that are not allowed in periodic crystals, such as 5-fold, 8-fold, 10-fold, and 12-fold rotational symmetry. Despite their non-periodic nature, they exhibit sharp diffraction patterns, indicating a high degree of order. The atomic structure of quasicrystals can be described using concepts from higher-dimensional crystallography and Penrose tilings, which are non-periodic arrangements of geometric shapes that perfectly tile a plane.

The properties of quasicrystals are unique and differ from those of both crystalline and amorphous materials. They can exhibit low friction, high hardness, low thermal conductivity, and excellent electrical resistance. These properties make them potentially useful in a range of applications, including coatings for aerospace components, high-performance cutting tools, and thermal barrier coatings. Research into quasicrystals continues to explore their fundamental properties and potential technological uses.