Quasicrystals

Most crystals are composed of a three-dimensional arrangement of atoms that repeat in an orderly pattern. Depending on their chemical composition, they have different symmetries. For example, atoms arranged in repeating cubes have fourfold symmetry. Atoms arranged as equilateral triangles have threefold symmetries. But Quasicrystals behave differently than other crystals. They have an orderly pattern that includes pentagons, fivefold shapes, but unlike other crystals, the pattern never repeats itself exactly. They show unusual hardness and brittleness, low coefficients of friction, and high thermal and electrical resistance. Some proposed applications include wear-resistant surface treatments for other metals in ball bearings and frying pans. Nobel Prize in Chemistry in 2011 was given for work on Quasicrystals to Dan Shechtman. The definition of crystals was changed after the 1984 discovery of Quasicrystals by the Nobel Laureate Dan Shechtman. He had used a transmission electron microscope (TEM) to study the quasicrystals.