Kvasikristallien

Kvasikristallien, also known as quasicrystals, are solid materials that exhibit atomic arrangements which are ordered but not periodic. Unlike conventional crystals, which have repeating patterns of atoms, quasicrystals possess a structure that is long-range ordered but lacks translational symmetry. This means that while there is a definite arrangement of atoms, it does not repeat in a simple, predictable way throughout the material.

The discovery of quasicrystals in 1982 by Dan Shechtman revolutionized the understanding of solid-state physics and materials science. Prior to this, it was widely believed that all crystalline materials had to have periodic atomic structures. Quasicrystals challenged this fundamental assumption, demonstrating that ordered structures could exist without periodicity.

A key characteristic of quasicrystals is their possession of rotational symmetries that are forbidden in traditional crystallography, such as five-fold or ten-fold symmetry. These symmetries arise from the way the atoms are packed, creating complex but ordered patterns. The atomic structure of quasicrystals can be described using concepts like Penrose tiling, where aperiodic patterns are formed by fitting together geometric shapes.

Quasicrystals can be formed from various elements and alloys, often involving metals. They exhibit unique physical and chemical properties, including high hardness, low friction, and resistance to corrosion and oxidation. These properties make them attractive for potential applications in areas such as coatings, thermal insulation, and advanced electronics, although their practical implementation is still an area of ongoing research and development.