Festkristalline

Festkristalline is a Swedish term used in solid-state science to describe crystalline solids, materials in which atoms are arranged in an orderly, repeating three-dimensional lattice. Such long-range order gives rise to well-defined faces, a sharp melting point, and characteristic diffraction patterns when the material is subjected to X-rays or neutrons.

In a festkristalline material, the arrangement can be described by a crystal lattice and a repeating unit cell, from which the entire structure can be generated by translation. The possible arrangements form Bravais lattices, grouped into crystal systems based on symmetry. This periodic order contrasts with amorphous substances, which lack long-range order and typically do not have a single melting temperature.

Crystalline materials come in various bonding types, including ionic (for example, NaCl), covalent network (such as diamond or quartz), metallic, and molecular crystals (like ice or naphthalene). Their properties are often anisotropic, meaning they depend on direction within the crystal. They may exhibit cleavage along specific planes, distinct optical behavior (birefringence, refraction), and, in metals, high electrical conductivity.

Defects—such as vacancies, interstitials, and dislocations—are common in real crystals and influence mechanical strength, diffusion, and electronic properties. Crystallography and methods like X-ray diffraction are central to identifying structures and, in pharmacology, to understanding polymorphism.

Festkristalline materials are foundational in geology, electronics, optics, and materials science due to their predictable structures and a wide range of tunable properties arising from lattice arrangement.