Amorphous solid

An amorphous solid has particles arranged without the long-range periodic order of a crystal, while retaining short-range structure. It may soften over a temperature range rather than melting at a single temperature.

Crystalline solid: A solid whose particles form a repeating arrangement with long-range order. Its periodic structure marks the central distinction from amorphous solids.
Nucleation: The formation of small, stable clusters from which a new phase can grow. Crystallization begins when ordered nuclei form within a cooling or processing material.
Silica glass: An amorphous solid composed primarily of silicon dioxide. It is a familiar example whose disorder gives it transparency and workable softening behavior.
Quasicrystal: A solid with long-range order and sharp diffraction patterns but no periodic translational symmetry. It shows that nonperiodic structure can still possess long-range order unlike an amorphous solid.
Short-range order: Structural regularity among neighboring particles that does not persist over long distances. Amorphous solids retain this local organization despite lacking crystal-like periodicity.
Glass formation: The production of a rigid amorphous material by suppressing crystallization as a liquid cools or is processed. It is a common route from a disordered liquid to an amorphous solid.
Metallic glass: A metal alloy solidified into an amorphous structure rather than a crystalline one. Its unusual structure can combine high strength with elastic deformation.
Liquid: A fluid state that maintains volume but flows to take the shape of its container. Liquids also lack long-range periodic order, but their particles remain mobile enough to flow.
Glass transition: A temperature-dependent transition in which an amorphous material changes between glassy and more mobile states. It explains why many amorphous solids soften over a range instead of melting sharply.
Crystallization: The formation of a crystal from a disordered phase through the development of long-range order. It competes with glass formation when particles can reorganize during cooling.

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