Amorphous structure

An amorphous structure lacks a regularly repeating pattern over a large spatial scale and a periodic arrangement of its constituent units. The atoms or molecules are distributed irregularly. There is only a short-range order in the immediate vicinity of each particle. A long-range order, such as that found in a crystal lattice, is absent. Amorphous solids behave in a similar way to solidified liquids. 

Typical examples include silicate glasses, many plastics and metallic glasses. Such materials are usually isotropic. This means that their properties are roughly the same in all directions. Amorphous materials do not have a clearly defined melting point. Instead, they exhibit a glass transition region in which they become soft and viscoelastic.