Amorphous solid

An amorphous solid is a solid in which there is no long-range order of the positions of the atoms. (Solids in which there is long-range atomic order are called crystalline solids.) Most classes of solid materials can be found or prepared in an amorphous form. For instance, common window glass is an amorphous ceramic, many polymers (such as polystyrene) are amorphous, and even foods such as cotton candy are amorphous solids.

Related Topics:
Solid - Long-range order - Atom - Crystalline solids - Ceramic - Polymer - Polystyrene - Cotton candy

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Amorphous materials are commonly prepared by rapidly cooling molten material. The cooling reduces the mobility of material's molecules before they can pack into a more thermodynamically favorable crystaline state. Some materials, such as metals, are difficult to prepare in an amorphous state. Unless a material has a high melting temperature (as ceramics do) or a low crystallization energy (as polymers tend to), solidification must be done extremely rapidly.

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Amorphous solids can exist in two distinct states, the 'rubbery' state and the 'glassy' state. The temperature at which they transition between the glassy and rubbery states is called their glass transition temperature or Tg.

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