Amorphous Solids
Amorphous Solids
Amorphous solids lack a crystalline or long-range order to their atomic structure.Learning Objectives
Discuss the characteristics of amorphous solids.Key Takeaways
Key Points
- Solids can be classified into two types: crystalline and amorphous.
- Crystalline solids are the most common type of solid. They are characterized by a regular crystalline organization of atoms that confer a long-range order.
- Amorphous, or non-crystalline, solids lack this long-range order. Accordingly, they lack the elasticity, distinct melting points, and other properties of crystalline solids.
Key Terms
- amorphous: A solid that lacks the long-range order characteristics of a crystalline solid.
- crystalline: Having a regular three-dimensional molecular lattice structure.
Amorphous solids, on the other hand, are rigid, but they lack repeated periodicity or long-range order in their structure. These substances do not show a sharp distinction between the solid and liquid states. Amorphous solids lack a characteristic geometry, have identical properties along all axes, have wide ranges over which they melt, and break to form curved or irregular shapes.
It is important to note that these terms mark two extremes on a continuum. Most amorphous solids have some short-range order. At an atomic scale, it is difficult to distinguish between the two different types, even using advanced analytical techniques such as x-ray diffraction and transmission electron microscopy.
Amorphous solids include both natural and man-made materials. The most frequently cited example of an amorphous solid is glass. However, amorphous solids are common to all subsets of solids. Additional examples include thin film lubricants, metallic glasses, polymers, and gels. Samples of amorphous metallic glass are shown below.
Amorphous Solids: Amorphous metals have high strength.
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