Configuron: Difference between revisions
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Amorphous substances can fall into the usual categories of [[solid]], [[liquid]], [[gas]], or [[Plasma (physics)|plasma]]. But some substances which are amorphous, such as [http://en.wikipedia.org/wiki/Sand| sand] are [[fluid]]s. | Amorphous substances can fall into the usual categories of [[Amorphous solid|solid]], [[liquid]], [[gas]], or [[Plasma (physics)|plasma]]. But some substances which are amorphous, such as [http://en.wikipedia.org/wiki/Sand| sand] are [[fluid]]s. | ||
In principle, given a sufficiently high cooling rate, any liquid can be made into an [[amorphous solid]]. Cooling reduces molecular mobility. If the cooling rate is faster than the rate at which molecules can organize into a more thermodynamically favorable [[Crystal|crystalline]] state, then an amorphous solid will be formed. Because of [[entropy]] considerations, many polymers can be made into amorphous solids by cooling even at slow rates. In contrast, if molecules have sufficient time to organize into a structure with two- or three-dimensional order, then a crystalline (or [[Crystallinity|semi-crystalline]]) solid is formed. Water is one example. Because of its small molecular size and ability to quickly rearrange, it cannot be made amorphous without resorting to specialized hyperquenching techniques. These produce [[amorphous ice]]. | |||
== Acknowledgements == | == Acknowledgements == | ||
Revision as of 21:25, 28 May 2009
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An amorphous substance is any in which there is no long-range order over the positions of its constituent particles. These particles can be subatomic, atoms, ions, molecules, dust, crystallites, or grains, stones, boulders], or larger debris.
Amorphous substances can fall into the usual categories of solid, liquid, gas, or plasma. But some substances which are amorphous, such as sand are fluids.
In principle, given a sufficiently high cooling rate, any liquid can be made into an amorphous solid. Cooling reduces molecular mobility. If the cooling rate is faster than the rate at which molecules can organize into a more thermodynamically favorable crystalline state, then an amorphous solid will be formed. Because of entropy considerations, many polymers can be made into amorphous solids by cooling even at slow rates. In contrast, if molecules have sufficient time to organize into a structure with two- or three-dimensional order, then a crystalline (or semi-crystalline) solid is formed. Water is one example. Because of its small molecular size and ability to quickly rearrange, it cannot be made amorphous without resorting to specialized hyperquenching techniques. These produce amorphous ice.
Acknowledgements
The content on this page was first contributed by: Henry A. Hoff.
Initial content for this page in some instances came from Wikipedia.