Supercooling

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supercooling

[¦sü·pər′kül·iŋ]
(thermodynamics)
Cooling of a substance below the temperature at which a change of state would ordinarily take place without such a change of state occurring, for example, the cooling of a liquid below its freezing point without freezing taking place; this results in a metastable state.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Supercooling

 

cooling of matter to temperatures below those of equilibrium phase transition that brings the matter to a new state of aggregation, or another crystalline modification that does not result in a phase transition. A supercooled material is in a state of metastable equilibrium.

The phase transitions that are associated with loss of heat— condensation, crystallization, and polymorphic transformations —usually involve supercooling in their initial stages; the supercooling helps generate nuclei of the new phase in the form of tiny droplets or crystallites. It is difficult to form nuclei at the phase-transition temperature because the nuclei feature higher pressure or solubility and thus cannot be in equilibrium with the initial phase at this temperature. Under conditions where the generation and growth of nuclei of a new phase are inhibited, for example, during recrystallization of a solid and during crystallization of a highly viscous liquid, deep supercooling can be used to obtain a practically stable phase whose internal structure resembles that of phases at higher temperatures. This procedure is the basis for steel-quenching processes and for the production of glass. The degree to which water vapor is supercooled in the atmosphere determines whether precipitation will occur in the form of rain, snow, or hail.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Their findings confirmed that a strong supercooling effect took place.
Due to the supercooling effect, TPU-6 exhibited monotropic behavior, as observed from the mesophase only on cooling.
"Another theory is that a supercooling effect takes place, whereby water that starts off hot is able to freeze without turning to ice."