Difference between revisions of "Polyamorphic systems"

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(General reading)
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Some solid compounds can exist in two or more '''polymorphs''' with different atomic structures but the same chemical composition.
 
Some solid compounds can exist in two or more '''polymorphs''' with different atomic structures but the same chemical composition.
In the case of a pure element, this behavior is termed '''allotropy''' (Ref. 2).
+
In the case of a pure element, this behavior is termed '''allotropy'''.
 
The existence of liquid polymorphs is known as '''polyamorphism''', i.e. the ability of a substance to exist in several different amorphous modifications.  
 
The existence of liquid polymorphs is known as '''polyamorphism''', i.e. the ability of a substance to exist in several different amorphous modifications.  
Note: glasses are not in thermodynamic equilibrium, so such transformations do not correspond to true phase transitions from one stable liquid to another (Ref. 1).
+
Note: glasses are not in thermodynamic equilibrium, so such transformations do not correspond to true phase transitions from one stable liquid to another.
 
===Polyamorphic systems===
 
===Polyamorphic systems===
 
*[[Germanium]]
 
*[[Germanium]]
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*[[Water]]
 
*[[Water]]
 
==General reading==
 
==General reading==
 +
#[http://dx.doi.org/10.1126/science.267.5206.1924 C. A. Angell "Formation of Glasses from Liquids and Biopolymers", Science '''267''' pp. 1924 - 1935 (1995)]
 
#[http://dx.doi.org/10.1126/science.275.5298.322 Peter H. Poole, Tor Grande, C. Austen Angell, Paul F. McMillan "Polymorphic Phase Transitions in Liquids and Glasses", Science '''275''' pp. 322 - 323 (1997)]
 
#[http://dx.doi.org/10.1126/science.275.5298.322 Peter H. Poole, Tor Grande, C. Austen Angell, Paul F. McMillan "Polymorphic Phase Transitions in Liquids and Glasses", Science '''275''' pp. 322 - 323 (1997)]
 
#[http://dx.doi.org/10.1038/35003088 Paul McMillan "Phase transitions: Jumping between liquid states", Nature '''403''' pp. 151-152 (2000)]
 
#[http://dx.doi.org/10.1038/35003088 Paul McMillan "Phase transitions: Jumping between liquid states", Nature '''403''' pp. 151-152 (2000)]
 
#[http://dx.doi.org/10.1126/science.1104417 Jeff L. Yarger and George H. Wolf "Polymorphism in Liquids", Science '''306''' pp. 820 - 821 (2004)]
 
#[http://dx.doi.org/10.1126/science.1104417 Jeff L. Yarger and George H. Wolf "Polymorphism in Liquids", Science '''306''' pp. 820 - 821 (2004)]

Revision as of 16:06, 30 April 2007

Some solid compounds can exist in two or more polymorphs with different atomic structures but the same chemical composition. In the case of a pure element, this behavior is termed allotropy. The existence of liquid polymorphs is known as polyamorphism, i.e. the ability of a substance to exist in several different amorphous modifications. Note: glasses are not in thermodynamic equilibrium, so such transformations do not correspond to true phase transitions from one stable liquid to another.

Polyamorphic systems

General reading

  1. C. A. Angell "Formation of Glasses from Liquids and Biopolymers", Science 267 pp. 1924 - 1935 (1995)
  2. Peter H. Poole, Tor Grande, C. Austen Angell, Paul F. McMillan "Polymorphic Phase Transitions in Liquids and Glasses", Science 275 pp. 322 - 323 (1997)
  3. Paul McMillan "Phase transitions: Jumping between liquid states", Nature 403 pp. 151-152 (2000)
  4. Jeff L. Yarger and George H. Wolf "Polymorphism in Liquids", Science 306 pp. 820 - 821 (2004)