Polyamorphic systems

Polyamorphic systems and liquid-liquid transitions. 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

Real systems that present liquid-liquid transitions:

• Carbon
• Germanium
• n-butanol
• Phosphorus
• Silica
• Silicon
• Triphenyl phosphite
• Water
• Yttria–alumina

Models

Idealised models that present liquid-liquid transitions:

• Buldyrev and Stanley model
• Hemmer and Stell model
• Jagla ramp model
• Roberts and Debenedetti model
• Square shoulder + square well model

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)
5. Paul F. McMillan "Polyamorphic transformations in liquids and glasses", Journal of Materials Chemistry 14 pp. 1506-1512 (2004)
6. Peter H. Poole, Ivan Saika-Voivod and Francesco Sciortino "Density minimum and liquid–liquid phase transition", Journal of Physics: Condensed Matter 17 pp. L431-L437 (2005)
7. Martin C. Wilding, Mark Wilson and Paul F. McMillan "Structural studies and polymorphism in amorphous solids and liquids at high pressure", Chemical Society Reviews 35 pp. 964-986 (2006)