High pressure effects on liquid viscosity and glass transition behaviour, polyamorphic phase transitions and structural properties of glasses and liquids

Paul F. McMillan*, Martin C. Wilding

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Citations (SciVal)

Abstract

Since the pioneering work of Bridgman it has been known that pressure affects the glass transition of polymers and liquid state viscosities. Usually the T(g) and viscosity both increase as a function of pressure as expected from 'free volume' theories. However, H(2)O provided a notable exception in that the viscosity passes through a minimum at low temperature. It was thought that this might be linked to the anomalous thermal expansion behavior. However further research on geologically important aluminosilicate liquids revealed that they could show anomalous viscosity decreases with increasing pressure and this behavior is given a structural interpretation as five-fold coordinated Si(4+) and Al(3+) species are formed. Also the existence of polyamorphism or density-driven liquid-liquid phase transitions in certain systems can lead to anomalies in the T(g) or eta vs. P relations. This may be the case for H(2)O, for example. Current research is focusing on investigating structural changes in liquids and glasses at high pressure as the rich variety of behavior is becoming recognized. Both experimental studies and computer simulations are important as the underlying phenomonology is linked to changes in the glass or liquid structure as a function of densification. (C) 2009 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)722-732
Number of pages11
JournalJournal of Non-Crystalline Solids
Volume355
Issue number10-12
Early online date09 Apr 2009
DOIs
Publication statusPublished - 01 May 2009
Event21st International Congress on Glass and Entropy - Trencin, Slovakia
Duration: 25 Jun 200727 Jun 2007

Keywords

  • AMORPHOUS SOLIDS
  • INDUCED COORDINATION CHANGES
  • 5-COORDINATED SILICON
  • CALCIUM ALUMINATE LIQUIDS
  • SI-29 NMR
  • X-RAY-DIFFRACTION
  • IN-SITU
  • MOLECULAR-DYNAMICS SIMULATIONS
  • Pressure effects
  • SILICATE-GLASSES
  • TEMPERATURE AL-27 NMR
  • Short-range order

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