Composition and polyamorphism in supercooled yttria-alumina melts

G. N. Greaves*, M. C. Wilding, D. Langstaff, F. Kargl, L. Hennet, C. J. Benmore, J. K. R. Weber, Quang Vu Van, O. Majerus, P. F. McMillan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Citations (SciVal)

Abstract

By extending recent work on liquid-liquid transitions in supercooled yttria-alumina AYx liquids we draw attention to the compositional dependence of the structure factor of the high density liquid, arguing that this is sufficiently sensitive to discriminate between liquids at the level of a few %. Comparing structure factor differences between liquids of different compositions and in the same liquid AY20 between high and low temperatures straddling the transition at 1788 K between a high density liquid (HDL) and a low density liquid (LDL) enables compositional phase separation to be ruled out. It points instead to kinetic changes in polyhedral configurational order being the drivers for this polyamorphic transformation. Rotor behaviour observed in levitated liquid drops used in the high temperature experiments enables the reversibility of the LLT transition (LLT) and the associated changes in entropy and density to be identified. Evidence for criticallike behaviour in the structural relaxation time and in the fluctuation correlation length is presented. By reexamining recent work which failed to find the structural and thermal signatures for the LLT in liquid AY20 at 1788 K we present evidence for the LLT occurring instead in liquid AY15 at 1940 K, suggesting that the liquid-liquid transition temperature in AYx liquids decreases with increasing yttria content.
Original languageEnglish
Pages (from-to)435-441
Number of pages7
JournalJournal of Non-Crystalline Solids
Volume357
Issue number2
Early online date16 Sept 2010
DOIs
Publication statusPublished - 15 Jan 2011
Event6th International Discussion Meeting on Relaxation in Complex Systems - Rome, Italy
Duration: 30 Aug 200905 Sept 2009

Keywords

  • diffraction and scattering measurements
  • supercooled liquieds
  • glass formation
  • phases and equilibria
  • structure
  • fluctuations
  • critical phenomena

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