Composition and polyamorphism in supercooled yttria-alumina melts
Greaves, GN and Wilding, MC and Langstaff, D and Kargl, F and Hennet, L and Benmore, CJ and Weber, JKR and Van, QV and Majerus, O and McMillan, PF (2011) Composition and polyamorphism in supercooled yttria-alumina melts. Journal of Non-Crystalline Solids, 352 (2), pp. 435-441. ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS. DOI: 10.1016/j.jnoncrysol.2010.06.072.
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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 critical-like behaviour in the structural relaxation time and in the fluctuation correlation length is presented. By re-examining 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. (C) 2010 Elsevier B.V. All rights reserved.
|Title:||Composition and polyamorphism in supercooled yttria-alumina melts|
|Date:||15 January 2011|
|Journal or Publication Title:||Journal of Non-Crystalline Solids|
|In Open Access:||No|
|In ISI Web of Science:||Yes|
|Page Range:||pp. 435-441|
|Publisher:||ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS|
|Keywords:||Diffraction and scattering measurements; Supercooled liquids; Glass formation; Phases and equilibria; Structure; Fluctuations; Critical phenomena|
|HGF - Research field:||Aeronautics, Space and Transport|
|HGF - Program:||Raumfahrt|
|HGF - Program Themes:||R - no assignement|
|DLR - Research area:||Raumfahrt|
|DLR - Program:||R - no assignement|
|DLR - Research theme (Project):||R -- no assignement|
|Institutes and Institutions:||Institute of Materials Physics in Space|
|Deposited By:||Dr Florian Kargl|
|Deposited On:||25 Aug 2011 10:49|
|Last Modified:||07 Feb 2013 20:33|
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