Composition and polyamorphism in supercooled yttria-alumina melts

GREAVES, G. N., WILDING, Martin, LANGSTAFF, D., KARGL, F., HENNET, L., BENMORE, C. J., WEBER, J. K. R., VAN, Q. Vu, MAJERUS, O. and MCMILLAN, P. F. (2011). Composition and polyamorphism in supercooled yttria-alumina melts. Journal of Non-Crystalline Solids, 357 (2), 435-441.

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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 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.

Item Type:	Article
Research Institute, Centre or Group - Does NOT include content added after October 2018:	Materials and Engineering Research Institute > Engineering Research
Departments - Does NOT include content added after October 2018:	Faculty of Science, Technology and Arts > Department of Engineering and Mathematics
Identification Number:	https://doi.org/10.1016/j.jnoncrysol.2010.06.072
Page Range:	435-441
Depositing User:	Martin Wilding
Date Deposited:	27 Jun 2018 11:54
Last Modified:	18 Mar 2021 11:46
URI:	https://shura.shu.ac.uk/id/eprint/21483

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