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Science 24 October 2008:
Vol. 322. no. 5901, pp. 566 - 570
DOI: 10.1126/science.1160766
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Reports

Detection of First-Order Liquid/Liquid Phase Transitions in Yttrium Oxide-Aluminum Oxide Melts

G. N. Greaves,1* M. C. Wilding,1 S. Fearn,1 D. Langstaff,1 F. Kargl,1 S. Cox,1 Q. Vu Van,1 O. Majérus,2 C. J. Benmore,3 R. Weber,4 C. M. Martin,5 L. Hennet6

We combine small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) with aerodynamic levitation techniques to study in situ phase transitions in the liquid state under contactless conditions. At very high temperatures, yttria-alumina melts show a first-order transition, previously inferred from phase separation in quenched glasses. We show how the transition coincides with a narrow and reversible maximum in SAXS indicative of liquid unmixing on the nanoscale, combined with an abrupt realignment in WAXS features related to reversible shifts in polyhedral packing on the atomic scale. We also observed a rotary action in the suspended supercooled drop driven by repetitive transitions (a polyamorphic rotor) from which the reversible changes in molar volume (1.2 ± 0.2 cubic centimeters) and entropy (19 ± 4 joules mole–1 kelvin–1) can be estimated.

1 Centre for Advanced Functional Materials and Devices, Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth SY23 3BZ, UK.
2 Ecole Nationale Supérieure de Chimie de Paris, 11 rue Pierre et Marie Curie, 75231, Paris, France.
3 Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
4 Materials Development, 3090 Daniels Court, Arlington Heights, IL 60004, USA.
5 Synchrotron Radiation Source, STFC Daresbury Laboratory, Warrington, Cheshire, WA4 4AD, UK.
6 CNRS-CEMHTI, 1d Avenue de la Recherche Scientifique, 45071 Orléans Cedex 9, France.

* To whom correspondence should be addressed. E-mail: gng{at}aber.ac.uk

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Liquids and Structural Glasses Special Feature: Physical vapor deposition as a route to hidden amorphous states.
K. J. Dawson, K. L. Kearns, L. Yu, W. Steffen, and M. D. Ediger (2009)
PNAS 106, 15165-15170
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