Diamond Light Source Proceedings

Poster paper

In situ measurement of the structure of supercooled oxide liquids

M. Wildinga1 c1, C. J. Benmorea2, J. K. R. Webera3 and J. B. Parisea4

a1 Institute of Mathematics and Physics, Aberystwyth University, Aberystwyth Sy23 3BZ, UK

a2 Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA

a3 Materials Development Inc., Arlington Heights, IL 6004, USA

a4 Department of Geosciences, Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, USA

Abstract

This paper will describe the results of in situ high-energy X-ray measurements performed on stable and supercooled oxide liquids using containerless techniques. As will be discussed in the companion paper (Weber et al.), the use of an aerodynamic levitator furnace with laser heating allows the structures of refractory oxide liquids to be probed. Because of the contactless nature of this sample environment liquids can be deeply supercooled, and this provides opportunities to study the metastable structures of supercooled liquids. Of particular interest are the so-called fragile liquids that depart from Arrhenius-law viscosity behaviour and that, by definition, have temperature-dependent structures. The focus of this paper is the study of two oxide systems, MgO–SiO2 and Al2O3–SiO2. These two liquids have highly disordered stable liquid structures that differ substantially from the structures of the equivalent glasses. We present data showing how these structures change when supercooled and demonstrate dramatic changes in short-range (coordination number) and intermediate-range order during vitrification. These data have been collected by isothermal measurement and also fast quenching methods using the recently developed method of rapid acquisition using a Perkin Elmer amorphous silicon flat panel detector; this gives a large Q coverage for incident energies of >115 keV. The rapid data acquisition enables the vitrification process to be observed directly.

(Received June 11 2010)

(Revised December 03 2010)

(Accepted January 24 2011)

(Online publication February 28 2011)

Correspondence

c1 Email address for correspondence: mbw@aber.ac.uk