Structure of normal and supercooled liquid aluminum oxide

We have made a new determination of the structure of liquid aluminum oxide over a wide temperature range, including the supercooled region, using synchrotron X-ray diffraction. Measurements were performed over a wide scattering vector range, 0.5-16 angstrom(-1). Specimens of aluminum oxide were aerodynamically levitated and laser-heated to temperatures in excess of the melting temperature of 2327 K. Diffraction measurements were performed in a temperature range of 2000-2600 K, which included the supercooled liquid state. Measurements performed in argon (reducing) and oxygen (oxidizing) atmospheres show little structural difference, in contrast to reported differences in optical properties. The X-ray results are in excellent agreement with those of a molecular dynamics simulation performed with an A initio interaction potential.