X-ray diffraction on levitated liquids: application to liquid 80%Co-20%Pd alloy

We describe the use of a novel levitation apparatus for structural studies on liquid materials using synchrotron X-ray scattering. The apparatus has been employed in investigations of the structural properties of a range of liquid ceramic, metallic, and semiconducting materials in the temperature range of 1000-3500 K. The apparatus uses conical nozzle levitation to stably position solid and liquid specimens at temperatures >1000 K. Specimens are heated with a 270 W, CO2 laser to melt, overheat and supercool the specimens in the desired temperature range. We report the first measurements of the total structure factor, S(Q), and pair distributions function, G(r), of liquid 80%Co-20%Pd in both the normal and supercooled states. This alloy has been previously reported to exhibit magnetic order in the supercooled Liquid state. No abrupt structural change was observed as the alloy was supercooled, although it was not possible to cool the liquid to temperatures at which magnetic ordering has been reported. (C) 1999 Elsevier Science B.V. All rights reserved.