First X-Ray Scattering Studies on Electrostatically Levitated Metallic Liquids: Demonstrated Influence of Local Icosahedral Order on the Nucleation Barrier

Abstract

To explain the unusual stability of undercooled liquids against crystallization, Frank hypothesized that the local structures of undercooled liquids contain a significant degree of icosahedral short-range order, which is incompatible with long-range periodicity. We present here the first direct experimental demonstration of Frank's complete hypothesis, showing a correlation between the nucleation barrier and a growing icosahedral short-range order with decreasing temperature in a ${\mathrm{T}\mathrm{i}}_{39.5}{\mathrm{Z}\mathrm{r}}_{39.5}{\mathrm{N}\mathrm{i}}_{21}$ liquid. A new experimental facility, BESL (Beamline Electrostatic Levitation), was developed to enable the synchrotron x-ray structural studies on deeply undercooled, reactive liquids.