Surface Freezing in Liquid Gold-Silicon Eutectic Alloy investigated with Surface X-ray Diffraction

ORAL

Abstract

The formation of a 2D AuSi crystalline lattice on top of liquid AuSi eutectic alloy was found in surface X-ray diffraction experiments. Up to 12 degree above bulk melting temperature ($T_ {melt}$ = 361$^{\circ}$C) we observe a powder like, 2D crystalline lattice. Increasing the temperature we find a first order phase transition. GID diffraction data was used to determine the 2D lattice parameters and the domain size was estimated to be larger than 0.9 $\mu m$. Normalized X-ray reflectivity shows an increase of a factor of 20 in comparison to classical systems, indicating that atomic layering normal to the surface is significantly enhanced for AuSi. Synchrotron measurements were performed at ChemMatCARS, Advanced Photon Source, Argonne National Lab and supported by DOE grants DE-FG02-88-ER45379 and DE-AC02-98CH10886.

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Authors

  • Reinhard Streitel

  • Oleg G. Shpyrko

    Center for Nanoscale Materials, ANL

  • Alexei Grigoriev

  • Venkat Balagurusamy

    Physics Dept., Univ. of Pennsylvania

  • Peter Pershan

    Harvard University, DEAS and Physics Dept, Harvard University, Cambridge, MA 02138, DEAS, Harvard University, Cambridge,MA, 02138