AVS 47th International Symposium
    Surface Science Monday Sessions
       Session SS3-MoA

Paper SS3-MoA6
Comparison of Behavior of Wetting-related Adsorption Transitions in the Ga-Pb, Ga-Tl, Ga-Pb-Tl Systems

Monday, October 2, 2000, 3:40 pm, Room 210

Session: Surface Diffusion and Wetting
Presenter: H. Shim, Carnegie Mellon University
Authors: H. Shim, Carnegie Mellon University
P. Wynblatt, Carnegie Mellon University
D. Chatain, CRMC2-CNRS, France
Correspondent: Click to Email
In this presentation, we summarize investigations of prewetting behavior in three Ga-rich liquid alloy systems, Ga-Pb, Ga-Tl and Ga-Pb-Tl. The adsorption of Pb and/or Tl at the surfaces of these alloys was determined by Auger electron spectroscopy, as a function of temperature and composition. Most of the surface composition measurements reported were performed below the freezing points of the alloys (~300 K) where the alloys exist in a supercooled liquid state. However, measurements cannot be conducted below about 240 K, where the alloys undergo non-equilibrium freezing (presumably by homogeneous nucleation). Extrapolation to lower temperatures of the results obtained in the meta-stable liquid state (between 300 and 240 K) indicates the existence of possible prewetting critical points at about 240 K for Ga-Pb alloys, and at about 150 K for Ga-Tl alloys. The motivation for studying Ga-Pb-Tl ternary alloys was that small additions of Tl might raise the prewetting critical point of Ga-Pb to temperatures above 240 K, and lead to more definitive observations of prewetting behavior. However, although ternary Tl additions do lead to increased Pb adsorption, as expected, the temperature of a possible prewetting critical point is lowered even further to about 215 K.