Temperature dependence of surface-melting-induced faceting of surfaces vicinal to Pb(111)

We present a medium-energy ion-scattering investigation of Pb surfaces with orientations in the [110] zone vicinal to Pb (111), at high temperature. Both surfaces inclined towards the (110) orientation and surfaces inclined towards the (001) orientation exhibit surface-melting-induced faceting. Faceting occurs not only close to the bulk melting point, but over a range of temperatures extending at least from 589.6 K up to the bulk melting point (600.7 K). Just below the melting point, the dry facet orientation for vicinal surfaces inclined towards (110) is 3.1°±O.6°, the dry facet orientation towards the (001) surface is 7. 3°±O.8°, and for both directions the melted facet orientation is approximately 14.5° with respect to the (111) plane. Between 593.8 and 600.7 K, the observed dry facet orientations vary less than 3°. A model calculation in terms of interfacial free energies is used to describe the facet orientations and their temperature dependence. We relate our results to recent equilibrium shape observations of Pb crystallites.