Domain structure, segregation and morphology of the Pt3Sn(111) surface

Using spot-profile analysis low-energy electron diffraction, we have studied the domain structure and morphology of the Pt,Sn(lll) surface after sputtering at room temperature and subsequent anneal treatments which result in the formation of the previously reported (root 3 x root 3)R30 degrees and (2 x 2) structures. In addition, we present new results on the temperature-dependent composition of the outermost layer and the subsurface region that is obtained from quantitative analysis of low-energy ion scattering and Auger electron spectroscopy experiments. The combination of these results and previous experiments yields a detailed picture of the evolution of the surface region during the anneal treatments. Finally, we propose the existence of a phase transition at high temperatures between the (2 x 2) phase and a (2 x 2)' phase (not previously observed) on the basis of reversible changes in the SPA-LEED. LEIS and AES data. (C) 1998 Elsevier Science B.V. All rights reserved.