DOMAIN-STRUCTURE, SEGREGATION AND MORPHOLOGY OF THE PT3SN(111) SURFACE

Using spot-profile analysis low-energy electron diffraction, we have s tudied the domain structure and morphology of the Pt,Sn(lll) surface a fter sputtering at room temperature and subsequent anneal treatments w hich 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 res ults on the temperature-dependent composition of the outermost layer a nd the subsurface region that is obtained from quantitative analysis o f low-energy ion scattering and Auger electron spectroscopy experiment s. The combination of these results and previous experiments yields a detailed picture of the evolution of the surface region during the ann eal treatments. Finally, we propose the existence of a phase transitio n 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 SP A-LEED. LEIS and AES data. (C) 1998 Elsevier Science B.V. All rights r eserved.