Structure of the (001)- and (111)-oriented surfaces of the ordered fccPt3Sn alloy by low-energy-electron-diffraction intensity analysis

The surface structure and composition of the (001)- and (111)-oriented surfaces of the ordered ${\mathrm{Pt}}_3$Sn alloy were determined by low-energy-electron-diffraction intensity analysis. For both orientations the surface structure corresponds to a bulk truncation model. For the (001) surface, the mixed ‘‘PtSn’’ plane forms the outermost surface layer. Sn atoms in the outermost plane are also significantly upwardly displaced (by about 0.2 Å) for both the (001) and the (111) surfaces.