Calculation of the Surface Segregation of Pd-Cu, Pd-Ag, and Pd-Au Alloys

Abstract

ABSTRACTThe surface composition of the (111) surfaces of the binary alloys Pd-Cu, Pd-Ag, and Pd-Au have been computed by Monte Carlo computer simulation with the energetics determined by the Embedded Atom Method. Ag and Au are found to segregate to the first atomic layer of their alloys with Pd while for Pd-Cu alloys the degree of segregation is small but occurs mainly on the second atomic plane. The short-range order of the surfaces is addressed by studying the relative abundance of different compositions of nearest neighbor triangles on the (11) surfaces. The presence of triangles containing only atoms of one element is found to be suppressed by the short-range order. This result is shown to follow from the enhancement for these alloys of nearest neighbor pairs of atoms of different types.