Comparison of surface structure and segregation in AgAu and NiPd alloys

The structure and composition of a single-crystal AgAu(1 0 0) alloy surface was studied using low energy electron diffraction. The surface was found to be moderately enriched in silver, while the second atomic layer has an essentially bulklike composition. The first interlayer distance exhibits a small contraction, with a small expansion found in the second interlayer. This structure composition behavior is compared to that found in the low index surfaces of the NiPd alloy, which has compositional oscillations and a more complex surface relaxation behavior.