The surface composition of Pt25Ni75(111) has been determined by ion scattering spectroscopy and Auger electron spectroscopy. The surface layers are found to be enriched in Pt due to preferential sputtering. Thermal treatment induces further segregation of Pt at the topmost atomic layer. From the different sampling depths of ISS and AES composition profiles are deduced, which show a strong dependence on the temperature during thermal treatment. At an annealing temperature of 770 K the thermally induced Pt segregation is determined by the composition of the sputter induced altered layer being enriched in Pt. However, at an annealing temperature of 970 K the sputter induced altered layer has disappeared and the Pt segregation at the topmost atomic layer is determined by the bulk composition.
Corresponding author: W. Hofer (hofer).