Surface composition of Pt25Ni75(111) investigated by ISS and STM

P. Weigand, C. Nagl, M. Schmid and P. Varga

Institut für Allgemeine Physik, Technische Universität Wien, A-1040 Wien, Austria

Fresenius J. Anal. Chem. 346 (1993) 281-283

Ion scattering spectroscopy results show Pt enrichment in the topmost atomic layers of a Pt25Ni75(111) single crystal due to preferential sputtering. The increased lattice constant caused thereby leads to subsurface lattice mismatch dislocations, which have been studied by scanning tunneling microscopy. Agreement is found for the Pt concentration estimated from the density of dislocations and the results obtained by ISS. Thermal annealing induces further segregation of Pt in the topmost atomic layer. The composition of the subsurface layers has been studied and a strong dependence on the annealing temperature has been found. The observed Pt enrichment in the first monolayer for the thermodynamic equilibrium state agrees well with a thermodynamic theory.

Part of this work is on display in the IAP/TU Wien STM Gallery (see the dislocations page).

Corresponding author: M. Schmid (schmid< encoded email address >).