Segregation phenomena on PtxNi1-x low-index single crystal surfaces studied by STM

P. Varga, M. Schmid, and W. Hofer

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

Surface Review and Letters 3 (1996) 1831-1845

Surface segregation changes the composition of alloy surfaces. It influences both the geometrical and the chemical structure of the surface. In this paper segregation phenomena are shown for low index single crystal surfaces of different PtNi alloys which can be seen only by scanning tunneling microscopy (STM).

STM experiments performed with atomic resolution revealed the existence of subsurface dislocation networks. A closer study of the conditions of their existence allowed us to understand the effects of preferential sputtering and annealing on the segregation behaviour (i.e. building up a rather stable altered layer and its disappearance only at elevated temperatures). In addition, local chemical ordering in small domains and shifted row reconstructions with a large and varying periodicity (i.e. phenomena that are hardly seen by other methods like e.g. LEED) have been observed.

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

Corresponding author: P. Varga (varga< encoded email address >).