Ni growth on vicinal Pt(111): low temperature exchange and formation of ordered surface alloys

We present an STM study of submonolayer Ni growth on Pt(997). We show that Ni atoms exchange with Pt already at T = 150 K both at terrace and at step sites. A one-dimensional ordered alloy forms at the step edges. For T < 300 K Ni atoms on the terraces are randomly embedded in Pt. Deposition of 0.2 ML Ni at T = 300 K results in a 2 x 2 substitutional alloy corresponding to a Ni20Pt80 composition of the surface topmost layer. (C) 2001 Elsevier Sci ence B.V. All rights reserved.