Reconstruction of the Pt50Ni50(100) surface : a LEED and STM study

• The structure of the Pt50Ni50(100) surface was investigated by low energy electron diffraction (LEED) and scanning tunnelling spectroscopy (STM). Superstructures corresponding to 12 × 1 and 19 × 1 reconstructions were observed in the LEED pattern, and these reconstructions were identified with atomic resolution by STM. The reconstructed surface layer has a quasi-hexagonal atomic mesh with almost (111) atomic density and is divided into terraces and domains the size of which can be more than a thousand Ã¥ngströms. The domains are corrugated with protrusions made up by 5 × 1 subunits of the quasi-hexagonal mesh and with valleys containing depressed atoms or 2 × 1 subunits. The 12 × 1 and 19 × 1 periodicities are determined by the sequence of valleys; depending on the thermal treatment, one or the other dominates but both generally coexist on the terrace. Owing to the complexity of the structure, LEED calculations were performed for a simplified model with surface atoms situated in a planar net and uniform quasi-hexagonal meshes. We find that in both reconstructions the two surface layers are significantly enriched with platinum. The top layer enrichment is consistent with previous Auger measurements. © 1995.

Ämnesord

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Nyckelord

Alloys

Low energy electron diffraction (LEED)

Low index single crystal surfaces

Scanning tunneling microscopy

Surface relaxation and reconstruction

Surface segregation

Surface structure

morphology

roughness

and topography

Atoms

Calculations

Heat treatment

Low energy electron diffraction

Morphology

Platinum alloys

Relaxation processes

Single crystals

Surface roughness

Atomic density

Atomic resolution

Quasi hexagonal atomic mesh

Surface reconstruction

Surface relaxation

Surface topography

Surface structure

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