Oscillatory compositional depth profiles in surface segregation of a Pt-Rh alloy

Abstract

Surface segregation of a Pt-Rh alloy is studied with the single-atom chemical analysis capability of the atom-probe field ion microscope. We find the composition of the near-surface layers of the I 001 I plane to oscillate with the depth of the atomic layers having the top layer enriched with Pt. This oscillatory feature persists down to a depth of over ten atomic layers. The amplitudes of the oscillations decrease with the annealing temperature. In contrast, for Pt-Rh alloys containing a small amount of sulfur, the top alloy layer is enriched with Rh but a similar oscillation exists.

Automobile exhaust catalysis at the atomic scale: atom‐probe investigations on platinum alloys

“…Segregation effects in Pt-Rh alloys at high temperatures under vacuum or with trace gases are also observed with AP. 8,9 In vacuo Pt enrichment is seen at high (>873 K) temperatures, while Rh surface segregation is induced by oxygen. Many studies stress this highly sensitive nature of the surface composition to adsorbed gases; for example, trace sulfur poisoning reverses the high-temperature Pt segregation.…”

“…Many studies stress this highly sensitive nature of the surface composition to adsorbed gases; for example, trace sulfur poisoning reverses the high-temperature Pt segregation. 8 In-depth reviews are available of various gas interactions with FIM specimens 10 and on adsorption/reactions of typical exhaust gases onto single-crystal and FIM surfaces.…”

Molecular dynamics simulation of crystallization kinetics and homogenous nucleation of Pt–Rh alloy

“…Pure Pt has high melting point, excellent workability to form complex shapes, excellent resistance at room temperature and oxidation resistance. When Pt is alloyed with one or more of the elements such as Pd, Rh, and Pb, the physical properties can be improved in the areas of microstructure mechanic [4][5][6]. For example, the Pt-Rh alloys are used for the production of thin wires intended for catalytic nets.…”

Equilibrium atomic compositions of MoxRe1−x(001) and MoxW1−x(001) disordered alloys

“…It is well known that the surface composition of binary alloys can differ substantially from that in the bulk. This is the phenomenon of surface segregation which has been studied for a long time, from the experimental point of view [1][2][3][4][5][6][7][8][9][10][11][12] as well as theoretically . The determination of the equilibrium concentration profile, i.e., the variation of the atomic composition of an alloy near the surface, is a major goal of these investigations.…”