Face-related segregation reversal at Pt50Ni50 surfaces studied with the embedded atom method

Deurinck, Patricia; Creemers, Claude

doi:10.1016/s0039-6028(99)00886-9

Cited by 19 publications

(12 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…% Pt, thus failing completely to reproduce the segregation reversal phenomenon. Recent EAM calculations with parameters derived specifically for the NiPt alloys 14 and empirical calculations by Hofer and Mezey 15 give results in agreement with experiment.…”

Section: Introductionsupporting

confidence: 66%

Bulk ordering and surface segregation inNi50Pt50

et al. 2001

View full text Add to dashboard Cite

Interatomic interactions obtained from the effective screened generalized-perturbation method have been applied in Monte Carlo simulations to derive the bulk and surface-alloy configurations for Ni 50 Pt 50 . The calculated order-disorder transition temperature and short-range order parameters in the bulk compare well with experimental data. The surface-alloy compositions for the ͑111͒ and ͑110͒ facets above the ordering transition temperature are also found to be in a good agreement with experiments. It is demonstrated that the segregation profile at the ͑110͒ surface of NiPt is mainly caused by the unusually strong segregation of Pt into the second layer and the interlayer ordering due to large chemical nearest-neighbor interactions.

show abstract

Section: Introductionsupporting

confidence: 66%

Bulk ordering and surface segregation inNi50Pt50

et al. 2001

View full text Add to dashboard Cite

show abstract

“…IV) simulations. In this work, we chose to simulate segregation in extended surfaces of disordered Pt-Ni alloys at T=1200 K for a direct comparison with previous experiments [12][13][14][15][16][17][18] and simulations [19][20][21][22][23][24]. T=600 K is a typical reduction temperature for bimetallic nanoparticle catalysts [5] and is used here to investigate segregation in Pt-Ni nanoparticles.…”

Section: Monte Carlo Methodsmentioning

confidence: 99%

“…It has been reported that the Pt-Ni alloy catalysts may even have enhanced activity compared to pure platinum catalysts, depending on how the surfaces are prepared [11]. Surface segregation phenomena in the Pt-Ni system have been extensively studied both in experiment [12][13][14][15][16][17][18] and theory [19][20][21][22][23][24]. Some very interesting phenomena in the Pt-Ni single crystal alloy surfaces (such as anisotropic surface segregation, oscillatory segregation profiles, and face-related segregation reversal) have been found.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Monte Carlo simulations of segregation in Pt-Ni catalyst nanoparticles

Wang

Hove

Ross

et al. 2004

The Journal of Chemical Physics

133

144

View full text Add to dashboard Cite

We have investigated the segregation of Pt atoms in the surfaces of Pt-Ni nanoparticles, using Modified Embedded Atom Model potentials and the Monte Carlo method. The nanoparticles are assumed to have disordered fcc configurations at two fixed overall concentrations (50 at.% Pt and 75 at.% Pt). We use four kinds of nanoparticle shapes [cube, tetrahedron, octahedron, and cubo-octahedron] terminated by {111} and {100} facets to examine the extent of the Pt segregation to the nanoparticle surfaces and determine the equilibrium structures of Pt-Ni nanoparticles at T=600 K. The model particles contain between 560 and 4631 atoms (particle size ranging from 2.5 to 5 nm).Our results imply that a complete {100}-facet reconstruction could make the cubooctahendral Pt-Ni nanoparticles most energetically favorable, consistent with experimental observations. We predict that at 600 K due to segregation the equilibrium Pt 50 Ni 50 nanoparticles with fewer than 2000 atoms and Pt 75 Ni 25 nanoparticles with fewer than 4000 atoms would achieve a surface-sandwich structure, in which the Pt atoms are enriched in the outermost and third atomic shells while the Ni atoms are enriched in the second atomic shell. We also find that due to an order-disorder transition the Pt 50 Ni 50 cubo-octahedral nanoparticles containing more than 2000 atoms would form a core-shell structure with a Pt-enriched surface and a Pt-deficient homogenous core. *Corresponding

show abstract

“…Monte Carlo (MC) simulation methods based on the Metropolis algorithm [23] have been successfully used in previous surface segregation calculations for various alloys (for example, Pt-Ni [24], Ni-Cu [25], and Al-Mg [26]). These MC methods are particularly advantageous in studying segregation phenomena in the equilibrium alloy structure, because they can circumvent slow physical dynamic processes (such as diffusion) in the system and provide an averaged composition profile over a thermodynamic equilibrium ensemble [27].…”

Section: Monte Carlo Methodsmentioning

confidence: 99%

Monte Carlo simulations of segregation in Pt-Re catalyst nanoparticles

Wang

Hove

Ross

et al. 2004

The Journal of Chemical Physics

View full text Add to dashboard Cite

. We predict that due to the segregation process the equilibrium Pt-Re nanoparticles would achieve a core-shell structure, with a P t-enriched shell surrounding a Pt-deficient core. For fcc cubo-octahedral Pt 75 Re 25 nanoparticles, the shells consist of almost 100 at.% of Pt atoms. Even in the shells of hcp truncated hexagonal bipyramidal Pt 50 Re 50 nanoparticles, the concentrations of Pt atoms exceed 85 at. % (35 at.% higher than the overall concentration of Pt atoms in these nanoparticles).Most prominently, all Pt atoms will segregate to the surfaces in the hcp truncated hexagonal bipyramidal Pt 25 Re 75 nanoparticles containing less than 1 000 atoms. We also find that the Pt atoms segregate preferentially to the vertex sites, less to edge sites, and least to facet sites on the shell of Pt-Re

show abstract

Face-related segregation reversal at Pt50Ni50 surfaces studied with the embedded atom method

Cited by 19 publications

References 33 publications

Bulk ordering and surface segregation inNi50Pt50

Bulk ordering and surface segregation inNi50Pt50

Monte Carlo simulations of segregation in Pt-Ni catalyst nanoparticles

Monte Carlo simulations of segregation in Pt-Re catalyst nanoparticles

Contact Info

Product

Resources

About