Ni-Pt Phase Diagram: Experiment and Theory

Dahmani, Chiheb; Cadeville, M.C.; Sanchez, Juan M; Morán‐López, J. L.

doi:10.1103/physrevlett.55.1208

Cited by 174 publications

(95 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The surface-sandwich structure is also formed for cubo-octahedral Pt 50 Ni 50 nanoparticles containing fewer than 2000 atoms. However, the equilibrium structures of cubo-octahedral Pt 50 Ni 50 nanoparticles containing more than 2000 atoms are more like a core-shell structure: Pt is enriched in the outermost shell and depleted in the homogenous core.…”

Section: Surface-sandwich Structure Of Pt-ni Nanoparticlesmentioning

confidence: 96%

“…2(b)) fcc nanoparticles, the atomic cohesive energy for a given number of atoms follows the decreasing order: cube > tetrahedron > octahedron ≈ cubo-octahedron. For Pt 50 Ni 50 nanoparticles, the cubooctahedral shape is about 0.003 eV/atom more stable than the octahedral shape. In contrast, the average energy for each atom in the Pt 75 Ni 25 octahedral nanoparticles is about 0.001 eV lower than in the cubo-octahedral nanoparticles.…”

Section: A Segregation In Un-relaxed Pt-ni Nanoparticlesmentioning

confidence: 99%

“…We believe that the strong ordering tendency in the core region of larger nanoparticles accounts for this behavior. For bulk Pt 50 Ni 50 alloys, the disordered fcc structure will change to the ordered L1 0 structure below 900K [50]. It is known that the order-disorder transition temperature of nanoparticles is a function of their size and shape [51,52].…”

Section: Surface-sandwich Structure Of Pt-ni Nanoparticlesmentioning

confidence: 99%

“…Moreover, it is conceivable that the energy difference between {100} and {111} facets will increase with the increase of concentration of Pt atoms in nanoparticles. Hence, compared to the octahedral nanoparticles solely terminated with {111} facets, the cubo-octahedral nanoparticles terminated with {111} and {100} facets could have lower energy for Pt 50 …”

Section: A Segregation In Un-relaxed Pt-ni Nanoparticlesmentioning

confidence: 99%

See 3 more Smart Citations

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

Section: Surface-sandwich Structure Of Pt-ni Nanoparticlesmentioning

confidence: 96%

Section: A Segregation In Un-relaxed Pt-ni Nanoparticlesmentioning

confidence: 99%

Section: Surface-sandwich Structure Of Pt-ni Nanoparticlesmentioning

confidence: 99%

Section: A Segregation In Un-relaxed Pt-ni Nanoparticlesmentioning

confidence: 99%

See 2 more Smart Citations

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

show abstract

“…Early experiments indicated that disordered NiPt is ferromagnetic [3], while in the ordered phase it is paramagnetic [4]. Other authors found ordered NiPt to be antiferromagnetic [5].…”

Section: Introductionmentioning

confidence: 99%

Magnetic transition in NiPt alloy systems: experiment and theory

Kumar

Padmalekha

Mukhopadhyay

et al. 2005

Journal of Magnetism and Magnetic Materials

View full text Add to dashboard Cite

show abstract

Prediction of Phase Diagrams

de¹

2002

Characterization of Materials

View full text Add to dashboard Cite

A phase diagram is a graphical object, usually determined experimentally, indicating phase relationships in thermodynamic space. Usually, one coordinate axis represents temperature; the others may represent pressure, volume, concentrations of various components, and so on. This unit is concerned only with temperature‐concentration diagrams, limited to binary (two‐component) and ternary (three‐component) systems. Since more than one component is considered, the relevant thermodynamic systems are alloys, by definition, of metallic, ceramic, or semiconductor materials. The emphasis here is placed primarily on metallic alloys. Phase diagrams can be classified broadly into two main categories: experimentally and theoretically determined. The object of the present unit is the theoretical determination—i.e., the calculation of phase diagrams, meaning ultimately their prediction. But calculation of phase diagrams can mean different things: there are prototype, fitted, and first‐principles approaches. Prototype diagrams are calculated under the assumption that energy parameters are known a priori or given arbitrarily. Fitted diagrams are those whose energy parameters are fitted to known, experimentally determined diagrams or to empirical thermodynamic data. First‐principles diagrams are calculated on the basis of energy parameters calculated from essentially only the knowledge of the atomic numbers of the constituents, hence by actually solving the relevant Schrödinger equation. Theory also enters in the experimental determination of phase diagrams, as these diagrams not only indicate the location in thermodynamic space of existing phases but also must conform to rigorous rules of thermodynamic equilibrium (stable or metastable). The fundamental rule of equality of chemical potentials imposes severe constraints on the graphical representation of phase diagrams, while also permitting an extraordinary variety of forms and shapes of phase diagrams to exist, even for binary systems. That is one of the attractions of the study of phase diagrams, experimental or theoretical: their great topological diversity subject to strict thermodynamic constraints. In addition, phase diagrams provide essential information for the understanding and designing of materials, and so are of vital importance to materials scientists. For theoreticians, first‐principles (or ab initio ) calculations of phase diagrams provide enormous challenges, requiring the use of advanced techniques of quantum and statistical mechanics.

show abstract

Ni-Pt Phase Diagram: Experiment and Theory

Cited by 174 publications

References 9 publications

Monte Carlo simulations of segregation in Pt-Ni catalyst nanoparticles

Monte Carlo simulations of segregation in Pt-Ni catalyst nanoparticles

Magnetic transition in NiPt alloy systems: experiment and theory

Prediction of Phase Diagrams

Contact Info

Product

Resources

About