Patchy Multishell Segregation in Pd−Pt Alloy Nanoparticles

Barcaro, Giovanni; Fortunelli, Alessandro; Polak, M.; Rubinovich, Leonid

doi:10.1021/nl200322s

Cited by 95 publications

(96 citation statements)

References 29 publications

(51 reference statements)

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“…The same behavior is observed in NPs. Barcaro [170] predicted an oscillation in Size and composition dependence of the particle shape computed for a homogeneous alloy (basic Wulff), a segregating alloy with an infinite reservoir approximation (bulk model), and the "true" alloy Wulff mode for N=1000 atoms and 3000 atoms respectively. For N=1000 atoms a total segregation leads to an incomplete core/shell structure.…”

Section: Patchy Multishell Segregationmentioning

confidence: 99%

Engineered inorganic core/shell nanoparticles

et al. 2014

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It has been for a long time recognized that nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic structures. At first, size effects occurring in single elements have been studied. More recently, progress in chemical and physical synthesis routes permitted the preparation of more complex structures. Such structures take advantages of new adjustable parameters including stoichiometry, chemical ordering, shape and segregation opening new fields with tailored materials for biology, mechanics, optics magnetism, chemistry catalysis, solar cells and microelectronics. Among them, core/shell structures are a particular class of nanoparticles made with an inorganic core and one or several inorganic shell layer(s). In earlier work, the shell was merely used as a protective coating for the core. More recently, it has been shown that it is possible to tune the physical properties in a larger range than that of each material taken separately. The goal of the present review is to discuss the basic properties of the different types of core/shell nanoparticles including a large variety of heterostructures. We restrict ourselves on all inorganic (on inorganic/inorganic) core/shell structures. In the light of recent developments, the applications of inorganic core/shell particles are found in many fields including biology, chemistry, physics and engineering. In addition to a representative overview 2 of the properties, general concepts based on solid state physics are considered for material selection and for identifying criteria linking the core/shell structure and its resulting properties. Chemical and physical routes for the synthesis and specific methods for the study of core/shell nanoparticle are briefly discussed.

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Section: Patchy Multishell Segregationmentioning

confidence: 99%

Engineered inorganic core/shell nanoparticles

et al. 2014

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“…Immiscible elements in the bulk tend to be separated by a planar interface, but it is often the case that the same two elements form rounded core-shell particles at the nanoscale, adopting thus a segregation pattern which does not minimize the interfacial area. Novel chemical ordering patterns such as the patchy multishell segregation recently observed in Pd-Pt nanoalloys, 37 or the dynamical coexistence of Cu-rich and Ag-rich facets in Cu-Ag nanoalloys, 27 clearly illustrate the complexity of the structural problem at the nanoscale.…”

Section: Introductionmentioning

confidence: 99%

Identifying structural and energetic trends in isovalent core-shell nanoalloys as a function of composition and size mismatch

Aguado

López²

2011

The Journal of Chemical Physics

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We locate the putative global minimum structures of Na x Cs 55−x and Li x Cs 55−x nanoalloys through combined empirical potential and density functional theory calculations, and compare them to the structures of 55-atom Li-Na and Na-K nanoalloys obtained in a recent paper [A. Aguado and J. M. López, J. Chem. Phys. 133, 094302 (2010)]. Alkali nanoalloys are representative of isovalent metallic mixtures with a strong tendency towards core-shell segregation, and span a wide range of size mismatches. By comparing the four systems, we analyse how the size mismatch and composition affect the structures and relative stabilities of these mixtures, and identify useful generic trends. The Na-K system is found to possess a nearly optimal size mismatch for the formation of poly-icosahedral (pIh) structures with little strain. In systems with a larger size mismatch (Na-Cs and Li-Cs), frustration of the pIh packing induces for some compositions a reconstruction of the core, which adopts instead a decahedral packing. When the size mismatch is smaller than optimal (Li-Na), frustration leads to a partial amorphization of the structures. The excess energies are negative for all systems except for a few compositions, demonstrating that the four mixtures are reactive. Moreover, we find that Li-Cs and Li-Na mixtures are more reactive (i.e., they have more negative excess energies) than Na-K and Na-Cs mixtures, so the stability trends when comparing the different materials are exactly opposite to the trends observed in the bulk limit: the strongly non-reactive Li-alkali bulk mixtures become the most reactive ones at the nanoscale. For each material, we identify the magic composition x m which minimizes the excess energy. x m is found to increase with the size mismatch due to steric crowding effects, and for Li x Cs 55−x the most stable cluster has almost equiatomic composition. We advance a simple geometric packing rule that suffices to systematize all the observed trends in systems with large size mismatch (Na-K, Na-Cs, and Li-Cs). As the size mismatch is reduced, however, electron shell effects become more and more important and contribute significantly to the stability of the Li-Na system.

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“…Filtering can be implemented in a multi-mode fashion e.g. by coupling first-principles calculations with analytic potentials [14], or analytic potentials and effective Hamiltonians [17], and so on, i.e., by coupling a theoretical method with its higher neighboring one along the multi-scale hierarchical ladder. It is thus intrinsically and nicely connected with multi-scale modeling [16].…”

Section: Structure Prediction Methodsmentioning

confidence: 99%

Atomistic and Electronic Structure Methods for Nanostructured Oxide Interfaces

Barcaro

Sementa

Negreiros

et al. 2016

Oxide Materials at the Two-Dimensional Limit

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An overview is given of methods for the computational prediction of the atomistic and electronic structures of nanoscale oxide interfaces. Global optimization approaches for structure prediction, together with total energy and electronic structure methods are reviewed and discussed. Our aim is to furnish conceptual instruments to select the optimal (i.e., the most accurate and least costly) method for treating a given system, and to understand the potentialities and limi-

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Patchy Multishell Segregation in Pd−Pt Alloy Nanoparticles

Cited by 95 publications

References 29 publications

Engineered inorganic core/shell nanoparticles

Engineered inorganic core/shell nanoparticles

Identifying structural and energetic trends in isovalent core-shell nanoalloys as a function of composition and size mismatch

Atomistic and Electronic Structure Methods for Nanostructured Oxide Interfaces

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