Core–shell <i>vs.</i> multi-shell formation in nanoalloy evolution from disordered configurations

Nelli, Diana; Ferrando, Riccardo

doi:10.1039/c9nr02963j

Cited by 87 publications

(65 citation statements)

References 75 publications

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“…Bimetallic nanoalloys are synthesized either in gas phase or in solution 1,2,31 . However, these methods may not result in equilibrium structures due to the non-equilibrium processes and the kinetics of the synthesis procedure 8,32 . One possible method through which we may verify the results of the current work experimentally is to coat the AgCu nanoalloys of desired size with silica in a colloidal solution as is done for monometallic particles 33,34 .…”

Section: Discussionmentioning

confidence: 99%

Role of core-shell energetics on anti-Mackay, chiral stacking in AgCu nanoalloys and thermally induced transition to chiral stacking

Settem

Kanjarla

2020

Sci Rep

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Role of core-shell energetics on anti-Mackay, chiral stacking in Agcu nanoalloys and thermally induced transition to chiral stacking Manoj Settem & Anand K. Kanjarla in Agcu nanoalloys a size-dependent transition to the chiral stacking from the anti-Mackay stacking has been predicted previously. this trend is explained by considering the interplay between the core-shell energetics. Results indicate that the energy changes in the Ag shell alone is not sufficient to explain the stability of the chiral stacking and the energy changes in the cu core also need to be considered. in addition to this, thermally induced transition to chiral stacking was observed at sizes where anti-Mackay stacking is energetically favourable. on transition to the chiral stacking, the Ag-Ag, Ag-cu and Cu-Cu bond lengths change significantly. These observations are also applicable for AgCu nanoalloys with incomplete Ag shells. Bimetallic nanoalloy systems exhibit novel properties due to synergistic effects between the constituent metals. Bimetallic nanoclusters and nanoparticles have been extensively studied as they afford the opportunity to tune their chemical and physical properties through composition and chemical ordering 1-3. Along with the geometrical structure of a bimetallic nanocluster, due to the presence of two elements, different types of chemical ordering are possible: phase segregated and mixed. Depending on the bimetallic system, phase segregation can manifest as core-shell structure 4,5 where one of the constituent element covers the other completely or two phases joined at an interface, usually referred to as "Janus" type arrangemen 6-8. Similarly, mixed chemical ordering can be ordered (as is the case for bimetallic systems that form intermetallic phases) 9 or disordered 10. It is essential to know the optimal structures as a function of the size and the composition in order to understand the properties of bimetallic nanoclusters. Finding the optimal structures involves exploring the potential energy surface (PES) 11. Typically, methods based on genetic algorithm 12 or Monte Carlo combined with energy minimization commonly referred to as "basin hopping" Monte Carlo 13 are used to explore the PES and find the optimal structures using empirical atom-atom potentials such as the second moment approximation to tight binding (SMATB) 14-17 potential or the embedded atom method (EAM) 18 potential. Finally, the putative global minima and the lowest lying isomers belonging to the different structural motifs are singled out for relaxation using density functional theory (DFT). This provides a database of optimal structures which can be used to compare with the experimentally synthesized bimetallic nanoclusters. Depending on the constituent atoms in a bimetallic nanoalloy, specific structural motifs can become energetically favourable. The anti-Mackay icosahedron becomes stable in alloy systems which have a tendency to phase segregate and have atomic size mismatch combined with low surface energy for the larger atoms 19-21. AgCu, AgNi...

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Section: Discussionmentioning

confidence: 99%

Role of core-shell energetics on anti-Mackay, chiral stacking in AgCu nanoalloys and thermally induced transition to chiral stacking

Settem

Kanjarla

2020

Sci Rep

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“…This is due to the fact that shape can attain equilibrium by atomic-level processes which involve the displacement of surface and subsurface atoms, while chemical ordering needs also the occurrence of diffusion events in the inner part of the aggregate. The latter are much slower than the former, as already shown in simulations of the equilibration phase-separating systems 8 .…”

Section: Formation Of Nanoalloys With Off-center Coresmentioning

confidence: 53%

“…6 Coalescence may be useful as a tool for producing specifically tailored cluster structures. 7 For example, coalescence of clusters of different elements may be used a Dipartimento di Fisica dell'Università di Genova, via Dodecaneso to produce nanoalloys with core-shell 8 or Janus structures 9,10 . Sintering can also also improve the electrical conductivity 11 and mechanical stability 12 of nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Tuning the coalescence degree in the growth of Pt–Pd nanoalloys

et al. 2021

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“…The resulting onion-type structures, in their simplest form core-shell clusters, have been studied in great detail recently. 45,63,64,105,[107][108][109][110][111] For cluster sizes in the range of several thousand atoms a computational treatment with advanced methods of electronic structure theory is not feasible, at least not the metallic structure as a whole. On the other side, meso-scaled approaches such as the coarse-grained Monte Carlo approach discussed above are incapable of describing diffusion and alloying processes which take place on the atomic scale.…”

Section: Structural Behavior Of Mixed-metallic Clustersmentioning

confidence: 99%

Metal clusters synthesized in helium droplets: structure and dynamics from experiment and theory

Ernst

Hauser

2021

Phys. Chem. Chem. Phys.

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Core–shell vs. multi-shell formation in nanoalloy evolution from disordered configurations

Abstract: The evolution towards equilibrium of AuCo, AgNi and AgCu nanoparticles takes place through a sequence of complex transformations.

Cited by 87 publications

References 75 publications

Role of core-shell energetics on anti-Mackay, chiral stacking in AgCu nanoalloys and thermally induced transition to chiral stacking

Role of core-shell energetics on anti-Mackay, chiral stacking in AgCu nanoalloys and thermally induced transition to chiral stacking

Tuning the coalescence degree in the growth of Pt–Pd nanoalloys

Metal clusters synthesized in helium droplets: structure and dynamics from experiment and theory

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