Surface reconstruction precursor to melting in Au309 clusters

Chen, Fuyi; Li, Ziyou; Johnston, Roy L.

doi:10.1063/1.3613650

Cited by 8 publications

(3 citation statements)

References 29 publications

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“…Kinetic studies for Au 309 showed restructuring between motifs above room temperature. 37 More recently, kinetic restructuring of Au 923 has been observed experimentally under electron irradiation by Wang and Palmer, 38 as well as characterisation of surface adatoms. 39 Structural transitions from Ih to M-Dh and FCC due to irradiation 38 occurred at larger N than predicted by previous phase diagrams for Au NCs, 40 leaving open the question of faceting preferences in these structures.…”

Section: Introductionmentioning

confidence: 97%

Faceting preferences for AuN and PdN nanoclusters with high-symmetry motifs

Logsdail

Johnston

2013

Phys. Chem. Chem. Phys.

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The structural preferences of nanoparticles are important for understanding their chemical properties and potential applications, and remain widely debated. Based on recent experimental observations, we present calculations on the stability of high-symmetry AuN and PdN clusters of various structural motifs, performing a systematic search of faceting preferences using mathematical constructs, a semi-empirical potential with two different parameter sets, and a quasi-Newtonian minimisation technique. We have studied the preferred ratios of (100) and (111) faces for two experimentally observed nanostructures: (a) FCC crystals, comparing octahedra with 8 (111) faces to cuboctahedra where the vertices have been systematically removed (for N < 1500); and (b) Marks-decahedra, with differing "stellation" depths (for N < 6000). For PdN and AuN we see preference towards minimisation of (100) surfaces using the parameter sets of both Cleri and Rosato [Cleri and Rosato, Phys. Rev. B: Condens. Matter Mater. Phys., 1993, 48, 22] and Baletto et al. [Baletto et al., J. Chem. Phys., 2002, 116, 3856]. Fully stellated Marks-decahedra are found to be unfavourable at large sizes, with truncated facets identified which are similar to recent experimental observations. We find however that these stellations are deeper in PdN particles than AuN. Truncated-octahedra are found to prefer much reduced (100) surfaces and increased (111) surface areas.

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Section: Introductionmentioning

confidence: 97%

Faceting preferences for AuN and PdN nanoclusters with high-symmetry motifs

Logsdail

Johnston

2013

Phys. Chem. Chem. Phys.

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“…The size of NPs makes them an attractive problem to address with computational techniques, and previous work using thermodynamic sampling has identified key transition pathways and barriers between structural motifs at a range of different nuclearities, ,− as well as demonstrating how the energy barriers change with chemical ordering in bimetallic NPs. − One well-characterized pathway is the martensitic transformation between icosahedral (Ih) and cuboctahedral (CO) motifs via the so-called sextuple diamond–square–diamond (DSD) mechanism: , Triangular facets are stretched and then rotated to form a diamond one and then transformed to a square facet (DS), with the reverse square–diamond process (SD) leading to reformation of the Ih from the CO. Recently, forward (SD) and backward (DS) transition pathways have been characterized at finite temperatures through molecular dynamics modeling for 147-atom Ag and AuAg NPs; , however, no such transition occurs for Au NPs, ,, showing that structural stability or transition barriers change considerably as a function of chemical composition. From a structural design perspective, controlling these transitions via chemical methods would be ideal, but there has been limited investigation of how to use NP composition to achieve this goal.…”

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Controlling Structural Transitions in AuAg Nanoparticles through Precise Compositional Design

Gould

Rossi

Catlow

et al. 2016

J. Phys. Chem. Lett.

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We present a study of the transitional pathways between high-symmetry structural motifs for AgAu nanoparticles, with a specific focus on controlling the energetic barriers through chemical design. We show that the barriers can be altered by careful control of the elemental composition and chemical arrangement, with core@shell and vertex-decorated arrangements being specifically influential on the barrier heights. We also highlight the complexity of the potential and free energy landscapes for systems where there are low-symmetry geometric motifs that are energetically competitive to the high-symmetry arrangements. In particular, we highlight that some core@shell arrangements preferentially transition through multistep restructuring of low-symmetry truncated octahedra and rosette-icosahedra, instead of via the more straightforward square-diamond transformations, due to lower energy barriers and competitive energetic minima. Our results have promising implications for the continuing efforts in bespoke nanoparticle design for catalytic and plasmonic applications.

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“…While at smaller size the martensinic transitions towards the Ih have been detected consistently by itMD, they have not ever been sampled in clusters of 309 atoms, apart for Cu 309 , in agreement with what observed in previous studies employing similar temperature increase rate. [24,33] Co structures rearrange one or more triangular (111) facets into fcc islands. Dh reorganize into structure presenting defects and Marks' like re-entrances [34] formed by surface peeling.…”

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Size dependent rearrangements in monometallic clusters

Rossi¹,

YeeYee²,

Pavan³

et al. 2017

Preprint

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Morphology and its stability are essential features to address physicochemical properties of metallic nanoparticles. By means of Molecular Dynamics based simulations we show a complex dependence on the size and material of common structural mechanisms taking place in mono-metallic nanoparticles at icosahedral magic sizes. We show that the well known Lipscomb's Diamond-Square-Diamond mechanisms, single-step screw dislocation motions of the whole cluster, take place only below a given size which is material dependent. Above that size, layer-by-layer dislocations and/or surface peeling are likely to happen, leading to low symmetry defected motifs. The material dependence of this critical size is similar to the crossover sizes among structural motifs, based on the ration between the bulk modulus and atomic cohesive energy.

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Surface reconstruction precursor to melting in Au309 clusters

Cited by 8 publications

References 29 publications

Faceting preferences for AuN and PdN nanoclusters with high-symmetry motifs

Faceting preferences for AuN and PdN nanoclusters with high-symmetry motifs

Controlling Structural Transitions in AuAg Nanoparticles through Precise Compositional Design

Size dependent rearrangements in monometallic clusters

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