1
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Zinzani S, Baletto F. Coalescence of AuPd nanoalloys in implicit environments. Phys Chem Chem Phys 2024; 26:21965-21973. [PMID: 38963293 DOI: 10.1039/d4cp00916a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/05/2024]
Abstract
The optimal design of nanoparticles and nanoalloys arises from the control of their morphology which depends on the synthesis process they undergo. Coalescence is widely accepted as one of the most common synthetic mechanisms, and it occurs both in the liquid and gas phases. Coalescence is when two existing seeds collide and aggregate into a larger object. The resulting aggregate is expected to be far from the equilibrium isomer, i.e. the global minimum of the potential energy surface. While the coalescence of nanoparticles is well studied in a vacuum, sparse computational studies are available for the coalescence in an environment. Using molecular dynamics simulations, we study the coalescence of Au and Pd nanoseeds surrounded by an interacting environment. Comparing the initial stages of the coalescence in a vacuum and the presence of an interacting environment, we show that the formation kinetics strongly depends on the environment and on the size of the nanoalloy. Furthermore, we show that it is possible to tune the resulting nanoalloys' surface chemical composition by changing their surrounding environment.
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Affiliation(s)
- Sofia Zinzani
- Università degli Studi di Milano - Dipartimento di Fisica, Via Celoria 16, Milano I-20133, Italy.
| | - Francesca Baletto
- Università degli Studi di Milano - Dipartimento di Fisica, Via Celoria 16, Milano I-20133, Italy.
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2
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Souza TM, Pena LB, Da Silva JLF, Galvão BRL. Data-driven stabilization of Ni mPd n-m nanoalloys: a study using density functional theory and data mining approaches. Phys Chem Chem Phys 2024; 26:15877-15890. [PMID: 38804680 DOI: 10.1039/d4cp00672k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Green hydrogen, generated through the electrolysis of water, is a viable alternative to fossil fuels, although its adoption is hindered by the high costs associated with the catalysts. Among a wide variety of potential materials, binary nickel-palladium (NiPd) systems have garnered significant attention, particularly at the nanoscale, for their efficacious roles in catalyzing hydrogen and oxygen evolution reactions. However, our atom-level understanding of the descriptors that drive their energetic stability at the nanoscale remains largely incomplete. Here, we investigate by density functional theory calculations the descriptors that drives the stability of the NimPdn-m clusters for different sizes (n = 13, 27, 41) and compositions. To achieve our goals, a large number of trial configurations were generated and selected using data mining algorithms (k-means, t-SNE) and genetic algorithms, while the most important physical-chemical descriptors were identified using Spearman correlation analysis. We have found that core-shell formation, with the smaller Ni atoms lying in the center of the particle, plays a major role in the stabilization of the nanoalloys, and this effect causes the alloys to assume a icosahedral-fragment configuration (as the unary nickel cluster) instead of a fcc fragment (as the unary palladium cluster). However, the core-shell formation in this alloy is unique in that Pd poor compositions exhibit scattered Pd atoms on the surface. As the palladium content increases, this gives rise to the complete Pd shell. This stabilization mechanism is quantitatively supported by the different correlations observed in the number of Ni-Ni and Pd-Pd bonds with energy, in which the latter tends to decrease alloy stability. Furthermore, a notable trend is the correlation between the coordination number of Ni atoms with alloy stabilization, while the coordination of Pd atoms shows an inverse correlation.
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Affiliation(s)
- Tiago M Souza
- Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil.
| | - Lucas B Pena
- Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil.
| | - Juarez L F Da Silva
- São Carlos Institute of Chemistry, University of São Paulo, P.O. Box 780, 13560-970 São Carlos, SP, Brazil
| | - Breno R L Galvão
- Centro Federal de Educação Tecnológica de Minas Gerais, CEFET-MG, Av. Amazonas 5253, 30421-169 Belo Horizonte, Minas Gerais, Brazil.
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque 87131, New Mexico, USA
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3
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Chepkasov IV, Radina AD, Kvashnin AG. Structure-driven tuning of catalytic properties of core-shell nanostructures. NANOSCALE 2024; 16:5870-5892. [PMID: 38450538 DOI: 10.1039/d3nr06194a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
The annual increase in demand for renewable energy is driving the development of catalysis-based technologies that generate, store and convert clean energy by splitting and forming chemical bonds. Thanks to efforts over the last two decades, great progress has been made in the use of core-shell nanostructures to improve the performance of metallic catalysts. The successful preparation and application of a large number of bimetallic core-shell nanocrystals demonstrates the wide range of possibilities they offer and suggests further advances in this field. Here, we have reviewed recent advances in the synthesis and study of core-shell nanostructures that are promising for catalysis. Particular attention has been paid to the structural tuning of the catalytic properties of core-shell nanostructures and to theoretical methods capable of describing their catalytic properties in order to efficiently search for new catalysts with desired properties. We have also identified the most promising areas of research in this field, in terms of experimental and theoretical studies, and in terms of promising materials to be studied.
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Affiliation(s)
- Ilya V Chepkasov
- Skolkovo Institute of Science and Technology, 121205, Bolshoi Blv. 30, Building 1, Moscow, Russia.
| | - Aleksandra D Radina
- Skolkovo Institute of Science and Technology, 121205, Bolshoi Blv. 30, Building 1, Moscow, Russia.
| | - Alexander G Kvashnin
- Skolkovo Institute of Science and Technology, 121205, Bolshoi Blv. 30, Building 1, Moscow, Russia.
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4
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Pena LB, Da Silva LR, Da Silva JLF, Galvão BRL. Underlying mechanisms of gold nanoalloys stabilization. J Chem Phys 2023; 159:244310. [PMID: 38153152 DOI: 10.1063/5.0180906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 12/04/2023] [Indexed: 12/29/2023] Open
Abstract
Gold nanoclusters have attracted significant attention due to their unique physical-chemical properties, which can be tuned by alloying with elements such as Cu, Pd, Ag, and Pt to design materials for various applications. Although Au-nanoalloys have promising applications, our atomistic understanding of the descriptors that drive their stability is far from satisfactory. To address this problem, we considered 55-atom model nanoalloys that have been synthesized by experimental techniques. Here, we combined data mining techniques for creating a large sample of representative configurations, density functional theory for performing total energy optimizations, and Spearman correlation analyses to identify the most important descriptors. Among our results, we have identified trends in core-shell formation in the AuCu and AuPd systems and an onion-like design in the AuAg system, characterized by the aggregation of gold atoms on nanocluster surfaces. These features are explained by Au's surface energy, packing efficiency, and charge transfer mechanisms, which are enhanced by the alloys' preference for adopting the structure of the alloying metal rather than the low-symmetry one presented by Au55. These generalizations provide insights into the interplay between electronic and structural properties in gold nanoalloys, contributing to the understanding of their stabilization mechanisms and potential applications in various fields.
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Affiliation(s)
- Lucas B Pena
- Departamento de Química, Centro Federal de Educação Tecnológica de Minas Gerais, 30421-169 Belo Horizonte, MG, Brazil
| | - Lucas R Da Silva
- São Carlos Institute of Chemistry, University of São Paulo, P.O. Box 780, 13560-970 São Carlos, SP, Brazil
| | - Juarez L F Da Silva
- São Carlos Institute of Chemistry, University of São Paulo, P.O. Box 780, 13560-970 São Carlos, SP, Brazil
| | - Breno R L Galvão
- Departamento de Química, Centro Federal de Educação Tecnológica de Minas Gerais, 30421-169 Belo Horizonte, MG, Brazil
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5
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Nelli D, Roncaglia C, Ferrando R, Kataya Z, Garreau Y, Coati A, Andreazza-Vignolle C, Andreazza P. Sudden collective atomic rearrangements trigger the growth of defect-free silver icosahedra. NANOSCALE 2023; 15:18891-18900. [PMID: 37975176 DOI: 10.1039/d3nr04530g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2023]
Abstract
The growth of Ag clusters on amorphous carbon substrates is studied in situ by X-ray scattering experiments, whose final outcome is imaged by electron microscopy. The real-time analysis of the growth process at room temperature shows the formation of a large majority of icosahedral structures by a shell-by-shell growth mode which produces smooth and nearly defect-free structures. Molecular dynamics simulations supported by ab initio calculations reveal that the shell-by-shell mode is possible because of the occurrence of collective displacements which involve the concerted motion of many atoms of the growing shell. These collective processes are a kind of black swan event, as they occur suddenly and rarely, but their occurrence is decisive for the final outcome of the growth. Annealing and ageing experiments show that the as-grown icosahedra are metastable, in agreement with the energetic stability calculations.
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Affiliation(s)
- Diana Nelli
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
| | - Cesare Roncaglia
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
| | - Riccardo Ferrando
- Dipartimento di Fisica, Università di Genova, Via Dodecaneso 33, 16146 Genova, Italy.
| | - Zeinab Kataya
- Université d'Orléans, CNRS, ICMN UMR7374, 1b rue de la Férollerie, F-45071 Orléans, France.
| | - Yves Garreau
- Synchrotron Soleil, L'Orme de Merisiers, F-91192 Gif-sur-Yvette, France
- Université de Paris, CNRS, Laboratoire Matériaux et Phénomènes Quantiques UMR7162, F-75013 Paris, France
| | - Alessandro Coati
- Synchrotron Soleil, L'Orme de Merisiers, F-91192 Gif-sur-Yvette, France
| | | | - Pascal Andreazza
- Université d'Orléans, CNRS, ICMN UMR7374, 1b rue de la Férollerie, F-45071 Orléans, France.
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Nelli D, Mottet C, Ferrando R. Interplay between interdiffusion and shape transformations in nanoalloys evolving from core-shell to intermixed structures. Faraday Discuss 2023; 242:52-68. [PMID: 36178100 DOI: 10.1039/d2fd00113f] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Nanoalloys are often grown or synthesized in non-equilibrium configurations whose further evolution towards equilibrium can take place through complex pathways. In this work, we consider bimetallic systems with tendency towards intermixing, namely AgAu, PtPd and AuCu. We analyze their evolution starting from non-equilibrium initial configurations, such as phase-separated core@shell ones, by means of molecular dynamics (MD) simulations. These systems present some differences, since AuCu bulk alloys make ordered phases at low temperature whereas AgAu and PtPd remain in solid solution. Moreover, Cu, Au and Ag have similar cohesive energies whereas Pt is much more cohesive than Pd. We consider both truncated octahedral and icosahedral initial shapes in the size range between 2 and 3 nm. For each AB system, we consider both A@B and B@A core@shell starting configurations. The evolution is characterized by monitoring the time-dependent degree of intermixing and the evolution of the shape. The simulations are performed up to temperatures close to the melting range. The approach to thermodynamic equilibrium is monitored by MD simulations and compared with the equilibrium chemical configurations obtained by Monte Carlo simulations.
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Affiliation(s)
- Diana Nelli
- Physics Department, University of Genoa, Via Dodecaneso 33, 16146, Genoa, Italy.
| | - Christine Mottet
- CINaM UMR 7325, Aix-Marseille University, CNRS, Campus de Luminy, 13288, Marseille, France.
| | - Riccardo Ferrando
- CINaM UMR 7325, Aix-Marseille University, CNRS, Campus de Luminy, 13288, Marseille, France.
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7
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Roncaglia C, Ferrando R. Machine Learning Assisted Clustering of Nanoparticle Structures. J Chem Inf Model 2023; 63:459-473. [PMID: 36597194 PMCID: PMC9875306 DOI: 10.1021/acs.jcim.2c01203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We propose a scheme for the automatic separation (i.e., clustering) of data sets composed of several nanoparticle (NP) structures by means of Machine Learning techniques. These data sets originate from atomistic simulations, such as global optimizations searches and molecular dynamics simulations, which can produce large outputs that are often difficult to inspect by hand. By combining a description of NPs based on their local atomic environment with unsupervised learning algorithms, such as K-Means and Gaussian mixture model, we are able to distinguish between different structural motifs (e.g., icosahedra, decahedra, polyicosahedra, fcc fragments, twins, and so on). We show that this method is able to improve over the results obtained previously thanks to the successful implementation of a more detailed description of NPs, especially for systems showing a large variety of structures, including disordered ones.
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Affiliation(s)
- Cesare Roncaglia
- Physics
Department, University of Genoa, Via Dodecaneso 33, 16146Genoa, Italy
| | - Riccardo Ferrando
- Physics
Department, University of Genoa and CNR-IMEM, Via Dodecaneso 33, 16146Genoa, Italy,E-mail:
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8
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Ramezanzadeh S, Akbarzadeh H, Mehrjouei E, Shamkhali AN, Abbaspour M, Salemi S. Yolk-shell nanoparticles with different cores: A molecular dynamics study. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.130019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Ball-Cup, Janus, core-shell and disordered-alloy rhodium-gold nanoparticles: An atomistic simulation on structural stability. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2022.129658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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10
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Liu J, Zhang L. Molecular dynamics simulations of the impurity effect on packing structures, local stresses, and thermodynamics of Ih silver clusters. Phys Chem Chem Phys 2022; 24:21040-21051. [PMID: 36000968 DOI: 10.1039/d2cp02814j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Molecular dynamics simulations are performed to investigate impurity effects on the changes of packing structures, atomic level pressure, and thermodynamics for icosahedral Ag clusters having 55 and 147 atoms. The simulation results indicate that, doping Cu atoms in different cluster shells can significantly affect their thermal stability and thermodynamic values. For the small size clusters, the doping in the interior apparently releases the stress, and improves the stability. The thermodynamic values of entropy and free energy can be used to indicate the order degree of the packing structures and structural transition. The shape changes are related to the local stresses at elevated temperatures.
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Affiliation(s)
- Jinhan Liu
- Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110819, China.,The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China.
| | - Lin Zhang
- The State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China. .,Department of Materials Physics and Chemistry, School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China
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11
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Vanzan M, Jones RM, Corni S, D'Agosta R, Baletto F. Exploring AuRh Nanoalloys: A Computational Perspective on the Formation and Physical Properties. Chemphyschem 2022; 23:e202200035. [PMID: 35156760 PMCID: PMC9314847 DOI: 10.1002/cphc.202200035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2022] [Revised: 02/09/2022] [Indexed: 11/12/2022]
Abstract
We studied the formation of AuRh nanoalloys (between 20-150 atoms) in the gas phase by means of Molecular Dynamics (MD) calculations, exploring three possible formation processes: one-by-one growth, coalescence, and nanodroplets annealing. As a general trend, we recover a predominance of Rh@Au core-shell ordering over other chemical configurations. We identify new structural motifs with enhanced thermal stabilities. The physical features of those selected systems were studied at the Density Functional Theory (DFT) level, revealing profound correlations between the nanoalloys morphology and properties. Surprisingly, the arrangement of the inner Rh core seems to play a dominant role on nanoclusters' physical features like the HOMO-LUMO gap and magnetic moment. Strong charge separations are recovered within the nanoalloys suggesting the existence of charge-transfer transitions.
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Affiliation(s)
- Mirko Vanzan
- Department of Chemical SciencesUniversity of PadovaVia Marzolo 135131PadovaItaly
| | - Robert M. Jones
- Department of PhysicsKing's College LondonStrandLondonWC2R 2LSUK
| | - Stefano Corni
- Department of Chemical SciencesUniversity of PadovaVia Marzolo 135131PadovaItaly
- CNR Institute of NanoscienceVia Campi 213/A41125ModenaItaly
| | - Roberto D'Agosta
- Department of Polymers and Advanced Materials: Physics, Chemistry and Technology (PMAS)Universidad del País Vasco UPV/EHUAvenida de Tolosa 7220018San SebastiánSpain
- IKERBASQUEBasque Foundation for SciencePlaza de Euskadi 548009BilbaoSpain
| | - Francesca Baletto
- Department of PhysicsKing's College LondonStrandLondonWC2R 2LSUK
- Department of PhysicsUniversity of MilanoVia Celoria 1620133MilanoItaly
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12
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Settem M, Srivastav AK, Kanjarla AK. Understanding the strain-dependent structure of Cu nanocrystals in Ag-Cu nanoalloys. Phys Chem Chem Phys 2021; 23:26165-26177. [PMID: 34797355 DOI: 10.1039/d1cp04145b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The structure of octahedral Ag-Cu nanoalloys is investigated by means of basin hopping Monte Carlo (BHMC) searches involving the optimization of shape and chemical ordering. Due to the significant size mismatch between Ag and Cu, the misfit strain plays a key role in determining the structure of Ag-Cu nanoalloys. At all the compositions, segregated chemical ordering is observed. However, the shape of the Cu nanocrystal and the associated defects are significantly different. At lower amounts of Cu (as little as 2 atom %), defects close to the surface are observed leading to a highly non-compact shape of the Cu nanocrystal which is non-trivial. The number of Cu-Cu bonds is relatively lower in the non-compact shape which is contrary to the preference of bulk Ag-Cu alloys to maximize the homo-atomic bonds. Due to the non-compact shape, {100} Ag-Cu interfaces are observed which are not expected. As the amount of Cu increases, the Cu nanocrystal undergoes a shape transition from non-compact to a compact octahedron. The associated defect structure is also modified. The structural changes due to the strain effects have been explained by calculating the atomic pressure maps and the bond length distributions. The trends relating to the structure have also been verified at larger sizes.
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Affiliation(s)
- Manoj Settem
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
| | - Ajeet K Srivastav
- Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology, Nagpur, 440010, India
| | - Anand K Kanjarla
- Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai, 600036, India. .,Ceramic Technologies Group - Center of Excellence in Materials and Manufacturing for Futuristic Mobility, Indian Institute of Technology Madras, Chennai, 600036, India
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13
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Akbarzadeh H, Mehrjouei E, Abbaspour M, Shamkhali AN, Izanloo C, Masoumi A. Pt core confined within an Au skeletal frame: Pt@Void@Au nanoframes in a molecular dynamics Perspective. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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14
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Lee HW, Jung E, Han GH, Kim MC, Kim D, Lee KY, Han SS, Yu T. Three-in-One Strategy to Improve Both Catalytic Activity and Selectivity: Nonconcentric Pd-Au Nanoparticles. J Phys Chem Lett 2021; 12:11098-11105. [PMID: 34752106 DOI: 10.1021/acs.jpclett.1c03256] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
In direct H2O2 synthesis, the Pd-Au alloy was considered as a potential catalyst because of its much better performance compared to the prototype Pd; unfortunately, achieving both high activity and selectivity remains a challenge. Here, we synthesized nonconcentric Pd-Au NPs in which Au domain shells are formed only partially on Pd domain cores and tested them for direct H2O2 synthesis. It has three exposed regions of Pd, Au domains, and Pd-Au interfaces in a single NP (hence, a 3-in-1 strategy). Creating nonconcentric forms was demonstrated convincingly by density functional theory calculations. The nonconcentric Pd-Au particles exhibit high and well-balanced performances that are hard to achieve with traditional alloyed Pd-Au. The number of Pd/Au interfaces was found to be the key factor and thus was optimized by controlling the Au precursor concentrations. The hitherto underutilized structure of nonconcentric bimetallic alloys can be useful and thus should be more actively investigated for catalyst development.
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Affiliation(s)
- Hong Woo Lee
- Computational Science Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
- Department of Chemical and Biological Engineering, Korea University, 145 Anam-ro, Seoul 02841, Republic of Korea
| | - Euiyoung Jung
- Department of Chemical Engineering, Integrated Engineering Major, Kyung Hee University, Yongin 17104, Republic of Korea
| | - Geun-Ho Han
- Department of Chemical and Biological Engineering, Korea University, 145 Anam-ro, Seoul 02841, Republic of Korea
| | - Min-Cheol Kim
- Computational Science Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Donghun Kim
- Computational Science Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Kwan-Young Lee
- Department of Chemical and Biological Engineering, Korea University, 145 Anam-ro, Seoul 02841, Republic of Korea
| | - Sang Soo Han
- Computational Science Research Center, Korea Institute of Science and Technology, Seoul 02792, Republic of Korea
| | - Taekyung Yu
- Department of Chemical Engineering, Integrated Engineering Major, Kyung Hee University, Yongin 17104, Republic of Korea
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15
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Nelli D, Pietrucci F, Ferrando R. Impurity diffusion in magic-size icosahedral clusters. J Chem Phys 2021; 155:144304. [PMID: 34654289 DOI: 10.1063/5.0060236] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Atomic diffusion is at the basis of chemical ordering transformations in nanoalloys. Understanding the diffusion mechanisms at the atomic level is therefore a key issue in the study of the thermodynamic behavior of these systems and, in particular, of their evolution from out-of-equilibrium chemical ordering types often obtained in the experiments. Here, the diffusion is studied in the case of a single-atom impurity of Ag or Au moving within otherwise pure magic-size icosahedral clusters of Cu or Co by means of two different computational techniques, i.e., molecular dynamics and metadynamics. Our simulations reveal unexpected diffusion pathways, in which the displacement of the impurity is coupled with the creation of vacancies in the central part of the cluster. We show that the observed mechanism is quite different from the vacancy-mediated diffusion processes identified so far, and we demonstrate that it can be related to the presence of non-homogeneous compressive stress in the inner part of the icosahedral structure.
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Affiliation(s)
- Diana Nelli
- Dipartimento di Fisica dell'Università di Genova, via Dodecaneso 33, Genova 16146, Italy
| | - Fabio Pietrucci
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IMPMC, 75005 Paris, France
| | - Riccardo Ferrando
- Dipartimento di Fisica dell'Università di Genova and CNR-IMEM, via Dodecaneso 33, Genova 16146, Italy
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