Competition of core-shell and Janus morphology in bimetallic nanoparticles: Insights from a phase-field model

P, Pankaj; Bhattacharyya, Saswata; Chatterjee, Subhradeep

doi:10.1016/j.actamat.2022.117933

Cited by 6 publications

(18 citation statements)

References 87 publications

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“…In the EPFM formalism [10] illustrated schematically in Fig. 1, a BNP system consisting of atomic species A and B is modeled by placing an isolated particle (β ) in an inert matrix (α).…”

Section: Model Formulationmentioning

confidence: 99%

“…A scaled composition field c describes phase separation of an initially homogeneous β to a mixture of β 1 and β 2 phases with equilibrium compositions c e ) for the scaling where X denotes the mole fraction of B and X β i is the equilibrium composition of phase β i at a given temperature. An auxiliary non-conserved phase-field variable φ is used to distinguish the particle from the matrix; we use a stationary and radially symmetric tanh profile for φ that varies smoothly across the particle surface from 0 in the matrix side to 1 inside the particle [10]. Total free energy of the system is then expressed as:…”

Section: Model Formulationmentioning

confidence: 99%

“…Defining an interpolating function h(φ ) = φ 3 (10 − 15φ + 6φ 2 ) that connects α and β (with φ being 0 and 1 inside α and β , respectively), the bulk free energy density f is given as 2 describes the free energy barrier between α and β , ω 0 sets the barrier height and χ controls solute segregation at the particle-matrix interface [10]. We use the following forms of free energy for α and β :…”

Section: Model Formulationmentioning

confidence: 99%

“…We non-dimensionalize all parameters in the equations using characteristic length L c , time τ c and energy E c . Details of the non-dimensionalization procedure are provided Supplementary Information A; further details of the model and its numerical implementation can be found elsewhere [10].…”

Section: Model Formulationmentioning

confidence: 99%

“…exhibit solid-state immiscibility, spinodal decomposition (SD) presents a likely kinetic pathway for morphology development in BNPs [9]. Recently, an embedded-domain phase-field model (EPFM) was employed [10] to study morphological development in BNPs through SD and understand how contact angle and particle size influence it.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Surface-directed and bulk spinodal decomposition compete to decide the morphology of bimetallic nanoparticles

Pankaj,

Bhattacharyya,

Chatterjee

2022

Preprint

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An embedded-domain phase-field formalism is used for studying phase transformation pathways in bimetallic nanoparticles (BNPs). Competition of bulk and surface-directed spinodal decomposition processes and their interplay with capillarity are identified as the main determinants of BNP morphology. The former is characterized by an effective bulk driving force ∆ f which increases with decreasing temperature, while the latter manifests itself through a balance of interfacial energies captured by the contact angle θ . The simulated morphologies, namely, core-shell, Janus and inverse core-shell, cluster into distinct regions of the ∆ f -θ space. Variation of θ with ∆ f in the Ag-Cu alloy system is computed as a function of temperature using a CALPHAD approach in which surface energies are estimated from a modified Butler equation. This θ − ∆ f trajectory for Ag-Cu, when superimposed on the morphology map, enables the prediction of different morphological transitions as a function of temperature. Therefore, the study establishes a unique thermodynamic framework coupled with phase-field simulations for predicting and tailoring nanoparticle morphology through a variation of processing temperature.

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“…In the EPFM formalism [10] illustrated schematically in Fig. 1, a BNP system consisting of atomic species A and B is modeled by placing an isolated particle (β ) in an inert matrix (α).…”

Section: Model Formulationmentioning

confidence: 99%

Section: Model Formulationmentioning

confidence: 99%

Section: Model Formulationmentioning

confidence: 99%

Section: Model Formulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Surface-directed and bulk spinodal decomposition compete to decide the morphology of bimetallic nanoparticles

Pankaj,

Bhattacharyya,

Chatterjee

2022

Preprint

Self Cite

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Transformation of oxide nanoparticles in a nickel-based ODS alloy aged at 1000 °C

Mao,

Li,

Liu

et al. 2023

J Mater Sci

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Capping Layer Determined Self-assembly of Au–Ag Bimetallic Janus Nanoparticles at An Oil/Water Interface by Molecular Dynamics Simulations

Zhang,

Jia,

Zhang

et al. 2023

J. Phys. Chem. B

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Bimetallic Janus nanoparticles (BJNPs) have gained more attention due to their unique catalytic and optical properties. The self-assembly of BJNPs is expected as an effective way to fabricate metamaterials suitable for different potential applications. However, the self-assembly dynamic process of BJNPs, which is key to achieving a controllable synthesis, is limited in both experimental and theoretical investigations. Herein, all-atom molecular dynamics (MD) simulations were employed to investigate the self-assembly process of 1-dodecanethiol (DDT)decorated Au−Ag BJNPs at an oil−water interface. We demonstrate that DDT's van der Waals (vdW) interaction dominates the self-assembly process. BJNPs form close-packed structures at both fast and slow evaporation rates. Au−Ag BJNPs exhibit relatively larger rotations at a low evaporation rate than those at a high evaporation rate, suggesting that the evaporation rate influences the orientation of the Au−Ag BJNPs. BJNPs tend to orient their electric dipole moments toward the external electric field, according to the ab initio MD simulation results. Based on the energy comparison and model analysis, it is found that the parallel array is more stable than the antiparallel one for the Au−Ag BJNP arrays. The dipole−dipole interaction difference between the parallel and antiparallel BJNP arrays obtained according to dipole moment obtained from ab initio calculation is qualitatively consistent with that obtained from MD simulations, indicating that the dipole plays a decisive role in determining the orientation of the BJNP array. This work uncovers the self-assembly dynamic process of BJNPs, paving the way for future applications.

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Competition of core-shell and Janus morphology in bimetallic nanoparticles: Insights from a phase-field model

Cited by 6 publications

References 87 publications

Surface-directed and bulk spinodal decomposition compete to decide the morphology of bimetallic nanoparticles

Surface-directed and bulk spinodal decomposition compete to decide the morphology of bimetallic nanoparticles

Transformation of oxide nanoparticles in a nickel-based ODS alloy aged at 1000 °C

Capping Layer Determined Self-assembly of Au–Ag Bimetallic Janus Nanoparticles at An Oil/Water Interface by Molecular Dynamics Simulations

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