Structural and thermal stabilities of Au@Ag core-shell nanoparticles and their arrays: A molecular dynamics simulation*

Abstract

Thermal stability of core-shell nanoparticles (CSNPs) is crucial to their fabrication processes, chemical and physical properties, and applications. Here we systematically investigate the structural and thermal stabilities of single Au@Ag CSNPs with different sizes and their arrays by means of all-atom molecular dynamics simulations. The formation energies of all Au@Ag CSNPs we reported are all negative, indicating that Au@Ag CSNPs are energetically favorable to be formed. For Au@Ag CSNPs with the same core size, their melting points increase with increasing shell thickness. If we keep the shell thickness unchanged, the melting points increase as the core sizes increase except for the CSNP with the smallest core size and a bilayer Ag shell. The melting points of Au@Ag CSNPs show a feature of non-monotonicity with increasing core size at a fixed NP size. Further simulations on the Au@Ag CSNP arrays with 923 atoms reveal that their melting points decrease dramatically compared with single Au@Ag CSNPs. We find that the premelting processes start from the surface region for both the single NPs and their arrays.

Computational understanding of the coalescence of metallic nanoparticles: a mini review

“…Jia et al studied the structural and thermal stability of single Au@Ag nanoparticles with different sizes and their arrays by MD simulations. 79 They found that the pre-melting processes start from the surface region for both the single nanoparticles and their arrays. The melting points of Au@Ag core-shell bimetallic nanoparticles showed a feature of non-monotonicity with increasing core size at a fixed nanoparticle size.…”

Surface Evolution of Cu–Ag Bimetallic Systems: From Experiments to Molecular Dynamics Simulation

“…Subsequently, Cu–Ag materials were heated from 300 to 1500 K in 1 ns (10 –9 s) with 1.2 K/ps. Finally, the open visualization tool (OVITO) was used to analyze the surface evolution of models during the sintering process …”

“…Finally, the open visualization tool (OVITO) was used to analyze the surface evolution of models during the sintering process. 31 Characterization. X-ray diffraction (XRD) phase analysis of the Cu−Ag particles was recorded using a Bruker D8 ADVANCE diffractometer (Bruker Co., Ltd., Billerica, America) with Cu Kα as the radiation source.…”

Sintering reaction and microstructure of MAl (M = Ni, Fe, and Mg) nanoparticles through molecular dynamics simulation*

“…[1,2] Considering the synergistic effects among metals, bimetallic nanoclusters are eliciting more research interest than monometallic ones. [3,4] Generally, the physical and chemical properties of binary metal clusters can be altered by varying their composition, atomic distribution, and structure, [5,6] enabling potential applications such as in catalysis fuel cells and hydrogen storage. [7] The structure types of bimetallic nanoalloys primarily include mixed structure, segregation structure, core-shell structure, and onion-like three-layer structure.…”