Au@void@AgAu Yolk–Shell Nanoparticles with Dominant Strain Effects: A Molecular Dynamics Simulation

Abstract

Au@void@AgAu yolk-shell nanoparticles with different morphologies were studied by classical molecular dynamics simulation. The results indicated that all of simulated yolk-shell nanoclusters with ∼3.8 nm size and different morphologies are unstable at room temperature, and collapse of the shell atoms into the void space completely fills it and creates more stable Au@AgAu core-shell structures. Also, it was observed that thermodynamic stabilities of the created core-shell structures strongly depend on the morphology of nanocluster, for which competition between strain and surface energy effects plays the key role in this phenomenon. Within this competition, strain effect is dominant and helps the stability of the created core-shell structure. Herein, the icosahedral nanocluster with the lowest strain effect exhibits the highest thermodynamic stability. By comparing the simulation results with experimental data, it was concluded that the essential factor that controls the stability of these nanoparticles is their size.

Understanding the Stability of Hollow Nanoparticles with Polycrystalline Shells

“…The stability of polycrystalline Au hNPs was investigated through MD simulations. While shell thickness and radius are commonly referenced as the relevant parameters to characterize hNPs, ,,,,− the presented simulations allow us to conclude that the grain boundary structure also plays a dominant role in their structural stability. In particular, it was found an inverse dependence on the stable/half-stable transition with the grain size reduction.…”

“…Lately, Akbarzadeh et al. , discuss the role of dominant surface effects, while Reyes et al note that metallic hNPs with lower stacking fault (SF) energy are prone to the structural collapse.…”

“…To the best of our knowledge, all the available atomistic studies of thermal and mechanical stability ,,− consider single-crystal hNPs, something difficult to obtain under realistic experimental conditions. In fact, for single-crystal hNPs, the failure is triggered by the slips of preferential planes due to surface stresses, , in the absence of other plasticity sources, and the stability of pristine samples can be idealized.…”

“…20−24 The first contribution employing MD simulations was made by Jiang et al 24 in Au hNPs; their work highlight that an Au hNP with a relatively large diameter in comparison with their thickness tends to be unstable or collapse even at room conditions. Lately, Akbarzadeh et al 25,26 discuss the role of dominant surface effects, while Reyes et al 23 note that metallic hNPs with lower stacking fault (SF) energy are prone to the structural collapse.…”

Pt–Co nanocluster in hollow carbon nanospheres

“…The temperature of the systems was controlled using Nosé–Hoover thermostat with a relaxation time of 0.1 ps. Previous works have also used successfully the same relaxation time for this thermostat . To investigate whether our systems have been achieved the equilibrium and stability, we have drawn the graphs of configurational energy, total energy, and temperature versus the simulation time for the different systems considered in this work and presented in Supporting Information Figures S5–S7.…”