Molecular dynamics simulations on the melting, crystallization, and energetic reaction behaviors of Al/Cu core-shell nanoparticles

Abstract

Using molecular dynamics simulations combined with the embedded atom method potential, we investigate the heating, cooling, and energetic reacting of core-shell structured Al-Cu nanoparticles. The thermodynamic properties and structure evolution during continuous heating and cooling processes are also investigated through the characterization of the total potential energy distribution, mean-square-distance and radial distribution function. Some behaviors related to nanometer scale Cu/Al functional particles are derived that two-way diffusion of Al and Cu atoms, glass phase formation for the fast cooling rate, and the crystal phase formation for the low cooling rate. Two-way atomic diffusion occurs first and causes the melting and alloying. In the final alloying structure, Cu and Al atoms mixed very well except for the outmost shell which has more Al atoms. For the investigation of the thermal stability and energetic reaction properties, our study show that a localized alloying reaction between the Al core and Cu shell is very slow when the initial temperature is lower than 600 K. But a two-stage reaction may occur when the initial temperature is 700 K. The reaction rate is determined by the solid-state diffusion of Al atoms in the Cu shell at the first stage, yet the reaction rate is much faster at the second stage, due to the alloying reaction between the liquid Al core and the Cu shell. At higher temperatures such as 800 K and 900 K, the alloying reaction occurs directly between the liquid Al core and the Cu shell.

Ignition and Oxidation of Core–Shell Al/Al2O3 Nanoparticles in an Oxygen Atmosphere: Insights from Molecular Dynamics Simulation

“…Generally, the melting point is defined as the temperature where sharp variations occur in the potential energy, translational order parameter, or radial distribution function profile. , In the current study, the inflection point in MSD was adopted to predict the melting . This point indicates the transition from solid to liquid analogously to phase transition in macroscopy.…”

Tunable mechanical and thermal properties of ZnS/CdS core/shell nanowires

“…In recent years, many experimental investigations have been carried out to synthesize and characterize different kinds of core/shell structures such as ZnO/ZnS [13], ZnO/CdS, [14] GaN/GaP, ZnO/TiO2 [15,16], CdSe/CdS [17,18], PbSe/CdSe [19,20], ZnS/CdS [21][22][23][24][25], CdS/ZnS [21,26,27], Ge/Si [28]. Both the classical molecular dynamics (MD) and density functional theory (DFT) methods have been used extensively to study the electronic [29][30][31][32][33][34][35], optical [29,36] and thermal [37][38][39][40][41][42][43][44][45][46][47][48] properties of the core/shell nanostructures. In contrast, mechanical properties of the core/shell nanostructures have so far not been investigated in details.…”

Simulation and Experimental Study of the Multisized Silver Nanoparticles Sintering Process Based on Molecular Dynamics

“…The atomic potential energy of silver nanoparticles during the melting process was calculated, and the temperature at which the atomic potential energy increased sharply was regarded as the melting point [ 32 , 33 ]. The atomic potential energy per atom instead of atomic potential energy was used in this work to better understand the size effects on the thermal stability of silver nanoparticles.…”