The formation of FecoreAlshell and FeshellAlcore nanoparticles, a molecular dynamics simulation

According to the surface segregation theory, bimetallic nanoparticles can easily form core-shell configuration. An atom with low surface energy and large atomic size distributes on the surface of the nanoparticle, and another atom occupies the internal position. In the present work, the diffusion and growth configuration of Fe-Al nanoparticles are examined. The calculated energy barriers for the interfacet diffusion via the hopping or the exchange mechanisms are larger than that for the intrafacet diffusion. The result suggests that both FecoreAlshell and FeshellAlcore nanoparticles can be obtained at proper temperatures. The growths of the Fe and Al adatoms on the icosahedron of Al and the rhombohedron of Fe are simulated by molecular dynamics along with embedded atom methods in the temperature range of 100-300 K. FeshellAlcore, a reversed core-shell configuration, is obtained at low temperatures.