Tug-of-War in Nanoparticles: Competitive Growth of Au on Au-Fe3O4 Nanoparticles

Mechanical property of dumbbell-like Au-Fe3O4 nanoparticles (NPs) is investigated from a synthetic point of view by overgrowing Au-2 on the Au-1-Fe3O4 NPs. The competitive growth of Au-2 on the preformed Au-1-Fe3O4 NPs induced an interesting tug-of-war between Au-2 and Fe3O4 in the formed Au-2-Au-1-Fe3O4 ternary nanostructure. An interpretation of the observed phenomena is proposed based on a mechanical analysis of the stress and strain distribution across the nanoparticle, which is further verified by control experiments with particle size tuned.