Effects of epitaxial strain on the melting of supported nickel nanoparticles
D Schebarchov and SC Hendy, PHYSICAL REVIEW B, 84, 085407 (2011).
We use molecular dynamics to investigate the effects of substrate- induced epitaxial strain on the melting temperature and equilibrium structure of supported metal nanoparticles. Our model system comprises Ni clusters supported on strained graphene. The clusters are modeled using an embedded atom potential, and the nickel-carbon interactions are described by a Lennard-Jones field with one parameter varied to control the substrate binding strength. We find that, after adjusting for curvature effects due to the clusters' free surface, the melting temperature of supported Ni clusters can shift by hundreds of degrees depending on the cluster-substrate epitaxial relationship. The order of magnitude of this effect is shown to be consistent with prior predictions based on thermodynamic modelling. We also find that sufficiently strong substrate binding leads to a solid-solid transition from icosahedral to lamellar-twinned fcc particles, which occurs via a melt-freeze process. These results illustrate how substrate-induced epitaxial strain can be used to control the phase of metal nanoparticles.
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