Melting of metallic nanoclusters: Alloying and support effects

Alloying and support effects on melting properties of metallic clusters were studied via molecular dynamics simulations. We used a tight binding semi-empirical potential to model the metal-metal interactions and a surface energy potential fitted to ab initio calculations for the metaloxide ones in the case of Pd/MgO(100). As expected, the support interaction increases the melting temperature as compared to free clusters. However, when referred to the size of the particle (taking into account the morphological change between free and supported clusters), we show that the linear dependence of the melting temperature with the reciprocal cluster radius remains unchanged between free and supported cluster. Inversely, the alloying effect is expected to decrease the melting temperature because of the eutectic behaviour in the phase diagram. However we show that stress relief in certain bimetallic clusters drives to a higher melting point than for the pure equivalent cluster.