Melting and Freezing of Pd nanoclusters: effect of the MgO(100) substrate

C. Mottet , Jacek Goniakowski (1)

1 GPS - Groupe de Physique des Solides

Melting and freezing of supported Pd nanoclusters on MgO(1 0 0) substrate are investigated using Molecular Dynamics with semi-empirical potentials for metal–metal interactions and a potential fitted to ab initio calculations for the metal–MgO(1 0 0) ones. We show that the oxide support delays the solid–liquid transition as compared to free clusters of same size, the shift in melting temperature being increased with decreasing cluster size. We find also that the hysteresis forming when the liquid cluster is refreshed (difference between melting and solidification temperatures) decreases faster for supported clusters than for free ones, vanishing at small sizes. We find a good agreement between our simulation results and simple phenomenological models describing the decrease of melting temperature as a function of the inverse radius of the particle. The delay in melting and advance in crystallization for supported clusters compared to free ones could be simply due to a reduction of the surface to volume ratio of the supported cluster compared to that of free cluster of same size.

Mots clés: Molecular dynamics; Clusters; Palladium; Magnesium oxides

C. Mottet, Jacek Goniakowski. Melting and Freezing of Pd nanoclusters: effect of the MgO(100) substrate. Surface Science : A Journal Devoted to the Physics and Chemistry of Interfaces, 2004, 566-568 (1), pp.443. ⟨10.1016/j.susc.2004.05.083⟩. ⟨hal-00004925⟩