Eur. Phys. J. B 74, 379-390 (2010)
https://doi.org/10.1140/epjb/e2010-00086-5

Structures, thermal stability, and melting behaviors of free-standing pentagonal multi-shell Pd-Pt nanowires

Physique des Solides Irradiés et des Nanostructures, CP234, Faculté des Sciences, Université Libre de Bruxelles, Bd du Triomphe, 1050 Bruxelles, Belgium

Corresponding author: dcheng@ulb.ac.be

Received: 17 September 2009
Revised: 15 January 2010
Published online: 9 March 2010

Abstract

Classical molecular dynamics and Metropolis Monte Carlo simulations were carried out to investigate the thermal stability and melting behaviors of free-standing Pd-Pt bimetallic nanowires (NWs) with pentagonal multi-shell-type (PMS-type) structure in the whole composition range. Equilibrium configurations at 100 K are predicted in the semi-grand canonical ensemble. Pd-Pt PMS-type NWs are stable with a multishell structure of alternating Pd and Pt compositions and Pd segregating systematically to the surface. On thermal heating, an interesting composition-dependent structural transformation from the PMS-type to face-centred-cubic (FCC) by overcoming a high energy barrier is observed for Pd-Pt bimetallic NWs before the melting. Consequently, the system energy is decreased. The FCC structure is found more stable than PMS-type over the whole range of composition. The melting of Pd-Pt bimetallic NWs is also studied. It is found to start at the edges, then propagate over the whole surface, and next to the interior. It occurs in a composition-dependent range of temperature.