Melting Properties and Structural Evolution of (Agx-Pd1x)256 Bimetallic Nanoclusters Supported on SWCNT: A Molecular Dynamics Simulation

Abstract

Abstract The heating and cooling processes of (Ag x -Pd 1 x ) 256 bimetallic nanoclusters supported on single walled carbon nanotube (SWCNT) with different concentrations (x = 0, 0.25, 0.5, 0.75, 1) were studied using molecular dynamics simulations at temperature range of 200–1600 K. Furthermore, the free bimetallic nanoclusters were simulated to investigate the effects of substrate on nanoclusters properties. The melting temperature of nanoclusters was obtained by using several methods. Structural changes, atoms segregation and dynamic properties of nanoclusters were also monitored during heating and cooling processes as a function of temperature and nanocluster concentration. In this paper, investigations focused on nanoclusters structural changes and segregation of Ag and Pd atoms during the melting and freezing processes. For this aim, several useful methods such as deformation parameters, radial deformation parameters, radial distribution function, density profile, mean square displacement, and self-diffusion coefficient were employed. The hysteresis in potential curves of heating and cooling processes was observed that increased for bimetallic nanoclusters and supported cases. Furthermore, atoms segregation and surface enrichment with Ag atoms and core enrichment with Pd atoms in nanoclusters were observed during the processes and results showed that these structural changes were strongly irreversible. Moreover, the dynamic properties of nanoclusters were affected by both atoms segregation and substrate surface.