Atomistic Simulation of Segregation in Ternary Pt–Pd–Ni Nanoalloy

Abstract

The results of comparative atomistic simulation are presented for segregation and thermally induced structural transformations (melting/crystallization) in binary Pt–Pd nanoalloys and ternary Pt–Pd–Ni nanoparticles, where Ni (20 at %) acted as a doping component. Atomistic simulation was carried out using an integrated approach combining molecular dynamics and Monte Carlo methods. In addition, two independently developed computer programs, LAMMPS and Metropolis, two different parameterizations of potentials corresponding to the embedded atom method, as well as an alternative force field, the tight-binding potential, were used for the simulation. Surface segregation of Pd was observed in both binary and ternary nanoparticles consisting of 2500 and 5000 atoms. Most noticeably, doping affected structural segregation, inducing a transition from a nanocrystal consisting of several fcc grains to a nanocluster with approximately pentagonal symmetry. It has been established that the size effect is more noticeable for parameters of the melting–crystallization hysteresis than for the structural segregation patterns, that is, the division of a nanoparticle into areas corresponding to different crystal structures and the segregation of components.