THERMAL STABILITY of ICOSAHEDRAL SHAPED PdmPt(13-m)Ag42 TERNARY NANOALLOYS: A MOLECULAR DYNAMICS STUDY

In this study, the structural and dynamical properties of 55 atom PdmPt(13-m)Ag42 ternary nanoalloys were investigated theoretically. In atomistic simulations, the Gupta many-body potential has been employed to describe the interatomic interactions [1][2]. The global minimum optimizations were performed by using the Basin-hopping algorithm [3]. It was resulted that all compositions of PdmPt(13-m)Ag42 ternary nanoalloys were obtained as icosahedral. Silver atoms predominantly segregate to the surface due to the lower surface and cohesive energy in comparison with palladium and platinum. We used classical Molecular Dynamics (MD) simulations in canonical ensemble conditions (NVT) to investigate the melting temperatures of ternary PdmPt(13-m)Ag42 nanoalloys. MD simulations were performed by DL_POLY_4 software [4]. The optimized icosahedral structures were taken as the initial configurations for MD simulations. The heating was started from Global Minimum structure to 1300 K with the increments of 1 K for avoiding the large temperature fluctuations. The traditional indicators of melting, Lindemann criterion and caloric curves were used to determine the melting temperatures. No simple correlation has been determined between alloy composition and melting temperatures. The highest melting temperature is about 734 K for Pd9Pt4Ag42 composition. Pd8Pt5Ag42 is the most stable composition according to the relative stability investigation. The simulation results showed that the melting takes place as a whole without any surface premelting.