Investigation of the chemical ordering for PdnPt(32−n)Rh6 nanoalloys in TO structure

Abstract

Using basin-hopping algorithm within the quantum corrected Sutton-Chen (Q-SC) many-body potential, a systematic investigation has been performed for the best chemical ordering structures of 38-atom trimetallic PdnPt[Formula: see text]Rh6 nanoalloys with truncated octahedral (TO) geometry. The atomic mixing degrees of Pd, Pt and Rh atoms were investigated by using order parameter ([Formula: see text]). The results show that demixing is energetically favorable for the investigated structures, where the number of Rh atoms fixed at 6. The only compositions with the number of hetero bonds lower than the homo bonds are Pt[Formula: see text]Rh6, Pd1Pt[Formula: see text]Rh6, Pd[Formula: see text]Pt[Formula: see text]Rh6 and Pd[Formula: see text]Rh6 which make segregation energetically favorable. The surface segregation of Pd atoms is explained by the lower cohesive energy of Pd atoms than Pt and Rh. The segregation of Pd atoms to the surface is also associated with the smaller surface energies compared with Pt and Rh atoms. Due to the comparable cohesive energies of Rh and Pt atoms, a computation occurs for filling the octahedral core between two kinds.