Stability and magnetic behaviour of 19-, 23- and 26-atom trimetallic Pt–Ni–Ag nanoalloys

Abstract

A systematic investigation of Pt2NinAg17-n, Pt3NinAg20-n and Pt4NinAg22-n trimetallic nanoalloy systems has been performed. We are particularly interested in learning the effect of systematic Ni atom addition on the stability, chemical ordering and magnetic behaviour of the nanoalloys. We have performed Gupta and Density Functional Theory (DFT) approaches on chosen systems. Our excess energy analysis showed that the most stable structure of the 19-, 23- and 26-atom nanoalloy systems found at Gupta level does not agree with those of DFT. However, DFT results confirm the Gupta level calculations for the lowest energy structures of the trimetallic systems with small shifts on bond lengths. We have computed the order parameter (R) and it was observed that Ag atoms prefer to locate on the surface and Pt atoms mostly prefer to locate in the inner site of the trimetallic nanoalloys. Besides, inner sites are heavily compressed with the substitution of Ni atoms for most compositions. It was also obtained that total magnetic moment of the nanoalloys follows an almost linear dependence on the Ni atom concentration. Thus, it can be said that total magnetic moment can be enhanced by ternary alloying with 3d magnetic element like Ni.