Segregation, core alloying, and shape transitions in bimetallic nanoclusters: Monte Carlo simulations

The stable structures and melting behaviors of silver-rich bimetallic clusters (Ag0.75M0.25)(N), where M=Au, Pt, and Ni, and containing up to N=309 atoms, were investigated by exchange Monte Carlo simulations. Ag-Au clusters are stable as a solid solution equilibrium phase below their melting point. Ag-Pt clusters exhibit a continuous transition from core/shell to alloy core/pure Ag shell. Ag-Ni clusters display a peculiar transformation to prolate shapes before the nickel core melts by alloying with silver at higher temperatures. All of these results are consistent with available experimental measurements.