Anisotropic stress release leads to structural transitions in AuPd nanoalloys D. Nelli 1 , C. Roncaglia 1 , C. Minnai 2 and R. Ferrando 1 1 Physics Department, University of Genoa, Italy, 2 OIST, Onna-son, Kunigami-gun, Japan Shape transformations in Pd-rich AuPd nanoalloys are studied by growth experiments and computer simulations. It is shown that increasing the Au content, a structural transformation from fcc truncated octahedra to icosahedra takes place [1]. The transition is sharper for growth conditions closer to equilibrium. The driving forces of the transition are singled out with the aid of computer simulations, specifically global optimization searches and free energy calculations within the harmonic superposition approximation. These calculations show that there is a reversal of the energetic stability between fcc and icosahedral structures when increasing the Au content. In addition, atomic stress calculations demonstrate that the introduction of Au impurities in the surface causes a better relaxation of the anisotropic surface stress in icosahedra than in fcc nanoparticles, which is at the origin of the observed shape transformation. References 1. D. Nelli, C. Roncaglia, R. Ferrando and C. Minnai, J. Phys. Chem. Lett., 2021, 12 , 4609-4615.
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