Shape Changes in AuPd Alloy Nanoparticles Controlled by Anisotropic Surface Stress Relaxation

The shape of AuPd nanoparticles is engineered by surface stress relaxation, achieved varying the Au content in Pd-rich compositions. are grown gas phase for several compositions and growth conditions. Their structure atomically resolved HRTEM/STEM EDX. In pure Pd distributions dominant structures FCC truncated octahedra (TO), while increasing there a transition to icosahedral (Ih) which atoms preferentially placed at nanoparticle surface. sharper conditions closer equilibrium. physical origin determined with aid computer simulations. Global optimization searches free energy calculations confirm that Ih become equilibrium content. Atomic demonstrate TO → change caused better relaxation anisotropic icosahedra.