Stable icosahedral nanoparticles in an as-grown Au-Fe alloy

The morphologies of Au-Fe alloy nanoparticles with an 11% Fe mean atomic co ncentration were investigated by means of high-resolution electron microsco py. The icosahedral morphology was very frequently found in the particles t hat were generated by the vapor condensation method with helium and deposit ed on an amorphous carbon film. A high fraction of the icosahedral morpholo gy still remained even after the supported particles were annealed at 723 K for Ih in a vacuum; this suggests the minimum-energy structure for the all oy particles is icosahedral. As for the low production rate of the icosahed ral morph ology in the pure Au particles produced under the same conditions , the present results indicate that the icosahedral form is stabilized by t he addition of Fe atoms into the Au particles.