Preparation and characterization of Au/Co nano-alloys

In this work we attempted to prepare binary alloy nanoparticles consisting of Au and Co, which is a typical phase-separation system in a bulk phase diagram, via a vacuum co-evaporation method. The crystal structure and lattice constant of the Au/Co nano-alloys obtained were investigated by means of a high-resolution transmission electron microscope and selected area electron diffraction. We obtained thermodynamically stable Au/Co nano-alloys with A1 structure upon heat-treatment at a certain temperature, and a partial transition from A1 to an ordered L10 structure also took place. The results in the present study demonstrated the thermodynamical differences on alloying behavior between bulk and nanoscopic materials.