Ion irradiation for controlling composition and structure of metal alloy nanoclusters in SiO2

An elemental selective de-alloying in Au–Ag nanometer sized clusters prepared by ion implantation has been found upon irradiation with ions of smaller atomic mass. Irradiation with He, Ne, Ar or Kr ions promotes a preferential extraction of Au from the alloy, resulting in the formation of Au-enriched satellite particles around the original AuxAg1−x clusters. The role played by the irradiation parameters (i.e. dose and energy of the implanted ions) has been systematically investigated. A correlation between the nuclear component of the energy released by the irradiating ions and the size of the satellite clusters is found. While the maximum distance of satellite cluster is correlated to the radiation dose.