Formation of Au−Ag Core−Shell Nanostructures in Silica Matrix by Sequential Ion Implantation

Abstract

Formation of Au core-Ag shell bimetallic nanoparticles in silica matrix is demonstrated through sequential implantation of Ag and Au ions and subsequent thermal annealing. Formation of core-shell structures is verified through optical absorption spectroscopy, high-resolution transmission electron microscopy, electron energy loss spectroscopy, and simulated optical extinction spectra. A mechanism for the formation of such unusual structures in ion-implanted silica is proposed. By controlling the implantation energy of the two ions properly and keeping the implantation sequence Ag first and then Au, it is possible to create Au core-Ag shell nanoparticles in the silica matrix with homogeneous distribution.