Fabrication of Cu-coated Ag nanocrystals in silica by sequential ion implantation

Metal nanocrystal glass composites were fabricated by single and sequential element implantations of Ag+ and Cu+ ions into high purity silica. Implantation doses (x10(16) ions/cm(2)) were 3Ag, 9Cu and 3Ag/9Cu. Composites were analyzed using Rutherford backscattering techniques (RBS), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and optical spectroscopy. An optical density spectrum based on the size distribution observed in the sequentially implanted sample for Cu shell and Ag core nanocrystals has been calculated using the dipole and quadrupole terms in a Mie series summation and is compared with the observed absorption spectrum. Results from TEM and EDS as well as the optical simulations demonstrate that Cu shell and Ag core nanocrystals are formed by the sequential implantation of Ag and Cu. (C) 2000 Elsevier Science B.V. All rights reserved.