Synthesis and characterization of ion-implanted Pt nanocrystals in SiO2

Pt nanocrystals (NCs) produced by ion implantation in SiO2 films were investigated by Rutherford backscattering spectroscopy (RBS), transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The implantations were performed at liquid nitrogen temperature using energies between 3.4 and 5.6 MeV and an ion fluence range of 2-30 x 10(16) cm(-2) and were followed by annealing in forming gas (95% N-2, 5% H-2) for one hour at temperatures between 500 and 1100 degrees C. TEM analysis revealed that the NCs are spherical in shape. The mean size of the NCs annealed at 1100 degrees C varied between 2.8 and 3.6 nm for the highest and lowest fluences, respectively, as determined with both TEM and SAXS. In contrast to previous studies on ion implanted metal NCs, larger Pt NCs are located far beyond the Pt peak concentration, potentially the result of a strongly defect mediated NC nucleation. (c) 2006 Elsevier B.V. All rights reserved.