A comparative study of heat-treated Ag:SiO2 nanocomposites synthesized by cosputtering and sol-gel methods

In this work, we compared formation and properties of heat-treated Ag nanoparticles in silica matrix synthesized by RF-reactive magnetron cosputtering and sol-gel methods separately. The sol-gel and sputtered films were annealed at different temperatures in air and in a reduced environment, respectively. The optical UV-visible spectrophotometry have shown that the absorption peak appears at 456 and 400 nm wavelength indicating formation of silver nanoparticles in SiO2 matrix for both the sol-gel and sputtering methods at 100 and 800 degrees C, respectively. XPS measurements showed that the metallic Ago nanoparticles can be obtained from both the techniques at these temperatures. According to XPS and AFM analysis, by increasing annealing temperature, the concentration of the Ag nanoparticles on the surface decreased and the nanoparticles diffused into the substrate for the sol-gel films, while for the films deposited by cosputtering method, the Ag surface concentration increased by increasing the temperature. Based on AFM observations, the size of nanoparticles on the surface were obtained at about 25 and 55 nm for sputtered and sol-gel films, respectively, supporting our optical data analysis. In comparison, the sputtering technique can produce Ag metallic nanoparticles with a narrower particle size distribution relative to the sol-gel method. Copyright (C) 2008 John Wiley & Sons, Ltd.