Annealing behavior of silver, copper, and silver–copper nanoclusters in a silica matrix synthesized by the sol-gel technique

Abstract

Silver, copper, and mixed silver–copper nanocluster-doped silica thin layers were prepared by the sol-gel process. Samples were heat treated in different annealing atmospheres (air, argon, or 5%H2–95%N2) in the temperature range 500–1100 °C. Specimens were characterized by optical absorption spectroscopy, Rutherford backscattering spectrometry, x-ray diffraction, and transmission electron microscopy. Cluster growth and dissolution, as well as migration of metal atoms towards the sample surface, with a subsequent evaporation, were observed to occur at temperatures that depend on the annealing atmosphere. In the mixed silver–copper system, the formation of Ag–Cu phase-separated clusters was observed.