IRRADIATION-INDUCED AG-COLLOID FORMATION IN ION-EXCHANGED SODA-LIME GLASS

Ion-exchanged glass samples were obtained by immersing soda-lime slides in molten salt baths of molar concentration in the range 1-20% AgNO3 in NaNO3, at temperatures varying from 320 to 350 degrees C, and processing times of the order of a few minutes. Irradiations of exchanged samples were subsequently performed by using H+, He+, N+ ions at different energies in order to obtain comparable projected ranges. The fluence was varied between 5 x 10(15) and 2 X 10(17) ions/cm(2). Most of the samples were treated at current densities lower than 2 mu A/cm(2), in order to avoid heating effects. Some samples were irradiated with 4 keV electrons, corresponding to a range of 250 nm. The formation of nanoclusters of radii in the range 1-10 nm has been observed after irradiation, depending on the treatment conditions. The precipitation process is governed by the electronic energy deposition of incident particles. The most desirable results are obtained for helium implants. The process was characterized by the use of Secondary Ion Mass Spectrometry (SIMS) and nuclear techniques (Rutherford Backscattering (RES), Nuclear Reactions (NRA)), in order to determine concentration-depth profiles and by optical absorption and Transmission Electron Microscopy (TEM) measurements for the silver nanoclusters detection and size evaluation.