Field-assisted ion diffusion of transition metals for the synthesis of nanocomposite silicate glasses

Field-assisted ion diffusion of metals was realized for the controlled doping of silicate glasses. Metallic films deposited onto the substrates by the rf-sputtering technique were used as the metal ions source. In particular, cobalt was, for the first time, introduced into a soda-lime glass by field-assisted ion exchange, giving rise to diffusion profiles that were observed to depend on the preparation parameters, namely, temperature and electric field intensity across the samples. This technique, which allowed to dope the glass matrix with high metal concentration values, can be used as the first step in combined methodologies for the preparation of nanostructured glass composites. The shape of the measured Co diffusion profiles indicates that the migration process depends not only on the experimental parameters but also on the behavior of alkali ions within the glass. Chemical phenomena occurring at the metal/glass interface also play a significant role in the penetration of the Co ions. The possibility of doping the glass with two different metal species was also investigated, with the aim to create the condition for the formation of core-shell or alloy nanoclusters. In particular, preliminary results on Co+Au field-assisted co-diffusion are presented.