Diffusion behavior of Ag in TiO2 nanofilms

Using magnetron sputtering, Ag/TiO2 bilayer nanofilms were deposited on glass substrates. Heat-treating the Ag/TiO2 nanofilms at 400 °C led to the formation of Ag nanoparticles, which dispersed inside the TiO2 films as well as the free surface of the TiO2 films. After heat treatment the sample at 500 °C, larger Ag nanoparticles could be observed on the surface, which means the particle size after heat treatment is temperature related. Anatase TiO2 phase was formed after the Ag/TiO2 films were heat-treated at 400 °C. SEM and TEM were used to investigate the morphology and structure of the films and it was found that Ag was not oxidized during heat treatment. The diffusion process of Ag in TiO2 film is also related to the order of Ag layer and TiO2 layer on glass substrate. Moreover, the diffusion process is much easier in amorphous than that in anatase structure.