Optical and structural characterization of TiO2 films doped with silver nanoparticles obtained by sol–gel method

• Nanostructured titanium oxide films with Ag nanoparticles are successfully deposited by sol–gel spin coating method.
• Structural and optical properties studied as a function of the annealing temperature and gas ambient.
• Metallic Ag without traces of silver oxides were found.

Nanostructured titanium oxide films with incorporated Ag nanoparticles were deposited by sol–gel spin coating method. The films were annealed at 300 °C, 400 °C, 500 °C and 600 °C in oxygen and nitrogen ambient. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and UV–VIS spectroscopy had been applied for studying the influence of the thermal treatments and the gas ambient on the structural and optical properties of TiO2 and TiO2:Ag films. The XRD analysis revealed the presence of metallic Ag phase without traces of silver oxides and these results were confirmed by FTIR spectra. It has been revealed that the annealing temperatures and the ambient, where the annealing is carried out is crucial for TiO2 crystallization, when there is Ag incorporation and especially for appearance of anatase and rutile phase. The nitrogen and oxygen ambient influences quite different the crystallization of TiO2:Ag films. Transmission and absorption spectra have been analyzed. Optical band gap values were evaluated for pure titania and Ag incorporated TiO2 films.