The structural studies of Ag containing TiO2–SiO2 gels and thin films deposited on steel

• The synthesis of SiO2 and TiO2–SiO2 containing Ag thin films.
• FTIR studies of SiO2, SiO2/Ag, TiO2–SiO2 and TiO2–SiO2/Ag gels and thin films.
• XRD phase analysis of SiO2, SiO2/Ag, TiO2–SiO2 and TiO2–SiO2/Ag gels.
• The morphology and structure of thin films surface described by SEM and AFM methods.
• The estimation of silver particles dimensions as 6–35 nm applying AFM method.

FTIR spectroscopic structural studies of titania-silica monolith samples as well as thin films deposited on steel were described in this work. Thin films were synthesized by the sol–gel method applying the dip coating as separate one-component TiO2 and/or SiO2 layers or as two-component TiO2–SiO2 thin films. Silver nanoparticles were incorporated into the structure from pure SiO2 sol, deposited then as an additional layer in those hybrid multilayers systems. Except the spectroscopic studies, XRD diffraction, SEM microscopy with EDX analysis and AFM microscopy were applied. The structural studies allow to describe and compare the structure and the morphology of thin films, as well those Ag free as Ag containing ones, also by the comparison with the structure of bulk samples. In FTIR spectra, the band observed at about 613 cm−1 can be connected with the presence of the non-tetrahedral cation in the structure and is observed only in the spectra of Ag containing bulk samples and thin films. The bands at 435–467 cm−1 are due to the stretching vibrations of Ti–O bonds or as well to the bending vibrations of O–Si–O one. In the ranges of 779–799 cm−1 and 1027–1098 cm−1, the bands ascribed to the symmetric stretching vibrations and asymmetric vibrations of Si–O–Si connections, respectively, are observed. SEM and AFM images gave the information on the microstructure and the topography of samples surface. XRD measurements confirmed the presence of only amorphous phase in samples up to 500 °C and allowed to observe the tendency of their crystallization.

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