The FTIR studies of gels and thin films of Al2O3–TiO2 and Al2O3–TiO2–SiO2 systems

In this work, samples in form of bulk ones and thin films were obtained using the sol–gel method. The bulk samples were heated at different temperatures (500 °C, 850 °C and 1100 °C) corresponding to the annealing process of coatings, deposited on different substrates by dipping and pulling out samples from the proper sol with the stable speed. Thin films of both Al2O3–TiO2 and Al2O3–TiO2–SiO2 systems were deposited on carbon, steel and titanium substrates in two different ways: as single layers obtained from Al2O3 sol, TiO2 sol and Al2O3 sol or deposited as mixed coatings from Al2O3–TiO2 sol as well as Al2O3–TiO2–SiO2 one.All bulk samples were studied by the FTIR spectroscopy and the X-ray diffractometry while thin films were also investigated by the electron microscopy.In the IR spectra of Al2O3–TiO2 samples, as well as gels and coatings, bands due to the vibrations of AlO bonds of the octahedrally and tetrahedrally coordinated aluminum were observed.The IR spectra of samples of Al2O3–TiO2–SiO2 system differ from that of Al2O3–TiO2 ones in presence of bands assigned to the SiO bond vibrations and in positions of bands due to AlO bond vibrations. In all spectra of bulk samples and coatings, the positions of TiO bond vibrations were ascribed basing on the IR spectra of the pure anatase and rutile.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The bulk samples and thin films from Al2O3–TiO2 and Al2O3–TiO2–SiO2 systems. ► Amorphous and homogenous materials up to 500 °C. ► Al in octahedral coordination. ► Al in tetrahedral coordination when substitutes Si.