We present a simple and reproducible method to obtain TiO2 and Fe2O3 mixed-oxide thin films by reactive radio-frequency sputtering. The influence of iron concentration on the structural properties of the layers has been studied. Structural characterization, carried out by electron microscopy analysis, allowed one to correlate the inhibition of the grain growth of titania to the presence of iron oxide and to its segregation at grain boundaries. This behavior should be ascribed to a superficial-tension phenomenon. As a possible application of these thin films, we have investigated the gas-sensing properties toward CO, with particular focus on the role of Fe. The layers were capable to sense CO down to the level requested for environmental monitoring.

TiO2and W:TiO2 thin films have been prepared by a chemically modified sol-gel technique, that implies hydrolysis and condensation of tetraethylortotitanate in the presence of a polymer dissolved in ethanol. Oxide-polymer films were deposited by dip-coating. Annealing at 500°C results in nanosized structurally stable oxides films. For doping tungsten(V)ethoxide was used in concentration that led to a final W/Ti atomic ratio of 1/33, 5/33, 10/33. The morphological and structural characteristics of thin films were studied through microraman, GIXRD, SEM and TEM. A microstructural comparison between pure and doped TiO2 layers is reported. Ethanol and methanol sensing properties are tested.

The oxidation of tin layers deposited onto alumina substrates is investigated with the aim to identify the different steps of the process and obtain information on the sample homogeneity, phase segregation, and degree of oxidation. It is shown that at least three phases coexist at 450 °C, Sn, SnO, and SnO2, and remarkable inhomogeneities, already visible at an optical inspection, are found in the thin film. A micro-Raman mapping of the layer shows that these inhomogeneities are related to the presence of different Sn oxidation states, as evidenced by the inhomogeneous distribution of SnO and SnOx Raman bands. The thin film becomes homogeneous after annealing treatments above 550 °C, where only the SnO2 cassiterite phase is detected.