**6. Conclusion**

**Figure 16.** 3D micrographs of (a) 2% Nb-doped TiO<sup>2</sup>

96 Titanium Dioxide - Material for a Sustainable Environment

**Figure 17.** UV-Vis spectra of several TiO<sup>2</sup>

of layers.

and Nb/TiO<sup>2</sup>

tice parameters, whose d101 changed to 3.49 for pure TiO<sup>2</sup>

The increase of niobium content in the thin film promoted a considerable variation in the lat-

tallite size decreased from 11 to 7 nm, which agreed with the DFT results previously reported.

and (b) pure TiO<sup>2</sup>

, calcined at 500°C.

thin films with different calcination temperatures and numbers

and to 3.55 for 3% Nb/TiO<sup>2</sup>

. The crys-

The sol-gel deposition parameters such as the density of the precursor solution, concentration of oxides, viscosity, withdrawal velocity, number of dips, and drying temperature influence the characteristics of the films such as thickness, porosity, refractive index, particle size, particle shape, and oxidation degree. Someway, all dopants used improved the quality and the range of application of the TiO<sup>2</sup> films. The addition of SiO<sup>2</sup> in the TiO2 films changes their mechanical, optical, and surface properties. The addition of Ag increases its photocatalytic activity, improving fungicide and bactericide properties of the films. The hydrophobicity/hydrophilicity change capacity was improved too. The doping with Nb improves the mechanical resistance of the films. All these properties can be applied in the confection of best photocatalytic surfaces to be used in the production of solar energy, self-cleaning surface, and optical and nonlinear optical devices.
