Structural, optical and electrical properties of nanocrystalline TiO2, SnO2 and their composites obtained by the sol–gel method

In this paper we describe structural, optical and electrical properties of nanocrystalline TiO2, SnO2 and their composites obtained by the sol–gel method. The materials were characterized by X-ray diffraction (XRD), surface area estimated from the N2 physisorption isotherm (BET), high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy (STEM). Moreover, the paper examines optical and electrical properties of nanocomposites. In fact attention is particularly focused on the properties of the composites with various chemical compositions. An abrupt change in the optical and electrical properties has been observed, passing from the sample with the maximum amount of TiO2 to a maximum amount of SnO2. The sensor made of composite containing 58.5% of SnO2 exhibited the best NH3 sensing features.