B. Vendemiati

Semiconductor Gas Sensors for Environmental Monitoring

The main semiconductor oxides for gas sensing have been examined, describing the synthesis processes and the morphological and structural properties. The powders have been deposited as thick films through screen-printing technique to achieve gas sensors. The sensing layers have been studied with regard to semiconductor behaviour, surface barrier potential heights and gas sensing properties. The interaction of humidity with semiconductor oxides has been considered with the aim to compensate, using an algorithm, its effect in gas detection. Finally, nitrogen oxides monitoring, contemporaneously performed in several sites of Italy, has been described.

Nanostructured (Sn,Ti, Nb)O2 Solid Solution for Hydrogen Sensing

A novel co-precipitation route for preparing pure nanograined (Ti, Sn, Nb)O2 solid solution has been accomplished. The solid solution containing the three elements has been synthesized with the molar ratios for Sn:Ti:Nb 100:42:5. Electron microscopy and X-ray diffraction have been adopted to observe the morphology, the crystalline structure and the mean grain radius. Calcining at 550, 650, 850 or 1050 °C for 2h, showed rutile-like single-phase. The prepared powders have been deposited to produce gas sensors in form of thick films through screen-printing technology. SEM micrographs of both powders and films showed regularly-shaped particles with grain dimensions at nanometric level, the nanostructure being maintained up to 1050°C. The sensors have been tested with different reducing gases showing large responses to hydrogen and good selectivity.