Nanostructured pure and Nb-doped TiO2 as thick film gas sensors for environmental monitoring

Thick films of nanostructured TiO2 and Niobium-doped TiO2 have been fabricated by screen-printing technology starting from pure Titania and Niobium-doped Titania powders; the powders were prepared by laser pyrolysis method which provides nanosized particles. The laser powders are crystalline with anatase structure and an average specific surface area of approximately 100 m(2) g(-1); their grain size ranges from 10 up to 25 nm, the particles are spherical monocristalline and without internal porosity. In this work we evidentiated that TiO2-based thick film sensors exhibit a suitable sensitivity to atmospheric environmental monitoring provided that the microstructural properties of the materials are suitably correlated to the required electrical features. Moreover nanostructured particles were obtained at high firing temperature by adding a proper metal ions to inhibit the grain sintering. Finally, prototype sensors based on pure titania sensing film have been prepared and tested in field for environmental monitoring application. (C) 1999 Elsevier Science S.A. AU rights reserved.