Pure and Nb-doped TiO2 thick-films were prepared by screen-printing, starti
ng from nanosized powders. Grain growth and crystalline phase modification
occurred as consequence of firing at high temperature. It has been shown th
at niobium addition inhibits grain coarsening and hinders anatase-to-rutile
phase transition. These semiconducting films exhibited n-type behavior, wh
ile Nb acted as donor-dopant. Gas measurements demonstrated that the films
are suitable for CO or NO2 sensing. Microstructural characterization by ele
ctron microscopy and differential thermal analysis (DTA) highlights the dep
endence of gas-sensing behavior on film's properties. (C) 2000 Elsevier Sci
ence S.A. All rights reserved.