Abstract

High specific surface area (SSA) nanocrystalline powders and dip-coated TiO2 films have been prepared by particulate sol-gel route aided with polymeric fugitive agents (PFA), namely trehalose dihydrate (THD), polyethylene glycol (PEG6000) and hydroxypropyl cellulose (HPC). Powders obtained without PFA, heat-treated at 160 degrees C show a SSA of 181 m(2)/g, a value that could be increased up to 271 and 223 m(2)/g for samples heat-treated at 300 degrees C when PEG6000 and HPC were used, respectively, whereas SSA of 201 m(2)/g were achieved by using THD and subsequence heat-treating at 500 degrees C. Such surface area is one of the highest reported in the literature under these conditions. Crystallite sizes vary from 1 nm for as-produced powders up to 4 nm for powders heat-treated at 600 degrees C. It was found that crystallite size, microstructure, specific surface area and phase transformation are strongly dependent upon the PFA/TiO2 ratio and annealing temperature. Films produced under optimised conditions showed excellent microstructural properties for gas sensing applications. (c) 2006 Elsevier B.V. All rights reserved.