Nanocrystalline Anatase Titania Thin Films Synthesized by Spray Pyrolysis for Gas Detection

Nanocrystalline (NC) materials are exhibiting small particle size and large surface area which may be applied for gas sensors. Nano-crystalline TiO2 films are synthesized by spray pyrolysis technique. The XRD investigation for the deposited films shows that they have only polycrystalline anatase phase with nano-size. The AFM photographs reveal the nano-size of the constituents. The crystallite size and crystallinity of the samples are discussed with respect to the film thickness and deposition temperature. The dc resistivity dependence on temperature for samples is studied and correlated with the preparation parameters. The sample resistance is measured in the presence of technologically important gases CO, O2 and H2. The sensitivity and response time of the samples to the tested gases are assigned at varied operating temperature. It is found that optimum operating temperature for H2 and CO is 330o C and 310o C, respectively. Also, the maximum sensitivity is 90% and 70%, and the response time is about 8 and 3 seconds for H2 and CO respectively, at the proceeding operating temperature.