Preparation of nano-scale titania thick film and its oxygen sensitivity

Titania is a very important material for oxygen sensors. In this work, nano-scale titania films were prepared on alumina substrates by screen print. After being calcined at 800 degreesC, all films became rutile. The oxygen sensing properties were studied and compared,with the film made from micro-scale titania. The resistance of films were examined at various temperature and oxygen partial pressures. It was found that the nano-scale film demonstrated better properties than micro-scale film for use as an oxygen sensor. The oxygen sensitivity was obviously improved (13%) when the grain size was nano-scale. The improvement of oxygen sensitivity of nano-scale film may profit from its large surface area, which provides a high oxygen vacancy concentration. (C) 2000 Elsevier Science B.V. All rights reserved.