Improvement of the oxygen gas sensitivity in doped TiO2 thick films

The titania (TiO2) thick films were prepared by using screen-printing technology of 0.00, 0.20 and 0.40 wt.\% Nb and 0.40 wt.\% Cr concentration on alumina substrate. These thick films were sintered at 1300 degrees C for 5 h in the atmosphere to obtain rutile phase of TiO2. The material characterization was done by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The sensitivity measurements were carried out as a function of operating temperature (400-600 degrees C) in Nb doped TiO2 sensor and (600-800 degrees C) in Cr doped sensor as a function of oxygen partial pressure. The response time measurements in Nb doped sensors were carried out at operating temperatures (400-600 degrees C) at 1200 ppm oxygen partial pressure and operating temperatures (600-800 degrees C) at 1000 ppm oxygen partial pressure in Cr doped TiO2 sensor. The results show that Nb doped sensor exhibits higher sensitivity at 550 degrees C as compared to pure TiO2 sensor, while in the other case, Cr doped sensor shows high sensitivity towards oxygen at 700 degrees C. The result indicates that grain growth cab can be modified by using suitable doping which is responsible for improving stability and sensitivity of the sensor. (C) 1999 Elsevier Science S.A. All rights reserved