Influence of doping on sensitivity and response time of TiO2 oxygen gas sensor

The recent trend in gas sensor research is to achieve higher gas sensitivit y and shorter response time at low operating temperatures. In the present s tudy, titanium dioxide was studied as an oxygen gas sensor at different chr omium (Cr) dopant concentrations. The sensitivity and response time measure ments were carried out as a function of operating temperature and oxygen pa rtial pressure. A higher sensitivity and shorter response time was observed at 700 degrees C in 0.40 wt % Cr doped sensor as compared to an undoped se nsor, which showed higher sensitivity at 800 degrees C. The 0.40 wt % Cr do ped sensor shows 13 times higher sensitivity as compared to undoped sensor. The porosity of the material decreases as Cr concentration increases. A la rge number of operation cycles were performed on the sensor, which shows th e stability of the device over long period. The sensitivity and response ti me of the sensor were also correlated with electronic structure results obt ained from x-ray photoelectron spectroscopy. (C) 2000 American Institute of Physics. [S0034-6748(00)00302-6].