Characteristics and sensing properties of dipped La0.8Sr0.2Co1-xNixO3-delta film for CO gas sensors

La0.8Sr0.2Co1-xNixO3-delta films (x = 0.4, 0.5 and 0.6) prepared by dipping method showed maximum sensitivity to 50 ppm CO at a lower operating temper ature (180-200 degrees C). The sensing properties of La0.8Sr0.2Co1-xNixO3-d elta films to CO are a function of temperature and Ni content. The maximum sensitivity was obtained for a doping of 50 mol% Ni at an operating tempera ture of 200 degrees C. The response mechanism of sensitivity of metal oxide s to CO gas is a surface reaction process and this reaction was thermally a ctivated. The log-log plots of G/G(0) to CO concentration showed a linear r elationship. The resistivity of the films is also showed as a function of C O concentration. Tn an exponential plot of resistivity versus CO concentrat ion, the experimental results give a good march to the relationship of R ap proximate to KCCOalpha. (C) 1999 Published by Elsevier Science Ltd. All rig hts reserved.