Gas sensing characteristics of Co3O4thick films with metal oxides

and -based thick films with additives such as (5 wt.%), (5 wt.%), (5 wt.%) and -ZnO(5 wt.%) were fabricated by screen printing method on alumina substrates. Their structural properties were examined by XRD and SEM. The sensitivities to iso-, , CO, and NO gases were investigated with the thick films heat treated at , and . From the gas sensing properties of the films, the films showed p-type semiconductor behaviors. (5 wt.%) thick film heat treated at showed higher sensitivity to i- and CO gases than other thick-films. (5 wt.%) thick film heat treated at showed the sensitivity of 170 % to 3000 ppm iso- gas and 100 % to 100 ppm CO gas at the working temperature of . The response time to i- and CO gases showed rise time of about 10 seconds and fall time of about minutes. The selectivity to i- and CO gases was enhanced in the (5 wt.%) thick film.