Microstructure and CO gas sensing properties of porous ZnO produced by starch addition

Abstract

Effects of corn starch addition on the microstructure and CO gas response were studied by sintering ZnO at 600 similar to 900 degrees C for 3 h in air. The addition of 5 wt% corn starch as the fugitive phase decreased both the grain size and the sintered density of ZnO at all sintering temperatures and thus increased the sensitivity to 200 ppm CO. The increasing relative density and grain size with sintering temperature was accompanied by a decreasing CO gas sensitivity after maximum at 700 degrees C. The temperature showing the maximum CO gas sensitivity decreased with decreasing grain size. Humidity decreased both the hysteresis of electrical conductivity and CO gas sensitivity. (C) 1997 Elsevier Science S.A. All rights reserved.