MICROSTRUCTURE AND CO GAS-SENSING PROPERTIES OF POROUS ZNO PRODUCED BY STARCH ADDITION

Effects of corn starch addition on the microstructure and CO gas respo nse 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 de creased both the grain size and the sintered density of ZnO at all sin tering temperatures and thus increased the sensitivity to 200 ppm CO. The increasing relative density and grain size with sintering temperat ure was accompanied by a decreasing CO gas sensitivity after maximum a t 700 degrees C. The temperature showing the maximum CO gas sensitivit y decreased with decreasing grain size. Humidity decreased both the hy steresis of electrical conductivity and CO gas sensitivity. (C) 1997 E lsevier Science S.A. All rights reserved.