An amorphous-like x alpha-(FeO3)-O-2-(1-x)ZrO2 solid solution system for low temperature resistive-type oxygen sensing

An amorphous-like solid solution of x alpha -Fe2O3-(1 - x)ZrO2 powders has been prepared using the high-energy ball milling technique, and their physi cal and structural properties have been systematically characterised using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The oxy gen gas sensing properties of the screen-printed thick film gas sensors fab ricated from such mechanically alloyed materials have been characterised us ing an automatic gas sensing measurement system. Experimental results show that the particle size of the powders is drastically milled down to 8 nm af ter 120 h of high-energy ball milling. The TEM result has also revealed an amorphous-like structure agglomerating the sparing nanocrystalline grains t ogether. The resistive-type sensors demonstrate good oxygen gas sensitivity at a very low operating temperature of 320 degreesC. It is believed that t he extraordinary high concentration of oxygen vacancies is the critical fac tor. This sensing mechanism will be discussed. (C) 2001 Elsevier Science B. V. All rights reserved.