Oxygen sensitivity of nanostructured cerium oxide prepared by a thermochemical process

Abstract

Ultra fine cerium oxide (ceria, CeO2) powder was synthesized by a thermochemical process and tested for its feasibility as an oxygen gas sensor. Procedures of the process consisted of the preparation of a precursor powder by spray drying a ceriumnitrate solution and the heat treatment in air to evaporate volatile components from the precursor, thereby forming nanostructured CeO2. The powder produced had a loose agglomerated structure with extremely fine CeO2 particles about 15 nm in size, yielding a very high specific surface area (110 m2/g). The average grain size of a sample sintered from the ceria powder at 1000 oC was about 40 nm. At 600 oC, its oxygen sensitivity, n (logσ log(PO2/Po)−n) was about 0.25, which was considerably higher than that measured from the porous samples possessing micrometer- or 100~200 nanometer-size grains.