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 cerium-nitrate 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 m(2)/g). The average grain size of a sample sintered from the ceria powder at 1000 degrees C was about 40 mu. At 600 degrees C, its oxygen sensitivity, n (log sigma proportional to log(P-O2/P-o)(-n)) was about 0.25, which was considerably higher than that measured from the porous samples possessing micrometer- or 100 similar to 200 nanometer-size grains.

Keywords: ceria (CeO2); oxygen gas sensor; nanoparticles; thermochemical process