High Oxygen Sensitivity of Nanocrystalline Ceria Prepared by a Thermochemical Process

Nanostructured ceria powder was synthesized by a thermochemical process and investigated its applicability for an oxygen gas sensor. An amorphous precursor powders prepared by spray drying a cerium-nitrate solution were transformed successfully into nanostructured ceria by heat-treatment in air atmosphere. The powders were a loose agglomerated structure with extremely fine $CeO_2$ particles about 15 nm in size, resulting in a very high specific surface area $(110\;m^2/g)$. The oxygen sensitivity and the response time $t_{90}$ measured at sintered sample at $1000^{\circ}C$ was about -0.25 and very short, i.e., $3{\sim}5$ seconds, respectively.