OXYREDUCTION STUDIES ON NANOSTRUCTURED CERIUM OXIDE

The effect of high surface area in porous nanostructured cerium oxide on chemical equilibrium with oxygen gees phase was investigated. Nanos tructured cerium oxide was prepared by chemical precipitation. These m aterials were compacted and sintered at 600 degrees C to porous nanost ructured solids. Sample weight under varying oxygen partial pressure a nd temperature was measured and compared with microcrystalline CeO2 re ference sample. The change in sample weight relative to the oxidized s ample was used to determine the degree of reduction. The interfacial e quilibrium of cerium oxide surface with oxygen gas phase was analyzed on the basis of the van't Hoff equation. The binding enthalpy of oxyge n was determined to -7.5 eV per oxygen atom. (C) 1997 Acta Metallurgic a Inc.