Redox property-local structure relationships in the ph-loaded CeO2-ZrO2 mixed oxides

The local structure of the M-O bond in CeO2-ZrO2 mixed oxides is investigat ed with the aim of finding a correlation between structural parameters and oxygen exchange properties. It is found that insertion of ZrO2 into the CeO 2 lattice strongly perturbs the symmetry of the M-O bond. As the content of CeO2 in CeO2-ZrO2 solid solution is increased from 20 to 80 mol%, tetragon al, (t, t', t ") and cubic phases are formed. The local symmetry of the Zr- O bond is strongly perturbed by the increase in CeO2 content while no signi ficant modification of the first Ce-O coordination sphere is found, except for lengthening of the Ce-O bond consistent with lattice parameter increase . The perturbation of the Zr-O coordination sphere, which leads to highly d isordered oxygen in the lattice, is indicated as responsible for the high o xygen mobility in CeO2-ZrO2 mixed oxides. (C) 1999 Academic Press.