Structural defects in a nano-scale powder of CeO2 studied by pulsed neutron diffraction

Pulsed neutron diffraction measurements on nano-scale powder of ceria, CeO2, uncovered new structural features which appear to be intimately related to the function of this material as an oxygen storage medium in automotive three-way catalytic converters. The results of the pair-distribution function (PDF) analysis and the Rietveld refinement of the neutron diffraction data indicate the presence of interstitial oxygen defects in the octahedral sites of the fluorite structure. The defects were found to disappear following high-temperature treatment. It is suggested that these weakly bound interstitial oxygen defects provide oxygen mobility that facilitates the oxygen storage capacity of ceria in the catalytic converters. (C) 2000 Elsevier Science Ltd. All rights reserved.