CERIA·ZIRCONIA-BASED COMPOSITE OXIDE OXYGEN ABSORPTION/RELEASE MATERIAL, EXHAUST GAS CLEANING CATAL

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Provided are the following : a ceria·zirconia-based composite oxide oxygen absorption/release material which has a rapid oxygen absorption/release rate and which has an OSC function capable of responding rapidly to an exhaust gas composition in which there are no large fluctuations in terms of atmosphere but which changes rapidly close to the stoichiometric air-fuel ratio; an exhaust gas cleaning catalyst; and a honeycomb structure for exhaust gas cleaning. This oxygen absorption/release material is a ceria·zirconia-based composite oxide and is characterized by having a composition whereby the molar ratio of cerium and zirconium is such that cerium / (cerium + zirconium) is 0.33-0.90 and the ion conductance, as measured using an alternating current impedance method, is 1×10-5 S/cm or more at 400°C, and in that one or more rare earth metal ions M selected from among Sm3+, Eu3+, Pr3+, Gd3+ and Dy3+, each of which has a coordination number of more than 7.0, are contained at a quantity of 0.5-15 mol.% relative to the total quantity of cations.