| 摘要 |
PROBLEM TO BE SOLVED: To provide a ceria-zirconia composite oxide endowed simultaneously with a sufficiently superior oxygen storage capacity (OSC) and a sufficiently advanced heat resistance and capable of exhibiting a sufficiently superior oxygen storage capacity (OSC) even after having been exposed to a high temperature over an extended period.SOLUTION: The provided ceria-zirconia composite oxide is a ceria-zirconia composite oxide including a composite oxide of ceria and zirconia wherein the ratio, in terms of particle number, of primary particles of the ceria-zirconia composite oxide having diameters of 1.5-4.5 μm with respect to all primary particles of the composite oxide is 50% or above, wherein the inclusion ratio, in terms of molar ratio ([cerium] : (zirconium]), of cerium and zirconium within the ceria-zirconia composite oxide is confined to a range of 43 : 57-55 : 45, and wherein the intensity ratio of the diffraction line of 2&thetas;=14.5° with respect to the diffraction line of 2&thetas;=29° [I(14/29) value] and the intensity ratio of the diffraction line of 2&thetas;=28.5° with respect to the diffraction line of 2&thetas;=29° [I(28/29) value] each calculated from an X-ray diffraction pattern using CuKα and obtained as a result of an X-ray diffraction measurement rendered after heating at a temperature condition of 1,100°C for 5 hours in atmospheric air respectively satisfy the following conditions: I(14/29) value≥0.015 and I(28/29) value≤0.08. |
