| 摘要 |
PROBLEM TO BE SOLVED: To provide a ceria-zirconia composite oxide capable of inhibiting the thermal degradation of an oxygen storage material and exhibiting oxygen absorption/release functions initially at approximately 400°C.SOLUTION: In a ceria-zirconia composite oxide, 0.5-5.0 mol% of at least one type selected from the group consisting of praseodymium, lanthanum, and yttrium is included with respect to the total cation content within the composite oxide in a state where the inclusion ratio thereof is being confined, in terms of molar ratio ([cerium+at least one type selected from the group consisting of praseodymium, lanthanum, and yttrium] : [zirconium)], to a range of 43 : 57-48 : 52 and where the intensity ratio of the respective diffraction lines at 2&thetas;=14.5° and 2&thetas;=29°calculated from an X-ray diffraction pattern using CuKα after heating within atmospheric air [I(14/29) value] and the corresponding intensity ratio at 2&thetas;=28.5°and 2&thetas;=29° [I(28/29) value] satisfy I(14/29) value≥0.02I(28/29) value≤0.08. |
