CERIA-ZIRCONIA BASE COMPOSITE OXIDE, METHOD FOR PRODUCING THE SAME, AND CATALYST FOR PURIFICATION OF EXHAUST GAS USING THE CERIA-ZIRCONIA BASE COMPOSITE OXIDE

摘要

A ceria-zirconia base composite oxide contains a composite oxide of ceria and zirconia. In the ceria-zirconia base composite oxide, a content ratio between cerium and zirconium in the composite oxide is in a range from 43:57 to 48:52 in terms of molar ratio ([cerium]: [zirconium]). An intensity ratio of a diffraction line at 2&thetas;=14.5° to a diffraction line at 2&thetas;=29° {I(14/29) value} and an intensity ratio of a diffraction line at 2&thetas;=28.5° to the diffraction line at 2&thetas;=29° {I(28/29) value}, which are calculated from an X-ray diffraction pattern obtained by an X-ray diffraction measurement using CuKa after heating under a temperature condition of 1100° C. in air for 5 hours, respectively satisfy the following conditions: I(14/29)value≧0.015, and I(28/29)value≦̸0.08.