CERIUM-ZIRCONIUM-BASED COMPOSITE OXIDE AND METHOD FOR PRODUCING SAME

Provided is a cerium-zirconium-based composite oxide having an excellent OSC, high catalytic activity, and excellent heat resistance, and also provided is a method for producing the same. The cerium-zirconium-based composite oxide comprises cerium, zirconium, and a third element other than these elements. The third element is (a) a transition metal element or (b) at least one or more elements selected from the group consisting of rare earth elements and alkaline earth metal elements. After a heat treatment at 1,000°C to 1,100°C for 3 hours, (1) the composite oxide has a crystal structure containing a pyrochlore phase, (2) a value of {I111/(I111+I222)} x 100 is 1 or more, and (3) the composite oxide has an oxygen storage capacity at 600°C of 0.05 mmol/g or more, and an oxygen storage capacity at 750°C of 0.3 mmol/g or more.