K2NIF4 TYPE COMPOSITE OXIDE AND EXHAUST GAS PURIFYING CATALYST

PROBLEM TO BE SOLVED : To provide a K2NiF4 type composite oxide which is excellent in reactivity with water and heat resistance so as to be suitable as a catalyst for an automobile, does not make rather high in manufacturing cost, and sufficiently ensures a specific surface area of the oxide so as to suitably use it as an exhaust gas purifying catalyst. SOLUTION : The K2NiF4 type composite oxide has a composition of the formula : Sr2-XLnXMnO4 (wherein Ln is at least one element among lanthanoids type rare earth elements; the range of X is 0.1≤X≤0.5).