GARNET-TYPE COMPOSITE METAL OXIDE AND METHOD FOR PRODUCING SAME

One or more embodiments of the present invention are to provide a method for producing a composite metal oxide having an excellent crystallinity by a mechanochemical method. One or more embodiments of the present invention relate to a method for producing a garnet-type composite metal oxide containing Li, La, Zr and O. The method includes a step of treating a mixture containing raw material powders and a flux by a mechanochemical method to react the raw material powders, and the raw material powders contain a Li source powder, a La source powder and a Zr source powder. The raw material powders may further contain at least one selected from an Al source powder and a Ga source powder.