Patent ID: 7025946

Claim:
A method for producing a soft magnetic hexagonal ferrite sintered material composed of crystal particles of M-type hexagonal ferrite corresponding to a general chemical formula MFe 12 O 19 wherein M is at least one element selected from the group consisting of Ba, Sr and Pb, the method comprising the steps of: preparing a M-type hexagonal intermediate ferrite sintered material from a precursor powder mixture having a general chemical formula MFe 12 O 19 where M is the at least one element selected from the group consisting of Ba, Sr and Pb; decomposing the intermediate sintered material by acid treating the intermediate sintered material to dissolve particle boundaries therein, thereby obtaining powder of flat particles of M-type hexagonal ferrite; extracting powder having particle diameters of 5 μm to 100 μm to be used as seed crystals from the powder of flat particles; preparing a mixture of the seed crystals and fine powder of M-type hexagonal ferrite having particle diameters of less than 5 μm; and orienting the seed crystals in the mixture and subsequently sintering the mixture until the seed crystals grow to have an average particle diameter of 30 μm to 500 μm.