MAGNETOPLUMBITE-TYPE HEXAGONAL FERRITE POWDER, RADIO WAVE ABSORBER, AND METHOD FOR CONTROLLING RESONANT FREQUENCY OF MAGNETOPLUMBITE-TYPE HEXAGONAL FERRITE POWDER

摘要

A magnetoplumbite-type hexagonal ferrite powder which comprises a powder of magnetoplumbite-type hexagonal ferrite represented by formula (1) and a powder of a compound represented by formula (2) and Hα of which satisfies 19 kOe/m≤Hα≤28 kOe (wherein Hα represents the magnetic field intensity corresponding to 90% of the magnetization quantity under the application of an external magnetic field of 50 kOe); a radio wave absorber; and a method for controlling the resonant frequency of the magnetoplumbite-type hexagonal ferrite powder. In formula (1), A represents at least one metal element selected from the group consisting of Sr, Ba, Ca, and Pb, and x satisfies 1.5 ≤ x ≤ 8.0. In formula (2), A^a represents at least one metal element selected from the group consisting of Sr, Ba, Ca, and Pb. AFe_(12-x)Al_xO₁₉...Formula (1) A^aAl₂O₄...Formula (2)