Patent ID: 7540972

Claim:
A Mn—Zn based ferrite material comprising: as main constituents, Fe 2 O 3 : 53 to 56 mol %; ZnO: 7 mol % or less (inclusive of 0 mol %); and the balance: MnO; and as additives, Co: 0.15 to 0.65 % by weight in terms of Co 3 O 4 ; Si: 0.01 to 0.045 % by weight in terms of SiO 2 ; and Ca: 0.05 to 0.40 % by weight in terms of CaCO 3 ; wherein: the δ value (the cation defect amount) in the following ferrite composition formula (1) satisfies the relation 3.5×10 −3 <δ≦7×10 −3 ; and the mean grain size is larger than 8 μm and 15 μm or less; the composition formula (1) being represented as follows: (Zn a 2+ , Mn c 2+ , Mn d 3+ , Fe e 2+ , Fe f 3+ , Co g 2+ , Co h 3+ ) 3 O 4+δ Formula (1) wherein a+c+d+e+f+g+h=3, and δ=a +c+(3/2)d+e+(3/2)f+g+(3/2)h−4 with the proviso that g:h=1:2.