Patent ID: 8512589

Claim:
A Mn—Zn ferrite core comprising a basic component, subcomponents, and unavoidable impurities, wherein, as the sub-components, silicon oxide (in terms of SiO 2 ): 50 to 400 mass ppm and calcium oxide (in terms of CaO): 50 to 4000 mass ppm are added to the basic component consisting of iron oxide (in terms of Fe 2 O 3 ): 51.0 to 54.5 mol %, zinc oxide (in terms of ZnO): 8.0 to 12.0 mol %, and manganese oxide (in terms of MnO): balance; amounts of phosphorus, boron, sulfur, and chlorine in the unavoidable impurities are reduced as follows phosphorus: less than 3 mass ppm, boron: less than 3 mass ppm, sulfur: less than 5 mass ppm, and chlorine: less than 10 mass ppm; and a ratio of a measured specific surface of the Mn—Zn ferrite core to an ideal specific surface of the Mn—Zn ferrite core satisfies formula (1) below Measured specific surface/ideal specific surface<1500 (1) where the measured specific surface represents a specific surface (m 2 /g) determined by a BET method (multipoint method) in JIS Z 8830 (2001); and the ideal specific surface represents a specific surface (m 2 /g) calculated from size and mass of the core on an assumption that the core is in an ideal state of having no cavities.