| abstract |
A Mn-Zn-Co ferrite core includes a basic component, sub-components, 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): 1000 to 4000 mass ppm are added to the basic component consisting of iron oxide (in terms of Fe 2 O 3 ) : 51.0 to 53.0 mol%, zinc oxide (in terms of ZnO): more than 12.0 mol% and 18.0 mol% or less, cobalt oxide (in terms of CoO): 0.04 to 0.60 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-Co ferrite core to an ideal specific surface of the Mn-Zn-Co ferrite core satisfies formula (1) below M e a s u r e d s p e c i f i c s u r f a c e / i d e a l s p e c i f i c s u r f a c e < 1500 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. n This Mn-Zn-Co ferrite core has an excellent characteristic of an incremental permeability µΔ of 2000 or more continuously in a temperature range of -40°C to 85°C under the application of a direct-current magnetic field of 33 A/m. |