Patent ID: 7790053
Filing Date: 2010-09-07
Classification: C04B,H01F

Abstract:
1. A low-loss Mn—Zn ferrite comprising Fe, Mn and Zn as main components, Co, Ca and Si as first sub-components, and at least one of Va-group metals as a second sub-component, Ta being indispensable; Fe and Zn being 53-56% by mol (calculated as Fe 2 O 3 ) and 1-9% by mol (calculated as ZnO), respectively, and Mn being the balance (calculated as Mn 3 O 4 ), based on the total amount (100% by mol) of said main components; Co and Ca being 500-5000 ppm (calculated as CO 3 O 4 ) and 3000 ppm or less (calculated as CaCO 3 ), respectively, by mass based on the total amount of said main components, a mass ratio of Ca (calculated as CaCO 3 ) to Si (calculated as SiO 2 ) being 2 or more; Ta being 250 ppm or more (calculated as Ta 2 O 5 ); said ferrite having an average crystal grain size of less than 3.2 μm and volume resistivity ρ of 1 Ω·m or more, and a power loss Pcv of 350 kW/m 3 or less in a range of 0° C.-120° C. at a frequency of 2 MHz and a magnetic flux density of 25 mT.