| 摘要 |
An Mn-Zn ferrite wherein 0 to 5000 ppm of a Co oxide in a Co<SUB>3</SUB>O<SUB>4 </SUB>conversion is contained in a basic component constituted by Fe<SUB>2</SUB>O<SUB>3</SUB>: 51.5 to 57.0 mol % and ZnO: 0 to 15 mol % (note that 0 is not included) wherein the rest is substantially constituted by MnO; and a value alpha in a formula (1) below in said ferrite satisfies alpha>=0.93. <?in-line-formulae description="In-line Formulae" end="lead"?>alpha=((Fe<SUP>2+</SUP>-Mn<SUP>3+</SUP>-Co<SUP>3+</SUP>)x(4.29xA+1.91xB+2.19xC+2.01xD))/((A-B-C-D)x100) formula (1).<?in-line-formulae description="In-line Formulae" end="tail"?> Note that in the formula (1), (Fe<SUP>2+</SUP>-Mn<SUP>3+</SUP>-Co<SUP>3+</SUP>): [wt %], A: Fe<SUB>2</SUB>O<SUB>3 </SUB>[mol %], B: MnO [mol %], C: ZnO [mol %] and D: CoO [mol %]. According to the present invention, a highly reliable Mn-Zn ferrite used as a magnetic core of a power supply transformer, etc. of a switching power supply, etc., having a small core loss in a wide temperature range, furthermore, exhibiting a little deterioration of core loss characteristics under a high temperature (in a high temperature storage test) and having excellent magnetic stability, a transformer magnetic core and a transformer can be provided.
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