| 摘要 |
A carrier including a manganese ferrite core material having a layer on its surface such that 0.1<=K<=30, where K=(S/M)x100, S and M represent the standard deviation and average of M 2/ (M 1 +M 2 ), respectively, M ranging from 0.05 to 0.45, and M 1 and M 2 represent the content of iron and manganese, respectively, in a carrier particle. The carrier has a magnetization ranging from 45 to 75 emu/g at 1,000 Oe, a mass-averaged particle diameter, D 4 , ranging from 25 to 65 mum and carrier particles having a particle diameter not greater than 12 mum are included in an amount not greater than 0.3% by weight, and a ratio, D 4/ D 1 , ranging from 1 to 1.3, where D 1 is a number-averaged particle diameter of the carrier.
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