文摘
Although there is a tradeoff between high Bs and low core loss for MnZn power ferrite, in the current work, high Bs and a low core loss (Pcv) were achieved simultaneously by increasing the content of Fe2O3 and by adjusting the partial pressure of oxygen (PO2) during sintering process, respectively. Additionally, the influence of PO2 on the Pcv was also investigated. The MnZn ferrite cores were prepared by conventional ceramic process. With increase in PO2 from 0.35% to 1.90%, the bottom temperature of Pcv(T) curve shifted to a higher temperature, and simultaneously the minimum Pcv at the bottom temperature decreased continuously. Pcv in a low frequency range was divided into the hysteresis loss (Phv) and eddy current loss (Pev). Both Phv and Pev decreased with increasing PO2. At high PO2 cation vacancy was generated, which facilitated the transport of dopant, such as Ca and Si to the grain boundary region. This induced high resistance at the grain boundary which in turn reduced the Pev. Meanwhile, the transport of dopants from intragranular to grain boundary also reduces the defects in grains, which helped to decrease the Phv, coercivity and remanence.