MnZn power ferrite with high B-s and low core loss

摘要

Although there is a tradeoff between high B-s and low core loss for MnZn power ferrite, in the current work, high Bs and a low core loss (P-cv) were achieved simultaneously by increasing the content of Fe2O3 and by adjusting the partial pressure of oxygen (P-O2) during sintering process, respectively. Additionally, the influence of P-O2 on the Pc. was also investigated. The MnZn ferrite cores were prepared by conventional ceramic process. With increase in P-O2 from 0.35% to 1.90%, the bottom temperature of P-cv(T) curve shifted to a higher temperature, and simultaneously the minimum P-cv at the bottom temperature decreased continuously. P-cv in a low frequency range was divided into the hysteresis loss (P-hv) and eddy current loss (P-ev). Both P-hv, and P-ev decreased with increasing P-O2. At high P-O2 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 P-ev. Meanwhile, the transport of dopants from intragranular to grain boundary also reduces the defects in grains, which helped to decrease the P-hv, coercivity and remanence. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.