Study On The High Frequency Of Low Loss Mn-Zn Ferrites

MnZn power ferrites with abroad application prospects and development potential are the most important part of soft magnetic material. Because electronic devices become smaller and lighter, the better performance of MnZn ferrites core need to be required,such as higher working frequency, high saturated magnetic induction(Bs) and lower power loss. The recent years, the high frequency and low power loss of MnZn ferrites becomes the key direction. In this paper, the high frequency MnZn ferrites were manufactured by the technique of the oxide ceramic. It mainly researched the influence of the composition, the presintering, and dopants on the magnetic properties and microstructure of Mn Zn ferrites.Firstly, the paper elaborated the development states, advances and the basic theory of the high frequency MnZn ferrites at home and abroad in the last twenty years.Secondly, a brief introduction of the important parameters of MnZn ferrites materials and method of improving the performance of MnZn ferrites was made.The effect of microstructure and magnetic property with different content of Fe2O3 and ZnO was studied. The results showed that proper content of Fe2O3 and ZnO could improve the initial permeability and decrease the power loss. The best composition of MnZn ferrites was Fe2O3(53.5mol%), ZnO(8.5mol%), Mn3O4(38mol%). The different presintering was studied. The results showed that the magnetic property and microstructure of Mn Zn ferrites were best when the presintering was 900℃。After the research of composition and precalcining, the effects of different additives on the magnetic properties and microstructure were investigated. Dopant was one of the effect methods to improve the magnetic and microstructure of MnZn ferrites. The effect and mechanism of MnZn ferrites with different additives to improve the performance of MnZn ferrites were different. The amount of additives must be controlled in order to obtain the well performance of MnZn ferrites. Low and excess additives will make the magnetic and microstructure of MnZn ferrites worse. In this paper, the power loss, the initial permeability and macrostructure of high frequency of MnZn ferrites with different content of TiO2, Ta2O5, Nb2O5, and SnO2 were studied. The results showed that proper additives can improve the magnetic of magnetic greatly. The minimum power loss was 176kw/m3, and the maximum initial permeability was 1289.Lastly, the influence of the power loss and the initial permeability and microstructure of the high frequency of MnZn ferrites with TiO2 and Nb2O5, SnO2 and TiO2 co-doped were studied. The results showed that the content of TiO2 and Nb2O5 was 0.03wt% and 0.02wt%; the magnetic of MnZn ferrites was best. The power loss was 174kw/m3, the initial permeability was 1298. The proper additives of SnO2 and TiO2 can obtain the well performance of MnZn ferrites.