Effect Of Co₂O₃ Additives On The Electromagnetic Properties Of MnZn Ferrites With Fe-poor Composition

With the development of electronic information technology, electromagnetic pollution becomes increasingly serious. Soft magnetic ferrite belongs to absorbing material with magnetic media model, thus having good advantages in solving EMI resistance and good development prospects. What’s more, Fe-poor Mn Zn ferrite possesses unique electromagnetic properties for both Mn Zn ferrite and Ni Zn ferrite, and can receive good result in EMI resistance. In this paper, apart from the introduction of Mn Zn ferrites, the crystal structure, magnetic source, basic electromagnetic parameters, frequency characteristic and loss of Mn Zn ferrite were summarized, and the preparation technology and performance test method were also expounded. Mn Zn ferrites with Fe-poor composition were prepared by conventional ceramics preparation technique. Effects of Co2O3 doping and sintering temperature of Fe-poor Mn Zn ferrites were investigated. The possibility for applying Mn Zn ferrites with Fe poor composition to wireless charging and NFC was discussed.The results show that the doping of Co2O3 effectively improved magnetic properties of Fe-poor Mn Zn ferrite. When the main formula is Mn0.66Zn0.42Fe1.95O4, the addition of 0.64 wt% Co2O3 has significant effect on the promotion of initial permeability and resistivity, whereas has no obvious influence Bs and brings out the decrease of Br and Hc. Compared with the sample which has no Co2O3 doping,the impedance characteristics of sintered sample was improved obviously.The study for different sintering temperatures indicates that the appropriate sintering temperature can effectively improve the magnetic properties and make better for microstructure of Fe-poor Mn Zn ferrite. At 1300℃,the best impedance characteristics of sintered sample can be obtained when the doping amount of Co2O3 is 0.64 wt%. Compared with the sample sintered at 1240℃,its impedance increases by 28% at 10 MHz, having a certain promotion.The further adjustment experiments of Co2O3 doping content and sintering temperature confirm. At 1240℃,while the doping amount of Co2O3 is 1.04 wt%, the optimal electromagnetic properties can be received, μi = 1896、Bs = 396 m T, μ′ = 275、μ″ = 178 at 13.56 MHz. Simulation software CST was employed to simulate field intensity distribution for NFC antenna and read/write distance was measured as an evidence of shielding ability, and the value of read/write distance was return to 54.5%.