Preparation And Studies Of Magnetic Properties Of High-performance Ni-Zn Ferrite

Cubic crystal spinel ferrite is a very important kind of soft magnetic materia and electrical product.Further enhancement in the performance of superpower soft ferrite in the condition of high frequency has been presently the tendency of advanced soft ferrite products,development in China.On the basis of Ni-Zn ferrite and the adoption of ceramic sintering,this paper aims to study the technics of industrialized production and the approach to improve material's capacity by series of studies on the effect upon Ni-Zn ferrite' performance caused by the change of the rate of Ni²⁺,Zn²⁺ion,simple replace of Cu²⁺,Mn⁴⁺,Co³⁺and complex dope.1.Through the preparation of Ni_0.5Zn_0.5Fe₂O₄ and the test performance,it is found that lattice constant,grain size,saturation magnetiation,and coercitive force have an obvious variation with the temperature change of presingter and singtering.The main reason for this is the occupation of Ni ion in crystal lattice has changed in pace with processing temperature,from which ferrite,M_s can be accomodated to the condition of craft and some relevant craft conditions.2.A formula of(Ni_0.38Zn_0.62)Fe₂O₄ presingter in 850℃,M_s reached the maximum in 1070℃singtering.The conclusion can be reached,that is,Ms became stong and then weak with the increase of Ni ion.The amount of Ni ion in B adjusted molecular magnetic moment of ferrite and settled down the major formula to get high-initial permeability next.3.The study of(Cu_0.15Ni_0.23Zn_0.62)Fe₂O₄ found that the mix of Cu ion greatly decreased the temperature of ferrite technics to 750℃,due to liquid phase reaction of Cu in lower temperature.In addition,electric conductivity of Cu ion is relatively high so much so that the power loss of ferrite is greatly increased.4.At presingter of 750℃(Ni_0.222Mn_0.008Cu_0.15Zn_0.62)Fe₂O₄ singtering of 1130℃, because Mn has complicated chemical valence which results in the instability of Mn ionic radius,the occupation of Mn ion was affected and the immense change of molecular magnetic moment led to great variation of pergormance and technics of ferrite doped with Mn,the formula of(Ni_0.21Mn_0.008Cu_0.15Zn_0.62)Fe₂O₄ was finally fixed.5.At presingter of 750℃(Co_0.01Ni_0.21Mn_0.008Cu_0.15Zn_0.62)Fe₂O₄ singtering of 1250℃,because Co has relatively strong magnetic anisotropy and intense suppress upon ferrite grain growth,initial permeability rapidly fell with the increase of Co ion and the power loss decreased by a large scale.In this way,the application of superpower in the condition of high frequency has been achieved.