The Influence Of Addition On The Properties Of MnZn Ferrites

MnZn ferrite is the most important component of soft magnetic materials, accounts for a sizeable proportion of the magnetic, the inductance core and magnetic appliance are made of MnZn ferrite magnetic materials is the most important soft ferrite materials. It application of frequency from a few hundred to several Gigabit Hertz. Their combined output accounts for more than 60% of the total output of soft ferrite materials, so the MnZn ferrite development is more noticeable. In this paper, aiming at expatiator the high permeability of MnZn ferrite crystal structure, magnetic source of magnetic domain theory and basic characterization parameters; Formulation of MnZn ferrite doping, doping process and the process is studied doping reaction, Effective additive to improve the performance of the material conditions necessary. Based on the study mainly additive P₂O₅, SnO₂,Nb₂O₅, Nd₂O₃ and CaCO₃ the impact of calcium carbonate were discussed in detail. MnZn ferrite with the reaction:MnO+Fe₂O₃→MnFe₂O₄ZnO+Fe₂O₃→ZnFe₂O₄Aiming at research of the traditional ceramic techniques of MnZn ferrite soft magnetic materials Preparation Process and the corresponding principle. Sum up the process of soft ferrite materials development in recent decades. Review of the domestic soft ferrite materials and devices at the development, application and market. Department of MnZn ferrite material of which are soft with an emphasis on that area in its broader application. Soft Ferrite will continue to high-frequency, high-rate and low-loss magnetic direction. We study and analysis system the point view of the feasibility from Magnetic technology. Indicate the infection of the formula with doping on the magnetic properties of samples, Use of modern analytical tools , test and analysis the characteristic ofμi,Bs,Ps,Tc. Use the appropriate formula and sintering of magnetic properties of samples can be further enhanced.The test was prepared from the start of Microstructure analysis, research of P₂O₅,SnO₂,Nb₂O₅, Nd₂O₃ and CaO₃ 's adulterant Group to fit the conditions and varying proportions of incorporation.To study the high rate of MnZn ferrite magnetic properties of materials. Take a few P₂O₅ can make Ferrite grain size increases. Improving the uniformity, Initial permeability rate. But Grain increase porosity,Initial permeability rate.Loss also increased significantly . In the formula of the material Zn_0.15Mn_0.78Fe_2.07O₄, When the content of doping is Nb₂O₅ ,the count of doping is 0.12wt%,μ_i is 12697. Because Ca2+ exists in the grain boundary. CaCO₃ incorporation of a small amount of ferrite grain size will increase. Uniformity improvement, Initial permeability rate increase. But if CaCO₃ doping overdoses, grain will increase the porosity, Lower initial permeability rate. SaO₂ incorporation, As Sn⁴⁺ exist in the grain boundaries, fulfill the balance to satisfy the conditions, Near the grain boundaries of metal ions cause an increase in vacancies, This will speed up the movement of domain walls , Nd₂O₃ the melting point of 1520℃, Power ferrite not participate in the solid state reaction, And primarily in the grain boundary, Prevent grain growth. Thus come into being the fine grain microstructure uniformity. When the excessive addition of Nd₂O₃, Lead to more grain boundary porosity. Therefore enough densification, lower densities, properties affected.In terms of high permeability MnZn ferrite, the key of High permeability rate lies in the selection of suitable composition and doping, And added lo the appropriate sintering process . Choose a suitable formula. Doping and sintering process at the appropriate conditions can be obtainedμi was high as 15K MnZn ferrite magnetic materials. Adequate and effective impurity P₂O₅,SnO₂,Nb₂O₅,Nd₂O₃ and CaCO₃ can promote the ferrite grains and calcium carbonate growth. Sintered density, and increase permeability rate.In the Mn-Zn ferrite, the introduction of impurity ions have three main defect: (1)Size of impurity ions and ionic radius of the matrix is similar, impurity ions replace certain nodes of lattice, it is the replacement defects. (2) impurity ions is smaller in comparion with the base ion radius, impurity ions squeeze into the space lattice, it is the gap defects. (3) Impurity ions is bigger than the radius of the matrix ions, impurity ions can squeeze into the gap between matrix ions and oxygen ions in space, forming defects. Study found that Mn-Zn ferrite introduce certain impurities, if such additives can satisfy these three defects, the introduction of the crystal will change the overall performance , all aspects of its nature will change, For example, the introduction of the P⁵⁺ ,If the introduction of impurities meet only one or two in three defective, change is more likely that a particular aspect of the performance, such as Nb⁵⁺, Sn⁴⁺,Ca²⁺ doping.According to energy level, Mn-Zn ferrite intermingle impurities, the periodic potential are interfered and create additional constraints state near impurity atoms, in the forbidden band plus the impurity level. The introduction of alien impurity process of free energy (A A) changes in expression:AΔ=ΔU-TΔSAs lattice defects caused strain,ΔU is positive. Moreover, due to the presence of point defects is to make the system levels of chaos increased, that caused the increase in entropy, and a free can be reduced, impurity defects make free energy lower. With the doping atom radius, the Mn-Zn ferrite resistivity is increased, the reason of Nd resistivity mutation is that Nd is lanthanide metal, incorporation of Mn-Zn ferrite, formed deep level of impurities by strong electronic shackles, and the spatial scales are very small, the effect of lattice distortion is large.