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Fabrication and Magnetic Properties of Mn-Zn Ferrites

Author: LiYueXin
Tutor: WangZhi
School: Tianjin University
Course: Materials Physics and Chemistry
Keywords: Sol - gel method Ferrite PH value Doping Temperature coefficient Initial permeability Grain size
CLC: TM277
Type: Master's thesis
Year: 2010
Downloads: 52
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Abstract


The main aim of this paper is to study the basic procedures of fabricating Mn-Zn ferrites by the sol-gel synthesis. First, we analyzed the influences of different PH values on magnetic properties of Mn0.2Zn0.8Fe2O4ferrite. Secondly, we synthesized the Mn-Zn ferrites doped with Co and examined the effect of the dopant on Mn-Zn ferrites and finally the magnetic properties of MnXZn1-XFe2O4 ferrites (x= 0.2, 0.3, 0.4 and 0.5) were investigated.In order to study the influnence of different PH values (PH=2,3,4,5,6) on magnetic properties of MnZn ferrites, we prepared sufficient samples of Mn0.2Zn0.8Fe2O4 ferrites. As proved in the experiments, when PH equals to 5, the quality of ferrites’saturation magnetization and coercivity is believed to be acceptable. PH values affect the complexing process proceeded between complexing agents and metallic ions. Furthermore, the size of particles would be affected, leading to different magnetic properties. When PH equals to 5, the result of complexation is preferable.In order to improve the temperature stability of ferrites, we synthesized the Co-doped Mn0.4Zn0.6Fe2O4 ferrite and prepared ring-shaped samples, on which we measured the changes of initial premeability with temperatures and calculated the temperature coefficient a(?) from the (?) i (?) T curve. It was found, by our experiments, that the temperature coefficient of permeability rose at first and then droped with the content of Co increasing and the preferable temperature stability, corresponding to the lowest temperature coefficient is achieved when the content of Co dopant is 5%. On the other hand, the initial permeability decreased gradually with increasing Co dopants, which is closely related to the trend of Co2+occupying the octahedral sites in spinel structure.Through examining MnXZn1-XFe2O4 (x= 0.2、0.3、0.4、0.5) with different proportions of Mn and Zn, it is concluded that the proportion would exert major effects on the structural characteristics and magnetic properties such as the saturation magnetization, coercivity, as well as the grain size. By XRD and VSM experiments to the ferrite powder, we obeserved that the maximum saturation magnetization and the minimum coercivity appeared at x = 4, which is significantly relevant to the alteration of exchanging process resulting from the content and the placehold trend of Zn2+

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CLC: > Industrial Technology > Electrotechnical > Electrical materials > Magnetic materials,ferrite > Ferrite,oxide magnetic materials
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