Study On Preparation Of Mn-Zn Ferrite By Oxide Co-precipitation And Effect Of RE-doped

Mn-Zn ferrite is a key material of modern electron industry and information industry, widely used in switching power supplies, transformer magnetic cores, information memory systems, medical diagnose, anti-electronmagnetic interference and so on. With the rapid development of telecommunication and computer technology, the higher and higher requirements are put forward for the Mn-Zn ferrite. In order to improve the properties of Mn-Zn ferrite, researches are focused on the following three aspects: (1)adjusting the proportion of the material composition,(2)the improvement on preparation method,(3)chemistry dopant. In this paper the preparation of Mn-Zn ferrite and the effect of RE-doped on Mn-Zn ferrite by oxide co-precipitation method were studiedIn this paper Mn-Zn ferrite nanometer powder was synthesized in solution on the basis of preparation of Fe₃O₄ by oxide co-precipitation method. The effects of concentration of solution,PH value,heat-treatment and surfactant were studied on the phase ,microstructure and magnetic properties of the Mn-Zn ferrite samples.The results indicate the single phase Mn-Zn ferrite nanometer powder can be prepared directly by oxide co-precipitation method, and the concentration and PH value of solution are two key factors of the method, and the the higher concentration and PH values,the higher crystallinity and saturation magnetization. Fe₂O₃ exists in the Mn-Zn ferrite samples after they are heat-treated at different temperatures in air and the content of Fe₂O₃ reduces with the rising of heat-treatment temperature, while the saturation magnetizations increase. But Fe₂O₃ does't exist in the Mn-Zn ferrite samples after they are heat-treated at 600℃in air and then cooled in nitrogen atmosphere. The saturation magnetization of Mn-Zn ferrite samples cooled in nitrogen atmosphere is higher than that of Mn-Zn ferrite samples cooled in air.The surfactant CTAB added to solution can reduce agglomeration of the nanometer particles efficiently, the crystallite granularity and saturation magnetization decrease with the increasing of the ratio of the surfactant and water weight.Secondly Mn_0.5-Zn_0.5RE_xFe_2-xO₄(RE=Y,Nd,Gd,Dy)nanometer powder was prepared by oxide co-precipitation method .The results indicate the single phase Mn_0.5-Zn_0.5RE_xFe_2-xO₄ can be prepared directly by oxide co-precipitation method, the crystallite granularity of Mn_0.5-Zn_0.5RE_xFe_2-xO₄(RE=Y,Nd,Gd,Dy)samples and the saturation magnetizations of Y or Nd doped Mn-Zn ferrite decrease monotonously with the increasing of the content (x) ,but the saturation magnetizations of Gd or Dy doped Mn-Zn ferrite increase firstly and then reduce except x=0.04.At x=0.04 the saturation magnetizations reach the minimum.