Flow In Disguise Preparation Of Mn-zn Ferrite And Its Performance Test

As an important sort of soft magnetic materials, Mn-Zn ferrite have been used widespreadly. How to simplify the manufacture craft of it and improve the product performance are also the key point which the people studies now. In this paper, the Mn-Zn ferrite crystal with typical spinel structure were prepared with rheologic phase method under a lower calcination temperature. The preparation process, the reaction mechanism, and the properties of magnetism and microwave absorption of the obtained Mn-Zn ferrite powders were investigated.In order to obtain the Mn-Zn ferrite precursor particles which has ultra-fine property, the optimum technological condition was observed through the orthogonal experiments. In the rheologic phase process of preparation, the leading factors that affect the size of the particle were ratio of the ion concentration (A), temperature of reaction (B),time of reaction (C), calcination temperature (D). Results showed that when the ratio of the ion concentration was 0.33, temperature of reaction was 80℃, time of reaction was 12h and calcination temperature was 300℃, the ultra-fine Mn-Zn ferrite precursor could be obtained. Effect of additives on the product was also investigated. The result showed that using CH₃COONa as additives, particle reunion was less serious and crystallization performance was more perfect.By comparing the process and the product, it was found that some crystals have already formed in the precursor with rheologic phase method, while the precursor with co-precipitation method was almost amorphous; calcinated under 400℃with theologic phase method, Mn-Zn ferrite crystal which have typical spinel structure and better thermostability was obtained, but ,the crystal obtained with co-precipitation method must be calcinated over 850℃, and its thermostability was worse; That two kinds of methods to prepare crystal have experienced the similar process, dissolvingâ†'diffusingâ†'coringâ†'growing up. However, "tiny area solution" with rheologic phase method was formed in the process.The effect of Zn content, calcination temperature and preparation methods of Mn_1-xZn_xFe₂O₄ on magnetism and microwave absorption were investigated. The results showed that with the rheologic phase method when the Zn content x was 0.3 and calcination temperature was 400℃, magnetism and microwave absorption of samples were better. The effect of Ce-doping of Mn_0.7Zn_0.3Fe_2-xCe_xO₄ on microwave absorption were investigated, too. The results showed that Ce-doping could improve microwave absorption of samples greatly. When Ce-doping content x was 0.03, microwave absorption was best, which absorbing microwave apex could reach -37dB, and the bandwidth value was 0.6GHz at-10dB.