溶剂热法制备纳米磁性四氧化三锰的研究

【作者】 陈权启；

【导师】 黄可龙；

【作者基本信息】 中南大学 ， 应用化学， 2003， 硕士

【摘要】 本论文利用正交实验的方法研究了溶剂热法制备纳米四氧化三锰的工艺条件，用XRD、TEM、Mastersize、振动样品磁强计等仪器及化学分析方法对产物进行了检测、分析。研究结果表明，高锰酸钾的浓度、反应温度是影响产物粒径的主要因素；反应时间是影响产物的成分与晶型的主要因素；四氧化三锰的磁性随着晶粒粒径的增加而变小。得出溶剂热法制备纳米四氧化三锰的最佳反应条件为：高压反应釜中的填充度（f）为0.8，反应温度为260℃，反应浓度为C＜0.015g．mL^-1，反应时间为10小时。所得产物的平均粒径为25nm，比饱和磁化强度为σ=3.58emu．g^-1，四氧化三锰的锰总含量为71.96％。 参照溶液的成核理论及熔体的成核理论，通过理论推导及相关的数学方法，得出本实验溶剂热法制备纳米四氧化三锰的动力学公式：溶剂热成核速率公式、晶核生长速率公式为，产物颗粒粒径与浓度、温度、时间的函数关系式，从理论上较好地解释了本实验的相关现象与溶剂热反应的温度、溶液的浓度的关系。 为了研究四氧化三锰的磁性产生机理，在制备的过程中通过选择不同的反应途径及加入不同的杂质，检测反应产物的组成及磁性。结合Neel理论、尖晶石型结构中的离子分布及相关的磁学知识，初步探讨了影响四氧化三锰的磁性机理。更多还原

【Abstract】 The preparation technological conditions of nanometer trimaganese tetroxide by the solvothermal method are determined through the rthogonal experiment. We have found the optimal technological conditions: filling percentage is 0.8 in the reaction, reaction temperature is 260癈,the concentration of KMnO4 is below 0.015g.mL-1,the reaction time is 10 hours. The product has been characterized with the XRD, TEM, Mastersize and the composition of the material is analyzed by the chemical method. The result shows that the concentration of KMnO4, reaction temperature are the main factors influence the particle size, the composition and crystal type are affected by the reaction temperature, the magnetism of the product reduces with the reaction temperature increasing. The particle size of MnsO4 is about 25nm,staturation magnetization is about 3.58emu.g-1 and the total manganese of the product is 71.96%.Consulting the concerned reference theory of crystal nucleus growth in solution and crystal nucleus growth in metal bath, a dynamic formula of nanometer Mn3O4 produced by the solvothermal method is deduced. It can explain the relation between the phenomena and the reaction temperature, concentration of solution on some extent.In order to investigate the mechanism of the nanometer Mn3O4, the impurities are added in the different reaction routes, then the composition and the magnetism are tested. According to the result of the test, combining the theory of Neel, distribution of metal ion in the spinel structure and the correlative theories of magnetism, the mechanism of magnetism and the factors influenced the magnetism are investigated.更多还原