溶胶凝胶法制备锰锌铁氧体粉体的工艺优化与分析

Optimization on Preparation Process of Mn-Zn Ferrite Powder by Sol-gel Method

采用柠檬酸作为络合剂,通过溶胶凝胶法制备了设计组成为Zn0.2Mn0.8Fe2O4锰锌铁氧体粉体,并通过XRD、VSM(振动样品磁强计)等手段研究了工艺参数对物相、磁性能的影响。结果表明,前驱体溶液的pH值及络合剂的用量对锰锌铁氧体粉体的物相及磁性能均有影响,当金属离子与柠檬酸的物质的量比(以下统称为金柠比)为1:1且前驱体溶液pH值为3时,产物的物相与磁性能较为理想,后续热处理温度为450℃时,磁性能参数Ms出现极大值,达到了46.8emu/g。在热处理过程中使用Ar保护气体可以有效抑制高温α-Fe2O3相的产生,从而可以通过提高热处理温度的方法来改善粉体的结晶度。但过高的温度将导致材料组分中的Zn2+以ZnO的形式挥发,而使产物组分偏离设计组成,反而造成磁性能的降低。

Mn-Zn ferrite powder with the composition of Zn0.2 Mn0.8 Fe2O4 were prepared by the sol-gel method using citric acid as complexing agent. The phase and the magnetic properties related to the effect of process parameters were investigated by XRD, VSM. The results show that Mn-Zn ferrite phase and magnetic properties are affected by the pH value of precursor solution and the amount of complexing agent. The reaction products with desirable phase composition and magnetic property were obtained when the molar ratio of metal ions and citric acid is 1 ： 1 and the pH value of the precursor is 3. A maximum saturation magnetization of 46.8 emu/g can be achieved when the as-prepared ferrite powder are postsintered at 450 ℃ under Ar flux. The enhancement in magnetic property is attributed to the improvement of crystallinity. The sintering process should be carried out under Ar flux to inhibit the formation of α- the composition deviation, thereby degrading lead to the volatile of Zn^2＋ in the form of ZnO, resulting in the magnetic property.