有机凝胶先驱体转化法制备尖晶石型铁氧体MnFe2O4纤维

Preparation of Spinel Ferrite MnFe_2O_4 Fibers by Organic Gel-Polymer Derived Process

以柠檬酸和金属盐为原料，采用有机凝胶先驱体转化法成功制备出了纳米晶MnFe2O4铁氧体纤维。通过FTIR，TG-DTA，XRD，SEM和振动样品磁强计（VSM）对纤维前驱体凝胶的结构、热分解过程及热处理产物的物相、形貌以及纤维的磁性能等进行了表征。结果表明，当柠檬酸与金属粒子的摩尔比CA：Fe^3＋：Co^2＋=4：2：1和pH值等于4.5时形成的凝胶具有良好的可纺性，在凝胶形成过程中金属离子可能以单齿形式配位于柠檬酸根阴离子，形成了线型分子结构。所制得的纤维表面光滑、致密，纤维直径在1-20μm，长径比较大。600℃焙烧2h后得到的Mn铁氧体纤维的晶粒粒径在12nm左右。随机分布的MnFe2O4铁氧体纤维在常温下的比饱和磁化强度为6.59A·m^2·kg^-1，矫顽力为4.3kA·m^-1。

The spinel type MnFe204 ferrite fibers are successfully prepared by the organic gel-polymer derived process from raw materials of metal salts and citric acid. The structure, morphology and thermal decomposition process of the gel precursors, and the fibers derived from thermal decomposition of these precursors are characterized by FTIR, thermogravimetric-differential thermal analysis （TG-DSC）, X-ray diffraction （XRD）, and scanning electron microscope （SEM ）. The electromagnetic performances of ferrite fibers are measured by vibrating sample magnetometer （VSM ）. Results show that the gel obtained at CA：Fe^3＋：Co^2＋=4：2：1 and pH=4.5 exhibits a good spinning performance, and linear-type struc-tural molecule for the gel precursor is possibly formed by a single dentate liganding type between citric acid and metal ion during the complexation reaction. These prepared spinel fibers with the smooth and compact surface have diameters of 1-20μm, with a high length-to-diameter factor. The MnFe2O4 ferrite fibers obtained by sintering at 600℃ for 2 h consist of grain size of about 12 nm. The randomly oriented MnFe2O4 ferrite fibres has a specific saturated magnetization of 6.59A·m^2·kg^-1 and a coercivity of 4.3kA·m^-1 at ambient temperature.