M型锶铁氧体中空纤维的制备和表征

以柠檬酸和金属盐为原料，采用有机凝胶先驱体转化法制备了M型锶铁氧体（SrFe₁₂O₁₉）中空纤维. 通过FTIR、TG/DSC、XRD、SEM和VSM等技术对所得纤维进行了表征. 结果表明，凝胶的可纺性与其化学组成和pH值有关，当柠檬酸与金属离子的摩尔比为1.5∶1.0，pH=4.2左右时，凝胶的可纺性最好. 经1100℃焙烧后，制备的M型锶铁氧体中空纤维具有较大的长径比，直径可小于1μm，中空孔径约为纤维直径的一半，组成纤维的晶粒形貌为六角片状，晶粒尺寸为236nm，在室温下的饱和磁化强度为53.5A·m²/kg，矫顽力为386.96kA/m. 纤维显示出一定的形状各向异性，当定向排列的纤维平行和垂直磁场时，矫顽力分别为391.66和358.72kA/m.

Preparation and Characterization of M-type Strontium Ferrite Hollow Fibers

The M type strontium ferrite （SrFe₁₂O₁₉） hollow fibers were prepared by the organic gel-precursor transformation method using citric acid and metal salts as raw materials. The gel-precursors and the as-prepared fibers were characterized by FTIR, XRD, TG/DSC, SEM and VSM. The results show that the gel spinnability is related with the chemical composition and pH value. The gel exhibits an appropriate spinning performance when the molar ratio of citric acid to the total metal ions is 1.5∶1.0 and the pH value is around 4.2. The M-type strontium ferrite hollow fibers obtained are characterized with high aspect ratio, thin diameters and ratio of the hollow diameter to the fiber diameter being about 1/2.The fibers calcined at 1100℃ are composed of SrFe₁₂O₁₉ nanoparticles with hexagonal plate morphology and average particle size of about several hundred nanometers. At room temperature, the saturation magnetization and coercivity of the M-type strontium ferrite hollow fibers calcined at 1100℃ are 53.5A·m²/kg and 386.96kA/m, respectively. These M-type strontium ferrite hollow fibers possess a shape anisotropy characteristic and the coercivity for the aligned hollow fibers parallel and parpendicular to the applied field is correspondingly 391.66kA/m and 358.72kA/m.