针状纳米SrFe12O19的溶胶-凝胶法制备及磁性研究

采用柠檬酸-EDTA的联合络合溶胶-凝胶法制得了针状纳米锶铁氧体磁性微粒。利用XRD对样品的物相进行分析，利用TEM对样品形貌和粒径进行表征，并利用振荡样品磁强计(VSM)对样品进行了磁性能研究。结果表明，相对于柠檬酸法制备的纯锶铁氧体微粒，EDTA加入后制备的SrFe₁₂O₁₉微粒仍保持六方磁铅石型结构，但是粒径减小，形貌向一维发展，且内禀矫顽力H_c显著提高。并直接对凝胶加热，使其发生自蔓延燃烧，省去了凝胶的干燥过程，制备周期缩短1/4以上，同时自蔓延燃烧使SrFe₁₂O₁₉的内禀矫顽力提高10%左右，通过洗涤前驱体使得SrFe₁₂O₁₉纯度得到提高，进而使比剩余磁化强度和比饱和磁化强度提高20%左右，最终制得了粒径为30 nm，长径比为5∶1，内禀矫顽力、比饱和磁化强度与比剩余磁化强度分别为6 446.9 Oe、68.9 emu·g^-1和40.2 emu·g^-1的针状纳米SrFe₁₂O₁₉。

Needle-like Nano-SrFe12O19 Particles; Preparation by Sol-gel Method and Magnetic Properties

The needle-like nano-strontium ferrite magnetic particles were prepared by co-complexion sol-gel method with citric acid and EDTA. The crystal phase of the sample was analyzed by XRD, the morphology and particle size were observed by TEM, the magnetic properties were studied by vibrating sample magnetometer(VSM). The result indicates that the structure of the prepared nano-SrFe₁₂O₁₉ particle remains hexagonal magneto-plum bite type. As for the nano-SrFe₁₂O₁₉ particle without EDTA addition, the diameter of the particle deceases. The morphology has a tendency to develop to one-dimension, and coercivity(H_c) increases enormously. The sol was heated directly until the self-propagating burning reaction, eliminating the drying step from the process, the preparation period of SrFe₁₂O₁₉ was thus shortened by about 1/4, the coercivity of nano-SrFe₁₂O₁₉ increased by about 10%. The purity of the nano-SrFe₁₂O₁₉ was higher due to the washing process of precursor, and the saturation(M_s) and remanent magnetization(M_r) of the sample increased by about 20%. The needle-like nano-strontium ferrite with the diameter of 30 nm and the slenderness ratio of 5 was prepared, and Hc, Ms, Mr of the sample were 6446.9 Oe, 68.9 emu·g^-1, 40.2 emu·g^-1, respectively.