Amorphous CoFe2O4 Nanoparticles: Synthesis, Crystallization Process, and Magnetic Properties

作者：Danh Bich Do^*; Nguyen Dang Phu; Nguyen Van Hung; Luc Huy Hoang; Le Thi Mai Oanh; Do Minh Thanh; Nguyen Van Minh

来源：IEEE Transactions on Magnetics, 2014, 50(6): 2502904.

DOI：10.1109/TMAG.2014.2306814

• Amorphous materials
• ferrite
• magnetic particles
• magnetic properties
• microwave oven

Amorphous CoFe2O4 nanoparticles have been successfully synthesized by the chemical microwave-assisted method. The crystallization process and the hard magnetic properties of prepared nanoparticles were systematically investigated in terms of thermal analysis and in situ measurement of magnetization dynamics. The as-prepared sample was amorphous, which was confirmed by various techniques, such as high resolution transmission electron microscopy, with electron diffraction and X-ray diffraction. The thermal analysis using differential scanning calorimetry showed that crystallization from CoFe2O4 amorphous state to CoFe2O4 crystalline started at 290 degrees C. Crystallization activation energy was determined using the Kissinger model with a value of 1.09 eV. A study of the temperature dependence of magnetization supported the crystallization process of cobalt ferrite nanoparticles. Magnetic measurement indicated that the as-prepared amorphous particles were superparamagnetic. Compared with the bulk material, the observed value of saturation magnetization of the annealed sample was significantly low (27 emu/g) due to its nanocrystalline nature.

• 出版日期2014-6