Low-Temperature Preparation of Superparamagnetic CoFe2O4 Microspheres with High Saturation Magnetization
Key Lab for Special Functional Materials of Ministry of Education, Henan University, 475004, Kaifeng, People’s Republic of China
Nanoscale Research Letters 2010, 5:1817-1821 doi:10.1007/s11671-010-9718-7Published: 11 August 2010
Based on a low-temperature route, monodispersed CoFe2O4 microspheres (MSs) were fabricated through aggregation of primary nanoparticles. The microstructural and magnetic characteristics of the as-prepared MSs were characterized by X-ray diffraction/photoelectron spectroscopy, scanning/transmitting electron microscopy, and vibrating sample magnetometer. The results indicate that the diameters of CoFe2O4 MSs with narrow size distribution can be tuned from over 200 to ~330 nm. Magnetic measurements reveal these MSs exhibit superparamagnetic behavior at room temperature with high saturation magnetization. Furthermore, the mechanism of formation of the monodispersed CoFe2O4 MSs was discussed on the basis of time-dependent experiments, in which hydrophilic PVP plays a crucial role.