尺寸可控的CoFe_2O_4纳米粒子的制备及其磁性

Size-Controlling Preparation of CoFe_2O_4 Nano-Particles and Its Magnetic Properties

采用共沉淀方法制备了一系列CoFe2O4纳米粒子.X射线衍射、透射电镜和拉曼光谱的分析显示,通过改变NaOH浓度,可以制备单相的CoFe2O4纳米粒子,晶格常数在0.830-0.840 nm之间,晶粒尺寸在9.0-65.0 nm之间.研究结果表明,样品的矫顽力随着样品的尺寸的增加而增大,9.0 nm的CoFe2O4纳米粒子的矫顽力为0.283 2 T,而65.0 nm的CoFe2O4纳米粒子的矫顽力为0.467 4 T,饱和磁化强度与CoFe2O4纳米磁性粒子表面原子的不同分布有关.

Nano particles of cobah ferrite have been prepared using co-precipitation method with NaOH as precipitators. X-ray diffraction, transmission electron microscope and Raman analysis confirm the formation of single-phase cobalt ferritenano particles. The crystal constants are between0.830 nmand 0.840 nm, and the grain sizes are between 9.0 nm and 65.0 nm, depending on pH values of the suspensions. Magnetic measurements show that the coercivity of CoFe2O4 nano-particles increases with the in creasing of grain size, the coercivity of CoFe2O4 nano particles of 9.0 nm and 65.0 nm are 0. 283 2 T and 0.467 4 T, respectively, while the saturation magndization shows much dependence on the distribution of Co^2＋ and Fe^2＋ surface ion.