CoFe2O4纳米颗粒的溶液合成及磁性能

Synthesis of CoFe_2O_4 Nanoparticles via Solution Method and Their Magnetic Properties

以Co(NO3)2.6H2O和Fe(NO3)3.9H2O为原料,采用直接溶液合成法制备CoFe2O4纳米粉体。分析了纳米粉体的物相结构、微观形貌及合成机理,研究了热处理温度对粉体磁性能的影响。结果表明:所得CoFe2O4粉体为立方尖晶石铁氧体,颗粒细小、分散均匀,平均粒径约为5nm。500℃以下热处理的粉体表现出良好的超顺磁性;500℃以后,随热处理温度上升,颗粒尺寸变大,粉体的比饱和磁化强度Ms、比剩余磁化强度Mr和矫顽力Hc均增大。室温下CoFe2O4粉体的Ms为3.4A.m2/kg。当热处理温度为900℃时,Ms增大到59.5A.m2/kg,Hc增大到97.0kA/m。

CoFe2O4 nanoparticles were prepared by a direct synthesis method from solution using Co（NO3）2·6H2O and Fe（NO3）3· 9H2O as raw materials. The phase structure, micro-morphology and synthesis mechanism of the nanoparticles were analyzed. The effect of annealing temperature on the magnetic properties of the samples was investigated. The results show that the products are cubic spinel-type ferrites with the average particle size of 5 nm, and the nanoparticles are well-dispersed. When the annealing temperature was 〈 500 ℃, the nanopraticles exhibited a superparamagnetic behavior. When the annealing temperature was 〉 500 ℃, the particle size, the specific saturation magnetization （Ms）, the specific remnant magnetization （Mr） and the coercivity （Hc） of nanoparticles all increased with the increase of the annealing temperature. The Ms of nanoparticles was 3.4 A·m^2/kg at room temperature. When the annealing temperature was 900 ℃, the Ms and the Hc for the nanoparticles were 59.5 A·m^2/kg and 97.0 kA/m, respectively.