共沉淀法制备CoFe2O4纳米颗粒及其磁电性能表征

摘要

通过热力学计算确定Me-NaOH-NH3·H2O体系中钴离子和铁离子的最佳共沉淀pH值,然后采用化学共沉淀法制备了CoFe2O4的前驱体粉体,再经过热处理制得纯相CoFe2O4粉体,并用X射线衍射仪、扫描电镜、振动样品磁强计和精密阻抗分析仪对其进行表征.结果表明,在pH值=11.4的的共沉淀条件下制备得到前驱体粉体,经400 ℃煅烧就已经开始形成CoFe2O4粉体,温度继续升高生成纯相粉体;并且样品的饱和磁化强度Ms、剩磁Mr及矫顽力Hc随温度升高先增大后减小,在500 ℃(接近居里温度点)附近达到最大值分别为Ms=14.40 A·m2/kg,Mr=3.15 A·m2/kg,Hc=3.22 kA/m,与以往研究报道不同.%The most appropriate pH value for Co2+ and Fe3+ to precipitate in the Me-NaOH-NH3·H2O system was calculated by thermodynamic calculation, then the precursor of CoFe2O4 was synthesized by coprecipitation method.After that, the pure CoFe2O4 powders were obtained from the precursor through the heat treatment.X-ray diffractometer, scanning electron microscope, vibrating sample magnetometer and precision impedance analyzer were employed to characterize the samples.The results show that the precursor synthesized under the coprecipitation condition of pH=14 begins to form the CoFe2O4 powders when calcined at 400 ℃ and the powders become purer with the increase of temperatures.The saturation magnetization, residual magnetization and coercivity increase first and then decrease with the rise of temperature and reach the maximum value of 14.40, 3.15 A·m2/kg and 3.22 kA/m at 500 ℃, which is close to the Curie temperature.The results are different from the previous reports of surveys.