溶胶-凝胶法制备纳米复合永磁材料中溶液pH值的影响

用溶胶-凝胶法制备了纳米复合永磁材料FesmO3/Fe2O3,通过XRD、TG/DTG、SEM及VSM的表征,研究了溶液pH值对凝胶形态、焙烧温度和磁性能的影响.实验结果表明,溶液pH值对焙烧温度和样品相态有显著的影响,在低pH值分段焙烧时,可得纳米复合永磁材料FeSmO3/Fe2O3,当pH值升到7时,只能得到单相粉体FeSmO3.分段焙烧400℃、2h及650℃、1h后,得到平均粒径在30nm、软磁相与硬磁相发生强烈的交换耦合作用的纳米复合永磁材料,由于交换耦合作用使纳米复相具有优异于单相的磁性能.

Influence of pH Value of Solution in Preparation of Nanocomposite Permanent Magnetic Material by Sol-gel Method

The nanocomposite permanent magnetic material FeSmO3/Fe2 O3 is prepared by sol-gel method and the influences of pH value of the precursor solution on the gel morphology,annealing temperature and magnetic properties are study by X-ray diffraction(XRD),thermogravimetric differential and thermogravimetric(TG/DTG),scan electron microscopy(SEM),and vibrating sample magnetometer(VSM).Experimental results show that the pH value of the precursor solution has a significant influence on the annealing temperature and phases,and the nanocomposite FeSmO3/Fe2 O3 can be obtained at low pH value via subsection annealing temperature.When the pH value increases to 7,powders are single-phase FeSmO3.The microstructure of the nanocomposite permanent magnetic material consists of hard magnetic phase and soft magnetic phase with an average size of 30nm when annealed by subsection at 400℃for 2 hours and then at 650℃for 1 hour.These small particles allow effective exchange coupling between two phases and display enhancement of permanent magnetic properties compared with pure FeSmO3.The sol-gel technique is more preferable for the preparation of nanocomposite because its process is easy,the experiment is simple and the product is stable.