热处理温度对纳米 CoFe 2O 4/ SiO 2复合材料结构和磁性的影响

采用溶胶2凝胶法制备了纳米 Co Fe 2O 4/ SiO 2复合材料。利用 X射线衍射(XRD) 、 透射电镜( TEM) 、 振动样品磁强计(VSM)和 Mssbauer 效应研究了纳米复合材料结构、 晶粒尺寸及磁性。结果表明 , 样品中 Co Fe 2O 4的晶粒尺寸随着热处理温度的提高而增加 , 非晶态 SiO 2的存在有效地抑制了 Co Fe 2O 4晶粒的生长。VSM结果表明 , 样品的比饱和磁化强度和矫顽力随 Co Fe 2O 4晶粒尺寸的增加而变大。Mssbauer 效应结果表明 , 随着热处理温度的提高 , 样品从超顺磁和磁有序的混合状态转变为完全的磁有序状态。

Influence of heat treat temperature on structure and magnetic properties of CoFe 2O 4/ SiO 2 nanocomposite

The Co Fe 2O 4/ SiO 2 nanocomposite was prepared by the sol2 gel method. The st ructure , crystalline size and magnetic properties of samples were investigated by XRD , TEM , VSM and Mssbauer effect . The result s show that the grain size of Co Fe 2O 4increases with the increasing of heating temperature , and the growth of Co Fe 2O 4 grain is rest ricted effectively with the existence of amorphous SiO 2. VSM result s show that the saturation magnetization and coercivity of the samples increase with the increasing of the grain size. With the rise in t reatment temperature , the samples t ransform f rom the superparamagnetic and magnetic order mixed state to an entire magnetic order state ,which is confirmed by the Mssbauer effect .