退火温度对纳米Co0.8Mg0.2Fe2O4/SiO2复合薄膜结构和磁性的影响

Effects of Annealing Temperature on Structure and Magnetic Properties of Co_(0.8)Mg_(0.2)Fe_2O_4/SiO_2 Nanocomposite Films

采用溶胶-凝胶旋涂法制备纳米Co0.8Mg0.2Fe2O4/SiO2复合薄膜。用X射线衍射仪、原子力显微镜及振动样品磁强计分析复合薄膜的结构、表面形貌和磁性,研究退火温度对复合薄膜结构和磁性的影响。结果表明:经800℃退火处理的样品中已形成Co0.8Mg0.2Fe2O4晶相;随着退火温度的提高,Co0.8Mg0.2Fe2O4晶粒尺寸变大,晶格常数减小;随着Co0.8Mg0.2Fe2O4晶粒尺寸的增大,样品的磁化强度和剩磁比变大,矫顽力先增大后减小,经1 100℃退火处理样品的垂直膜面矫顽力达到296.1 kA/m;样品存在较明显的垂直磁各向异性。

Co0.8Mg0.2Fe2O4/SiO2 nanocomposite films were prepared by the sol-gel method.Structure,morphology and magnetic properties of the nanocomposite films were characterized by the X-ray diffraction,atomic force microscopy and vibrating sample magnetometry（VSM）,and effects of annealing temperature on structure and magnetic properties of the nanocomposite films were studied.Results show that the sample exhibits a Co0.8Mg0.2Fe2O4 spinel structure after being annealed at 800 ℃.With the increasing of the annealing temperature,the grain size of Co0.8Mg0.2Fe2O4 in the nanocomposite films increases,while the lattice constant de-creases.The VSM results show that magnetization and remanence ratio（Mr/Ms） increases with the increasing of the grain size of Co0.8Mg0.2Fe2O4,while the coercivity of samples tends to increase first,and then decrease.Perpendicular coercivity of the sample annealed at 1 100 ℃ reaches 296.1 kA/m.The films possess an obvious perpendicular magnetic anisotropy.