Co_(0.8)Fe_(2.2)O_4多孔微球的制备及交换偏置效应

Synthesis and exchange bias effect of nano-structure Co_(0.8)Fe_(2.2)O_4 porous microspheres

通过溶剂热反应合成纳米结构Co0.8Fe2.2O4多孔微球.用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)表征样品的结构和形貌,结果表明:所制备的Co0.8Fe2.2O4多孔微球由许多纳米颗粒组装而成,直径约200 nm.用振动样品磁强计(VSM)测量Co0.8Fe2.2O4多孔微球的变温磁性,发现低温下Co0.8Fe2.2O4多孔微球存在显著的正交换偏置效应.组成Co0.8Fe2.2O4多孔微球的纳米颗粒可看作一个表面反铁磁排列与内部亚铁磁排列共存的系统,且内部亚铁磁与表面反铁磁的相互作用为反铁磁性,Co0.8Fe2.2O4纳米颗粒系统具有正交换偏置效应.

Co0.8Fe2.2O4 porous nanostructure microspheres were prepared by solvothermal reaction. X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM） were used to characterize the structure and morphology of samples. The results showed that the prepared Co0.8Fe2.2O4 porous microspheres with about 200 nm diameter, were assembled by many nanoparticles. The magnetic properties were evaluated with a vibrating sample magnetometer （VSM）. The significant positive exchange bias effect was found at lower temperature in Co0.8Fe2.2O4 porous microspheres.Co0.8Fe2.2O4 porous microspheres were assembled by many nanoparticles, and the nanoparticles could be seen as a surface antiferromagnetic arrangement and internal ferrimagnetic ordering coexistence system. The interaction between internal ferrimagnetic layer and antiferromagnetic surface layer was antiferromagnetic, so the Co0.8Fe2.2O4 nanoparticles system possessed positive exchange bias effect.