Fabrication of the novel Fe2+αO3+α–CoFe2O4 composite fibers and their magnetic properties

Abstract

Soft-hard magnetic composites have attracted much attention as magnetic materials for permanent magnets due to high coercivity and saturation magnetization in various fields such as motor, storage device and magnetic actuators. Hard magnetic materials with low saturation magnetization improve magnetic properties through exchange coupling effect with soft magnetic materials. Rare earth metals, which are used as magnetic materials in permanent magnetic, have issued such as high cost due to resource scarcity. Transition metals have been used for fabricating magnetic material with high magnetic properties due to low cost and abundant in the resource. Spinel magnetic materials with transition metals have excellent chemical, thermal stability, large magnetocrystalline anisotropy and magnetic properties. Composite magnetic materials in one dimensional (1D) morphology are effective in improving coercivity. In this work, soft-hard composite fiber has been fabricated by electrospinning method using iron oxide as soft magnetic material and cobalt ferrite as hard magnetic material. The change in the oxidation state of iron oxide can be controlled with sintering atmosphere and influences on the magnetic properties. In comparing with simple CoFe2O4, the fabricated Fe3O4–CoFe2O4 exhibits excellent saturation magnetization of 133.63 emu g−1 and enhanced coercivity of 2746.9 Oe.