Fabrication of CoFe2O4 hollow fibers by direct annealing of the electrospun composite fibers and their magnetic properties

CoFe2O4 hollow fibers have been fabricated by direct annealing of electrospun polyvinylpyrrolidone (PVP)/nitrate salts composite nanofibers. In this approach, composite fibers were firstly synthesized by electrospinning PVP/nitrate salts solution, and then calcined at high temperature with appropriate heating rate to form hollow CoFe2O4 fibers. The crystal structure, morphology and magnetic properties of the CoFe2O4 hollow fibers were investigated by using the X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and SQUID magnetometry, respectively. The results indicate that the phase structure of hollow fibers belongs to cubic spinel structure, hollow fibers after annealing at high temperature still remain the one-dimensional texture and the wall of hollow fibers consists of many nanoparticles. The magnetic measurement showed that the hollow one dimensional structure has some novel magnetic properties, which may make them useful in electromagnetic and spintronic devices