Indexed on: 08 Feb '15Published on: 08 Feb '15Published in: Applied Physics A
This work reports the fabrication and properties of carbon/cobalt ferrite (C/CoFe2O4) composite nanofibers by using electrospinning technique followed by carbonization process under mixed air and argon atmosphere. The as-prepared samples were characterized by means of thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray absorption spectroscopy, and vibrating sample magnetometry. It was found that the structure of CoFe2O4 was cubic spinel with the variation of crystallite size between 22 and 54 nm depending on the magnetic source content. X-ray absorption near-edge spectra at the Fe (7,112 eV) and Co (7,709 eV) absorption K-edge were used to confirm the Fe3+ and Co2+ oxidation states of CoFe2O4 nanoparticles. The X-ray absorption fine structure analysis indicated that CoFe2O4 nanoparticles had a structure analogous to bulk-inverted spinel structure. All composite nanofibers exhibited ferromagnetic behavior related to the distribution of cations over tetrahedral and octahedral sites, whereas diamagnetic behavior was observed in pure carbon nanofibers. The magnetization was clearly enhanced with respect to the increase of magnetic source content, whereas the coercivity and the squareness (Mr/Ms) were dependent of crystallite size.