Crystallization of the NiZn ferrite nanofibers fabricated by electrospinning method

Polyvinyl pyrrolidone nanofibers including nickel, zinc, and iron precursors were fabricated via the electrospinning method. To convert as-spun nanofibers to Ni0.5Zn0.5Fe2O4 oxide nanofibers which is capable of shielding an electromagnetic wave, heat treatment conditions were optimized. To obtain the heat treatment condition that can exclude amorphous carbon black and secondary crystal phase, samples were taken at each temperature while the calcination process and analyzed. According to the X-ray diffraction (XRD) analysis, the Ni0.5Zn0.5Fe2O4 crystal phase started to appear from 300 degrees C, but it was confirmed through energy dispersive spectroscopy (EDS) analysis that heat treatment of 500 degrees C or more was required to remove most of the carbon black. When the calcination temperature exceeds 650 degrees C, crystal nuclei starts to grow and the fiber surface condition becomes rough, so it was confirmed that the heat treatment conditions should be selectively determined according to the application field.