Structural and magnetic properties of Ni/C core-shell nanofibers prepared by one step co-axial electrospinning method

Nickel/carbon (Ni/C) nanofibrous structures with magnetic material nickel in the core and carbon in the shell are fabricated by the co-axial electrospinning method. The crystallinity, morphology, elemental composition, and microstructure of the carbonized nanofibers are characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDX), and high-resolution transmission electron microscope (HRTEM) respectively. Rietveld refinement method of XRD pattern was carried out to determine the structural parameters of face-centered cubic (FCC) Ni with space group Fm3m. The average crystallite size and the lattice strain have been calculated using the Williamson-Hall (W-H) plot method. It is demonstrated that the compressive lattice strain is attributed due to the presence of polymer-derived carbon material. Raman data confirms the formation of pure C in the Ni/C nanofibers. Furthermore, a vibrating sample magnetometer (VSM) is used for the magnetic measurement of the Ni/C nanofibers. It is observed that the nanofibers show typical ferromagnetic behavior having the optimum value of saturation magnetization of 5.12 emu/g. The temperature-dependent magnetic measurements suggest the ferromagnetic behavior of Ni/C nanofibers within the room temperature (300 K).