Preparation And Characterization Of Nickel Nanofibers And Nanoparticles

During the past decade, Ni nanofibers, as a novel magnetic material, have been attracted intensive attention due to their potential applications in fields such as sensors, biomagnetic devices and hydrogen fuel cell. There are many methods to prepared nanofibers, such as template method, self-assembly method and so on. In recent years, electrospinning method has been used to prepare some1-D nanostructure nanofibers. Compared with the conventional methods mentioned above, electrospinning is a simple and effective method to produce continuous nanofibers with uniform diameters. However, synthesis of nickel nanofibers by electrospinning has been seldom reported.In this paper Ni nanofibers were successfully obtained by electrospinning using the raw materials of Ni(NO3)2and PVA. In order to compare the properties of Ni nanofibers, Nickel nanoparticles were obtained by Sol-Gel method. These nanomaterials were characterized by XRD, FTIR, TG-DSC, SEM, TEM, VSM and laser particle analyzer.PVA/Ni(NO3)2composite nanofibers were prepared successfully by electrospinning. The parameters to control the fiber’s diameter and continuity in the electrospinning process were also studied, and the PVA concentration of13wt%, applied voltage of20kV and collector distance of15cm were used as the optimal parameters to prepare composite nanofibers and PVA/Ni(NO3)2composite nanofiber membranes were obtained.Ni nanofibers and nanotubes with different structures were successfully fabricated by changing the heating rate. PVA/Ni(NO3)2composite nanofibers were calcined in the air at500℃, when the heating rate was1℃/min, the NiO nanowires were obtained. The NiO nanofibers were obtained with a rising rate of10℃/min. When the temperature rise rate was more than10℃/min, the NiO nanofibers with a ray-tube structure were obtained. NiO nanowires and the nanofibers with a ray-tuber structure were reduced into Ni nanowires at300℃, and the nanotubes were collapsed, when NiO nanotube were reduced at300℃.The nickel nanoparticles were prepared successfully by Sol-Gel method, The synthesis procedures are:(1) preparation of precursor xerogel by oven-dry of solution made from nickel nitrates and citric acid,(2) synthesis of nanostructure NiO powders by calcining precursor xerogel in air,(3) reduction by hydrogen into Ni powders. In this paper, the content of the citric acid had positive effects on grain size of Ni nanoparticles, the grain size were decrease with the content of the citric acid.The magnetic property was measured by VSM, The saturation magnetization, coercivity and remanent magnetization of the obtained Ni nanofibers was75.3Oe tol85Oe,46.3emu/g to51.9emu/g and7.9to16.9emu/g, respectively. The samples appeared magnetic agglomeration due to the great effect of the remnant magnetization.In the current work, the nickel nanofibers were prepared by electrospinning and nanoparticles were prepared by Sol-Gel method, the microstructure and magnetic properties were studied as well. The electrospinning, a new way to prepare nickel nanofibers, provides valuable information for the fabrication of other nanomaterials.