Cobalt Nickel Copper And Cobalt Nickel Zinc Ferrite Nanofibers Fabricated By Electrospinning:Their Structure And Magnetic Properties Research

This paper mainly studies the morphology, structure and magnetic aspects of ferrite nanofibers which is producted by the sol-gel combined with electrospinning technology.Electrostatic spinning technology has been widely used in the fiber preparation technology,owing to its effortless operation, controllable preparation process and low equipment requirements. In this study, the long continuous ferrite nanofibers were prepared by the improvement and adjustment of the electrospinning equipment. In the experiment, metal nitrates were used as raw materials, and dimethylformamide ?DMF? or anhydrous ethanol?C2H5OH? was used as solvent and citric acid ?C6H8O7·H2O? was used as the complexing agent of metal cation in solution while polyvinylpyrrolidone ?PVP? was used as a viscous agent. Then the corresponding precursor sol was prepared by appropriate metering ratio. Then,Co_0.6Ni_0.3Cu_0.1Fe₂O₄ and Co_0.6Ni_0.3Zn_0.1Fe₂O₄ precursor filaments were prepared by electrospinning. The two kinds of precursor were analysed by hot wire thermogravimetry differential scanning analyzer?TG-DSC? to get the appropriate calcination temperature. After the subsequent heat treatment, corresponding nano fibers can be obtained. The morphology,structure, composition and magnetic aspects of the prepared nanofibers were characterized and researched by using modern materials such as X-ray diffractometer?XRD?, scanning electron microscope?SEM?, X-ray energy dispersive spectrometer?EDS?, vibrating sample magnetometer?V SM?.TG-DSC analysis of the Co_0.6Ni_0.3Cu_0.1Fe₂O₄ precursor filaments which were prepared by sol-gel and electrospinning found that Co_0.6Ni_0.3Cu_0.1Fe₂O₄ precursor filaments were completely decomposed at 480? and there are two distinct exothermic peaks at 210?-480?.Co_0.6Ni_0.3Cu_0.1Fe₂O₄ nanofibers which were prepared at 500? and 600? analysed by SEM and XRD , showing a good continuity and the diameter is about 200nm. Co_0.6Ni_0.3Cu_0.1Fe₂O₄ nanofibers prepared at 700? has a smooth surface, good dispersion, uniform diameter and the diameter is about 80-120nm. With the increase of the calcination temperature, the continuity of Co_0.6Ni_0.3Cu_0.1Fe₂O₄ nanofibers were destroyed, the graininess is enhanced and some fibers are even broken, and the spinel structure of the fiber tends to be complete as the temperature increases. From the VSM test,the hysteresis loops of Co_0.6Ni_0.3Cu_0.1Fe₂O₄ nanofibers have obvious characteristics of hard magnetic materials, and the shape is broad and the coercivity is high. In the temperature varying from 500? to 900?, the saturation magnetization and residual magnetization of Co_0.6Ni_0.3Cu_0.1Fe₂O₄ nanofibers increased with the temperature gradually increased, while the coercivity showed a tendency to increase first and then decrease; the maximum coercivity is 1088.870e, at 700?. The remanence ratio at 700?, 800? and 900? are around 0.56, as the magnetic recording material with good performance. The coercivity of Co_0.6Ni_0.3Zn_0.1Fe₂O₄ nanofibers are relatively small to Co_0.6Ni_0.3Cu_0.1Fe₂O₄ nanofibers, The hysteresis loop is slightly biased towards soft magnetic materials and its saturation magnetization is higher than Co_0.6Ni_0.3Cu_0.1Fe₂O₄ nanofibers at the same temperature. When the calcination temperature is 700?, the morphology of Co_0.6Ni_0.3Zn_0.1Fe₂O₄ nanofibers is about 80-120nm. With the increase of calcination temperature, especially at 800?, the surface of nanofibers became rough and grainy was enhanced. After calcination at 900?, the fiber breaks and the surface were more rough, and part of the fiber morphology had been destroyed. Co_0.6Ni_0.3Zn_0.1Fe₂O₄ nanofibers have obvious spinel structure at 500?-900?, indicating that the cubic spinel phase of Co_0.6Ni_0.3Zn_0.1Fe₂O₄ has been formed at 500?, and with the calcination temperature increases,the degree of crystallization is getting higher and higher at 900?. After the calcination at 500?-900?, the difference in magnetic properties of Co_0.6Ni_0.3Zn_0.1Fe₂O₄ nanofibers is shown. In particular,the saturation magnetization of Co_0.6Ni_0.3Zn_0.1Fe₂O₄ nanofibers increased from 49.64emu/g to 67.63emu/g while the temperature increased from 500?to 900?, and coercivity showed a trend to increase firstly and then decrease with the the maximum coercivity of 545.81Oe at 700?.After the calcination under 500?, 600?, 700?, 800? and 900?, the intensity of saturation magnetization of Co_0.6Ni_0.3Zn_0.1Fe₂O₄ nanofibers increased by 14.5%, 7%,16%,10.7% and 8% than Co_0.6Ni_0.3Cu_0.1Fe₂O₄ nanofibers respectively while the coercive force decreased by 38%, 51%, 50%, 46% and 46.7% respectively.