CNTs with core-shell structure were successfully synthesized by a microwave-assisted polyol method,and magnetic Ni nanoparticles were employed as a catalyst. The preparation method is fast and simple. The structures,morphology and magnetic properties of the as-synthesized samples were investigated using Raman spectrometer,X-ray diffraction (XRD),transmission electron microscopy (TEM),vibrating sample magnetometer (VSM),respectively. The XRD results suggested that Ni particles used as a catalyst in our experiment were nano-sized. In this paper,magnetic Ni nanoparticles were employed as a catalyst,and an electric spark on metal Ni nanoparticles with the microwave eddy current effect could induce CNTs’ formation with the further reaction. The length of hollow carbon nanotubes was micro-sized and the diameters of most of the CNTs were varying from 18 to 20 nm according to the TEM images. Magnetic measurements demonstrated that CNTs with core-shell structure indicated a characteristic ferromagnetic behavior compared with Ni nanoparticles.
采用陶瓷工艺制备了 Al 替代的 Ni0．5 Zn0．5 Alx Fe2-x O 4（x ＝0～0．10）铁氧体材料,用 XRD、B-H分析仪和阻抗分析仪对其结构和磁性能进行了研究.实验发现,最佳烧结温度为1250℃,过高和过低的烧结温度不利于降低磁芯损耗.当 Al3＋替代量 x ＝0．06时,铁氧体能获得较好综合磁性能.
