Yuhong Mi

Preparation of CNTs-supported Fe3O4 and Fe3C Nano-particles and the Investigation on their Magnetic Properties

Magnetite (Fe3O4) nanoparticles uniformly loaded on multi-walled carbon nanotubes (MWCNTs) were synthesized by a wet chemistry method, and then carbon coated Fe3C nanoparticles supported by MWCNTs were prepared by heat-treatments subsequently in nitrogen at 600 degC and in acetylene atmosphere at 500 degC. The as-prepared nanoparticles were all single crystals with a size distribution ranging from 10 to 60nm upon TEM and XRD measurements. The magnetic properties of these two kinds of nanoparticles were measured using vibrating sample magnetometer (VSM) at room temperature. The results show that above materials are useful for magnetic materials, and the method to produce magnetic nanoparticles coated with graphite is rather simple

Hydrothermal Fabrication of Spindle-type alpha-Fe 2 O 3 Nanoparticle and its Magnetic Property

Spindle-type α-Fe₂O₃ nanoparticles have been synthesized via a hydrothermal method, using Fe(NO₃)₃, NH₄Cl and ethylene glycol as starting precursors. The resultant products were characterized by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). The results indicate that the synthesized individual spindle-type α-Fe₂O₃ nanoparticles are single crystals, and their hysteresis loops show that they have two kinds of magnetic properties, diamagnetism and paramagnetism

Large-Scale Synthesis of Herringbone Carbon Nanofibers on Nonsupported Nickel Catalyst

Carbon nanofibers (CNFs) are synthesized at 450-650degC by a catalytic CVD method using nickel powders reduced from nickel carbonate as catalyst without other supporting materials, and acetylene as carbon source. It is found that the nickel powders present a considerable catalytic efficiency in the growth of the CNFs at the temperature between 500-550degC. TEM observation shows that a large portion of the product prepared at 550degC have a helix-like shape and some CNFs are filled with nickel nanowires. HRTEM observation further reveals that the CNFs are herringbone-like and well graphitized.