Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
622342 | Chemical Engineering Research and Design | 2008 | 5 Pages |
Abstract
Carbon-encapsulated cobalt and nickel nanoparticles with core/shell structure have been successfully synthesized with maize-derived starch as carbon source and metal nitrate as metal precursors in flowing hydrogen. The as-prepared M@Cs materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction technique (XRD) and vibrating sample magnetometer (VSM). The effects of the metal precursors on the structure and the size of the M@Cs materials were investigated, and the magnetic properties of the M@Cs materials were measured. The results show that the structure and the size of the M@Cs materials are different in terms of the different metal precursors. The Co@Cs materials are made of the fcc-Co core and the graphitic carbon shell, of which the core diameter is in a range of 20-35Â nm, while the Ni@Cs materials are composed of fcc-Ni core and the amorphous carbon shell, of which the core diameter ranges from 30 to 50Â nm. The hysteresis loops of the as-made M@Cs materials show that some of the nanoparticles are in a superparamagnetic state at room temperature. A mechanism is proposed to explain the growth process of the M@Cs materials. It is believed that the starch with the helical structure is responsible for the formation of the M@Cs materials featuring the core/shell structure.
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Authors
C. Yu, J.S. Qiu,