Structure and magnetic properties of carbon-encapsulated Ni nanoparticles

Carbon encapsulated Ni (Ni@C) nanoparticles with core/shell structure have been synthesized by levitational gas condensation (LGC) method. The methane (C[H.sub.4]) gas was used for the coating on the surface of Ni nanoparticles. The as-prepared Ni@Cs were characterized by X-ray diffraction (XRD), vibrating samples magnetometer (VSM), and transmission electron microscopy (TEM). The particles had core structure of diameter at and below 10 nm and were covered by carbon 2-3 nm thin layers. The hysteresis loop of the as-prepared Ni@Cs materials with unsaturated magnetization shows a superparamagnetic state at room temperature. Index Terms--Carbon encapsulation, levitational gas condensation (LGC), magnetic behavior, nano particle, Ni.