Preparation and Characterization of Fe Based Nanopowders Synthesized by Chemical Vapor Condensation Process

摘要

Nano-sized Fe based powders had been synthesized by the new and versatile process, Chemical Vapor Condensation (CVC) process and studied by means of HRTEM, XRD and vibration sample magnetometer. We have successfully synthesized Fe, Fe-Co, Fe-C and Fe-N nanopowders using the precursors of Fe(CO)_5 and Co_2(CO)_8 under various carrier gases. The influence of experimental parameters on structure and phase composition of nanopowders was investigated. Fe nanopowders with uniform dispersion were in the order of 5 to 13nm in mean size and core-shell structure. Fe-Co alloyed powder also showed core-shell structure, which consisted of metallic core and oxide shell. Their saturation magnetization showed maxium values at 40wt.% Co and coercivity increased with increasing Co content. Various kind Fe-C and Fe-N composite nanopowders could be synthesized by controlling the carrier gases and precursor decomposition temperature, etc. The main phase of Fe-C nanopowders shifted from Fe_3C to α-Fe with the change of reaction temperature and carrier gas flow rate. The core/shell structure of iron oxide-coated Fe-N nanopowders correlated with the experimental parameters of the CVC process, which strongly affected their magnetic properties.