Fabrication of ferromagnetic iron carbide nanoparticles by a chemical vapor condensation process

Iron carbide Fe3C nanoparticles were fabricated by a chemical vapor condensation (CVC), and their structural and magnetic properties were investigated. It was found that the formation of iron carbide nanoparticles strongly depended on reaction temperature and pressure. The iron carbide was formed only above 650 degrees C at 101 kPa (760 Torr) but never formed in vacuum (1.33 Pa) regardless of reaction temperature. The fabricated iron carbide nanoparticles were spherical with T-c of about 240 degrees C. While the particles formed at 650 degrees C (similar to 30nm) possessed a typical core-shell structure, those formed at 800 degrees C (similar to 50nm) did not have such structure. The nanoparticles fabricated at 650 degrees C and 800 degrees C at 101 kPa, exhibited M-s of similar to 125 A m(2)/kg whereas H-i(c) of the former was slightly higher (similar to 63 kA/m) than that of the latter (similar to 40 kA/m). (C) 2006 Elsevier B.V. All rights reserved.