Synthesis and characteristics of iron nanoparticles in a carbon matrix along with the catalytic graphitization of amorphous carbon

Iron nanoparticles in a carbon matrix were synthesized by in situ pyrolysis of maleic anhydride and ferrocene, using different molecular weight percentages. The characterization and magnetic properties of the carbon-iron system were investigated systematically. Transmission electron microscope (TEM) images showed that the as-prepared samples consist of nanometric dark grains (iron-rich phase) embedded in a light matrix (carbon-rich phase). X-ray diffraction and TEM selected area diffraction revealed catalytic graphitization and iron phases present in the sample. The carbon-metal system shows a finite hysteresis loop even at room temperature indicating its ferromagnetic nature. The saturation magnetization equals the bulk iron carbide value at low temperature. The coercive force exhibits 1/d dependence at low temperature having a maximum H-C of 2 kOe for the lowest iron concentration sample. (C) 2004 Elsevier Ltd. All rights reserved.