Fe3C nanopowder synthesized by laser pyrolysis and its annealing behaviour

We describe the Fe3C-based nanopowder obtained through the laser-induced pyrolysis of the gas mixture of Fe(CO)(5) and C2H4. This ferromagnetic nanopowder was characterized by XRD, HRTEM and magnetic measurements. Aggregated core-shell nanoparticles were identified in the nanopowder; Fe3C cores were coated with pyrolytic carbon. The mean coherence domain size estimated by the Scherrer formula was 18 nm. Basic magnetic characteristics were measured at 20 degrees C: H-C = 42.0 kA m(-1); sigma(R) = 31.2 A m(2) kg(-1); sigma(s) = 95.7 A m(2) kg(-1) (at 1200 kA m(-1)). The Curie temperature T-C was 227 degrees C. Thermally induced phase transformations are discussed. Copyright (C) 2006 John Wiley & Sons, Ltd.