The CO2 laser pyrolysis of gas phase reactants provides a powerful and versatile tool for producing nanostructures of various chemical compositions. Typically, the laser pyrolysis technique is based on a cross-flow-configuration reactor, in which a CO2 laser orthogonally irradiates a narrow and uniform reaction zone, achieved by the confinement (by means of a coaxial buffer gas flow) of the reactant gas stream emerging from a nozzle. In this way, very pure nano-scale materials (the reaction takes place in the gas phase, far from polluting walls) may be prepared. Their properties and structures are controlled by the main process parameters (nature of the gas (vapor) precursor, gas flow rate, pressure, laser power). Being based on the resonance between the laser wavelength and the absorption bands of the gas precursors, the technique cannot avoid some drawbacks like to be addressed to materials possessing gaseous precursors. The reaction yield may be small, depending mostly on the precursors of the specific synthesized nanostructures.
Iron-based materials have a huge number of applications: magnetic storage media, sensors, catalysts etc. New approaches to their functionality are opened if particles in the nanometer size range are used. We present here comprehensive investigations of different iron-based nano-phase compounds prepared by laser pyrolysis. Sensitized iron pentacarbonyl-based mixtures were used. Various structural characteristics of the reaction products were evidenced: filamentary shaped iron nanostructures, iron carbides, gamma iron oxide and composites. Mean size diameters ranging from 1.5 to 9 nm and sharp particle distributions were often obtained. The combined results of several analytical methods (TEM, HREM, EELS, XRD, IR and Raman spectroscopy, thermal analysis) were used to characterize the different morphologies and crystallographic features.