Papers by Author: Marcin Podsiadły

Abstract: Nanocrystalline cobalt was carburised with ethylene in the range 340– 500°C to obtain Co(C) nanocapsules. The carbon deposit was reduced by a flow of hydrogen in the range 500– 560°C. The reduction kinetics were studied using thermogravimetry, described by the equation: α = Α[1-exp(-kt)n]. The apparent activation energy of the reduction process of the carbon deposit was determined. After carburisation and reduction the samples were examined by XRD and HRTEM.

Abstract: Agglomerated cobalt magnetic nanoparticles coated with carbon, dispersed in a paraffin matrix, were prepared and investigated by FMR (ferromagnetic resonance) at room temperature. Four samples with different C/Co content, ranging from 0.175 to 1.011, dispersed at low concentration in paraffin were investigated. Very intense and broad FMR spectra with different intensities, line widths and positions of the resonance fields were recorded for the samples. A strong dependence of the FMR signal intensity and resonance on the concentration of magnetic nanoparticles was observed. Various magnetic interactions affecting the observed FMR spectra have been analyzed. It was found that with increasing concentrations of magnetic nanoparticles the magnetic dipole interaction between the agglomerates plays a more important role.