Preparation, microstructure and magnetic properties of Fe-containing SiC ceramic nanocomposites derived from Fe(CO)5-modified AHPCS

Fe-containing SiC ceramic nanocomposites were prepared by pyrolysis of iron pentacarbonyl (Fe(CO)5)-modified allylhydridopolycarbosilane (AHPCS-Fe(CO)5). The cross-linking mechanism and ceramization of the AHPCS-Fe(CO)5 precursors were studied by nuclear magnetic resonance, Fourier transform infrared spectroscopy and thermal gravimetric analysis. It is suggested that hydrosilylation, dehydrocoupling and the reaction of Si–H bonds with CO groups evolved by Fe(CO)5 decomposition are involved in the cross-linking of the AHPCS-Fe(CO)5 precursor. The crystallization behavior, microstructure and magnetic properties of the obtained Fe-containing SiC ceramic nanocomposites were investigated by techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometry. The results indicate that the α-Fe crystallites together with β-SiC crystallites and poorly organized turbostratic carbon are dispersed in an amorphous SiCxOy matrix, which might be responsible for the soft magnetization of the obtained ceramic composites. The iron content and the magnetic properties of the final ceramic could be easily tuned by the amount of Fe(CO)5 in the precursor.