Unusual magnetic behavior of SiCN/multiwalled carbon nanotubes nanocomposites

Multiwalled carbon nanotubes (MWCNTs) have been dispersed homogeneously throughout a preceramic polysilazane matrix. The homogenized mixture was then warm pressed and subsequently pyrolyzed in Ar atmosphere at 1100 °C, yielding an amorphous silicon carbonitride (SiCN)/MWCNT nanocomposite. The hysteresis loop of the 5 vol % CNT/SiCN composite revealed a ferromagneticlike behavior up to 5000 Oe and a semiconductinglike feature at a higher applied field. The magnetic behavior of CNT-rich composites is due mainly to defects and to the interaction between the nanotubes and the SiCN matrix, which is indicated by a shift in the G and D bands of graphitic carbon as determined by Raman spectroscopy.