Electrical transport and dielectric relaxation in FeO-polypyrrole hybrid nanocomposites.

The polymerization of pyrrole in an aqueous medium in the presence of nanodimensional FeO using ammonium peroxodisulphate (APS) as oxidant results in the formation of polypyrrole-FeO nanocomposites. Characterization of the composites was carried out by Fourier transform infrared spectroscopy, x-ray diffraction, scanning and transmission electron microscopy. The magnetization data exhibit a small hysteresis loop at room temperature. The Mössbauer spectra at room temperature reveal the doublet structure, characteristic of the superparamagnetic phase in magnetite (FeO). The composite samples reveal ordered semiconducting behaviour. Polypyrrole is the dominating component in the transport process of the nanocomposites. A very large dielectric constant of about 11 000 at room temperature has been observed. The interface between polypyrrole and FeO plays an important role in producing a large dielectric constant in the composite.