Electrical transport and dielectric relaxation in Fe₃O₄–polypyrrole hybrid nanocomposites

The polymerization of pyrrole in an aqueous medium in the presence of nanodimensional Fe3O4 using ammonium peroxodisulphate (APS) as oxidant results in the formation of polypyrrole-Fe3O4 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 Mossbauer spectra at room temperature reveal the doublet structure, characteristic of the superparamagnetic phase in magnetite (Fe3O4). 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 Fe3O4 plays an important role in producing a large dielectric constant in the composite.