Polyaniline (PAni) and magnetite (Fe3O4) are well known semiconducting materials, whose conducting mechanisms are quite different � localized conductivity for magnetite and long-range conductivity for PAni. Fe3O4 nanoparticles can be used to polymerize aniline, forming a PAni/Fe3O4 hybrid nanocomposite. We have used dielectric relaxation spectroscopy (DRS) to study the microstructural evolution and electrical behavior of this nanocomposite. The dc conductivity for pure magnetite was approximately 10-6 S cm-1, while the values for the PAni/Fe3O4 nanocomposites were one order of magnitude higher. The Fe3O4 nanoparticles behaves like a material composed by packed grains, with substantial grain volume and grain boundary effects, leading to one dielectric response at high frequency and another at low frequency. The partial consumption of Fe3O4 during the polymerization results in smaller magnetic crystals embedded within the PAni matrix, and the decreased number of crystallite interfaces leads to lower interfacial resistance. Hence, formation of PAni causes a decrease in the material's volume resistance and imparts long-range conduction pathways on the material. This work shows the feasibility of following the microstructural evolution of a nanocomposite by DRS, in particular changes in the conduction mechanisms of the material.

Localized to long-range conductivity in polyaniline/magnetite nanocomposites followed by dielectric relaxation spectroscopy

246th National Meeting (2013)

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