Electrical and magnetic properties of polyaniline/Fe3O4 nanostructures

• Published in: Physica. B, Condensed matter Condensed matter, 2005-12, Vol.370 (1-4), p.121-130
• Main Authors: YUNZE LONG, ZHAOJIA CHEN, DUVAIL, Jean Luc, ZHIMING ZHANG, MEIXIANG WAN
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport in multilayers, nanoscale materials and structures; Exact sciences and technology; Magnetic properties and materials; Magnetic properties of nanostructures; Physics
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2005.09.009

We report on electrical and magnetic properties of polyaniline (PANI) nanotubes (150nm in diameter) and PANI/Fe3O4 nanowires (140nm in diameter) containing Fe3O4 nanoparticles with a typical size of 12nm. These systems were prepared by a template-free method. The conductivity of the nanostructures is 10-1-10-2S/cm; and the temperature dependent resistivity follows a lnrhoT-1/2 law. The composites (6 and 20wt% of Fe3O4) show a large negative magnetoresistance compared with that of pure PANI nanotubes and a considerably lower saturated magnetization (Ms=3.45emu/g at 300K and 4.21emu/g at 4K) compared with the values measured from bulk magnetite (Ms=84emu/g) and pure Fe3O4 nanoparticles (Ms=65emu/g). AC magnetic susceptibility was also measured. It is found that the peak position of the AC susceptibility of the nanocomposites shifts to a higher temperature ( > 245K) compared with that of pure Fe3O4 nanoparticles (190-200K). These results suggest that interactions between the polymer matrix and nanoparticles take place in these nanocomposites.