Composites of nanotubular polyaniline containing Fe₃O₄ nanoparticles

Results of charge-transport and magnetic measurements of nanotubular polyaniline (PANI) composites containing Fe₃O₄ nanoparticles (～10nm) synthesized by a "template-free" method are reported. The T ^-1/2 resistivity has been observed, and dc magnetic susceptibility data are fitted to an equation \chi=\chi_P^*+C/T. With increasing weight ratio of Fe₃O₄, the electrical conductivity and temperature- independent susceptibility \chi_P^* increase, and the Curie-type susceptibility is suppressed at low temperatures. Further discussions have been given. The PANI-H₃PO₄/Fe₃O₄ composite containing 27wt% of Fe₃O₄ nanoparticles is superparamagnetic, exhibiting very little hysteresis even at 5K.