CONICET | Buscador de Institutos y Recursos Humanos

Mossbauer effect (ME) was used to characterize the magnetic particles of an iron oxide / polyaniline (PANI)nanocomposites, containing dodecylbencensulfonic acid (DBSA) as a surfactant and dopant, with both magnetic and conducting properties. Different amounts of a same batch of Fe3O4 nanoparticles were successfully disposed by FeCl3 solution to prevent their aggregation in the solution by the application of common ion effect. The same magnetite bulk was a used for the whole set of prepared nanocomposites. As usually observed in nanostructured systems, the ME patterns are broad. However, the average hyperfine parameters can be retrieved and distinction between 2+ and 3+ contributions is possible. Despite the followed preparation route, and depending on iron concentration, these patterns are consistent with the presence of either maghemite or magnetite phases. For low iron concentration values ( 3 wt. %) the nanoparticles behave superparamagnetically at RT, for intermediate concentration values ( 16 wt. %) most of the moments are blocked at LN temperature while for high concentration values ( 43 wt. %) the moments are blocked at RT. At room temperature, the conductivity of the composites increased from 0.18 to 3.69 S/cm when the content of magnetic particles varied from zero to 16 wt. %. Percolation occurs at 36 wt. %. For higher iron content ( 43 wt. %), the decrease in conductivity may be due to blockage of conduction path by the nanoparticles embedded in the PANI matrix. These results are compared and discussed with the magnetic properties of the resulting composites previously investigated with a Quantum Design magnetometer (PMPS).