Mossbauer effect phase determination in iron oxide-polyaniline nanocomposite. Preliminar characterization of their magnetic and transport behaviour.

J. C. APHESTEGUY; S. E. JACOBO; C. E. RODRIGUEZ TORRES; ,M. B. FERNÁNDEZ VAN RAAP; , AND F. H. SÁNCHEZ .

Iguassu Falls

Conferencia; International Conference on the Applications of the Mössbauer Effe; 2007

M¨ossbauer 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. Differentamounts of a same batch of Fe3O4 nanoparticles were successfully disposed by FeCl3solution to prevent their aggregation in the solution by the application of common ioneffect. 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 ironconcentration, these patterns are consistent with the presence of either maghemite ormagnetite phases. For low iron concentration values ( 3 wt. %) the nanoparticles behavesuperparamagnetically at RT, for intermediate concentration values ( 16 wt.%) mostof 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 ofthe composites increased from 0.18 to 3.69 S/cm when the content of magnetic particlesvaried 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 thenanoparticles embedded in the PANI matrix. These results are compared and discussedwith the magnetic properties of the resulting composites previously investigated with aQuantum Design magnetometer (PMPS).Email: raap@fisica.unlp.edu.arKeywords: Composites, Polyaniline, M¨ossbauer Effect, Nanomagnetism