Synthesis, characterization and low frequency AC conduction of polyaniline/niobium pentoxide composites

Abstract

New types of conducting polyaniline-niobium pentoxide (PANI/Nb2O5) nanocomposites have been synthesized by in situ deposition technique by placing fine grade powder of Nb2O5 during in situ polymerization of aniline. The composites formed were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). XRD and TEM indicated the dominant role-played by Nb2O5 particles, whereas XPS indicated incomplete protonation of imine moieties. SEM images indicated a systematic morphological variation of particles aggregated in the composite matrix as compared to the pristine PANI. Three step decomposition patterns were observed for PANI and its composites. AC conductivity and dielectric response of the composites were investigated in the frequency range, 102-106 Hz. AC conductivity obeyed the power law index, which decreased with increasing wt.% of Nb2O5. PANI showed high dielectric constant, which could be related to conductivity relaxation phenomenon. Both dielectric constant and dielectric loss decreased with increasing wt.% of Nb2O5. Variations in measured AC response parameters with increasing Nb2O5 contents of the composite followed systematic trends that are similar to those observed with decreasing temperature and level of doping. © 2006 Elsevier B.V. All rights reserved.