Effect of silver nanoparticle embedment on the frequency dispersive conductivity and electrical relaxation dynamics in dodecylbenzenesulfonic acid-doped polyaniline

Abstract

The present work aims at studying electrical relaxations in silver–polyaniline nanocomposites using dielectric spectroscopy. The nanocomposites of dodecylbenzenesulfonic acid-doped polyaniline (PANI) with different concentrations of silver nanoparticles (~6–12 nm) are synthesized by simple wet-chemical route. The temperature dependence of dc conductivity in all the samples follows three-dimensional variable range-hopping conduction mechanism. The loss factor, after having subtracted the dc contribution, shows a relaxation peak which simultaneously attributes to the frequency dispersion in conductivity spectra. The observed dielectric relaxation is well fitted by the Havriliak–Negami function, and the fitting parameters are determined. The temperature dependence of characteristic relaxation frequency and dc conductivity is in line with each other and bear a resemblance to the origin of dc transport and dielectric relaxation in these systems. The temperature behavior of the relaxation strength confirms that an exclusive hopping conduction of polarons in the disordered PANI matrix can be considered as the origin of the observed electrical properties of the systems. Further, the self-similar behavior of the real part of normalized ac conductivity, within the measured temperature range, also confirms the above inferences. The variation of frequency exponent with temperature suggests that ac conduction is due to the correlated barrier hopping of polarons which strongly affected by the dispersion of silver nanoparticles within the PANI matrix.