AC conductivity and dielectric spectroscopic studies of polypyrrole-titanium dioxide hybrid nanocomposites

摘要

Dielectric spectroscopy and AC conductivity measurements have been employed to investigate the electrical properties of disordered materials in a wide range of temperature. In this work, conducting polypyrrole-titanium dioxide (PPy-TiO_2) hybrid nanocomposites have been synthesized by oxidizing pyrrole in presence of different concentration (wt%) of TiO_2 nanopartieles. Thermal stability of the nanocomposites increases with the increase in TiO_2 wt%. The dielectric and electric modulus studies of as prepared samples were carried out over a frequency range of 42 Hz-5 MHz. The dielectric constant and dielectric loss for all the nanocomposite samples were observed to decrease with the increase of frequency. Electric modulus analysis has been carried out to understand the electrical relaxation processes. The dielectric relaxation time of nanocomposites decreases with the increase of TiO_2 nanoparticles concentration. AC conductivity measurements show that correlated barrier hopping conduction mechanism can be employed for pure PPy and PPy-5 wt% TiO_2 nanocomposites, whereas large polaron tunnelling mechanism is applicable for higher concentration of TiO_2 (10-25 wt%) in PPy-TiO_2 nanocomposites.