Dielectric spectroscopy of doped polyaniline

Dielectric constant and AC conductivity measurements on lightly doped polyaniline (PAN) have been made over the frequency range of 100 Hz–1 MHz and in the temperature range of 77–410 K. At temperatures below 100 K, the AC conductivity data could be described by the relation; σ(ω)=Aωs, where the parameter `sʹ lies close to unity and decreases with the increase in temperature. The measured AC conductivity is substantially higher than the DC conductivity in the low temperature region and is mainly controlled by the process of dipolar origin. The observed dielectric behavior does not exhibit well defined loss peaks. In the absence of well defined loss peaks, another approach of dielectric modulus has been utilized. Analysis in terms of the dielectric modulus explains the conductivity behavior of the system although it fails to explain the temperature variation of dielectric constant. The activation energy calculated from DC, dipolar and modulus analysis have approximately the same value which support the existence of a thermally activated behavior in the system.