Hopping transport in HCl doped conducting polyaniline

The present work includes a study on the transport property based on the measurement of the electrical conductivity of HCl doped conducting polyaniline in the presence as well as in the absence of a magnetic field in the temperature range 1.8 K less than or equal to T less than or equal to 300 K. It has been observed that the conductivity of the samples increases with increasing temperature and the conductivity ratio [r = sigma(300 K)/sigma(1.8 K)] is large for the sample having higher dopant concentration. A crossover from Mott (T-1/4) to Efros-Shklovskii (ES) (T-1/2) in temperature dependent conductivity of the samples is observed at 10 K. In the presence of a magnetic field the electrical conductivity varies as T-3/4. From the plot of conductivity versus temperature, different physical quantities like density of states, molecular vibrational frequency, hopping distance and localization length have been determined. (C) 1999 Published by Elsevier Science B.V. All rights reserved.