TRANSPORT STUDIES IN H3PO4-DOPED POLYANILINE

An experimental study of the temperature and frequency dependence (in the audio and rf and microwave regions) of the conductivity of H3PO4-d oped polyaniline samples is presented. The dopant concentration of the samples varies between 0.09M and 3.60M. For all the samples studied, the temperature dependence of the de conductivity is consistent with t he expression for Mott's variable-range hopping. On the other hand, in the temperature range 88 less than or equal to T less than or equal t o 298 K and in the audio frequency range 20 Hz less than or equal to f less than or equal to 1 MHz, we remark that the ac conductivity to (s igma(ac)) does not vary much with frequency. From our wide-band measur ement in the microwave region, however, we find that, for the O.09M-do ped sample, sigma(ac) varies as omega(s) with s congruent to 0.6; usin g Mott's model for the hopping conduction in the ac regime, we find th at this value of s yields a reasonable estimation for the hopping prob ability: v(ph) similar to 6.92 X 10(13) s(-1).