Large polaron tunneling and anomalous dielectric response in complex layered systems

Electrical conductivity and dielectric spectra of nanocomposites of conducting polyaniline and layered vanadyl phosphate VOPO4∙2H2O are studied at low temperature. Electrons and protons contribute to electrical conduction having the maximum conductivity of the order ∼10−5Scm−1. A discontinuity in electrical conductivity has been observed at about 210K. Conductivity with higher activation energy is dominated by protons. Smaller activation energy at lower temperature may be due to major electron conduction. Large polaron tunneling contributes to the electrical conduction process. The dielectric spectra exhibit anomalous frequency dispersion. Two frequency exponents in dielectric spectra are distinguished by considering intercluster and intracluster displacement of charge carriers.