Conduction mechanism in un-irradiated and γ-irradiated PVA-H3PO4 polymer electrolytes

The a.c. conductivity and the dielectric properties of both un-irradiated and gamma-irradiated PVA-H3PO4 complexed electrolytes are investigated as a function of frequency and temperature. The dielectric constant and dielectric loss have been studied in the frequency range of 10 kHz-1 MHz and in the temperature domain of 303-383 K. The a. c. conductivity is found to obey the Universal power law. The variation of frequency exponent with temperature obtained from experimental results has been used to explain the mechanism of ion transport. It has been shown that correlated barrier hopping is the suitable model to study the electrical conduction mechanism of the complexed system. According to this model the maximum barrier height was calculated to be 0.31 eV for un-irradiated sample while for gamma-irradiated, it was 0.28 eV. Moreover, the frequency exponent, which is a function of temperature, decreases slowly in the lower temperature range and at a faster rate in higher temperature range. The electrical activation energy at various frequencies was estimated in the range of 0.44-0.80 eV in two distinct temperature ranges. (C) 2009 Elsevier B.V. All rights reserved.