Conduction Mechanism and Dielectric Properties in Polyaniline/Titanium Dioxide Composites
The conductivity and dielectric properties of polyaniline (PANI) and PANI/TiO2 composites have been studied over a temperature range (313-393 K) and frequency range (25 Hz- 50 MHz). The nature of temperature and frequency-dependent conductivity can be explained by Jonscher’s universal power law and used to find the related parameters such as frequency exponent (s), dc conductivity (σdc), and crossover frequency (ωH). Besides, the frequency exponent analysis through a distinct model suggests that the conduction occurred through small polaron tunnelling in all compositions and at different temperatures. On the other hand, the enthalpy of migration (Hm), dissociation enthalpy of cation from its indigenous location alongside a compensating center (Hf), and the activation energy were also calculated using the Arrhenius relation. The temperature-dependent dc conductivity was examined in the framework of the theoretical model; Mott’s variable range hopping model (VRH) and experimental results were in good agreement with the 3-dimensional VRH model. As a function of temperature, dielectric constants (ε’ and ε”) increase while decreasing with an increasing dopant. Being such a high dielectric constant value, these composites can be used as frequency converters, modulators, and dielectric amplifiers.
Polyaniline; Conductivity; Activation energy; Dielectric constants
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