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 (σ_dc), and crossover frequency (ω_H). 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 (H_m), dissociation enthalpy of cation from its indigenous location alongside a compensating center (H_f), 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.