Investigation of dielectric relaxation behavior, electric modulus and a.c conductivity of low doped polyaniline cadmium oxide (PANI-CdO) nanocomposites

In situ chemical polymerization method was used to synthesize the polyaniline (PANI) and polyaniline cadmium oxide (PANI-CdO) nanocomposites. The morphology and structure of pure PANI and PANI-CdO nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, whereas electrical properties were studied by dielectric, electric modulus and a.c conductivity. Various dopant-to-polymer ratios were used to investigate their effect on the characteristics of the synthesized samples. The SEM images exhibited granular as well as flaky structures of PANI and PANI-CdO nanocomposites. The XRD patterns revealed that pure PANI exhibits amorphous nature, while PANI-CdO nanocomposites exhibit polycrystalline nature. The crystallinity and intensity of (XRD) peaks of composite are enhanced by increasing CdO contents. The dielectric measurements show a decrease in dielectric constant, dielectric loss and a decrease in tangent loss with the increase in frequency and nearly constant values at higher frequencies, while the values of dielectric properties increase with the rise in temperature and doping concentration. The electric field modulus was used to analyze the relaxation behavior of the synthesized samples and found to be increased with frequency and decreased with the temperature and CdO concentration. The a.c conductivity was observed to increase with the increase in frequency and temperature for PANI and PANI-CdO composites. The changing behavior of the frequency exponent (S) at various temperatures was analyzed to observe different conduction mechanisms, and a correlated barrier hopping model (CBH) was found to be observed in PANI-CdO composites as well as in pure PANI. The Log a.c conductivity decreases versus the inverse of temperature and with increase in frequency that confirms that the hopping mechanism is the dominant charge transport mechanism.