Characterization and ion transport studies through impedance spectroscopy on (1-x)Pb(NO3)2:xAl2O3 composite solid electrolytes

In this paper, we attribute the conduction mechanism in (1-x)Pb(NO3)2:xCeO2 composite solid electrolytes due to the hopping of polyanion (NO3−). The matrix of composites, nano-alumina (60 nm) dispersed into Pb(NO3)2, was synthesized and characterized through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM) to understand structural, thermal, and morphological properties. XRD and FTIR studies confirm the biphasic nature of composites. FTIR studies reveal the presence of OHˉ and NO3ˉ ions in all the composites. Impedance and modulus spectra were used as tools to study the electrical properties of composites in the temperature range 30 to 330 °C and frequency range 1 Hz to 10 MHz to understand ion transport mechanism. Analysis of AC conductivity data reveals that non-overlapping small polaron tunneling [NSPT] seems to be an appropriate model to understand hopping mechanism of conducting ion species. Maximum enhancement of conductivity was observed in the composite with 10 mol% Al2O3 dispersed system. The distribution of frequency response of imaginary part of modulus response denotes non-Debye behavior at all individual temperatures. The peaks which were obtained from the plots of frequency-dependent imaginary part of modulus, plotted with respect to temperature, had shown an Arrhenius behavior. The values “β” from Kohlrausch-Williams-Watts (KWW) function and n from Johnson power law were found to be temperature-dependent in all these composites.