AC conductivity and modulus studies on (1-x)β-PbF2:xCeO2 composite solid electrolytes

Abstract

Cubic Lead fluoride [β-PbF2] composite solid electrolyte systems are prepared by dispersing nano CeO2 (< 100nm) in different mol% (5, 10, 15, 20, 25) through the mechanical milling method. XRD and FTIR (ATR method) studies confirm that these are formed in two-phase systems. Scanning Electron Microscope (SEM) images of dispersed systems showed a change in surface morphology with respect to the host. Complex impedance spectroscopy is employed in the frequency range 0.5 to 10 MHz by varying temperatures from 30 to 350°C to study the electric and dielectric properties. Analysis of impedance and modulus spectra revealed the non-Debye nature of these composites. Conductivity measurements on these composites suggest that the frequency exponent (n) in Jonscher’s power law is found to be temperature dependent. The overlapping large polaron tunneling (OLPT) model could be suggested as a suitable hopping mechanism. The variation of the ‘β’ value obtained from the Kohlrausch-Williams-Watts (KWW) function shows a similar variation of ‘n’ in the Jonscher’s power law with temperature.