Impedance Spectroscopic Studies of B2O3-Substituted CeO2-Gd2O3 Systems

Abstract

In this paper, the change in the conduction mechanism due to B2O3 addition in a ceria-based nanoceramic system is understood by studying the nature of conductivity and the variation of electric modulus function with frequency at different temperatures. The studies revealed that oxide ion conduction in the prepared system is prominent only after 500°C. The activation energy for electrical conduction and oxide ion hopping in the system is found to be 0.26 eV and 0.85 eV, respectively. The discrepancy in the values of the activation energies itself is evidence of a different mechanism other than oxide ion hopping occurring in the present sample. The electric modulus function shows two relaxation peaks at lower temperatures corresponding to short-range and long-range relaxation for the charge carriers. Relaxation energies for the processes are found to be 0.27 eV and 0.95 eV. This is evidence of the occurrence of Maxwell–Wagner relaxation phenomena in the ceramic system. Explicitly, thermally activated oxide ion migration, along with the relaxation of electrons at the site of the bound pair (B–Vo)· is observed in the prepared nanocrystalline system.