Impedance spectroscopy analysis of CeNbO4.25

Monoclinic CeNbO_4.25 was prepared by solid state reaction. Complex impedance analysis indicated the presence of grain interior effect along with the grain boundary contribution. The values of ionic transference number t_i below 423 K were calculated to be about 0.5. The activation energies of ionic conductivity and electronic conductivity were deduced to be 36.0 and 37.2 kJ/mol, respectively. The real part of the AC conductivity was frequency dependent. At high frequencies corresponding to the grain interior effect, the non-Debye nature of the AC conductivity was interpreted by the correlated hopping of interstitial oxygen with the electron holes on the basis of the correlated barrier hopping (CBH) model.