Dielectric relaxation behavior and mechanism of Y2/3Cu3Ti4O12 ceramic

Y2/3Cu3Ti4O12 (YCTO) ceramics were sintered in air (YCTO-air) and pure O-2 atmosphere (YCTO-O-2), respectively. It was found that the permittivity and dielectric loss of YCTO-O-2 were decreased drastically in low frequency. The frequency dependent impedance (Z '') and modulus (M '') spectra of YCTO-air and YCTO-O-2 show a thermal activated process. The scaling behavior of both Z '' and M '' spectra further suggest that the distribution of relaxation times is temperature independent. The Cole-Cole plot in impedance formalism shows that electrical response of the samples originates from both grains and grain-boundaries. Conductivity (sigma') spectra follow Universal Dielectric Repose law. The short-range translation hopping assisted by small polaron hopping mechanisms for YCTO-O-2. Moreover, the scaling behavior of sigma' spectra further confirms that the distribution of local electrical response time is temperature independent. (C) 2017 Elsevier Ltd. All rights reserved.