Dielectric and AC conductivity behavior of BaBi2Nb2O9 ceramics

The complex dielectric and AC conductivity response of BaBi2Nb2O9 relaxor ferroelectric ceramics were studied as a function of frequency (100 Hz-10 MHz) at various temperatures. The observed dielectric behavior was characterized by two types of relaxation processes which were described by the 'universal relaxation law'. The frequency dependence of conductivity which showed a classical relaxor behavior followed the Jonscher's universal law sigma(omega) = sigma(0) + A omega(n). The exponent n exhibited a minimum in the vicinity of temperatures of dielectric anomaly while the pre-factor A showed a maximum. The temperature dependence of it followed the Vogel-Fulcher relation with activation energy of about 0.14eV. (c) 2006 Elsevier Ltd. All rights reserved.