Dielectric and complex impedance studies of BaTi0.85W0.15O3+δ ferroelectric ceramics

In the present work, tungsten substituted barium titanate have been synthesized and studied. The structural analysis indicates that the specimen is a single phase material with tetragonal crystal structure. The observed polarization-electric field hysteresis loop confirms the ferroelectric nature of the prepared compound. Variation of dielectric constant with temperature at different frequencies shows that the compound has a dielectric anomaly at 75 degrees C and exhibits diffuse type phase transition. Variation of dielectric loss with temperature at different frequencies shows a decrease in loss with increasing frequency. The Nyquist plots (Cole-Cole plots) have been measured at temperatures 325 degrees C, 345 degrees C and 365 degrees C. The plot at 365 degrees C shows a grain boundary effect. Relaxation time has been found to decrease with the rise in temperature and obey the Arrhenius relationship. The variations of d.c. conductivity as a function of temperature have also been studied.