Dielectric and complex impedance studies of BaTi_0·85W_0·15O_3+δ ferroelectric ceramics

Abstract

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 °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 °C, 345 °C and 365 °C. The plot at 365 °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.