Dielectric constant versus voltage and non-Ohmic characteristics of Bi2/3Cu3Ti4O12 ceramics prepared by different methods

Abstract

Bi2/3Cu3Ti4O12 (BCTO) ceramics were successfully prepared by traditional solid-state reaction method (BCTO-SS) and sol–gel method (BCTO-SG). Pure perovskite phase and dense structure were obtained in BCTO ceramics prepared by both methods. BCTO-SG ceramics showed a large dielectric constant of ~1.1×104 while BCTO-SS ceramics exhibited a low dielectric constant of ~3200. At 100kHz, the dielectric constant of BCTO-SS ceramics decreased with applied voltage increasing, while the dielectric constant of BCTO-SG ceramics increased with applied voltage increasing. Further study of the relationship between dielectric constant and voltage suggested BCTO-SG ceramics had larger defect concentration than BCTO-SS ceramics. The investigation of complex impedance indicated that the electrical properties of grain boundaries for all BCTO ceramics were evidently affected by applied voltages and the electrical properties of grains were independent of applied voltages. In addition, the non-Ohmic properties of BCTO ceramics were studied in detail. The non-linear coefficients of BCTO-SS and BCTO-SG ceramics were 1.65 and 1.01, respectively. The breakdown electric fields of BCTO-SS and BCTO-SG ceramics were found to be 1.21 and 0.48kV/cm, respectively. The potential barrier heights of BCTO-SS and BCTO-SG ceramics were calculated to be 0.549 and 0.485eV, indicating that the potential barriers at the grain boundaries for BCTO-SS and BCTO-SG ceramics are the Schottky-type barrier.