Ferroelectric properties and microstructures of Nd2O3-doped Bi4Ti3O12 ceramics

The electrical properties of Nd-doped bismuth titanate, Bi4-xNdxTi3O12 (BNT) ceramics prepared by a conventional electroceramic technique have been investigated. XRD analyses revealed Bi-layered perovskite structure in all samples, and indicated that Bi ions were only substituted near the Ti-O octahedron layers by Nd ions. SEM micrographs show randomly oriented and plate-like morphology. For the samples with x < 0.5, the current-voltage characteristics exhibit a negative differential resistance behavior, whereas that of the samples with x greater than or equal to 0.5 exhibit a simple ohmic behavior. The conducting filamentary model has been extended and used to explain the negative differential resistance phenomenon in Nd-doped bismuth titanate ceramics. The P-V hysteresis loop of sample with x = 0.25 were characterized by a large leakage current, and that of samples with x greater than or equal to 0.5 showed the saturated and undistorted hysteresis loops; the remanent polarization (P-r) and coercive field (E-c) of the BNT ceramic with x = 0.5 were above 19 muC/cm(2) and 50 KV/cm, respectively. The large value of remanent polarization and low coercive field of Nd-doped bismuth titanate ceramics promote these materials to potential applications. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.