Leakage mechanisms in rare-earth (La, Nd) doped Bi4Ti3O12 ferroelectric ceramics

Abstract

Dense Bi4Ti3O12 (BTO), Bi3.15La0.85Ti3O12 (BLaT) and Bi3.15Nd0.85Ti3O12 (BNdT) ferroelectric ceramics were synthesized by solid–state reaction method. All ceramics are orthorhombic bismuth-layered perovskite structure with plate-like grains of random orientation. The influences of La and Nd doping on the ferroelectric properties and leakage mechanism were investigated. The remanent polarizations (2P r) were determined to be 13.4, 23.9 and 32.6 μC/cm2 for BTO, BLaT, and BNdT, respectively. The leakage current density decreased markedly with La and Nd doping. The dominant leakage mechanism in both BTO and BLaT ceramics has been found to be the ohmic mechanism and the space-charge-limited current mechanism in the low and high electric field region, respectively. While in BNdT ceramics a quasi-ohmic behavior was found in the high electric field region, following the ohmic behavior in the low electric field region and trapped filled limited behavior in the intermediate electric field region.