Electrical Characteristics and Microstructures of (Gd, Dy)-Doped Bi₄Ti₃O₁₂ Ceramics

The electrical properties of Bi3.25Dy0.75Ti3O12 (BDT) and Bi3.25Gd0.75Ti3O12 (BGT) ceramics were investigated. The current-voltage curve of the BGT sample exhibits a negative differential resistance behavior, whereas that of the BDT sample exhibits a simple ohmic behavior. The impedance spectrum of the BDT and BGT samples indicate that both consist of semiconducting grain and moderately insulating grain boundary regions. XRD, SEM and EPMA analyses reveal crystalline phase characterized by a Bi-layered perovskite structure of Bi4Ti3O12 and the distribution of every element is uniform. Both BDT and BGT samples exhibit randomly oriented and plate-like morphology.