Effects of Nb doping on the dielectric and the electrical properties of Bi4Ti3O12 ceramics

Bi4Ti3-xNbxO12 (BTN) ceramics with different Nb concentrations were prepared by using a solid state reaction method. Crystallized single-phases and grain morphologies were confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis, respectively. The effects of Nb doping on the dielectric and the electrical properties were studied using the complex dielectric constant and the electrical conductivity. The Curie temperature decreased with increasing Nb doping. As the temperature was increased, a strong low-frequency dielectric dispersion was observed while the low-frequency dielectric dispersion remarkably decreased with increasing Nb doping. The ac conductivity of the Bi4Ti3O12 ceramic depended on the frequency and suddenly increased at temperatures above 100degreesC while that of the BTN ceramics increased at higher temperatures above 400degreesC. The conductivity decreased as much as two orders of magnitude. The Nb doping of Bi4Ti3O12 must give a lower conductivity to improve the ferroclectric properties.