Composition Range of Morphotropic Phase Boundary and Electrical Properties of NBT-BT System
(Na0.5Bi0.5)TiO3 (BNT) system ceramics are considered to be an excellent candidate for leadfree piezoelectric ceramics. In this paper, (1–x)Na0.5Bi0.5TiO3-xBaTiO3 (x = 0.03 ~ 0.10) was synthesized by conventional mixed-oxide technique. The powders were calcined at 950oC for 2 h and the pressed disks were sintered at 1145oC for 2 h in air atmosphere. The phase structure was investigated by X-ray diffraction technique (XRD). It is revealed that the morphotropic phase boundary (MPB) lies in a narrow composition range of x=0.05–0.08 but not a unique composition (x = 0.055 or 0.06) as shown before [1-4]. The microstructures of the ceramics were investigated by scanning electron microscopic. In addition, the piezoelectric and dielectric properties of this system were also investigated. It was indicated that both the piezoelectric and dielectric properties are better with the compositions lie near the tetragonal phase within the MPB than that whose compositions lie near the rhombohedral phase.
Wei Pan and Jianghong Gong
Y. J. Dai et al., "Composition Range of Morphotropic Phase Boundary and Electrical Properties of NBT-BT System", Key Engineering Materials, Vols. 336-338, pp. 206-209, 2007