Microstructure and electrical properties of niobium doped Bi4Ti3O12 layer-structured piezoelectric ceramics

Layer-structured Bi4Ti3−xNbxO12+x/2 (BiTN) ceramics, where x = 0.02–0.20, have been prepared by the conventional sintering technique. XRD results reveal the existence of an orthorhombic structure. The grain size decreases gradually and grain growth anisotropy is limited when x increases. The domain structures of BiTN ceramics differ on x. Nb5+ donor doping decreases markedly electrical conductivity of the materials and Tc shifts gradually to lower temperatures. In addition, low dielectric losses and good temperature stability of dielectric constant are obtained in a wide temperature range. Ferroelectric hysteresis loops of the materials are also determined on x. The best properties can be found in x = 0.08 and 0.11, indicating lower electrical conductivity, good temperature stability of dielectric properties and adequate piezoelectric properties.