The lead-free ceramics Bi0.44Na0.50Ba0.06TiO3-δ and Bi0.50Na0.44Ba0.06TiO3+δ were prepared via the conventional sintering method. The two kinds of ceramics were sintered at various temperatures. Their crystallite structure, microstructure, dielectric and ferroelectric properties were studied comparatively. The ceramics sintered at 1 150 ℃ have pure perovskite structure and dense microstructure with relative densities higher than 97%. The dielectric measurement shows that the dielectric spectra are different from each other obviously. Dielectric constant of the Bi0.44Na0.50Ba0.06TiO3-δ ceramics increases greatly with increasing temperature. The two kinds of ceramics show diffuse phase transition character. The values of maximum polarization, remanent polarization, and coercive field are 34.1 μC/cm2, 28.5 μC/cm2 and 53.7 kV/cm for Bi0.44Na0.50Ba0.06TiO3-δ. The corresponding values are 42.8 μC/cm2, 31.8 μC/cm2 and 48.2 kV/cm for Bi0.50Na0.44Ba0.06TiO3+δ. The ceramics Bi0.50Na0.44Ba0.06TiO3+δ shows better ferroelectric properties.

Bi0.5Na0.5TiO3; microstructure; dielectric; ferroelectric