Fabrication of BST nano-ceramics by two-step sintering

Ba_xSr_1-xTiO₃ [(BST), 0≤x≤1] is a solid solution ferroelectric material exhibiting a large dielectric constant non-linear change with an applied DC electric field. In this paper, Ba_0.6Sr_0.4TiO₃ ceramic was obtained by traditional ceramic processing and two-step sintering. The structural, surface morphological, dielectric properties, tunable properties of this material as well as the mechanism of their nonlinear dielectric constant under DC electric field were systematically examined. The grain size of samples fabricated by two-step sintering was about 300-500nm, while the average grain size of samples by traditionally sintered was 20μm. X-ray diffraction analyses indicated that the samples present perovskite phase. Scanning electron microscopy micrograph of sample indicated that the density increased to 97%. The kinetics of two-step sintering is also discussed, exploring the difference between densification diffusion and grain boundary mobility. The two-step sintered samples presented lower dielectric constant and dielectric loss than samples by traditionally sintered.