Effect of sintering temperature on structure and nonlinear dielectric properties of Ba_(0.6)Sr_(0.4)TiO_3 ceramics prepared by the citrate method

摘要

Ba_(0.6)Sr_(0.4)TiO_3 ceramics were prepared by a citrate precursor method. The structure and nonlinear dielectric properties of the resulting ceramics were investigated within the sintering temperature range 1200-1300 °C. Adopting fine Ba_(0.6)Sr_(0.4)TiO_3 powder derived from the citrate method was confirmed to be effective in reducing the sintering temperatures required for densification. The ceramic specimens sintered at 1230-1280 °C presented relative densities of around 95%. A significant influence of sintering temperature on the microstructure and nonlinear dielectric properties was detected. The discrepancy in nonlinear dielectric behavior among the specimens sintered at different temperatures was qualitatively interpreted in terms of the dielectric response of polar micro-regions under bias electric field. The specimens sintered at 1230 and 1250 °C attained superior nonlinear dielectric properties, showing relatively low dielectric losses (tan δ) of 0.24% and 0.22% at 10 kHz together with comparatively large figure of merits (FOM) of 121 and 142 at 10 kHz and 20 kV/cm, respectively.