Electrical properties of bismuth potassium titanate-strontium titanate ferroelectric ceramics

In this paper, lead-free (Bi_0.5K_0.5)TiO₃ ceramics doped with SrTiO₃ was prepared by the conventional solid state reaction method with sintering temperature at 1040°C. The samples were characterized by X-ray diffraction analysis and Scanning Electron Microscopy. The dielectric, ferroelectric properties were also investigated. The results of X-ray diffraction reveal that SrTiO₃ diffuse into the Bi_0.5K_0.5TiO₃ lattices to form a solid solution with a pure perovskite structure. After the introduction of SrTiO₃ into Bi_0.5K_0.5TiO₃, the dielectric constant at room temperature (ε_r) was found to decrease with increasing SrTiO₃. The broadness of the dielectric constant peak was observed with increasing SrTiO₃ content, especially that of the 0.94Bi_0.5K_0.5TiO₃ - 0.06 SrTiO₃ ceramic which exhibited a very broad curve over a wide temperature range. The Bi_0.5K_0.5TiO₃ - SrTiO₃ system was expected to be a new and promising candidate for lead-free capacitors.