Microstructure and electrical properties of (Ba_0.6Sr_0.4)_0.85Bi_0.1TiO₃ ceramics prepared by single-step, liquid-phase, solid-state reactive sintering

(Ba_0.6Sr_0.4)_0.85Bi_0.1TiO₃ ceramics have been obtained by single-step, liquid-phase, solid-state reactive sintering in the temperature range 1250–1350 °C using stoichiometric amounts of BaTiO₃, SrTiO₃ and Bi₄Ti₃O₁₂. Their microstructure and electrical properties have been studied by X-Ray diffraction and fluorescence, scanning and transmission electron microscopy and impedance spectroscopy. The relative density, D_r, relative permittivity, \( {\varepsilon}_r^{\prime } \), and dissipation factor, tan δ, at room temperature and the bulk and grain boundary resistivity, R_b and R_gb, and activation energies, \( {E}_a^b \) and \( {E}_a^{gb} \), are approximately independent of the sintering temperature with values around e.g. D_r ~97.5 %, \( {\varepsilon}_r^{\prime } \) ~1790, tan δ ~0.06 %, \( {R}_b^{500^oC} \) ~26 kΩ cm, \( {E}_a^{gb} \) ~1.03 eV, \( {R}_{gb}^{500^oC} \) ~217 kΩ cm and \( {E}_a^{gb} \) ~1.41 eV. By contrast, the temperature coefficient of capacitance, TCC, increases linearly from ~10 ppm ^oC⁻¹ to ~21 ppm ^oC⁻¹ on increasing sintering temperature. Comments on the influence of the sintering temperature on the chemical composition of the ceramics are made.