Ba-Zr codoped sodium bismuth titanate by novel alkoxyless wet chemical route: processing and electromechanical behavior

Abstract

Sodium bismuth titanate (NBT) based ceramics have been shown to be a promising lead-free alternative to commercial piezoelectrics and high capacitance materials. This article reports a novel aqueous citrate gel route for the synthesis of (Na_0.5Bi_0.5)_xBa_1-xTi_yZr_1-yO₃ powders. Instead of alkoxides, usually used in citrate gel route, aqueous citrate solutions of titanium and bismuth were prepared from their respective inorganic salts. These solutions were used to prepare powder of (Na_0.5Bi_0.5)_0.88Ba_0.12Ti_0.96Zr_0.04O₃. The process produced an amorphous xerogel that was readily crystallized to a pseudocubic perovskite phase when calcined at temperatures as low as 500 °C. The decomposition and oxidation of the xerogel was studied using TG-DTA, which showed complete removal of volatile components by 580 °C. The formation of crystalline phases was studied using XRD. SEM was used to evaluate the sintering behavior of the powder. The powder exhibits significant sintering at temperatures 800–900 °C. The polarization behavior of the sintered material was similar to one prepared by conventional solid state route. A maximum polarization of ∼24 μC/cm² and peak bipolar strain ∼0.095% at 44 kV/cm was achieved in the sintered material.