Synthesis and characterization of (Na0.85K0.15)0.5Bi0.5TiO3 ceramics by different methods

The (Na_0.85K_0.15)_0.5Bi_0.5TiO₃ (BNKT) powders were synthesized by solid-state method, sol-gel method and stearic acid method. Microstructure, piezoelectric and dielectric properties of the ceramics were investigated. Attempts had been made to understand the reaction processes by using thermo gravimetric (TG) and differential scanning calorimetry (DSC). The BNKT powders have a perovskite structure with average crystallite sizes of 168 nm, 85 nm and 79 nm, corresponding to the solid-state method, the sol-gel method and the stearic acid method, respectively. The ceramics derived from the powder synthesized by sol-gel method presents the most homogeneous microstructure and largest grain size (5-7 μm). The effects of average crystallite size on microstructures and electric properties of the BNKT ceramics were investigated. Both the piezoelectric properties and dielectric properties were enhanced with the increase of grain size.