Low-Temperature Sintering and Piezoelectric Properties of CuO-Added 0.95(Na0.5K0.5)NbO3-0.05BaTiO3 Ceramics

The sintering temperature of 0.95(Na0.5K0.5)NbO3–0.05BaTiO3 (NKN–BT) ceramics needs to be decreased below 1000°C to prevent Na2O evaporation, which can cause difficulties in poling and may eventually degrade their piezoelectric properties. NKN–BT ceramics containing CuO were well sintered at 950°C with grain growth. Poling was easy for all specimens. Densification and grain growth were explained by the formation of a liquid phase. The addition of CuO improved the piezoelectric properties by increasing the grain size and density. High piezoelectric properties of d33=230 pC/N, kp=37%, and ɛ3T/ɛ0=1150 were obtained from the specimen containing 1.0 mol% of CuO synthesized by the conventional solid‐state method.