Low‐Temperature Sintering and Piezoelectric Properties of CuO‐Added 0.95(Na _0.5 K _0.5 )NbO ₃ –0.05BaTiO ₃ Ceramics

Abstract

The sintering temperature of 0.95(Na 0.5 K 0.5 )NbO 3 –0.05BaTiO 3 (NKN–BT) ceramics needs to be decreased below 1000°C to prevent Na 2 O 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 d 33 =230 pC/N, k p =37%, and ɛ 3 T /ɛ 0 =1150 were obtained from the specimen containing 1.0 mol% of CuO synthesized by the conventional solid‐state method.