Microstructure and electrical properties of (Li, Ag, Ta, Sb)-modified (K0.50Na0.50)NbO3 lead-free ceramics with good temperature stability

0.98[(K0.4725Na0.4725Li0.055)NbO3]–0.02Ag(Ta1−xSbx)O3 lead-free piezoelectric ceramics were prepared by the conventional mixed-oxide method. The effects of the Sb content on the microstructure and the electrical properties of the ceramics were systematically investigated. The experimental results show that Sb strongly affects the microstructure and the electrical properties of the ceramics and that the partial substitution of Sb slightly decreases the Curie temperature (Tc) and shifts the orthorhombic–tetragonal phase transition temperature (TO–T) to below room temperature. The thermal-depoling behaviour, age characteristics and temperature stability of the ceramics with x = 0.40 were also studied. The ceramics with x = 0.40 exhibit optimum properties (d33 = 250 pC N−1, kp = 44%, Tc = 444 °C, er ~ 1186, tan δ ~ 2.7%, Pr ~ 32.0 µC cm−2, Ec ~ 14.8 kV cm−1), good thermal-depoling behaviour and age characteristics and improved temperature stability. These results show that the ceramic with x = 0.40 is a promising candidate material for high-temperature lead-free piezoelectric ceramics.