Influence of sintering temperature on piezoelectric properties of (K0.4425Na0.52Li0.0375)(Nb0.8925Sb0.07Ta0.0375)O3 lead-free piezoelectric ceramics

Microstructure characteristics, phase transition, and electrical properties of (K_0.4425Na_0.52Li_0.0375) (Nb_0.8925Sb_0.07Ta_0.0375)O₃ (KNLNST) lead-free piezoelectric ceramics prepared by normal sintering were investigated with an emphasis on the influence of sintering temperature. The microstructure and piezoelectric, ferroelectric, and dielectric properties were investigated, with a special emphasis on the influence of sintering temperature from 1,100 to 1,140 °C. Orthorhombic phases mainly exist in the ceramics sintered at 1,100–1,130 °C, whereas the tetragonal phase becomes dominant when sintering temperature is above 1,130 °C. Because of the existence of MPB-like transitional behavior, the piezoelectric coefficient (d ₃₃), electromechanical coupling coefficient (kp), and dielectric constant (ε) show peak values of 304pC/N, 0.48, and 1,909, respectively, which are obtained in the sample sintered at 1,120 °C, and its Curie temperature (T _C) is about 271 °C.