High-performance KNN-based piezoelectric ceramics for buzzer application

Piezoelectric ceramic materials are important components of piezoelectric buzzers, where the parameter of inverse piezoelectric coefficient ($d_{33}^{\ast }$) plays a decisive role in the performance of the buzzer. Here, we report the manufacture and performance of a lead-free ceramic-based (0.96(K_0.5Na_0.5)(Nb_0.96Sb_0.04)O₃–0.04(Bi_0.5Na_0.5)ZrO₃–1 mol% Al₂O₃, abbreviated as KNNS-BNZ-1 mol% Al₂O₃) piezoelectric buzzer and compare it with commercial (PbZr_0.5Ti_0.5O₃, abbreviated as PZT) ceramics. Briefly, KNN-based ceramics have a typical perovskite structure and piezoelectric properties of d₃₃ = 480 pC/N, k_p = 0.62 and $d_{33}^{\ast }=830$ pm/V, compared to d₃₃ = 500 pC/N, k_p = 0.6 and $d_{33}^{\ast }=918$ pm/V of the commercial PZT-4 ceramics. Our results show that the KNNS-BNZ-1 mol% Al₂O₃ ceramics have a similar sound pressure level performance over the testing frequency range to commercial PZT ceramics (which is even better in the 3–4 kHz range). These findings highlight the great application potential of KNN-based piezoelectric ceramics.