Fabrication and properties of lead-free piezoelectric buzzers made from K0.5Na0.5NbO3-based ceramics

Lead-free piezoelectric buzzers based on (K_0.975Li_0.025Na_0.5)Nb_0.95Sb{0.05}O₃ (KLNNS2.5-5) ceramics were fabricated and their properties were investigated. The KLNNS2.5-5 ceramics membranes with diameter of 15-16 mm and thickness of 0.10-0.11 mm were prepared by the roll forming process. The electrical properties of the lead-free piezo-ceramic membranes are k_p=0.445, d₃₃=150 pC/N, _r=466 (at 1 kHz), and tan delta=0.033 (at 1 kHz). The resonance frequency (f_r) of the super-thin buzzer disks is about 4.68 kHz. The sound pressure level (SPL) of the KLNNS2.5-5 buzzers reaches 84.2 dB at 2 kHz, which are comparable to that of the lead-based ones. The electro-acoustic properties of the KLNNS2.5-5 buzzers can basically satisfy the requirements (ges 80 dB) of microwave ovens applications. Results show that the KLNNS2.5-5 ceramics are promising candidates for practical application in buzzers.