Properties of (Bi0.5Na0.5)TiO3-BaTiO3-(Bi0.5Na0.5)(Mn1/3Nb2/3)O3 Lead-Free Piezoelectric Ceramics and Its Application to Ultrasonic Cleaner

The lead-free piezoelectric ceramics 0.82(Bi0.5Na0.5)TiO3-0.15BaTiO(3)-0.03(Bi0.5Na0.5)(Mn1/3Nb2/3)O-3 (abbreviated as BNT-BT-BNMN) was prepared by a conventional process of ceramic engineering. The X-ray diffractometer (XRD) analysis showed that all compositions could form a single perovskite phase. The ceramics showed excellent piezoelectric properties with a coupling factor k(t) = 41%, a mechanical quality factor Q(m) = 500, a piezoelectric constant d(33) = 110 pC/N, a relative permittivity epsilon(T)(33)/epsilon 0 = 520, a dissipation factor tan delta = 0.66%, a Curie point T-c = 260 degrees C, and a density rho = 5.5 g/cm(3). The physical properties of the ceramics were superior to those of hard Pb(Zr,Ti)O-3 (PZT). The high-power characteristics of the ceramics were superior to those of hard PZT. A cylinder sample of lead-free ceramics was used to fabricate a bolt-clamped Langevin transducer (BLT) for application in the ultrasonic cleaner. The vibration velocity of BLT using the ceramics was higher than that of hard PZT under the same input power. The cleaning effect of an ultrasonic cleaner using the BLTs was very high and sufficiently good for commercial application. (C) 2009 The Japan Society of Applied Physics