High-frequency ultrasonic transducer fabricated with lead-free piezoelectric single crystal

High-frequency (25 MHz) ultrasonic transducers with Na 0.5 Bi 0.5 TiO 3 -BaTiO 3 (NBT-BT) lead-free piezoelectric single crystal as the active elements are fabricated and characterized. The impedance measurement reveals that the poled [001]-oriented NBT-BT single crystal exhibits a high thickness electromechanical coefficient k t of 0.52 and a low clamped dielectric constant of 80. The -6-dB bandwidth of the transducer is 46.16% and the insertion loss at the center frequency is -31.89 dB. The good performance of the transducer indicates that the NBT-BT single crystal would be a promising lead-free material for ultrasonic transducer applications.