Optimizing the piezoelectric vibration of Pb(Mg1/3Nb2/3)O3-0.25PbTiO3 single crystal by alternating current polarization for ultrasonic transducer

Alternate current poling (ACP) is an effective method to enhance the piezoelectric performance of Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) (PMN-xPT) single crystals dramatically. For their application in piezoelectric transducers for medical imaging, the beam mode vibration of PMN-0.25PT single crystal resonators after ACP was investigated by combining experimental impedance measurements and finite element simulation. The complete material coefficients of PMN-0.25PT single crystals were obtained by using pulse-echo ultrasound and inverse impedance spectroscopy. Compared to traditional direct current poling (DCP), the beam mode electromechanical coupling coefficient (k(33)') of PMN-0.25PT for ACP reaches up to 89.1% from 84.5% of DCP. As the attribution of the special periodic stripe domain structure (109 degrees domain), the lateral vibration will be suppressed effectively in the array transducer. This indicates that AC-poled PMN-0.25PT single crystals can be an efficient strategy to obtain higher sensitivity and a larger bandwidth in ultrasonic transducers.